159-694: Hepatitis C is an infectious disease caused by the hepatitis C virus (HCV) that primarily affects the liver ; it is a type of viral hepatitis . During the initial infection period, people often have mild or no symptoms. Early symptoms can include fever, dark urine, abdominal pain, and yellow tinged skin . The virus persists in the liver, becoming chronic , in about 70% of those initially infected. Early on, chronic infection typically has no symptoms. Over many years however, it often leads to liver disease and occasionally cirrhosis . In some cases, those with cirrhosis will develop serious complications such as liver failure , liver cancer , or dilated blood vessels in
318-456: A prion . The benefits of identification, however, are often greatly outweighed by the cost, as often there is no specific treatment, the cause is obvious, or the outcome of an infection is likely to be benign . The diagnosis is aided by the presenting symptoms in any individual with an infectious disease, yet it usually needs additional diagnostic techniques to confirm the suspicion. Some signs are specifically characteristic and indicative of
477-422: A runny nose . In certain cases, infectious diseases may be asymptomatic for much or even all of their course in a given host. In the latter case, the disease may only be defined as a "disease" (which by definition means an illness) in hosts who secondarily become ill after contact with an asymptomatic carrier . An infection is not synonymous with an infectious disease, as some infections do not cause illness in
636-530: A 2021 report that 58 million people globally were living with chronic hepatitis C as of 2019. About 1.5 million people are infected per year, and about 290,000 people die yearly from hepatitis C–related diseases, mainly from liver cancer and cirrhosis. Hepatitis C infection rates increased substantially in the 20th century due to a combination of intravenous drug abuse and the reuse of poorly sterilized medical equipment. However, advancements in treatment have led to notable declines in chronic infections and deaths from
795-474: A backup of blood and increases pressure. This results in portal hypertension . Effects of portal hypertension include: Some signs that may be present include changes in the nails (such as Muehrcke's lines , Terry's nails , and nail clubbing ). Additional changes may be seen in the hands ( Dupuytren's contracture ) as well as the skin/bones ( hypertrophic osteoarthropathy ). As the disease progresses, complications may develop. In some people, these may be
954-399: A build-up of fluid in different parts of the body such as the legs ( edema ) and abdomen ( ascites ). Other signs of advancing disease include itchy skin, bruising easily, dark urine , and yellowing of the skin . These features are a direct consequence of liver cells not functioning: Liver cirrhosis makes it hard for blood to flow in the portal venous system . This resistance creates
1113-425: A colonization is often only a matter of circumstance. Non-pathogenic organisms can become pathogenic given specific conditions, and even the most virulent organism requires certain circumstances to cause a compromising infection. Some colonizing bacteria, such as Corynebacteria sp. and Viridans streptococci , prevent the adhesion and colonization of pathogenic bacteria and thus have a symbiotic relationship with
1272-441: A combination of pegylated interferon alpha and ribavirin for a period of 24 or 48 weeks, depending on HCV genotype . This treatment produces cure rates of 70–80% for genotype 2 and 3, respectively, and 45–70% for genotypes 1 and 4. Adverse effects with these treatments were common, with 50–60% of those being treated experiencing flu-like symptoms and nearly a third experiencing depression or other emotional issues. Treatment during
1431-523: A day is associated with improvements in the liver enzymes ALT , AST , and GGT . Even in those with liver disease, coffee consumption can lower fibrosis and cirrhosis. Generally, liver damage from cirrhosis cannot be reversed, but treatment can stop or delay further progression and reduce complications. A healthy diet is encouraged, as cirrhosis may be an energy-consuming process. A recommended diet consists of high-protein, high-fiber diet plus supplementation with branched-chain amino acids. Close follow-up
1590-469: A disease and are called pathognomonic signs; but these are rare. Not all infections are symptomatic. In children the presence of cyanosis , rapid breathing, poor peripheral perfusion, or a petechial rash increases the risk of a serious infection by greater than 5 fold. Other important indicators include parental concern, clinical instinct, and temperature greater than 40 °C. Many diagnostic approaches depend on microbiological culture to isolate
1749-399: A disease. This amplification of nucleic acid in infected tissue offers an opportunity to detect the infectious agent by using PCR. Third, the essential tools for directing PCR, primers , are derived from the genomes of infectious agents, and with time those genomes will be known if they are not already. Thus, the technological ability to detect any infectious agent rapidly and specifically
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#17327826495491908-423: A hospital stay. Lastly, a community-acquired infection is one in which the infection is acquired from a whole community. One manner of proving that a given disease is infectious, is to satisfy Koch's postulates (first proposed by Robert Koch ), which require that first, the infectious agent be identifiable only in patients who have the disease, and not in healthy controls, and second, that patients who contract
2067-531: A host with depressed resistance ( immunodeficiency ) or if they have unusual access to the inside of the body (for example, via trauma ). Opportunistic infection may be caused by microbes ordinarily in contact with the host, such as pathogenic bacteria or fungi in the gastrointestinal or the upper respiratory tract , and they may also result from (otherwise innocuous) microbes acquired from other hosts (as in Clostridioides difficile colitis ) or from
2226-502: A host. As bacterial and viral infections can both cause the same kinds of symptoms, it can be difficult to distinguish which is the cause of a specific infection. Distinguishing the two is important, since viral infections cannot be cured by antibiotics whereas bacterial infections can. There is a general chain of events that applies to infections, sometimes called the chain of infection or transmission chain . The chain of events involves several steps – which include
2385-434: A link between virulence and transmissibility. Diagnosis of infectious disease sometimes involves identifying an infectious agent either directly or indirectly. In practice most minor infectious diseases such as warts , cutaneous abscesses , respiratory system infections and diarrheal diseases are diagnosed by their clinical presentation and treated without knowledge of the specific causative agent. Conclusions about
2544-518: A number of basic dyes due to the electrostatic attraction between negatively charged cellular molecules and the positive charge on the dye. A cell is normally transparent under a microscope, and using a stain increases the contrast of a cell with its background. Staining a cell with a dye such as Giemsa stain or crystal violet allows a microscopist to describe its size, shape, internal and external components and its associations with other cells. The response of bacteria to different staining procedures
2703-622: A number of years can cause alcoholic liver disease. Liver damage has also been attributed to heroin usage over an extended period of time as well. MASH has a number of causes, including obesity , high blood pressure , abnormal levels of cholesterol , type 2 diabetes , and metabolic syndrome . Less common causes of cirrhosis include autoimmune hepatitis , primary biliary cholangitis , and primary sclerosing cholangitis that disrupts bile duct function, genetic disorders such as Wilson's disease and hereditary hemochromatosis , and chronic heart failure with liver congestion . Diagnosis
2862-404: A particular pathogen at all (no matter how little) but also is often used in a sense implying a clinically apparent infection (in other words, a case of infectious disease). This fact occasionally creates some ambiguity or prompts some usage discussion; to get around this it is common for health professionals to speak of colonization (rather than infection ) when they mean that some of
3021-493: A pathogen from the appropriate clinical specimen. In a microbial culture, a growth medium is provided for a specific agent. A sample taken from potentially diseased tissue or fluid is then tested for the presence of an infectious agent able to grow within that medium. Many pathogenic bacteria are easily grown on nutrient agar , a form of solid medium that supplies carbohydrates and proteins necessary for growth, along with copious amounts of water. A single bacterium will grow into
3180-429: A pathogen. A fluorescence microscope is then used to detect fluorescently labeled antibodies bound to internalized antigens within clinical samples or cultured cells. This technique is especially useful in the diagnosis of viral diseases, where the light microscope is incapable of identifying a virus directly. Other microscopic procedures may also aid in identifying infectious agents. Almost all cells readily stain with
