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113-516: Contrary to popular belief, West Nile virus was not named directly after the Nile River , but rather, after the West Nile district of Uganda where the virus was first isolated in 1937. Like most other flaviviruses, WNV is an enveloped virus with icosahedral symmetry . Electron microscope studies reveal a 45–50 nm virion covered with a relatively smooth protein shell; this structure

226-433: A Turkish officer, Selim Bimbashi, were made between 1839 and 1842, and two got to the point about 30 kilometres (20 miles) beyond the present port of Juba , where the country rises and rapids make navigation very difficult. Lake Victoria was first sighted by Europeans in 1858 when British explorer John Hanning Speke reached its southern shore while traveling with Richard Francis Burton to explore central Africa and locate

339-466: A cap on viral mRNA or snatches a cap from host mRNA and attaches that cap to viral mRNA. Within the phylum, −ssRNA viruses that infect arthropods appear to be basal and the ancestors of all other −ssRNA viruses. Arthropods frequently live together in large groups, which allows for viruses to be transmitted easily. Over time, this has led to arthropod −ssRNA viruses gaining a high level of diversity. While arthropods host large quantities of viruses, there

452-576: A combined six classes, five of which are monotypic down to lower taxa: Negative-strand RNA viruses are classified as Group V in the Baltimore classification system, which groups viruses together based on their manner of mRNA production and which is often used alongside standard virus taxonomy, which is based on evolutionary history. Therefore, Group V and Negarnaviricota are synonymous. Negative-strand RNA viruses caused many widely known diseases. Many of these are transmitted by arthropods, including

565-767: A distance of 20 days' journey till it reaches the nearest Ethiopians." Modern exploration of the Nile basin began with the conquest of the northern and central Sudan by the Ottoman viceroy of Egypt, Muhammad Ali , and his sons from 1821 onward. As a result of this, the Blue Nile was known as far as its exit from the Ethiopian foothills and the White Nile as far as the mouth of the Sobat River. Three expeditions under

678-506: A distinct virus around 1000 years ago. This initial virus developed into two distinct lineages. Lineage 1 and its multiple profiles is the source of the epidemic transmission in Africa and throughout the world. Lineage 2 was considered an African zoonosis . However, in 2008, lineage 2, previously only seen in horses in sub-Saharan Africa and Madagascar, began to appear in horses in Europe, where

791-468: A factor of 15 at Aswan. Peak flows of over 8,212 m /s (290,000 cu ft/s) occurred during late August and early September, and minimum flows of about 552 m /s (19,500 cu ft/s) occurred during late April and early May. The Bahr al Ghazal and the Sobat River are the two most important tributaries of the White Nile in terms of discharge. The Bahr al Ghazal's drainage basin

904-513: A nearly ubiquitous geographical distribution, being present on all major land masses except Antarctica and Iceland. Nevertheless, changes in climate and land use on ecological timescales can variously expand or fragment their distribution patterns, raising consequent concerns for human health. Nile River The Nile (also known as the River Nile or Nile River ) is a major north-flowing river in northeastern Africa . It flows into

1017-512: A vaccine for human use and several candidates have been produced but none are licensed to use. The best method to reduce the risk of infections is avoiding mosquito bites. This may be done by eliminating standing pools of water, such as in old tires, buckets, gutters, and swimming pools. Mosquito repellent , window screens , mosquito nets , and avoiding areas where mosquitoes occur may also be useful. Like other tropical diseases which are expected to have increased spread due to climate change, there

1130-466: Is a prominent trait among many −ssRNA viruses, and −ssRNA viruses range from having genomes with one segment, typical for members of the order Mononegavirales , to genomes with ten segments, as is the case for Tilapia tilapinevirus . There is no clear trend over time that determines the number of segments, and genome segmentation among −ssRNA viruses appears to be a flexible trait since it has evolved independently on multiple occasions. Most members of

1243-465: Is an archaeological site located in alluvial deposits formed by an ancient channel of the Nile in the Affad region of southern Dongola Reach , Sudan. There are two theories about the age of the integrated Nile. One is that the integrated drainage of the Nile is of young age and that the Nile basin was formerly broken into series of separate basins, only the most northerly of which fed a river following

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1356-467: Is an infection by the West Nile virus, which is typically spread by mosquitoes . In about 80% of infections people have few or no symptoms . About 20% of people develop a fever , headache, vomiting, or a rash. In less than 1% of people, encephalitis or meningitis occurs, with associated neck stiffness, confusion, or seizures. Recovery may take weeks to months. The risk of death among those in whom

