114-612: Ebola , also known as Ebola virus disease ( EVD ) and Ebola hemorrhagic fever ( EHF ), is a viral hemorrhagic fever in humans and other primates , caused by ebolaviruses . Symptoms typically start anywhere between two days and three weeks after infection. The first symptoms are usually fever , sore throat , muscle pain , and headaches . These are usually followed by vomiting , diarrhoea , rash and decreased liver and kidney function, at which point some people begin to bleed both internally and externally. It kills between 25% and 90% of those infected – about 50% on average. Death
228-408: A coma near the end of life. Those who survive often have ongoing muscular and joint pain, liver inflammation , and decreased hearing, and may have continued tiredness, continued weakness, decreased appetite, and difficulty returning to pre-illness weight. Problems with vision may develop. It is recommended that survivors of EVD wear condoms for at least twelve months after initial infection or until
342-424: A septic state . EBOV is thought to infect humans through contact with mucous membranes or skin breaks. After infection, endothelial cells (cells lining the inside of blood vessels), liver cells, and several types of immune cells such as macrophages, monocytes , and dendritic cells are the main targets of attack. Following infection, immune cells carry the virus to nearby lymph nodes where further reproduction of
456-654: A PHEIC at this stage", a notion that is not part of the PHEIC criteria laid down in the IHR. After confirmed cases of Ebola in neighbouring Uganda in June 2019, Tedros Adhanom , the director-general of the WHO, announced that the third meeting of a group of experts would be held on 14 June 2019 to assess whether the Ebola spread had become a PHEIC. The conclusion was that while the outbreak
570-710: A PHEIC would be an inappropriate way to raise money for the epidemic. Following a visit to the DRC in July 2019, Rory Stewart , the UK's DfID minister, called for the WHO to declare it an emergency. Acknowledging a high risk of spread to the capital of North Kivu, Goma , a call for a PHEIC declaration was published on 10 July 2019 in The Washington Post by Daniel Lucey and Ron Klain (the former United States Ebola response coordinator ). Their declaration stated that "in
684-441: A PHEIC, as the outbreak was considered over. On 30 January 2020, the WHO declared the outbreak of COVID-19 , centered on Wuhan in central China , a PHEIC. On 5 May 2023, the WHO ended the PHEIC declaration for COVID-19. On the date of the declaration, there were 7,818 cases confirmed globally, affecting 19 countries in five of the six WHO regions. Previously, the WHO had held EC meetings on 22 and 23 January 2020 regarding
798-505: A PHEIC, it had occurred in only three countries. Therefore, it was argued that the declaration of the H1N1 outbreak as a PHEIC, was fueling public fear. A 2013 study sponsored by the WHO estimated that, although similar in magnitude to seasonal influenza, it cost more life-years than seasonal flu, due to a shift toward mortality among persons less than 65 years of age. The second PHEIC was the 2014 polio declaration , issued on 5 May 2014 with
912-672: A PHEIC, the WHO Director-General is required to take into account factors that include the risk to human health and international spread as well as advice from an international committee of experts, the IHR Emergency Committee (EC), one of whom should be an expert nominated by the State within whose region the event arises. Rather than being a standing committee, the EC is created on an ad hoc basis. Until 2011,
1026-545: A PHEIC, with six in favor and nine against. On 23 July 2022, the WHO director-general declared the outbreak a PHEIC. On 11 May 2023, the WHO ended the PHEIC declaration for Mpox, six days after doing so for COVID-19. On the date of the declaration, there were 17,186 cases reported globally, affecting 75 countries in all six WHO regions, with five deaths reported outside Africa and 72 deaths in African countries. The WHO had previously held an EC meeting on 23 June 2022 regarding
1140-741: A PHEIC. As of November 2021, taking into account recent events in Afghanistan, a large number of unvaccinated children, increasing mobile people in Pakistan and the risks associated with the COVID-19 pandemic among others, polio remains a PHEIC. Confirmed cases of Ebola were being reported in Guinea in December 2013 and Liberia in March 2014 and Sierra Leone by May 2014. On 8 August 2014, following
1254-452: A case of Ebola was confirmed in Goma, which has an international airport and a highly mobile population. Subsequently, the WHO announced a reconvening of a fourth EC meeting on 17 July 2019, when they officially announced it "a regional emergency, and by no means a global threat" and declared it as a PHEIC, without restrictions on trade or travel. In response to the declaration, the president of
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#17327662995511368-414: A decrease in the platelet count, an increase in the blood serum liver enzymes , and reduced blood clotting ability measured as an increase in both the prothrombin (PT) and activated partial thromboplastin times (PTT). The hematocrit may be elevated. The serum urea and creatine may be raised but this is dependent on the hydration status of the patient. The bleeding time tends to be prolonged. With
1482-485: A diverse group of animal and human illnesses . VHFs may be caused by five distinct families of RNA viruses : the families Filoviridae , Flaviviridae , Rhabdoviridae , and several member families of the Bunyavirales order such as Arenaviridae , and Hantaviridae . All types of VHF are characterized by fever and bleeding disorders and all can progress to high fever, shock and death in many cases. Some of
1596-422: A few hours in a dried state, and can survive for a few days within body fluids outside of a person. The Ebola virus may be able to persist for more than three months in the semen after recovery, which could lead to infections via sexual intercourse . Virus persistence in semen for over a year has been recorded in a national screening programme. Ebola may also occur in the breast milk of women after recovery, and it
1710-594: A global emergency. As of 17 August 2024, over 15,600 cases and 537 deaths have been reported in the current outbreak, with approximately 96% of cases occurring in the Democratic Republic of the Congo (DRC). 12 other African countries, some for the first time, have also reported cases. In 2018, an examination of the first four declarations (2009–2016) showed that the WHO was noted to be more effective in responding to international health emergencies, and that