3339-432: A patient's blood or other body fluids for antigens or antibodies that indicate presence of a specific pathogen that the doctor suspects. Other techniques (such as X-rays , CAT scans , PET scans or NMR ) are used to produce images of internal abnormalities resulting from the growth of an infectious agent. The images are useful in detection of, for example, a bone abscess or a spongiform encephalopathy produced by
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#17327826495493498-470: A persistent infection by infecting different cells of the body. Some viruses once acquired never leave the body. A typical example is the herpes virus, which tends to hide in nerves and become reactivated when specific circumstances arise. Persistent infections cause millions of deaths globally each year. Chronic infections by parasites account for a high morbidity and mortality in many underdeveloped countries. For infecting organisms to survive and repeat
3657-709: A result of chronic liver disease . Damage to the liver leads to repair of liver tissue and subsequent formation of scar tissue. Over time, scar tissue and nodules of regenerating hepatocytes can replace the parenchyma, causing increased resistance to blood flow in the liver's capillaries —the hepatic sinusoids —and consequently portal hypertension , as well as impairment in other aspects of liver function. The disease typically develops slowly over months or years. Stages of cirrhosis include compensated cirrhosis and decompensated cirrhosis. Early symptoms may include tiredness , weakness , loss of appetite , unexplained weight loss , nausea and vomiting, and discomfort in
3816-403: A result of an infectious disease with immunosuppressive activity (such as with measles , malaria or HIV disease ). Primary pathogens may also cause more severe disease in a host with depressed resistance than would normally occur in an immunosufficient host. While a primary infection can practically be viewed as the root cause of an individual's current health problem, a secondary infection
3975-471: A result of their presence or activity within the normal, healthy host, and their intrinsic virulence (the severity of the disease they cause) is, in part, a necessary consequence of their need to reproduce and spread. Many of the most common primary pathogens of humans only infect humans, however, many serious diseases are caused by organisms acquired from the environment or that infect non-human hosts. Opportunistic pathogens can cause an infectious disease in
4134-589: A risk factor. A fomite ( / ˈ f oʊ m aɪ t / ) or fomes ( / ˈ f oʊ m iː z / ) is any inanimate object that, when contaminated with or exposed to infectious agents (such as pathogenic bacteria , viruses or fungi ), can transfer disease to a new host . Personal-care items such as razors, toothbrushes, and manicuring or pedicuring equipment can be contaminated with blood. Sharing such items can potentially lead to exposure to HCV. Appropriate caution should be taken regarding any medical condition that results in bleeding , such as cuts and sores. HCV
4293-411: A severe illness affecting the brain, remain undiagnosed, despite extensive testing using the standard of care ( microbiological culture ) and state-of-the-art clinical laboratory methods. Metagenomic sequencing-based diagnostic tests are currently being developed for clinical use and show promise as a sensitive, specific, and rapid way to diagnose infection using a single all-encompassing test. This test
4452-418: A sign of elevated right atrial pressure . Portal vein pulsatility are usually measured by a pulsatility indices (PI). A number above a certain values indicates cirrhosis (see table below). Other scans include CT of the abdomen and MRI . A CT scan is non-invasive and may be helpful in the diagnosis. Compared to the ultrasound, CT scans tend to be more expensive. MRI provides excellent evaluation; however,
4611-402: A single partner. There are a number of diagnostic tests for hepatitis C , including HCV antibody enzyme immunoassay (ELISA), recombinant immunoblot assay , and quantitative HCV RNA polymerase chain reaction (PCR). HCV RNA can be detected by PCR typically one to two weeks after infection, while antibodies can take substantially longer to form and thus be detected. Diagnosing patients
4770-417: A specific identification of an infectious agent only when such identification can aid in the treatment or prevention of the disease, or to advance knowledge of the course of an illness prior to the development of effective therapeutic or preventative measures. For example, in the early 1980s, prior to the appearance of AZT for the treatment of AIDS , the course of the disease was closely followed by monitoring
4929-432: A visible mound on the surface of the plate called a colony , which may be separated from other colonies or melded together into a "lawn". The size, color, shape and form of a colony is characteristic of the bacterial species, its specific genetic makeup (its strain ), and the environment that supports its growth. Other ingredients are often added to the plate to aid in identification. Plates may contain substances that permit
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5088-430: A vital role in many metabolic processes in the body including protein synthesis, detoxification, nutrient storage (such as glycogen ), platelet production and clearance of bilirubin . With progressive liver damage; hepatocyte death and replacement of functional liver tissue with fibrosis in cirrhosis, these processes are disrupted. This leads to many of the metabolic derangements and symptoms seen in cirrhosis. Cirrhosis
5247-411: Is a liver biopsy . This is usually carried out as a fine-needle approach , through the skin ( percutaneous ), or internal jugular vein (transjugular). Endoscopic ultrasound-guided liver biopsy (EUS), using the percutaneous or transjugular route, has become a good alternative to use. EUS can target liver areas that are widely separated, and can deliver bi-lobar biopsies. A biopsy is not necessary if
5406-509: Is a sequela or complication of that root cause. For example, an infection due to a burn or penetrating trauma (the root cause) is a secondary infection. Primary pathogens often cause primary infection and often cause secondary infection. Usually, opportunistic infections are viewed as secondary infections (because immunodeficiency or injury was the predisposing factor). Other types of infection consist of mixed, iatrogenic , nosocomial , and community-acquired infection. A mixed infection
5565-526: Is a biomarker for fibrosis that may be used instead of a biopsy. Other laboratory studies performed in newly diagnosed cirrhosis may include: Markers of inflammation and immune cell activation are typically elevated in cirrhotic patients, especially in the decompensated disease stage: A recent study identified 15 microbial biomarkers from the gut microbiota . These could potentially be used to discriminate patients with liver cirrhosis from healthy individuals. The gold standard for diagnosis of cirrhosis
5724-629: Is a high expense. Portable ultrasound is a low cost tool to identify the sign of liver surface nodularity with a good diagnostic accuracy. Cirrhosis is also diagnosable through a variety of new elastography techniques. When a liver becomes cirrhotic it will generally become stiffer. Determining the stiffness through imaging can determine the location and severity of disease. Techniques include transient elastography , acoustic radiation force impulse imaging , supersonic shear imaging and magnetic resonance elastography . Transient elastography and magnetic resonance elastography can help identify
5883-507: Is active but does not produce noticeable symptoms may be called inapparent, silent, subclinical , or occult . An infection that is inactive or dormant is called a latent infection . An example of a latent bacterial infection is latent tuberculosis . Some viral infections can also be latent, examples of latent viral infections are any of those from the Herpesviridae family. The word infection can denote any presence of
6042-774: Is also associated with autoimmune disorders such as Sjögren's syndrome , lichen planus , a low platelet count , porphyria cutanea tarda , necrolytic acral erythema , insulin resistance , diabetes mellitus , diabetic nephropathy , autoimmune thyroiditis , and B-cell lymphoproliferative disorders . 20–30% of people infected have rheumatoid factor – a type of antibody. Possible associations include Hyde's prurigo nodularis and membranoproliferative glomerulonephritis . Cardiomyopathy with associated abnormal heart rhythms has also been reported. A variety of central and peripheral nervous system disorders has been reported. Chronic infection seems to be associated with an increased risk of pancreatic cancer . People may experience other issues in
6201-464: Is also included in the scoring. The classification system includes class A, B, or C. Class A has a favorable prognosis while class C is at high risk of death. The Child-Pugh score is a validated predictor of mortality after a major surgery. For example, Child class A patients have a 10% mortality rate and Child class B patients have a 30% mortality rate while Child class C patients have a 70–80% mortality rate after abdominal surgery. Elective surgery