1469-642: Is approximately 1,218 m /s (43,000 cu ft/s) in October and minimum flow is about 609 m /s (21,500 cu ft/s) in April. This fluctuation is caused by the substantial variation in the flow of the Sobat, which has a minimum flow of about 99 m /s (3,500 cu ft/s) in March and a peak flow of over 680 m /s (24,000 cu ft/s) in October. During the dry season (January to June)

1582-512: Is cleaved by furin , a host cell protease, into the M protein, thereby producing an infectious mature virion. The mature viruses are then secreted out of the cell. WNV is one of the Japanese encephalitis antigenic serocomplex of viruses, together with Japanese encephalitis virus, Murray Valley encephalitis virus , Saint Louis encephalitis virus and some other flaviviruses. Studies of phylogenetic lineages have determined that WNV emerged as

1695-464: Is concern that changing weather conditions will increase West Nile Virus spread. Climate change will affect disease rates, ranges, and seasonality and affects the distribution of West Nile Virus. Projected changes in flood frequency and severity can bring new challenges in flood risk management , allowing for increased mosquito populations in urban areas. Weather conditions affected by climate change including temperature, precipitation and wind may affect

1808-438: Is constructed, the mRNA is released by RdRp. In genomes that encode more than one transcribable portion, RdRp can continue scanning to the next start sequence to continue with transcription. Some −ssRNA viruses are ambisense , meaning that both the negative genomic strand and positive antigenome separately encode different proteins. In order to transcribe ambisense viruses, two rounds of transcription are performed: first, mRNA

1921-615: Is disagreement about the degree to which cross-species transmission of arthropod −ssRNA viruses occurs among arthropods. Plant and vertebrate −ssRNA viruses tend to be genetically related to arthropod-infected viruses. Furthermore, most −ssRNA viruses outside of arthropods are found in species that interact with arthropods. Arthropods therefore serve as both key hosts and vectors of transmission of −ssRNA viruses. In terms of transmission, non-arthropod −ssRNA viruses can be distinguished between those that are reliant on arthropods for transmission and those that can circulate among vertebrates without

2034-539: Is flanked by 5′ and 3′ non-coding stem loop structures. The coding region of the genome codes for three structural proteins and seven nonstructural (NS) proteins , proteins that are not incorporated into the structure of new viruses. The WNV genome is first translated into a polyprotein and later cleaved by virus and host proteases into separate proteins (i.e. NS1, C, E). Structural proteins (C, prM/M, E) are capsid, precursor membrane proteins, and envelope proteins, respectively. The structural proteins are located at

2147-755: Is in Egypt. Below the Aswan Dam , at the northern limit of Lake Nasser, the Nile resumes its historic course. North of Cairo , the Nile splits into two branches (or distributaries) that feed the Mediterranean: the Rosetta Branch to the west and the Damietta to the east, forming the Nile Delta . The annual sediment transport by the Nile in Egypt has been quantified. Below the confluence with

2260-570: Is no specific treatment for the disease; pain medications may reduce symptoms. Severe disease may also occur in horses. Several vaccines for these animals are now available. Before the availability of veterinary vaccines, around 40% of horses infected in North America died. According to the Centers for Disease Control and Prevention , infection with West Nile Virus is seasonal in temperate zones. Climates that are temperate, such as those in

2373-409: Is particularly useful. If dead birds are found in a neighborhood, the event should be reported to local authorities. This may help health departments do surveillance and determine if the birds are infected with West Nile Virus. Despite the commercial availability of four veterinary vaccines for horses, no human vaccine has progressed beyond phase II clinical trials . Efforts have been made to produce

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2486-533: Is possible in mosquitoes, and might potentially be important in overwintering. In the urban or spillover cycle, infected mosquitoes that have fed on infected birds transmit the virus to humans. This requires mosquito species that bite both birds and humans, which are termed bridge vectors. The virus can also rarely be spread through blood transfusions, organ transplants, or from mother to baby during pregnancy, delivery, or breastfeeding. Unlike in birds, it does not otherwise spread directly between people. West Nile fever

2599-465: Is produced directly from the genome; second, mRNA is created from the antigenome. All ambisense viruses contain a hairpin loop structure to stop transcription after the protein's mRNA has been transcribed. Negative-strand RNA viruses contain a ribonucleoprotein complex composed of the genome and an RdRp attached to each segment of the genome surrounded by a capsid. The capsid is composed of proteins whose folded structure contains five alpha-helices in