1824-537: A list of diseases that are always notifiable . SARS , smallpox , wild type poliomyelitis , and any new subtype of human influenza are always a PHEIC and do not require an IHR decision to declare them as such. Large scale health emergencies that attract public attention do not necessarily fulfill the criteria to be a PHEIC. ECs were not convened for the cholera outbreak in Haiti , chemical weapons use in Syria , or
1938-468: A majority of people with filoviral hemorrhagic fevers (e.g., Ebola and Marburg virus ), Crimean–Congo hemorrhagic fever (CCHF), and the South American hemorrhagic fevers caused by arenaviruses , but only in a small minority of patients with dengue or Rift Valley fever . Five families of RNA viruses have been recognised as being able to cause hemorrhagic fevers. The pathogen that caused
2052-405: A minimum, a fit-tested , HEPA filter-equipped respirator (such as an N95 mask ), a battery-powered, air-purifying respirator, or a positive pressure supplied air respirator to be worn by personnel coming within 1.8 meter (six feet) of a VHF patient. Groups of patients should be cohorted (sequestered) to a separate building or a ward with an isolated air-handling system. Environmental decontamination
2166-419: A priority of Doctors Without Borders . Ebolaviruses can be eliminated with heat (heating for 30 to 60 minutes at 60 °C or boiling for five minutes). To disinfect surfaces, some lipid solvents such as some alcohol-based products, detergents, sodium hypochlorite (bleach) or calcium hypochlorite (bleaching powder), and other suitable disinfectants may be used at appropriate concentrations. Education of
2280-399: A proper protective barrier between the dead body and the living. Social anthropologists may help find alternatives to traditional rules for burials. Transportation crews are instructed to follow a certain isolation procedure, should anyone exhibit symptoms resembling EVD. As of August 2014, the WHO does not consider travel bans to be useful in decreasing spread of the disease. In October 2014,
2394-560: A rapid antigen test which gives results in 15 minutes was approved for use by WHO. It is able to confirm Ebola in 92% of those affected and rule it out in 85% of those not affected. Early symptoms of EVD may be similar to those of other diseases common in Africa, including malaria and dengue fever . The symptoms are also similar to those of other viral haemorrhagic fevers such as Marburg virus disease , Crimean–Congo haemorrhagic fever , and Lassa fever . The complete differential diagnosis
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#17327662995512508-427: A reservoir. Traces of EBOV were detected in the carcasses of gorillas and chimpanzees during outbreaks in 2001 and 2003, which later became the source of human infections. However, the high rates of death in these species resulting from EBOV infection make it unlikely that these species represent a natural reservoir for the virus. Deforestation has been mentioned as a possible contributor to recent outbreaks, including
2622-437: A rise in cases of wild polio and circulating vaccine-derived poliovirus. The status achieved, as global eradication, was deemed to be at risk by air travel and border crossing overland, with small numbers of cases in Afghanistan, Pakistan, and Nigeria. In October 2019, continuing cases of wild polio in Pakistan and Afghanistan, in addition to new vaccine-derived cases in Africa and Asia, was reviewed and polio continued to be
2736-413: A second infection are better able to infect the macrophages, thus reducing the immune system's ability to fight off infection. Definitive diagnosis is usually made at a reference laboratory with advanced biocontainment capabilities. The findings of laboratory investigation vary somewhat between the viruses but in general, there is a decrease in the total white cell count (particularly the lymphocytes ),
2850-414: A secreted glycoprotein , small soluble glycoprotein (sGP or GP) is synthesised. EBOV replication overwhelms protein synthesis of infected cells and the host immune defences. The GP forms a trimeric complex , which tethers the virus to the endothelial cells. The sGP forms a dimeric protein that interferes with the signalling of neutrophils , another type of white blood cell. This enables the virus to evade
2964-466: A situation that is "serious, sudden, unusual, or unexpected", which may necessitate immediate international action. It can be seen as an "alarm system", a "call to action" and "last resort" measure. WHO Member States have 24 hours within which to report potential PHEIC events to the WHO. It does not have to be a member state that reports a potential outbreak, hence reports to the WHO may also be received informally, by non-governmental sources. Under
3078-531: A sudden influenza -like stage characterised by fatigue , fever , weakness , decreased appetite , muscular pain , joint pain , headache, and sore throat. The fever is usually higher than 38.3 °C (101 °F). This is often followed by nausea, vomiting, diarrhoea , abdominal pain, and sometimes hiccups . The combination of severe vomiting and diarrhoea often leads to severe dehydration . Next, shortness of breath and chest pain may occur, along with swelling , headaches , and confusion . In about half of
3192-489: Is a formal declaration by the World Health Organization (WHO) of "an extraordinary event which is determined to constitute a public health risk to other States through the international spread of disease and to potentially require a coordinated international response", formulated when a situation arises that is "serious, sudden, unusual, or unexpected", which "carries implications for public health beyond
3306-441: Is confirmed by isolating the virus, detecting its RNA or proteins, or detecting antibodies against the virus in a person's blood. Isolating the virus by cell culture , detecting the viral RNA by polymerase chain reaction (PCR) and detecting proteins by enzyme-linked immunosorbent assay (ELISA) are methods best used in the early stages of the disease and also for detecting the virus in human remains. Detecting antibodies against
3420-614: Is confirmed by testing blood samples for the presence of viral RNA , viral antibodies or the virus itself. Control of outbreaks requires coordinated medical services and community engagement, including rapid detection, contact tracing of those exposed, quick access to laboratory services, care for those infected, and proper disposal of the dead through cremation or burial. Prevention measures involve wearing proper protective clothing and washing hands when in close proximity to patients and while handling potentially infected bushmeat , as well as thoroughly cooking bushmeat. An Ebola vaccine