6360-480: Is also recommended for those with elevated liver enzymes, as this is frequently the only sign of chronic hepatitis. As of 2012, the U.S. Centers for Disease Control and Prevention (CDC) recommends a single screening test for those born between 1945 and 1965. In Canada, a one-time screening is recommended for those born between 1945 and 1975. As of 2022, no approved vaccine protects against contracting hepatitis C . A combination of harm reduction strategies, such as
6519-423: Is an infection that is caused by two or more pathogens. An example of this is appendicitis , which is caused by Bacteroides fragilis and Escherichia coli . The second is an iatrogenic infection. This type of infection is one that is transmitted from a health care worker to a patient. A nosocomial infection is also one that occurs in a health care setting. Nosocomial infections are those that are acquired during
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6678-422: Is an initial site of infection from which organisms travel via the bloodstream to another area of the body. Among the many varieties of microorganisms , relatively few cause disease in otherwise healthy individuals. Infectious disease results from the interplay between those few pathogens and the defenses of the hosts they infect. The appearance and severity of disease resulting from any pathogen depend upon
6837-434: Is associated with TGF β pathway that enhances contractile properties of HSCs leading to fibrosis. Furthermore, HSCs secrete TIMP1 and TIMP2 , naturally occurring inhibitors of matrix metalloproteinases (MMPs), which prevent MMPs from breaking down the fibrotic material in the extracellular matrix . As this cascade of processes continues, fibrous tissue bands (septa) separate hepatocyte nodules, which eventually replace
6996-411: Is associated with two to threefold increased risk of hepatitis C . This could be due to either improperly sterilized equipment or contamination of the dyes being used. Tattoos or piercings performed either before the mid-1980s, "underground", or nonprofessionally are of particular concern, since sterile techniques in such settings may be lacking. The risk also appears to be greater for larger tattoos. It
7155-493: Is based on blood tests , medical imaging , and liver biopsy . Hepatitis B vaccine can prevent hepatitis B and the development of cirrhosis from it, but no vaccination against hepatitis C is available. No specific treatment for cirrhosis is known, but many of the underlying causes may be treated by a number of medications that may slow or prevent worsening of the condition. Hepatitis B and C may be treatable with antiviral medications . Avoiding alcohol
7314-560: Is believed that ten million intravenous drug users are infected with hepatitis C ; China (1.6 million), the United States (1.5 million), and Russia (1.3 million) have the highest absolute totals. Occurrence of hepatitis C among prison inmates in the United States is 10 to 20 times that of the occurrence observed in the general population; this has been attributed to high-risk behavior in prisons such as IDU and tattooing with non-sterile equipment. Shared intranasal drug use may also be
7473-564: Is commonly classified with the Child–Pugh score (also known as the Child–Pugh–Turcotte score) . This system was devised in 1964 by Child and Turcotte, and modified in 1973 by Pugh and others. It was first established to determine who would benefit from elective surgery for portal decompression. This scoring system uses multiple lab values including bilirubin , albumin , and INR. The presence of ascites and severity of encephalopathy
7632-510: Is currently available. The only remaining blockades to the use of PCR as a standard tool of diagnosis are in its cost and application, neither of which is insurmountable. The diagnosis of a few diseases will not benefit from the development of PCR methods, such as some of the clostridial diseases ( tetanus and botulism ). These diseases are fundamentally biological poisonings by relatively small numbers of infectious bacteria that produce extremely potent neurotoxins . A significant proliferation of
7791-472: Is defined as the presence of detectable viral replication for at least six months. Though most experience minimal or no symptoms during the initial few decades of a chronic infection, chronic hepatitis C can be associated with fatigue and mild cognitive problems. After several years, chronic infection may cause cirrhosis or liver cancer . The liver enzymes measured from blood samples are normal in 7–53%. (Elevated levels indicate liver cells are being damaged by
7950-544: Is estimated that nearly half of prison inmates share unsterilized tattooing equipment. It is rare for tattoos in a licensed facility to be directly associated with HCV infection. Injection drug use (IDU) is a major risk factor for hepatitis C in many parts of the world. Of 77 countries reviewed, 25 (including the United States) were found to have a prevalence of hepatitis C of 60–80% among people who use injection drugs. Twelve countries had rates greater than 80%. It
8109-416: Is exceedingly rare. Symptoms and laboratory findings suggestive of liver disease should prompt further tests and can thus help establish a diagnosis of hepatitis C infection early on. Following the acute phase, the infection may resolve spontaneously in 10–50% of affected people; this occurs more frequently in young people and females. About 70% of those exposed to the virus develop a chronic infection. This
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#17327826495498268-445: Is generally a challenge as patients with acute illness generally present with mild, non-specific flu-like symptoms, while the transition from acute to chronic is sub-clinical. Chronic hepatitis C is defined as infection with the hepatitis C virus persisting for more than six months based on the presence of its RNA. Chronic infections are typically asymptomatic during the first few decades, and thus are most commonly discovered following
8427-499: Is generally considered safe at reduced doses. Nonsteroidal anti-inflammatory drugs (NSAIDs) are not recommended in those with advanced liver disease due to an increased risk of bleeding. Ultrasound surveillance for hepatocellular carcinoma is recommended in those with accompanying cirrhosis. Coffee consumption has been associated with a slower rate of liver scarring in those infected with HCV. More than 95% of chronic cases clear with treatment. Treatment with antiviral medication
8586-503: Is injured. All multicellular organisms are colonized to some degree by extrinsic organisms, and the vast majority of these exist in either a mutualistic or commensal relationship with the host. An example of the former is the anaerobic bacteria species, which colonizes the mammalian colon , and an example of the latter are the various species of staphylococcus that exist on human skin . Neither of these colonizations are considered infections. The difference between an infection and
8745-477: Is known about factors affecting cirrhosis risk and progression. However, many studies have provided increasing evidence for the protective effects of coffee consumption against the progression of liver disease. These effects are more noticeable in liver disease that is associated with alcohol use disorder. Coffee has antioxidant and antifibrotic effects. Caffeine may not be the important component; polyphenols may be more important. Drinking two or more cups of coffee
8904-535: Is more common in those also infected with hepatitis B , schistosoma , or HIV, in alcoholics , and in those of male sex. In those with hepatitis C, excess alcohol increases the risk of developing cirrhosis 5-fold. Those who develop cirrhosis have a 20-fold greater risk of hepatocellular carcinoma . This transformation occurs at a rate of 1–3% per year. Being infected with hepatitis B in addition to hepatitis C increases this risk further. Liver cirrhosis may lead to portal hypertension , ascites (accumulation of fluid in
9063-466: Is no vaccine against hepatitis C. Prevention includes harm reduction efforts among people who inject drugs, testing donated blood, and treatment of people with chronic infection. Chronic infection can be cured more than 95% of the time with antiviral medications such as sofosbuvir or simeprevir . Peginterferon and ribavirin were earlier generation treatments that proved successful in <50% of cases and caused greater side effects. While access to
9222-467: Is not an enzyme and has no metabolic function. Serological methods are highly sensitive, specific and often extremely rapid tests used to identify microorganisms. These tests are based upon the ability of an antibody to bind specifically to an antigen. The antigen, usually a protein or carbohydrate made by an infectious agent, is bound by the antibody. This binding then sets off a chain of events that can be visibly obvious in various ways, dependent upon
9381-418: Is not clear when transmission occurs during pregnancy, but it may occur both during gestation and at delivery. A long labor is associated with a greater risk of transmission. There is no evidence that breastfeeding spreads HCV; however, to be cautious, an infected mother is advised to avoid breastfeeding if her nipples are cracked and bleeding, or if her viral loads are high. Sexual transmission of hepatitis C