2712-519: Is similar to the dengue fever virus, another Flavivirus . The protein shell is made of two structural proteins: the glycoprotein E and the small membrane protein M. Protein E has numerous functions including receptor binding, viral attachment, and entry into the cell through membrane fusion . The outer protein shell is covered by a host-derived lipid membrane , the viral envelope . The flavivirus lipid membrane has been found to contain cholesterol and phosphatidylserine , but other elements of

2825-572: Is the largest of any of the Nile's sub-basins, measuring 520,000 square kilometers (200,000 sq mi) in size, but it contributes a relatively small amount of water, about 2 m /s (71 cu ft/s) annually, because tremendous volumes of water are lost in the Sudd wetlands. The Sobat River, which joins the Nile a short distance below Lake No, drains about half as much land, 225,000 km (86,900 sq mi), but contributes 412 cubic meters per second (14,500 cu ft/s) annually to

2938-504: Is the suffix used for virus subphyla. The subphylum Polyploviricotina follows the same pattern, Polyplo being taken from Ancient Greek πολύπλοκος, meaning complex. All viruses in Negarnaviricota are negative-sense, single-stranded RNA (−ssRNA) viruses. They have genomes made of RNA, which are single instead of double-stranded. Their genomes are negative sense, meaning that messenger RNA (mRNA) can be synthesized directly from

3051-545: Is traditionally considered to be the headwaters stream. However, the Blue Nile is the source of most of the water of the Nile downstream, containing 80% of the water and silt . The White Nile is longer and rises in the Great Lakes region. It begins at Lake Victoria and flows through Uganda and South Sudan. The Blue Nile begins at Lake Tana in Ethiopia and flows into Sudan from the southeast. The two rivers meet at

3164-560: Is twofold, first by personal protective actions and second by mosquito-control actions. When a person is in an area that has WNV, it is important to avoid outdoor activity, and if they go outside they should use a mosquito repellent with DEET. A person can also wear clothing that covers more skin, such as long sleeves and pants. Mosquito control can be done at the community level and include surveillance programs and control programs including pesticides and reducing mosquito habitats. This includes draining standing water. Surveillance systems in birds

3277-427: Is typically based on symptoms and blood tests. There is no human vaccine . The best way to reduce the risk of infection is to avoid mosquito bites. Mosquito populations may be reduced by eliminating standing pools of water, such as in old tires, buckets, gutters, and swimming pools. When mosquitoes cannot be avoided, mosquito repellent , window screens , and mosquito nets reduce the likelihood of being bitten. There

3390-496: Is unlikely to be important in natural transmission. WNV has a broad host range, and is also known to be able to infect at least 30 mammalian species, including humans, some non-human primates, horses, dogs and cats. Some infected humans and horses experience disease but dogs and cats rarely show symptoms. Reptiles and amphibians can also be infected, including some species of crocodiles, alligators, snakes, lizards and frogs. Mammals are considered incidental or dead-end hosts for

3503-644: The Democratic Republic of the Congo , Tanzania , Burundi , Rwanda , Uganda , Kenya , Ethiopia , Eritrea , South Sudan , Sudan , and Egypt . In particular, the Nile is the primary water source of Egypt, Sudan and South Sudan. The Nile is an important economic driver supporting agriculture and fishing. The Nile has two major tributaries : the White Nile and the Blue Nile . The White Nile

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3616-539: The Ebola virus , hantaviruses , influenza viruses , the Lassa fever virus , and the rabies virus . Negarnaviricota takes the first part of its name from Latin nega , meaning negative, the middle part rna refers to RNA, and the final part, viricota , is the suffix used for virus phyla. The subphylum Haploviricotina takes the first part of its name, Haplo , from Ancient Greek ἁπλός, meaning simple, and 'viricotina

3729-569: The Mediterranean Sea . The Nile is the longest river in Africa. It has historically been considered the longest river in the world , though this has been contested by research suggesting that the Amazon River is slightly longer. Of the world's major rivers, the Nile is one of the smallest, as measured by annual flow in cubic metres of water. About 6,650 km (4,130 mi) long, its drainage basin covers eleven countries:

3842-584: The N-terminal lobe (5-H motif) and three alpha-helices in the C-terminal lobe (3-H motif). Inside the capsid, the genome is sandwiched between these two motifs. Excluding the family Aspiviridae , −ssRNA viruses contain an outer viral envelope , a type of a lipid membrane that surrounds the capsid. The shape of the virus particle, called a virion, of −ssRNA viruses varies and may be filamentous, pleomorphic, spherical, or tubular. Genome segmentation