3534-701: Is considered evidence that these bats are a reservoir species of EBOV. In a 2002–2003 survey of 1,030 animals including 679 bats from Gabon and the Republic of the Congo , immunoglobulin G (IgG) immune defense molecules indicative of Ebola infection were found in three bat species; at various periods of study, between 2.2 and 22.6% of bats were found to contain both RNA sequences and IgG molecules indicating Ebola infection. Antibodies against Zaire and Reston viruses have been found in fruit bats in Bangladesh , suggesting that these bats are also potential hosts of
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3648-758: Is extensive and requires consideration of many other infectious diseases such as typhoid fever , shigellosis , rickettsial diseases , cholera , sepsis , borreliosis , EHEC enteritis , leptospirosis , scrub typhus , plague , Q fever , candidiasis , histoplasmosis , trypanosomiasis , visceral leishmaniasis , measles , and viral hepatitis among others. Non-infectious diseases that may result in symptoms similar to those of EVD include acute promyelocytic leukaemia , haemolytic uraemic syndrome , snake envenomation , clotting factor deficiencies/platelet disorders, thrombotic thrombocytopenic purpura , hereditary haemorrhagic telangiectasia , Kawasaki disease , and warfarin poisoning. An Ebola vaccine , rVSV-ZEBOV ,
3762-408: Is important for the infected and infection control People who care for those infected with Ebola should wear protective clothing including masks, gloves, gowns and goggles. The U.S. Centers for Disease Control (CDC) recommend that the protective gear leaves no skin exposed. These measures are also recommended for those who may handle objects contaminated by an infected person's body fluids. In 2014,
3876-410: Is not known when it is safe to breastfeed again. The virus was also found in the eye of one patient , in 2014, two months after it was cleared from his blood. Otherwise, people who have recovered are not infectious. The potential for widespread infections in countries with medical systems capable of observing correct medical isolation procedures is considered low. Usually when someone has symptoms of
3990-534: Is not known. Plants, arthropods , rodents , and birds have also been considered possible viral reservoirs. Bats were known to roost in the cotton factory in which the first cases of the 1976 and 1979 outbreaks were observed, and they have also been implicated in Marburg virus infections in 1975 and 1980. Of 24 plant and 19 vertebrate species experimentally inoculated with EBOV, only bats became infected. The bats displayed no clinical signs of disease, which
4104-415: Is not only confined to infectious diseases, and may cover an emergency caused by exposure to a chemical agent or radioactive material. It can be seen as an "alarm system", a "call to action", and "last resort" measure. Multiple surveillance and response systems exist worldwide for the early detection and effective response to contain the spread of disease. Time delays occur for two main reasons. The first
4218-641: Is often due to shock from fluid loss , and typically occurs between six and 16 days after the first symptoms appear. Early treatment of symptoms increases the survival rate considerably compared to late start. An Ebola vaccine was approved by the US FDA in December 2019. The virus spreads through direct contact with body fluids , such as blood from infected humans or other animals, or from contact with items that have recently been contaminated with infected body fluids. There have been no documented cases, either in nature or under laboratory conditions, of spread through
4332-545: Is particularly common in parts of Africa where the disease mostly occurs and health systems function poorly. There has been transmission in hospitals in some African countries that reuse hypodermic needles. Some health-care centres caring for people with the disease do not have running water. In the United States the spread to two medical workers treating infected patients prompted criticism of inadequate training and procedures. Human-to-human transmission of EBOV through
4446-637: Is prevention of antigen specific immune response. The third mechanism is apoptosis of lymphocytes. The fourth mechanism is when infected macrophages interact with toxic cytokines , leading to diapedesis and coagulation deficiency. From the vascular perspective, the virus will infect vascular endothelial cells, leading to the reorganization of the VE-cadherin catenin complex (a protein important in cell adhesion). This reorganization creates intercellular gaps in endothelial cells. The gaps lead to increased endothelial permeability and allow blood to escape from
4560-444: Is the delay between the first case and the confirmation of the outbreak by the healthcare system, allayed by good surveillance via data collection, evaluation, and organisation. The second is when there is a delay between the detection of the outbreak and widespread recognition and declaration of it as an international concern. The declaration is promulgated by an emergency committee (EC) made up of international experts operating under
4674-536: Is the most dangerous of the known EVD-causing viruses, and is responsible for the largest number of outbreaks. The fifth and sixth viruses, Reston virus (RESTV) and Bombali virus (BOMV), are not thought to cause disease in humans, but have caused disease in other primates. All six viruses are closely related to marburgviruses . Ebolaviruses contain single-stranded, non-infectious RNA genomes . Ebolavirus genomes contain seven genes including 3'-UTR - NP - VP35 - VP40 - GP - VP30 - VP24 - L - 5'-UTR . The genomes of
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4788-442: Is the nucleoprotein, whose concentration in the host cell determines when L switches from gene transcription to genome replication. Replication of the viral genome results in full-length, positive-strand antigenomes that are, in turn, transcribed into genome copies of negative-strand virus progeny. Newly synthesised structural proteins and genomes self-assemble and accumulate near the inside of the cell membrane . Virions bud off from