9540-475: Is not spread through breast milk, food, water or casual contact such as hugging, kissing and sharing food or drinks with an infected person. It is one of five known hepatitis viruses: A , B , C, D , and E . Diagnosis is by blood testing to look for either antibodies to the virus or viral RNA . In the United States , screening for HCV infection is recommended in all adults age 18 to 79 years old. There
9699-408: Is not spread through casual contact, such as hugging, kissing, or sharing eating or cooking utensils, nor is it transmitted through food or water. Blood transfusion , transfusion of blood products, or organ transplants without HCV screening carry significant risks of infection. The United States instituted universal screening in 1992, and Canada instituted universal screening in 1990. This decreased
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#17327826495499858-417: Is often necessary. Antibiotics are prescribed for infections, and various medications can help with itching. Laxatives, such as lactulose , decrease the risk of constipation. Carvedilol increases survival benefit for people with cirrhosis and portal hypertension . Diuretics in combination with low salt diet reduce fluid in body which helps reduce oedema. Alcoholic cirrhosis caused by alcohol use disorder
10017-455: Is often preceded by hepatitis and fatty liver (steatosis), independent of the cause. If the cause is removed at this stage, the changes are fully reversible. The pathological hallmark of cirrhosis is the development of scar tissue that replaces normal tissue, which is normally organized into lobules . This scar tissue blocks the portal flow of blood through the organ, raising the blood pressure. This manifests as portal hypertension in which
10176-416: Is positive, a confirmatory test is then performed to verify the immunoassay and to determine the viral load . A recombinant immunoblot assay is used to verify the immunoassay and the viral load is determined by an HCV RNA polymerase chain reaction. If there is no RNA and the immunoblot is positive, it means that the person tested had a previous infection but cleared it either with treatment or spontaneously; if
10335-425: Is recommended due to the high risk of hepatocellular carcinoma arising from dysplastic nodules. Cirrhosis affected about 2.8 million people and resulted in 1.3 million deaths in 2015. Of these deaths, alcohol caused 348,000 (27%), hepatitis C caused 326,000 (25%), and hepatitis B caused 371,000 (28%). In the United States, more men die of cirrhosis than women. The first known description of
10494-434: Is recommended for all people with proven chronic hepatitis C who are not at high risk of death from other causes. People with the highest complication risk, which is based on the degree of liver scarring, should be treated first. The initial recommended treatment depends on the type of hepatitis C virus, if the person has received previous hepatitis C treatment, and whether the person has cirrhosis. Direct-acting antivirals are
10653-500: Is recommended in all cases. Autoimmune hepatitis may be treated with steroid medications . Ursodiol may be useful if the disease is due to blockage of the bile duct. Other medications may be useful for complications such as abdominal or leg swelling, hepatic encephalopathy , and dilated esophageal veins . If cirrhosis leads to liver failure , a liver transplant may be an option. Biannual screening for liver cancer using abdominal ultrasound , possibly with additional blood tests,
10812-425: Is referred to as infectious diseases . Infections are caused by infectious agents ( pathogens ) including: The signs and symptoms of an infection depend on the type of disease. Some signs of infection affect the whole body generally, such as fatigue , loss of appetite, weight loss, fevers , night sweats, chills, aches and pains. Others are specific to individual body parts, such as skin rashes , coughing , or
10971-404: Is referred to as colonization. Most humans are not easily infected. Those with compromised or weakened immune systems have an increased susceptibility to chronic or persistent infections. Individuals who have a suppressed immune system are particularly susceptible to opportunistic infections . Entrance to the host at host–pathogen interface , generally occurs through the mucosa in orifices like
11130-501: Is similar to current PCR tests; however, an untargeted whole genome amplification is used rather than primers for a specific infectious agent. This amplification step is followed by next-generation sequencing or third-generation sequencing , alignment comparisons , and taxonomic classification using large databases of thousands of pathogen and commensal reference genomes . Simultaneously, antimicrobial resistance genes within pathogen and plasmid genomes are sequenced and aligned to
11289-439: Is that microbial colonization is very common even in environments that humans think of as being nearly sterile . Because it is normal to have bacterial colonization, it is difficult to know which chronic wounds can be classified as infected and how much risk of progression exists. Despite the huge number of wounds seen in clinical practice, there are limited quality data for evaluated symptoms and signs. A review of chronic wounds in
11448-870: Is the invasion of tissues by pathogens , their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease , also known as a transmissible disease or communicable disease , is an illness resulting from an infection. Infections can be caused by a wide range of pathogens , most prominently bacteria and viruses . Hosts can fight infections using their immune systems . Mammalian hosts react to infections with an innate response, often involving inflammation , followed by an adaptive response. Specific medications used to treat infections include antibiotics , antivirals , antifungals , antiprotozoals , and antihelminthics . Infectious diseases resulted in 9.2 million deaths in 2013 (about 17% of all deaths). The branch of medicine that focuses on infections
11607-416: Is treated by abstaining from alcohol. Treatment for hepatitis-related cirrhosis involves medications used to treat the different types of hepatitis, such as interferon for viral hepatitis and corticosteroids for autoimmune hepatitis. Cirrhosis caused by Wilson's disease is treated by removing the copper which builds up in organs. This is carried out using chelation therapy such as penicillamine . When
11766-610: Is uncommon. Studies examining the risk of HCV transmission between heterosexual partners, when one is infected and the other is not, have found very low risks. Sexual practices that involve higher levels of trauma to the anogenital mucosa, such as anal penetrative sex , or that occur when there is a concurrent sexually transmitted infection , including HIV or genital ulceration , present greater risks. The United States Department of Veterans Affairs recommends condom use to prevent hepatitis C transmission in those with multiple partners, but not those in relationships that involve only
11925-419: Is under investigation. The consequences of occult infection appear to be less severe than with chronic infection but can vary from minimal to hepatocellular carcinoma. The rate of occult infection in those apparently cured is controversial but appears to be low. 40% of those with hepatitis but with both negative hepatitis C serology and the absence of detectable viral genome in the serum have hepatitis C virus in
12084-588: Is used in the taxonomic classification of microbes as well. Two methods, the Gram stain and the acid-fast stain, are the standard approaches used to classify bacteria and to diagnosis of disease. The Gram stain identifies the bacterial groups Bacillota and Actinomycetota , both of which contain many significant human pathogens. The acid-fast staining procedure identifies the Actinomycetota genera Mycobacterium and Nocardia . Biochemical tests used in
12243-647: Is usually reserved for those in Child class A patients. There is an increased risk for Child class B individuals and they may require medical optimization. Overall, it is not recommended for Child class C patients to undergo elective surgery. In the past, the Child-Pugh classification was used to determine people who were candidates for a liver transplant. Child-Pugh class B is usually an indication for evaluation for transplant. However, there were many issues when applying this score to liver transplant eligibility. Thus,
12402-605: The Journal of the American Medical Association 's "Rational Clinical Examination Series" quantified the importance of increased pain as an indicator of infection. The review showed that the most useful finding is an increase in the level of pain [likelihood ratio (LR) range, 11–20] makes infection much more likely, but the absence of pain (negative likelihood ratio range, 0.64–0.88) does not rule out infection (summary LR 0.64–0.88). Disease can arise if
12561-404: The fissures and enlargement of the spleen . An enlarged spleen , which normally measures less than 11–12 cm (4.3–4.7 in) in adults, may suggest underlying portal hypertension . Ultrasound may also screen for hepatocellular carcinoma and portal hypertension. This is done by assessing flow in the hepatic vein. An increased portal vein pulsatility may be seen. However, this may be
12720-433: The hepatic veins . In primary biliary cholangitis , there is fibrosis around the bile duct, the presence of granulomas and pooling of bile . Lastly in alcoholic cirrhosis, there is infiltration of the liver with neutrophils . Macroscopically, the liver is initially enlarged, but with the progression of the disease, it becomes smaller. Its surface is irregular, the consistency is firm, and if associated with steatosis