3955-651: The Paleogene and Neogene Periods (66 million to 2.588 million years ago) a series of separate closed continental basins each occupied one of the major parts of the Sudanese Rift System: Mellut rift , White Nile rift , Blue Nile rift , Atbara rift and Sag El Naam rift . The Mellut Basin is nearly 12 kilometers (7.5 mi) deep at its central part. This rift is possibly still active, with reported tectonic activity in its northern and southern boundaries. The Sudd swamp which forms

4068-466: The Rift Valley fever virus and the tomato spotted wilt virus . Among vertebrates, bats and rodents are common vectors for many viruses, including the Ebola virus and the rabies virus , transmitted by bats and other vertebrates, and the Lassa fever virus and hantaviruses , transmitted by rodents. Influenza viruses are common among birds and mammals. Human-specific −ssRNA viruses include

4181-456: The discharge at any given point along the main stem depends on many factors including weather, diversions, evaporation and evapotranspiration , and groundwater flow. Upstream from Khartoum (to the south), the river is known as the White Nile , a term also used in a limited sense to describe the section between Lake No and Khartoum. At Khartoum, the river is joined by the Blue Nile . The White Nile starts in equatorial East Africa, and

4294-511: The dove family are among the other common N. American birds in which high levels of antibodies against WNV have been found. WNV has been demonstrated in a large number of mosquito species, but the most significant for viral transmission are Culex species that feed on birds, including Culex pipiens , C. restuans , C. salinarius , C. quinquefasciatus , C. nigripalpus , C. erraticus and C. tarsalis . Experimental infection has also been demonstrated with soft tick vectors, but

4407-430: The dry season ) an appreciable incoming surface flow for many kilometres upstream, and found a new source, giving the Nile a length of 6,758 km (4,199 mi). The White Nile leaves Lake Victoria at Ripon Falls near Jinja, Uganda , as the "Victoria Nile." It flows north for some 130 kilometers (81 mi) to Lake Kyoga . The last part of the approximately 200 kilometers (120 mi) river section starts from

4520-499: The nervous system is affected is about 10 percent. West Nile virus (WNV) is usually spread by mosquitoes that become infected when they feed on infected birds, which often carry the disease . Rarely the virus is spread through blood transfusions, organ transplants, or from mother to baby during pregnancy, delivery, or breastfeeding, but it otherwise does not spread directly between people. Risks for severe disease include being over 60 years old and having other health problems. Diagnosis

4633-449: The nucleocapsid . The capsid proteins are one of the first proteins created in an infected cell; the capsid protein is a structural protein whose main purpose is to package RNA into the developing viruses. The capsid has been found to prevent apoptosis by affecting the Akt pathway. WNV is a positive-sense, single-stranded RNA virus . Its genome is approximately 11,000 nucleotides long and

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4746-600: The phylum Negarnaviricota , in the kingdom Orthornavirae and realm Riboviria . They are descended from a common ancestor that was a double-stranded RNA (dsRNA) virus , and they are considered to be a sister clade of reoviruses , which are dsRNA viruses. Within the phylum, there are two major branches that form two subphyla: Haploviricotina , whose members are mostly non-segmented and which encode an RdRp that synthesizes caps on mRNA, and Polyploviricotina , whose members are segmented and which encode an RdRp that snatches caps from host mRNAs. A total of six classes in

4859-471: The 5′ end of the genome and are cleaved into mature proteins by both host and viral proteases. Nonstructural proteins consist of NS1, NS2A, NS2B, NS3, NS4A, NS4B, and NS5. These proteins mainly assist with viral replication or act as proteases. The nonstructural proteins are located near the 3′ end of the genome. Once WNV has successfully entered the bloodstream of a host animal, the envelope protein, E, binds to attachment factors called glycosaminoglycans on

4972-552: The Bahr al Jabal at a small lagoon called Lake No , after which the Nile becomes known as the Bahr al Abyad , or the White Nile, from the whitish clay suspended in its waters. When the Nile floods it leaves a rich silty deposit which fertilizes the soil. The Nile no longer floods in Egypt since the completion of the Aswan Dam in 1970. An anabranch river, the Bahr el Zeraf , flows out of

5085-652: The Blue Nile begins in Ethiopia. Both branches are on the western flanks of the East African Rift . The source of the Blue Nile is Lake Tana in the Gish Abay region in the Ethiopian Highlands . The source of the White Nile, even after centuries of exploration, remains in dispute. The most remote source that is indisputably a source for the White Nile is the Kagera River ; however,