4902-563: Is theoretically possible due to the presence of Ebola virus particles in saliva, which can be discharged into the air with a cough or sneeze, but observational data from previous epidemics suggests the actual risk of airborne transmission is low. A number of studies examining airborne transmission broadly concluded that transmission from pigs to primates could happen without direct contact because, unlike humans and primates, pigs with EVD get very high ebolavirus concentrations in their lungs, and not their bloodstream. Therefore, pigs with EVD can spread
5016-531: Is thought to begin with a virion attaching to specific cell-surface receptors such as C-type lectins , DC-SIGN , or integrins , which is followed by fusion of the viral envelope with cellular membranes . The virions taken up by the cell then travel to acidic endosomes and lysosomes where the viral envelope glycoprotein GP is cleaved. This processing appears to allow the virus to bind to cellular proteins enabling it to fuse with internal cellular membranes and release
5130-486: Is typically accomplished with hypochlorite (e.g. bleach) or phenolic disinfectants . Medical management of VHF patients may require intensive supportive care. Antiviral therapy with intravenous ribavirin may be useful in Bunyaviridae and Arenaviridae infections (specifically Lassa fever, RVF, CCHF, and HFRS due to Old World Hantavirus infection) and can be used only under an experimental protocol as IND approved by
5244-428: Is unclear whether they played a role in spreading the disease to people. The natural reservoir for Ebola has yet to be confirmed; however, bats are considered to be the most likely candidate. Three types of fruit bats ( Hypsignathus monstrosus , Epomops franqueti and Myonycteris torquata ) were found to possibly carry the virus without getting sick. As of 2013, whether other animals are involved in its spread
5358-715: The 2009–2010 H1N1 (or swine flu) pandemic , the ongoing 2014 polio declaration , the 2013–2016 outbreak of Ebola in Western Africa , the 2015–16 Zika virus epidemic , the 2018–2020 Kivu Ebola epidemic , the 2020–2023 declaration for the COVID-19 pandemic , and the 2022–2023 and 2024 mpox outbreaks . The recommendations are temporary and require reviews every three months. Automatically, SARS , smallpox , wild type poliomyelitis , and any new subtype of human influenza are considered as PHEICs and thus do not require an IHR decision to declare them as such. A PHEIC
5472-622: The Fukushima nuclear disaster in Japan , for example. Further assessment is required for diseases that are prone to becoming pandemics , including, but not limited to cholera , pneumonic plague , yellow fever , and viral hemorrhagic fevers. A declaration of a PHEIC may appear as an economic burden to the state facing the epidemic. Incentives to declare an epidemic are lacking and the PHEIC may be seen as placing limitations on trade in countries that already are struggling. In order to declare
5586-480: The Lancet commission on COVID-19 published a report, calling the response to the pandemic "a massive global failure on multiple levels". The WHO responded by noting "several key omissions and misinterpretations in the report, not least regarding the public health emergency of international concern (PHEIC) and the speed and scope of WHO's actions." They stated that the report "offers the best opportunity to insist that
5700-669: The U.S. Food and Drug Administration (FDA). Interferon may be effective in Argentine or Bolivian hemorrhagic fevers (also available only as IND). The VHF viruses are spread in a variety of ways. Some may be transmitted to humans through a respiratory route. The viruses are considered by military medical planners to have a potential for aerosol dissemination, weaponization, or likelihood for confusion with similar agents that might be weaponized. Public health emergency of international concern A public health emergency of international concern ( PHEIC / f eɪ k / FAYK )
5814-517: The United States and the world . On 26 April 2009, more than one month after its first emergence, the initial PHEIC was declared when the H1N1 (or swine flu) pandemic was still in phase three . Within three hours on the same day, the WHO web site received almost two million visits, necessitating a dedicated web site for the swine influenza pandemic. At the time that H1N1 had been declared
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#17327662995515928-509: The West African Ebola virus epidemic . Index cases of EVD have often been close to recently deforested lands. Like other filoviruses , EBOV replicates very efficiently in many cells , producing large amounts of virus in monocytes , macrophages , dendritic cells and other cells including liver cells , fibroblasts , and adrenal gland cells . Viral replication triggers high levels of inflammatory chemical signals and leads to
6042-616: The World Health Organization , there were 24 outbreaks of Ebola resulting in a total of 2,387 cases, and 1,590 deaths . The largest Ebola outbreak to date was an epidemic in West Africa from December 2013 to January 2016, with 28,646 cases and 11,323 deaths. On 29 March 2016, it was declared to no longer be an emergency. Other outbreaks in Africa began in the Democratic Republic of the Congo in May 2017, and 2018. In July 2019,
6156-532: The cocoliztli epidemics in Mexico of 1545 and 1576 is still unknown, and the 1545 epidemic may have been bacterial rather than viral. Different hemorrhagic fever viruses act on the body in different ways, resulting in different symptoms. In most VHFs, it is likely that several mechanisms contribute to symptoms, including liver damage, disseminated intravascular coagulation (DIC), and bone marrow dysfunction. In DIC, small blood clots form in blood vessels throughout
6270-431: The 2005 International Health Regulations (IHR), states have a legal duty to respond promptly to a PHEIC. PHEIC is defined as: an extraordinary event which is determined to constitute a public health risk to other States through the international spread of disease and to potentially require a coordinated international response. This definition designates a public health crisis of potentially global reach and implies
6384-669: The CDC began recommending that medical personnel receive training on the proper suit-up and removal of personal protective equipment (PPE); in addition, a designated person, appropriately trained in biosafety, should be watching each step of these procedures to ensure they are done correctly. In Sierra Leone, the typical training period for the use of such safety equipment lasts approximately 12 days. In 2022 in Uganda, lighter personal protection equipment has become available as well as possibilities to monitor and communicate with patients from windows in