12879-468: The oral cavity , nose, eyes, genitalia, anus, or the microbe can enter through open wounds. While a few organisms can grow at the initial site of entry, many migrate and cause systemic infection in different organs. Some pathogens grow within the host cells (intracellular) whereas others grow freely in bodily fluids. Wound colonization refers to non-replicating microorganisms within the wound, while in infected wounds, replicating organisms exist and tissue
13038-447: The polymerase chain reaction (PCR) method will become nearly ubiquitous gold standards of diagnostics of the near future, for several reasons. First, the catalog of infectious agents has grown to the point that virtually all of the significant infectious agents of the human population have been identified. Second, an infectious agent must grow within the human body to cause disease; essentially it must amplify its own nucleic acids to cause
13197-538: The provision of new needles and syringes and treatment of substance use , decreases the risk of hepatitis C in people using injection drugs by about 75%. The screening of blood donors is important at a national level, as is adhering to universal precautions within healthcare facilities. In countries where there is an insufficient supply of sterile syringes , medications should be given orally rather than via injection (when possible). Recent research also suggests that treating people with active infection, thereby reducing
13356-456: The renin-angiotensin system (RAAS) which causes kidneys to reabsorb sodium and water, causing water retention and further ascites. Activation of the RAAS also causes kidney vasoconstriction and may cause kidney injury. Research has shown the pivotal role of the stellate cell , that normally stores vitamin A , in the development of cirrhosis. Damage to the liver tissue from inflammation leads to
13515-431: The right upper quadrant of the abdomen. As the disease worsens, symptoms may include itchiness , swelling in the lower legs , fluid build-up in the abdomen , jaundice , bruising easily , and the development of spider-like blood vessels in the skin . The fluid build-up in the abdomen may develop into spontaneous infections . More serious complications include hepatic encephalopathy , bleeding from dilated veins in
13674-403: The "strep test", they can be inexpensive. Complex serological techniques have been developed into what are known as immunoassays . Immunoassays can use the basic antibody – antigen binding as the basis to produce an electro-magnetic or particle radiation signal, which can be detected by some form of instrumentation. Signal of unknowns can be compared to that of standards allowing quantitation of
13833-630: The MELD score was created. The Model for End-Stage Liver Disease (MELD) score was later developed and approved in 2002. It was approved by the United Network for Organ Sharing (UNOS) as a way to determine the allocation of liver transplants to awaiting people in the United States. It is also used as a validated survival predictor of cirrhosis, alcoholic hepatitis, acute liver failure, and acute hepatitis. The variables included bilirubin, INR , creatinine , and dialysis frequency. In 2016, sodium
13992-546: The United States and Canada are aware of their status. Routine screening for those between the ages of 18 and 79 was recommended by the United States Preventive Services Task Force in 2020. Previously, testing was recommended for those at high risk, including injection drug users, those who have received blood transfusions before 1992, those who have been incarcerated, those on long-term hemodialysis , and those with tattoos. Screening
14151-485: The abdomen), easy bruising or bleeding , varices (enlarged veins, especially in the stomach and esophagus), jaundice , and a syndrome of cognitive impairment known as hepatic encephalopathy . Ascites occurs at some stage in more than half of those who have a chronic infection. The most common problem due to hepatitis C but not involving the liver is mixed cryoglobulinemia (usually the type II form) – an inflammation of small and medium-sized blood vessels . Hepatitis C
14310-435: The ability of that pathogen to damage the host as well as the ability of the host to resist the pathogen. However, a host's immune system can also cause damage to the host itself in an attempt to control the infection. Clinicians, therefore, classify infectious microorganisms or microbes according to the status of host defenses – either as primary pathogens or as opportunistic pathogens . Primary pathogens cause disease as
14469-487: The activation of stellate cells, which increases fibrosis through the production of myofibroblasts , and obstructs hepatic blood flow. In addition, stellate cells secrete TGF beta 1 , which leads to a fibrotic response and proliferation of connective tissue . TGF-β1 have been implicated in the process of activating hepatic stellate cells (HSCs) with the magnitude of fibrosis being in proportion to increase in TGF β levels. ACTA2
14628-458: The basis of a biochemical diagnosis of an infectious disease. For example, humans can make neither RNA replicases nor reverse transcriptase , and the presence of these enzymes are characteristic., of specific types of viral infections. The ability of the viral protein hemagglutinin to bind red blood cells together into a detectable matrix may also be characterized as a biochemical test for viral infection, although strictly speaking hemagglutinin
14787-497: The bile ducts, such as primary sclerosing cholangitis , causes of cirrhosis. Imaging of the bile ducts, such as ERCP or MRCP (MRI of biliary tract and pancreas) may aid in the diagnosis. The best predictors of cirrhosis are ascites, platelet count < 160,000/mm , spider angiomata, and a Bonacini cirrhosis discriminant score greater than 7 (as the sum of scores for platelet count, ALT/AST ratio and INR as per table). These findings are typical in cirrhosis: FibroTest
14946-463: The case of viral identification, a region of dead cells results from viral growth, and is called a "plaque". Eukaryotic parasites may also be grown in culture as a means of identifying a particular agent. In the absence of suitable plate culture techniques, some microbes require culture within live animals. Bacteria such as Mycobacterium leprae and Treponema pallidum can be grown in animals, although serological and microscopic techniques make
15105-476: The causative agent, Trypanosoma cruzi in a patient, which therefore makes it difficult to definitively make a diagnosis. In this case, xenodiagnosis involves the use of the vector of the Chagas agent T. cruzi , an uninfected triatomine bug, which takes a blood meal from a person suspected of having been infected. The bug is later inspected for growth of T. cruzi within its gut. Another principal tool in
15264-426: The cause is an iron overload , iron is removed using a chelation agent such as deferoxamine or by bloodletting . As of 2021, there are recent studies studying drugs to prevent cirrhosis caused by non-alcoholic fatty liver disease (NAFLD or NASH). The drug semaglutide was shown to provide greater NASH resolution versus placebo . No improvement in fibrosis was observed. A combination of cilofexor/ firsocostat
15423-436: The cause of the disease are based upon the likelihood that a patient came in contact with a particular agent, the presence of a microbe in a community, and other epidemiological considerations. Given sufficient effort, all known infectious agents can be specifically identified. Diagnosis of infectious disease is nearly always initiated by medical history and physical examination. More detailed identification techniques involve
15582-420: The clinical, laboratory, and radiologic data suggest cirrhosis. Furthermore, a small but significant risk of complications is associated with liver biopsy, and cirrhosis itself predisposes for complications caused by liver biopsy. Once the biopsy is obtained, a pathologist will study the sample. Cirrhosis is defined by its features on microscopy : (1) the presence of regenerating nodules of hepatocytes and (2)
15741-431: The color is yellow. Depending on the size of the nodules, there are three macroscopic types: micronodular, macronodular, and mixed cirrhosis. In the micronodular form ( Laennec's cirrhosis or portal cirrhosis), regenerating nodules are under 3 mm. In macronodular cirrhosis (post-necrotic cirrhosis), the nodules are larger than 3 mm. Mixed cirrhosis consists of nodules of different sizes. The severity of cirrhosis
15900-431: The composition of patient blood samples, even though the outcome would not offer the patient any further treatment options. In part, these studies on the appearance of HIV in specific communities permitted the advancement of hypotheses as to the route of transmission of the virus. By understanding how the disease was transmitted, resources could be targeted to the communities at greatest risk in campaigns aimed at reducing
16059-463: The condition is by Hippocrates in the fifth century BCE. The term "cirrhosis" was derived in 1819 from the Greek word "kirrhos", which describes the yellowish color of a diseased liver. Cirrhosis can take quite a long time to develop, and symptoms may be slow to emerge. Some early symptoms include tiredness, weakness, loss of appetite, weight loss, and nausea. Early signs may also include redness on