6498-493: The CDC defined four risk levels used to determine the level of 21-day monitoring for symptoms and restrictions on public activities. In the United States, the CDC recommends that restrictions on public activity, including travel restrictions, are not required for the following defined risk levels: The CDC recommends monitoring for the symptoms of Ebola disease for those both at "low risk" and at higher risk. Viral hemorrhagic fever Viral hemorrhagic fevers ( VHFs ) are
6612-413: The DRC, together with an expert committee led by a virologist, took responsibility for directly supervising action, while in protest of the declaration health minister Oly Ilunga Kalenga resigned. A review of the PHEIC had been planned at a fifth meeting of the EC on 10 October 2019 and on 18 October 2019 it remained a PHEIC until 26 June 2020 when it was decided that the situation no longer constituted
6726-531: The IHR (2005), which was developed following the SARS outbreak of 2002–2003. Between 2009 and 2016, there were four PHEIC declarations. The fifth was the 2018–2020 Kivu Ebola epidemic , declared in July 2019 and ended in June 2020. The sixth was the COVID-19 pandemic , declared in January 2020 and ended in May 2023. The seventh was the 2022–2023 mpox outbreak , declared in July 2022 and ended in May 2023. Under
6840-436: The IHR (2005), ways to detect, evaluate, notify, and report events were ascertained by all countries in order to avoid PHEICs. The response to public health risks also was decided. The IHR decision algorithm assists WHO Member States in deciding whether a potential PHEIC exists and whether the WHO should be notified. The WHO should be notified if any two of the four following questions are affirmed: The PHEIC criteria include
6954-494: The International Health Regulations as well as a new legally binding agreement (most likely a treaty) on pandemic prevention, preparedness, and response. Proposals include the possibility of issuing intermediate public health alerts (short of PHEICs) and determining public health emergencies of regional concern. Notably, although COVID-19 is routinely referred to as a pandemic, this word is not used in
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#17327662995517068-424: The International Health Regulations." With the emergency phase of the pandemic being regarded as having ended, more subtle and robust institutional responses and protocols are in the works for further iterations of this pandemic as well as global pandemics of whatever etiology . At the second IHR meeting for the 2022–2023 mpox outbreak on 21 July 2022, members of the emergency committee were divided about issuing
7182-456: The US it was ~18%, possibly due to improved prevention of disseminated intravascular coagulation . Recovery may begin between seven and 14 days after first symptoms. Death, if it occurs, follows typically six to sixteen days from first symptoms and is often due to shock from fluid loss . In general, bleeding often indicates a worse outcome, and blood loss may result in death. People are often in
7296-553: The VHF agents cause relatively mild illnesses, such as the Scandinavian nephropathia epidemica (a hantavirus ), while others, such as Ebola virus , can cause severe, life-threatening disease. Signs and symptoms of VHFs include (by definition) fever and bleeding: The severity of symptoms varies with the type of virus. The "VHF syndrome" (capillary leak, bleeding diathesis , and circulatory compromise leading to shock) appears in
7410-523: The WHO declared its fourth PHEIC in response to clusters of microcephaly and Guillain–Barré syndrome in the Americas , which at the time were suspected to be associated with the ongoing 2015–16 Zika virus epidemic . Later research and evidence bore out these concerns; in April, the WHO stated that "there is scientific consensus that Zika virus is a cause of microcephaly and Guillain–Barré syndrome." This
7524-554: The World Health Organization declared the Congo Ebola outbreak a world health emergency . The length of time between exposure to the virus and the development of symptoms ( incubation period ) is between 2 and 21 days, and usually between 4 and 10 days. However, recent estimates based on mathematical models predict that around 5% of cases may take longer than 21 days to develop. Symptoms usually begin with
7638-480: The absence of a trajectory toward extinguishing the outbreak, the opposite path—severe escalation—remains possible. The risk of the disease moving into nearby Goma, Congo—a city of 1 million residents with an international airport—or crossing into the massive refugee camps in South Sudan is mounting. With a limited number of vaccine doses remaining, either would be a catastrophe". Four days later, on 14 July 2019,
7752-415: The affected state's national border" and "may require immediate international action". Under the 2005 International Health Regulations (IHR), states have a legal duty to respond promptly to a PHEIC. The declaration is publicized by an IHR Emergency Committee (EC) of international experts, which was developed following the 2002–2004 SARS outbreak . Since 2005, there have been eight PHEIC declarations:
7866-487: The air between humans or other primates . After recovering from Ebola, semen or breast milk may continue to carry the virus for anywhere between several weeks to several months. Fruit bats are believed to be the normal carrier in nature ; they are able to spread the virus without being affected by it. The symptoms of Ebola may resemble those of several other diseases, including malaria , cholera , typhoid fever , meningitis and other viral hemorrhagic fevers. Diagnosis
7980-456: The air has not been reported to occur during EVD outbreaks, and airborne transmission has only been demonstrated in very strict laboratory conditions, and then only from pigs to primates , but not from primates to primates. Spread of EBOV by water, or food other than bushmeat, has not been observed. No spread by mosquitos or other insects has been reported. Other possible methods of transmission are being studied. Airborne transmission among humans
8094-485: The body, removing platelets necessary for clotting from the bloodstream and reducing clotting ability. DIC is thought to cause bleeding in Rift Valley, Marburg, and Ebola fevers. For filoviral hemorrhagic fevers, there are four general mechanisms of pathogenesis. The first mechanism is dissemination of virus due to suppressed responses by macrophages and dendritic cell (antigen presenting cells). The second mechanism