16218-484: The culture of infectious agents isolated from a patient. Culture allows identification of infectious organisms by examining their microscopic features, by detecting the presence of substances produced by pathogens, and by directly identifying an organism by its genotype. Many infectious organisms are identified without culture and microscopy. This is especially true for viruses, which cannot grow in culture. For some suspected pathogens, doctors may conduct tests that examine
16377-405: The degree of liver damage present; however, there are risks from the procedure. The typical changes seen are lymphocytes within the parenchyma, lymphoid follicles in portal triad , and changes to the bile ducts. There are a number of blood tests available that try to determine the degree of hepatic fibrosis and alleviate the need for biopsy. It is believed that only 5–50% of those infected in
16536-400: The destruction of the virus. Instrumentation can be used to read extremely small signals created by secondary reactions linked to the antibody – antigen binding. Instrumentation can control sampling, reagent use, reaction times, signal detection, calculation of results, and data management to yield a cost-effective automated process for diagnosis of infectious disease. Technologies based upon
16695-428: The diagnosis of infectious disease is microscopy . Virtually all of the culture techniques discussed above rely, at some point, on microscopic examination for definitive identification of the infectious agent. Microscopy may be carried out with simple instruments, such as the compound light microscope , or with instruments as complex as an electron microscope . Samples obtained from patients may be viewed directly under
16854-444: The entire liver architecture, leading to decreased blood flow throughout. The spleen becomes congested, and enlarged , resulting in its retention of platelets , which are needed for normal blood clotting. Portal hypertension is responsible for the most severe complications of cirrhosis. The diagnosis of cirrhosis in an individual is based on multiple factors. Cirrhosis may be suspected from laboratory findings, physical exam , and
17013-445: The environment as a result of traumatic introduction (as in surgical wound infections or compound fractures ). An opportunistic disease requires impairment of host defenses, which may occur as a result of genetic defects (such as chronic granulomatous disease ), exposure to antimicrobial drugs or immunosuppressive chemicals (as might occur following poisoning or cancer chemotherapy ), exposure to ionizing radiation , or as
17172-452: The esophagus and stomach . HCV is spread primarily by blood-to-blood contact associated with injection drug use , poorly sterilized medical equipment, needlestick injuries in healthcare, and transfusions . In regions where blood screening has been implemented, the risk of contracting HCV from a transfusion has dropped substantially to less than one per two million. HCV may also be spread from an infected mother to her baby during birth. It
17331-477: The esophagus , stomach , or intestines , and liver cancer . Cirrhosis is most commonly caused by medical conditions including alcohol-related liver disease , metabolic dysfunction–associated steatohepatitis (MASH – the progressive form of metabolic dysfunction–associated steatotic liver disease , previously called non-alcoholic fatty liver disease or NAFLD ), heroin abuse, chronic hepatitis B , and chronic hepatitis C . Heavy drinking over
17490-426: The expression of symptoms is often atypical, making a clinical diagnosis based on presentation more difficult. Thirdly, diagnostic methods that rely on the detection of antibodies are more likely to fail. A rapid, sensitive, specific, and untargeted test for all known human pathogens that detects the presence of the organism's DNA rather than antibodies is therefore highly desirable. There is usually an indication for
17649-404: The first signs of the disease. Cirrhosis has many possible causes, and more than one cause may be present. History taking is of importance in trying to determine the most likely cause. Globally, 57% of cirrhosis is attributable to either hepatitis B (30%) or hepatitis C (27%). Alcohol use disorder is another major cause, accounting for about 20–40% of the cases. The liver plays
17808-401: The first six months of infection (the acute stage) is more effective than when hepatitis C has entered the chronic stage. In those with chronic hepatitis B, treatment for hepatitis C results in reactivation of hepatitis B about 25% of the time. Cirrhosis due to hepatitis C is a common reason for liver transplantation , though the virus usually (80–90% of cases) recurs afterwards. Infection of
17967-476: The genotype. In the United States, about 70% of cases are caused by genotype 1, 20% by genotype 2 and about 1% by each of the other genotypes. Genotype 1 is also the most common in South America and Europe. The half life of the virus particles in the serum is around 3 hours and may be as short as 45 minutes. In an infected person, about 10 virus particles are produced each day. In addition to replicating in
18126-621: The graft leads to 10–30% of people developing cirrhosis within five years. Treatment with pegylated interferon and ribavirin post-transplant decreases the risk of recurrence to 70%. A 2013 review found no clear evidence as to whether antiviral medication is useful if the graft became reinfected. Several alternative therapies are claimed by their proponents to be helpful for hepatitis C , including milk thistle , ginseng , and colloidal silver . However, no alternative therapy has been shown to improve outcomes for hepatitis C patients, and no evidence exists that alternative therapies have any effect on
18285-403: The growth of some bacteria and not others, or that change color in response to certain bacteria and not others. Bacteriological plates such as these are commonly used in the clinical identification of infectious bacterium. Microbial culture may also be used in the identification of viruses : the medium, in this case, being cells grown in culture that the virus can infect, and then alter or kill. In
18444-484: The host's protective immune mechanisms are compromised and the organism inflicts damage on the host. Microorganisms can cause tissue damage by releasing a variety of toxins or destructive enzymes. For example, Clostridium tetani releases a toxin that paralyzes muscles, and staphylococcus releases toxins that produce shock and sepsis . Not all infectious agents cause disease in all hosts. For example, less than 5% of individuals infected with polio develop disease. On
18603-598: The host, preventing infection and speeding wound healing . The variables involved in the outcome of a host becoming inoculated by a pathogen and the ultimate outcome include: As an example, several staphylococcal species remain harmless on the skin, but, when present in a normally sterile space, such as in the capsule of a joint or the peritoneum , multiply without resistance and cause harm. An interesting fact that gas chromatography–mass spectrometry , 16S ribosomal RNA analysis, omics , and other advanced technologies have made more apparent to humans in recent decades
18762-532: The identification of infectious agents include the detection of metabolic or enzymatic products characteristic of a particular infectious agent. Since bacteria ferment carbohydrates in patterns characteristic of their genus and species , the detection of fermentation products is commonly used in bacterial identification. Acids , alcohols and gases are usually detected in these tests when bacteria are grown in selective liquid or solid media. The isolation of enzymes from infected tissue can also provide
18921-513: The immunoblot is negative, it means that the immunoassay was wrong. It takes about 6–8 weeks following infection before the immunoassay will test positive. A number of tests are available as point-of-care testing (POCT), which can provide results within 30 minutes. Liver enzymes are variable during the initial part of the infection and on average begin to rise at seven weeks after infection. The elevation of liver enzymes does not closely follow disease severity. Liver biopsies are used to determine
19080-658: The implementation and enforcement of stringent standard precautions in public and private medical and dental facilities are known to have been the primary cause of the spread of HCV in Egypt , the country that had the highest rate of infection in the world in 2012, and currently Egypt becomes the first country to achieve WHO validation on the path to elimination of hepatitis C. For more, see HONOReform (Hepatitis Outbreaks National Organization for Reform) . Mother-to-child transmission of hepatitis C occurs in fewer than 10% of pregnancies. There are no measures that alter this risk. It
19239-413: The infection cycle in other hosts, they (or their progeny) must leave an existing reservoir and cause infection elsewhere. Infection transmission can take place via many potential routes: The relationship between virulence versus transmissibility is complex; with studies have shown that there were no clear relationship between the two. There is still a small number of evidence that partially suggests