8208-517: The cases, the skin may develop a maculopapular rash , a flat red area covered with small bumps, five to seven days after symptoms begin. In some cases, internal and external bleeding may occur. This typically begins five to seven days after the first symptoms. All infected people show some decreased blood clotting . Bleeding from mucous membranes or from sites of needle punctures has been reported in 40–50% of cases. This may cause vomiting blood , coughing up of blood , or blood in stool . Bleeding into
8322-417: The cell, gaining their envelopes from the cellular membrane from which they bud. The mature progeny particles then infect other cells to repeat the cycle. The genetics of the Ebola virus are difficult to study because of EBOV's virulent characteristics. It is believed that between people, Ebola disease spreads only by direct contact with the blood or other body fluids of a person who has developed symptoms of
8436-469: The cells' ability to produce and respond to interferon proteins such as interferon-alpha , interferon-beta , and interferon gamma . The VP24 and VP35 structural proteins of EBOV play a key role in this interference. When a cell is infected with EBOV, receptors located in the cell's cytosol (such as RIG-I and MDA5 ) or outside of the cytosol (such as Toll-like receptor 3 (TLR3) , TLR7 , TLR8 and TLR9 ) recognise infectious molecules associated with
8550-499: The disease through droplets in the air or on the ground when they sneeze or cough. By contrast, humans and other primates accumulate the virus throughout their body and specifically in their blood, but not very much in their lungs. It is believed that this is the reason researchers have observed pig to primate transmission without physical contact, but no evidence has been found of primates being infected without actual contact, even in experiments where infected and uninfected primates shared
8664-795: The disease, they are unable to travel without assistance. Dead bodies remain infectious; thus, people handling human remains in practices such as traditional burial rituals or more modern processes such as embalming are at risk. Of the cases of Ebola infections in Guinea during the 2014 outbreak, 69% are believed to have been contracted via unprotected (or unsuitably protected) contact with infected corpses during certain Guinean burial rituals. Health-care workers treating people with Ebola are at greatest risk of infection. The risk increases when they do not have appropriate protective clothing such as masks, gowns, gloves and eye protection; do not wear it properly; or handle contaminated clothing incorrectly. This risk
8778-401: The disease. Body fluids that may contain Ebola viruses include saliva, mucus, vomit, feces, sweat, tears, breast milk, urine and semen . The WHO states that only people who are very sick are able to spread Ebola disease in saliva , and the virus has not been reported to be transmitted through sweat. Most people spread the virus through blood, feces and vomit. Entry points for the virus include
8892-729: The emergencies did not coincide with holidays. PHEIC was not invoked with the Middle Eastern Respiratory Syndrome (MERS) outbreak in 2013. Originating in Saudi Arabia, MERS reached more than 24 countries and resulted in 876 deaths by May 2020, although most cases were in hospital settings rather than sustained community spread. As a result, what constitutes a PHEIC has been unclear. PHEIC are not confined to only infectious diseases or biological ones. It may cover events caused by chemical agents or radioactive materials. Debate exists regarding whether
9006-474: The event. Upon declaration, the EC then makes recommendations on what actions the director-general and member states should take to address the crisis. The recommendations are temporary and require review every three months while in place. Summary of PHEIC declarations In the spring of 2009, a novel influenza A (H1N1) virus emerged. It was detected first in Mexico , North America . It spread quickly across
9120-654: The exception of yellow fever vaccine and Ebola vaccines , vaccines for VHF-associated viruses are generally not available. Post-exposure prophylactic (preventive) ribavirin may be effective for some bunyavirus and arenavirus infections. VHF isolation guidelines dictate that all VHF patients (with the exception of dengue patients) should be cared for using strict contact precautions, including hand hygiene, double gloves, gowns, shoe and leg coverings, and face shield or goggles. Lassa, CCHF, Ebola, and Marburg viruses may be particularly prone to nosocomial (hospital-based) spread. Airborne precautions should be utilized including, at
9234-475: The failures and lessons from the past 3 years are not wasted but are constructively used to build more resilient health systems and stronger political systems that support the health and wellbeing of people and planet during the 21st century." The formal end of the COVID-19 PHEIC is a matter of much nuance which carries its own risks, and as of March 2023, "WHO member states are negotiating amendments to
9348-438: The five different ebolaviruses (BDBV, EBOV, RESTV, SUDV and TAFV) differ in sequence and the number and location of gene overlaps. As with all filoviruses , ebolavirus virions are filamentous particles that may appear in the shape of a shepherd's crook, of a "U" or of a "6," and they may be coiled, toroid or branched. In general, ebolavirions are 80 nanometers (nm) in width and may be as long as 14,000 nm. Their life cycle
9462-547: The general public about the risk factors for Ebola infection and of the protective measures individuals may take to prevent infection is recommended by the World Health Organization . These measures include avoiding direct contact with infected people and regular hand washing using soap and water. Bushmeat , an important source of protein in the diet of some Africans, should be handled and prepared with appropriate protective clothing and thoroughly cooked before consumption. Some research suggests that an outbreak of Ebola disease in
9576-437: The immune system by inhibiting early steps of neutrophil activation. Furthermore, the virus is capable of hijacking cellular metabolism. Studies have shown that Ebola virus-like particles can reprogram metabolism in both vascular and immune cells. Filoviral infection also interferes with proper functioning of the innate immune system . EBOV proteins blunt the human immune system's response to viral infections by interfering with
9690-505: The intercellular structure and causes liver damage, leading to improper clotting . The widespread bleeding that occurs in affected people causes swelling and shock due to loss of blood volume . The dysfunctional bleeding and clotting commonly seen in EVD has been attributed to increased activation of the extrinsic pathway of the coagulation cascade due to excessive tissue factor production by macrophages and monocytes. After infection,
9804-410: The international system in dealing with these emergencies was "robust". Another review of the first four declarations, with the exception of wild polio, demonstrated that responses were varied. Severe outbreaks, or those that threatened larger numbers of people, did not receive a swift PHEIC declaration, and the study hypothesized that responses were quicker when American citizens were infected and when
9918-451: The liver enzymes alanine aminotransferase (ALT) and aspartate aminotransferase (AST); and abnormalities in blood clotting often consistent with disseminated intravascular coagulation (DIC) such as a prolonged prothrombin time , partial thromboplastin time , and bleeding time . Filovirions such as EBOV may be identified by their unique filamentous shapes in cell cultures examined with electron microscopy . The specific diagnosis of EVD
10032-493: The names of IHR EC members were not publicly disclosed; in the wake of reforms, now they are. These members are selected according to the disease in question and the nature of the event. Names are taken from the IHR Experts Roster . The director-general takes the advice of the EC, following their technical assessment of the crisis using legal criteria and a predetermined algorithm after a review of all available data on
10146-410: The nose, mouth, eyes, open wounds, cuts and abrasions. Ebola may be spread through large droplets ; however, this is believed to occur only when a person is very sick. This contamination can happen if a person is splashed with droplets. Contact with surfaces or objects contaminated by the virus, particularly needles and syringes, may also transmit the infection. The virus is able to survive on objects for
10260-415: The occurrence of Ebola in the United States and Europe and with the already intense transmission ongoing in three other countries for months, the WHO declared its third PHEIC in response to the outbreak of Ebola in Western Africa . Later, one review showed that a direct impact of this epidemic on America escalated a PHEIC declaration. It was the first PHEIC in a resource-poor setting. On 1 February 2016,
10374-670: The outbreak, but it was determined at that time that it was too early to declare a PHEIC, given the lack of necessary data and the then-scale of global impact. The WHO recognized the spread of COVID-19 as a pandemic on 11 March 2020. The emergency committee convened its third meeting on 30 April 2020, fourth on 31 July, fifth on 29 October, sixth on 14 January 2021, seventh on 15 April 2021, ninth in October 2021, tenth in January 2022, eleventh in April 2022, twelfth in July 2022, thirteenth in October 2022, fourteenth in January 2023, and fifteenth in May 2023. In September 2022,
10488-475: The outbreak, which had more than 2,100 cases in over 42 countries at that point; it did not reach the criteria for a PHEIC alert at the time. It was re-classified a PHEIC in August 2024. After an IHR meeting on 14 August 2024, the WHO declared an mpox outbreak in parts of Africa , of a new variant of the disease, a PHEIC. This marks the second time in three years that the WHO has classified an mpox outbreak as
10602-458: The production of interferon-beta. By inhibiting these immune responses, EBOV may quickly spread throughout the body. When EVD is suspected, travel, work history, and exposure to wildlife are important factors with respect to further diagnostic efforts. Possible non-specific laboratory indicators of EVD include a low platelet count ; an initially decreased white blood cell count followed by an increased white blood cell count ; elevated levels of
10716-487: The same air. Although it is not entirely clear how Ebola initially spreads from animals to humans, the spread is believed to involve direct contact with an infected wild animal or fruit bat. Besides bats, other wild animals that are sometimes infected with EBOV include several species of monkeys such as baboons , great apes ( chimpanzees and gorillas ), and duikers (a species of antelope ). Animals may become infected when they eat fruit partially eaten by bats carrying
10830-504: The semen of a male survivor tests negative for Ebola virus on two separate occasions. Survivors develop antibodies against Ebola that last at least 10 years, but it is unclear whether they are immune to additional infections. EVD in humans is caused by four of six viruses of the genus Ebolavirus . The four are Bundibugyo virus (BDBV), Sudan virus (SUDV), Taï Forest virus (TAFV) and one simply called Ebola virus (EBOV, formerly Zaire Ebola virus). EBOV, species Zaire ebolavirus ,
10944-456: The signalling proteins STAT1 and STAT2 are activated and move to the cell's nucleus . This triggers the expression of interferon-stimulated genes , which code for proteins with antiviral properties. EBOV's V24 protein blocks the production of these antiviral proteins by preventing the STAT1 signalling protein in the neighbouring cell from entering the nucleus. The VP35 protein directly inhibits
11058-488: The situation as "an Ebola gas can sitting in DRC that's just waiting for a match to hit it", while the WHO panel were unanimous in their decision that declaring it a PHEIC would not give any added benefit. The advice against declaring a PHEIC in October 2018 and April 2019, despite the criteria for doing so appearing to be met on both occasions, has led to the transparency of the IHR EC coming into question. The language used in
11172-456: The skin may create petechiae , purpura , ecchymoses or haematomas (especially around needle injection sites). Bleeding into the whites of the eyes may also occur. Heavy bleeding is uncommon; if it occurs, it is usually in the gastrointestinal tract . The incidence of bleeding into the gastrointestinal tract was reported to be ~58% in the 2001 outbreak in Gabon, but in the 2014–15 outbreak in
11286-464: The statements for the Kivu Ebola epidemic has been noted to be different. In October 2018, the EC stated "a PHEIC should not be declared at this time". In the 13 previously declined proposals for declaring a PHEIC, the resultant statements quoted "the conditions for a PHEIC are not currently met" and "does not constitute a PHEIC". In April 2019, they stated that "there is no added benefit to declaring