19398-427: The infectious agent also develop the disease. These postulates were first used in the discovery that Mycobacteria species cause tuberculosis . Cirrhosis Cirrhosis , also known as liver cirrhosis or hepatic cirrhosis , and end-stage liver disease , is a condition of the liver in which the normal functioning tissue, or parenchyma , is replaced with scar tissue ( fibrosis ) and regenerative nodules as
19557-399: The infectious agent does not occur, this limits the ability of PCR to detect the presence of any bacteria. Given the wide range of bacterial, viral, fungal, protozoal, and helminthic pathogens that cause debilitating and life-threatening illnesses, the ability to quickly identify the cause of infection is important yet often challenging. For example, more than half of cases of encephalitis ,
19716-402: The infectious agent, reservoir, entering a susceptible host, exit and transmission to new hosts. Each of the links must be present in a chronological order for an infection to develop. Understanding these steps helps health care workers target the infection and prevent it from occurring in the first place. Infection begins when an organism successfully enters the body, grows and multiplies. This
19875-472: The investigation of elevated liver enzyme levels or during a routine screening of high-risk individuals. Testing is not able to distinguish between acute and chronic infections. Diagnosis in infants is difficult as maternal antibodies may persist for up to 18 months. Hepatitis C testing typically begins with blood testing to detect the presence of antibodies to the HCV, using an enzyme immunoassay. If this test
20034-425: The light microscope, and can often rapidly lead to identification. Microscopy is often also used in conjunction with biochemical staining techniques, and can be made exquisitely specific when used in combination with antibody based techniques. For example, the use of antibodies made artificially fluorescent (fluorescently labeled antibodies) can be directed to bind to and identify a specific antigens present on
20193-417: The liver on biopsy. How commonly this occurs in children is unknown. The hepatitis C virus (HCV) is a small, enveloped, single-stranded, positive-sense RNA virus . It is a member of the genus Hepacivirus in the family Flaviviridae . There are seven major genotypes of HCV, which are known as genotypes one to seven. The genotypes are divided into several subtypes with the number of subtypes depending on
20352-586: The liver the virus can multiply in lymphocytes. Percutaneous contact with contaminated blood is responsible for most infections; however, the method of transmission is strongly dependent on both geographic region and economic status. Indeed, the primary route of transmission in the developed world is injection drug use , while in the developing world the main methods are blood transfusions and unsafe medical procedures. The cause of transmission remains unknown in 20% of cases; however, many of these are believed to be accounted for by injection drug use. Tattooing
20511-474: The liver) also determines the severity of cirrhosis, although it is hard to measure. A value of 16 mm or more means a greatly increased risk of death. Key prevention strategies for cirrhosis are population-wide interventions to reduce alcohol intake (through pricing strategies, public health campaigns, and personal counseling), programs to reduce the transmission of viral hepatitis, and screening of relatives of people with hereditary liver diseases. Little
20670-401: The liver, and portal hypertension . As cirrhosis can be caused by many different entities which injure the liver in different ways, cause-specific abnormalities may be seen. For example, in chronic hepatitis B , there is infiltration of the liver parenchyma with lymphocytes . In congestive hepatopathy there are erythrocytes and a greater amount of fibrosis in the tissue surrounding
20829-433: The mouth such as dryness , salivary duct stones , and crusted lesions around the mouth. Persons who have been infected with hepatitis C may appear to clear the virus but remain infected. The virus is not detectable with conventional testing but can be found with ultra-sensitive tests. The original method of detection was by demonstrating the viral genome within liver biopsies, but newer methods include an antibody test for
20988-529: The newer treatments was expensive, by 2022 prices had dropped dramatically in many countries (primarily low-income and lower-middle-income countries) due to the introduction of generic versions of medicines. Those who develop cirrhosis or liver cancer may require a liver transplant . Hepatitis C is one of the leading reasons for liver transplantation, though the virus usually recurs after transplantation. An estimated 58 million people worldwide were infected with hepatitis C in 2019. Approximately 290,000 deaths from
21147-531: The number of new infections. The specific serological diagnostic identification, and later genotypic or molecular identification, of HIV also enabled the development of hypotheses as to the temporal and geographical origins of the virus, as well as a myriad of other hypothesis. The development of molecular diagnostic tools have enabled physicians and researchers to monitor the efficacy of treatment with anti-retroviral drugs . Molecular diagnostics are now commonly used to identify HIV in healthy people long before
21306-455: The onset of illness and have been used to demonstrate the existence of people who are genetically resistant to HIV infection. Thus, while there still is no cure for AIDS, there is great therapeutic and predictive benefit to identifying the virus and monitoring the virus levels within the blood of infected individuals, both for the patient and for the community at large. Symptomatic infections are apparent and clinical , whereas an infection that
21465-514: The other hand, some infectious agents are highly virulent. The prion causing mad cow disease and Creutzfeldt–Jakob disease invariably kills all animals and people that are infected. Persistent infections occur because the body is unable to clear the organism after the initial infection. Persistent infections are characterized by the continual presence of the infectious organism, often as latent infection with occasional recurrent relapses of active infection. There are some viruses that can maintain
21624-415: The palms known as palmar erythema. People may also feel discomfort in the right upper abdomen around the liver. As cirrhosis progresses, symptoms can include neurological changes. This can consist of cognitive impairments, confusion, memory loss , sleep disorders , and personality changes. Steatorrhea or presence of undigested fats in stool is also a symptom of cirrhosis. Worsening cirrhosis can cause
21783-539: The pathogens are present but that no clinically apparent infection (no disease) is present. Different terms are used to describe how and where infections present over time. In an acute infection, symptoms develop rapidly; its course can either be rapid or protracted. In chronic infection, symptoms usually develop gradually over weeks or months and are slow to resolve. In subacute infections, symptoms take longer to develop than in acute infections but arise more quickly than those of chronic infections. A focal infection
21942-473: The person's medical history . Imaging is generally obtained to evaluate the liver. A liver biopsy will confirm the diagnosis; however, is generally not required. Ultrasound is routinely used in the evaluation of cirrhosis. It may show a small and shrunken liver in advanced disease. On ultrasound, there is increased echogenicity with irregular appearing areas. Other suggestive findings are an enlarged caudate lobe , liver surface nodularity widening of
22101-409: The potential for transmission, may be an effective preventive measure. Hepatitis C vaccine phase 1 clinical trials are set to begin in the summer of 2023. Those with chronic hepatitis C are advised to avoid alcohol and medications that are toxic to the liver . They should also be vaccinated against hepatitis A and hepatitis B due to the increased risk if also infected. Use of acetaminophen
22260-488: The preferred treatment and have been validated by testing for virus particles in patients' blood. More than 95% of people with chronic infection can be cured when treated with medications; this could be expensive, but by 2022 prices had dropped dramatically. The combination of sofosbuvir, velpatasvir, and voxilaprevir may be used in those who have previously been treated with sofosbuvir or other drugs that inhibit NS5A and were not cured. Prior to 2011, treatments consisted of
22419-498: The presence of fibrosis , or the deposition of connective tissue between these nodules. The pattern of fibrosis seen can depend on the underlying insult that led to cirrhosis. Fibrosis can also proliferate even if the underlying process that caused it has resolved or ceased. The fibrosis in cirrhosis can lead to destruction of other normal tissues in the liver: including the sinusoids , the space of Disse , and other vascular structures, which leads to altered resistance to blood flow in
22578-409: The pressure gradient between the portal circulation as compared to the systemic circulation is elevated. This portal hypertension leads to decreased sinusoidal flow from liver cells to nearby sinusoids in the liver, and increased lymph production with extravasation of lymph to the extracellular space, causing ascites. This also causes reduced cardiac return and central blood volume, which activates