11400-594: The treatment tents until it is necessary to enter if e.g. a patient's oxygen levels drop. The infected person should be in barrier-isolation from other people. All equipment, medical waste, patient waste and surfaces that may have come into contact with body fluids need to be disinfected . During the 2014 outbreak, kits were put together to help families treat Ebola disease in their homes, which included protective clothing as well as chlorine powder and other cleaning supplies. Education of caregivers in these techniques, and providing such barrier-separation supplies has been
11514-451: The vascular circulatory system. The reasons for variation among patients infected with the same virus are unknown but stem from a complex system of virus-host interactions. Dengue fever becomes more virulent during a second infection by means of antibody-dependent enhancement . After the first infection, macrophages display antibodies on their cell membranes specific to the dengue virus. By attaching to these antibodies, dengue viruses from
11628-412: The viral nucleocapsid . The Ebolavirus structural glycoprotein (known as GP1,2) is responsible for the virus' ability to bind to and infect targeted cells. The viral RNA polymerase , encoded by the L gene, partially uncoats the nucleocapsid and transcribes the genes into positive-strand mRNAs , which are then translated into structural and nonstructural proteins. The most abundant protein produced
11742-608: The virus and that the filoviruses are present in Asia. Between 1976 and 1998, in 30,000 mammals, birds, reptiles, amphibians and arthropods sampled from regions of EBOV outbreaks, no Ebola virus was detected apart from some genetic traces found in six rodents (belonging to the species Mus setulosus and Praomys ) and one shrew ( Sylvisorex ollula ) collected from the Central African Republic . However, further research efforts have not confirmed rodents as
11856-568: The virus is most reliable in the later stages of the disease and in those who recover. IgM antibodies are detectable two days after symptom onset and IgG antibodies can be detected six to 18 days after symptom onset. During an outbreak, isolation of the virus with cell culture methods is often not feasible. In field or mobile hospitals, the most common and sensitive diagnostic methods are real-time PCR and ELISA. In 2014, with new mobile testing facilities deployed in parts of Liberia, test results were obtained 3–5 hours after sample submission. In 2015,
11970-424: The virus takes place. From there the virus can enter the bloodstream and lymphatic system and spread throughout the body. Macrophages are the first cells infected with the virus, and this infection results in programmed cell death . Other types of white blood cells , such as lymphocytes , also undergo programmed cell death leading to an abnormally low concentration of lymphocytes in the blood. This contributes to
12084-430: The virus. Fruit production, animal behavior and other factors may trigger outbreaks among animal populations. Evidence indicates that both domestic dogs and pigs can also be infected with EBOV. Dogs do not appear to develop symptoms when they carry the virus, and pigs appear to be able to transmit the virus to at least some primates. Although some dogs in an area in which a human outbreak occurred had antibodies to EBOV, it
12198-460: The virus. On TLR activation, proteins including interferon regulatory factor 3 and interferon regulatory factor 7 trigger a signalling cascade that leads to the expression of type 1 interferons . The type 1 interferons are then released and bind to the IFNAR1 and IFNAR2 receptors expressed on the surface of a neighbouring cell. Once interferon has bound to its receptors on the neighbouring cell,
12312-420: The weakened immune response seen in those infected with EBOV. Endothelial cells may be infected within three days after exposure to the virus. The breakdown of endothelial cells leading to blood vessel injury can be attributed to EBOV glycoproteins . This damage occurs due to the synthesis of Ebola virus glycoprotein (GP), which reduces the availability of specific integrins responsible for cell adhesion to
12426-430: The wild animals used for consumption may result in a corresponding human outbreak. Since 2003, such animal outbreaks have been monitored to predict and prevent Ebola outbreaks in humans. If a person with Ebola disease dies, direct contact with the body should be avoided. Certain burial rituals , which may have included making various direct contacts with a dead body, require reformulation so that they consistently maintain
12540-425: Was a health emergency in the Democratic Republic of the Congo (DRC) and the region, it did not meet all the three criteria for a PHEIC. Despite the number of deaths reaching 1,405 by 11 June 2019 and 1,440 by 17 June 2019, the reason for not declaring a PHEIC was that the overall risk of international spread was deemed to be low, and the risk of damaging the economy of the DRC high. Adhanom also stated that declaring
12654-456: Was approved by the US FDA in December 2019. While there is no approved treatment for Ebola as of 2019, two treatments ( atoltivimab/maftivimab/odesivimab and ansuvimab ) are associated with improved outcomes. Supportive efforts also improve outcomes. These include oral rehydration therapy (drinking slightly sweetened and salty water) or giving intravenous fluids , and treating symptoms. In October 2020, atoltivimab/maftivimab/odesivimab (Inmazeb)
12768-689: Was approved for medical use in the United States to treat the disease caused by Zaire ebolavirus . Ebola was first identified in 1976, in two simultaneous outbreaks, one in Nzara (a town in South Sudan ) and the other in Yambuku ( the Democratic Republic of the Congo ), a village near the Ebola River , for which the disease was named. Ebola outbreaks occur intermittently in tropical regions of sub-Saharan Africa . Between 1976 and 2012, according to
12882-499: Was approved in the United States in December 2019. It appears to be fully effective ten days after being given. It was studied in Guinea between 2014 and 2016. More than 100,000 people have been vaccinated against Ebola as of 2019. The WHO reported that approximately 345,000 people were given the vaccine during the Kivu Ebola epidemic from 2018 to 2020. Community awareness of the benefits on survival chances of admitting cases early
12996-481: Was the first time a PHEIC was declared for a mosquito‐borne disease . This declaration was lifted on 18 November 2016. In October 2018 and then later in April 2019, the WHO did not consider the 2018–2020 Kivu Ebola epidemic to be a PHEIC. The decision was controversial, with Michael Osterholm , director of the Center for Infectious Disease Research and Policy (CIDRAP) responding with disappointment and describing
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