22737-412: The risk from one in 200 units to between one in 10,000 to one in 10,000,000 per unit of blood. This low risk remains as there is a period of about 11–70 days between the potential blood donor 's acquiring hepatitis C and the blood's testing positive depending on the method. Some countries do not screen for hepatitis C due to the cost. Those who have experienced a needle stick injury from someone who
22896-502: The risk of cirrhosis after 20 years varies between studies but has been estimated at ~10–15% for men and ~1–5% for women. The reason for this difference is not known. Once cirrhosis is established, the rate of developing hepatocellular carcinoma is ~1–4% per year. Rates of new infections have decreased in the Western world since the 1990s due to improved screening of blood before transfusion. Infectious disease An infection
23055-435: The stage of fibrosis. Compared to a biopsy , elastography can sample a much larger area and is painless. It shows a reasonable correlation with the severity of cirrhosis. Other modalities have been introduced which are incorporated into ultrasonagraphy systems. These include 2-dimensional shear wave elastography and point shear wave elastography which uses acoustic radiation force impulse imaging. Rarely are diseases of
23214-457: The target antigen. To aid in the diagnosis of infectious diseases, immunoassays can detect or measure antigens from either infectious agents or proteins generated by an infected organism in response to a foreign agent. For example, immunoassay A may detect the presence of a surface protein from a virus particle. Immunoassay B on the other hand may detect or measure antibodies produced by an organism's immune system that are made to neutralize and allow
23373-559: The taxonomically classified pathogen genomes to generate an antimicrobial resistance profile – analogous to antibiotic sensitivity testing – to facilitate antimicrobial stewardship and allow for the optimization of treatment using the most effective drugs for a patient's infection. Metagenomic sequencing could prove especially useful for diagnosis when the patient is immunocompromised . An ever-wider array of infectious agents can cause serious harm to individuals with immunosuppression, so clinical screening must often be broader. Additionally,
23532-503: The test. For example, " Strep throat " is often diagnosed within minutes, and is based on the appearance of antigens made by the causative agent, S. pyogenes , that is retrieved from a patient's throat with a cotton swab. Serological tests, if available, are usually the preferred route of identification, however the tests are costly to develop and the reagents used in the test often require refrigeration . Some serological methods are extremely costly, although when commonly used, such as with
23691-411: The use of live animals unnecessary. Viruses are also usually identified using alternatives to growth in culture or animals. Some viruses may be grown in embryonated eggs. Another useful identification method is Xenodiagnosis, or the use of a vector to support the growth of an infectious agent. Chagas disease is the most significant example, because it is difficult to directly demonstrate the presence of
23850-512: The virus or other disease). Late relapses after apparent cure have been reported, but these can be difficult to distinguish from reinfection. Fatty changes to the liver occur in about half of those infected and are usually present before cirrhosis develops. Usually (80% of the time) this change affects less than a third of the liver. Worldwide hepatitis C is the cause of 27% of cirrhosis cases and 25% of hepatocellular carcinoma. About 10–30% of those infected develop cirrhosis over 30 years. Cirrhosis
24009-409: The virus within six months, before the infection is considered chronic. Spontaneous resolution following acute infection appears more common in females and in patients who are younger, and may be influenced by certain genetic factors. Chronic HCV infection may also resolve spontaneously months or years after the acute phase has passed, though this is unusual. The World Health Organization estimated in
24168-815: The virus' core protein and the detection of the viral genome after first concentrating the viral particles by ultracentrifugation . A form of infection with persistently moderately elevated serum liver enzymes but without antibodies to hepatitis C has also been reported. This form is known as cryptogenic occult infection. Several clinical pictures have been associated with this type of infection. It may be found in people with anti-hepatitis-C antibodies but with normal serum levels of liver enzymes; in antibody-negative people with ongoing elevated liver enzymes of unknown cause; in healthy populations without evidence of liver disease; and in groups at risk for HCV infection including those on hemodialysis or family members of people with occult HCV. The clinical relevance of this form of infection
24327-801: The virus, mainly from liver cancer and cirrhosis attributed to hepatitis C, also occurred in 2019. The existence of hepatitis C – originally identifiable only as a type of non- A non- B hepatitis – was suggested in the 1970s and proven in 1989. Hepatitis C infects only humans and chimpanzees . Acute symptoms develop in some 20% of those infected. When this occurs, it is generally 4–12 weeks following infection (but it may take from 2 weeks to 6 months for acute symptoms to appear). Symptoms are generally mild and vague, and may include fatigue, nausea and vomiting, fever, muscle or joint pains , abdominal pain, decreased appetite and weight loss, jaundice (occurs in ~25% of those infected), dark urine, and clay-coloured stools. Acute liver failure due to acute hepatitis C
24486-571: The virus. The responses to treatment is measured by sustained viral response (SVR), defined as the absence of detectable RNA of the hepatitis C virus in blood serum for at least 24 weeks after discontinuing treatment, and rapid virological response (RVR), defined as undetectable levels achieved within four weeks of treatment. Successful treatment decreases the future risk of hepatocellular carcinoma by 75%. Prior to 2012, sustained response occurred in about 40–50% of those with HCV genotype 1 who received 48 weeks of treatment. A sustained response
24645-992: The virus. As a result, the number of chronic patients receiving treatment worldwide has grown from about 950,000 in 2015 to 9.4 million in 2019. During the same period, hepatitis C deaths declined from about 400,000 to 290,000. Previously, a 2013 study found high infection rates (>3.5% population infected) in Central and East Asia, North Africa and the Middle East, intermediate infection rates (1.5–3.5%) in South and Southeast Asia, sub-Saharan Africa, Andean, Central and Southern Latin America, Caribbean, Oceania, Australasia and Central, Eastern and Western Europe; and low infection rates (<1.5%) in Asia-Pacific, Tropical Latin America and North America. Among those chronically infected,
24804-568: Was HCV positive have about a 1.8% chance of subsequently contracting the disease themselves. The risk is greater if the needle in question is hollow and the puncture wound is deep. There is a risk from mucosal exposures to blood, but this risk is low, and there is no risk if blood exposure occurs on intact skin. Hospital equipment has also been documented as a method of transmission of hepatitis C , including reuse of needles and syringes, multiple-use medication vials, infusion bags, and improperly sterilized surgical equipment, among others. Limitations in
24963-697: Was added to the variables and the score is often referred to as MELD-Na. MELD-Plus is a further risk score to assess severity of chronic liver disease. It was developed in 2017 as a result of a collaboration between Massachusetts General Hospital and IBM . Nine variables were identified as effective predictors for 90-day mortality after a discharge from a cirrhosis-related hospital admission. The variables include all Model for End-Stage Liver Disease (MELD)'s components, as well as sodium, albumin, total cholesterol, white blood cell count, age, and length of stay. The hepatic venous pressure gradient (difference in venous pressure between incoming and outgoing blood to
25122-564: Was seen in 70–80% of people with HCV genotypes 2 and 3 following 24 weeks of treatment. A sustained response occurs for about 65% of those with genotype 4 after 48 weeks of treatment. For those with HCV genotype 6, a 48-week treatment protocol of pegylated interferon and ribavirin results in a higher rate of sustained responses than for genotype 1 (86% vs. 52%). Further studies are needed to determine results for shorter 24-week treatments and for those given at lower dosages. Around 30% (15–45%) of those with acute HCV infections will spontaneously clear
25281-528: Was studied in people with bridging fibrosis and cirrhosis. It was observed to have led to improvements in NASH activity with a potential antifibrotic effect. Lanifibranor is also shown to prevent worsening fibrosis. Regardless of the underlying cause of cirrhosis, consumption of alcohol and other potentially damaging substances is discouraged. There is no evidence that supports the avoidance or dose reduction of paracetamol in people with compensated cirrhosis; it
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