5198-569: The Blue Nile the only major tributary is the Atbarah River , also known as the Red Nile. Roughly halfway to the sea, it originates in Ethiopia north of Lake Tana , and is around 800 kilometers (500 mi) long. The Atbarah flows only while there is rain in Ethiopia and dries very rapidly. During the dry period of January to June, it typically dries up north of Khartoum . The Blue Nile ( Amharic : ዓባይ , ʿĀbay ) springs from Lake Tana in

5311-589: The Congo, but the Nile is not a border river at this point. After leaving Lake Albert, the river continues north through Uganda and is known as the Albert Nile . The White Nile flows into South Sudan just south of Nimule , where it is known as the Bahr al Jabal ("Mountain River" ). Just south of the town is the confluence with the Achwa River . The Bahr al Ghazal , 716 kilometers (445 mi) long, joins

5424-537: The Delta, and would have been pronounced ni-lo-he in the area around Memphis in the 8th century BCE. Hesiod at his Theogony refers to Nilus (Νεῖλος) as one of the Potamoi (river gods), son of Oceanus and Tethys . Another derivation of Nile might be related to the term Nil ( Sanskrit : नील , romanized :  nila ; Egyptian Arabic : نيلة ), which refers to Indigofera tinctoria , one of

5537-414: The Ethiopian rainy season when rainfall is especially high in the Ethiopian Highlands ; the rest of the year, the great rivers draining Ethiopia into the Nile have a weaker flow. In harsh and arid seasons and droughts, the Blue Nile dries out completely. The flow of the Blue Nile varies considerably over its yearly cycle and is the main contribution to the large natural variation of the Nile flow. During

5650-630: The Ethiopian Highlands, satellite imagery was used to identify dry watercourses in the desert to the west of the Nile. A canyon, now filled by surface drift, represents the Eonile that flowed during 23–5.3 million years before present. The Eonile transported clastic sediments to the Mediterranean; several natural gas fields have been discovered within these sediments. During the late- Miocene Messinian salinity crisis , when

5763-491: The Ethiopian Highlands. The Blue Nile flows about 1,400 kilometres to Khartoum, where the Blue Nile and White Nile join to form the Nile. Ninety percent of the water and ninety-six percent of the transported sediment carried by the Nile come from the Atbarah and Blue Nile, both of which originate in Ethiopia, with fifty-nine percent of the water coming from the Blue Nile. The erosion and transportation of silt only occurs during

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5876-874: The Kagera has tributaries that are in contention for the farthest source of the White Nile. Two start in Burundi: the Ruvyironza River (also known as the Luvironza) and the Rurubu River . In addition, in 2010, an exploration party in Rwanda went to a place described as the source of the Rukarara tributary, and by hacking a path up steep jungle-choked mountain slopes in the Nyungwe Forest found (in

5989-482: The Mediterranean Sea was a closed basin and evaporated to the point of being empty or nearly so, the Nile cut its course down to the new base level until it was several hundred metres below world ocean level at Aswan and 2,400 m (7,900 ft) below Cairo. This created a very long and deep canyon which was filled with sediment after the Mediterranean was recreated. At some point the sediments raised

6102-581: The Middle East and Africa, and described being told of the source of the Nile in Abyssinia (Ethiopia). Later in the 15th and 16th centuries, travelers to Ethiopia visited Lake Tana and the source of the Blue Nile in the mountains south of the lake. Supposedly, Paolo Trevisani ( c.  1452 –1483), a Venetian traveller in Ethiopia, wrote a journal of his travels to the origin of the Nile that has since been lost. Although James Bruce claimed to be

6215-624: The Nile near the southern point of the Great Bend. The Nile has been the lifeline of civilization in Egypt since the Stone Age , with most of the population and all of the cities of Egypt developing along those parts of the Nile valley lying north of Aswan. However, the Nile used to run much more westerly through what is now Wadi Hamim and Wadi al Maqar in Libya and flow into the Gulf of Sidra . As

6328-526: The Nile since ancient times. A tune, Hymn to the Nile , was created and sung by the ancient Egyptian peoples about the flooding of the Nile River and all of the miracles it brought to Ancient Egyptian civilization. Water buffalo were introduced from Asia, and the Assyrians introduced camels in the 7th century BCE. These animals were raised for meat and were domesticated and used for ploughing—or in

6441-454: The Nile valley north of the Aswan Dam . Nearly all the cultural and historical sites of Ancient Egypt developed and are found along river banks. The Nile is, with the Rhône and Po , one of the three Mediterranean rivers with the largest water discharge . The standard English names "White Nile" and "Blue Nile" refer to the river's source, derived from Arabic names formerly applied to only

6554-523: The Nile's Bahr al Jabal section and rejoins the White Nile. The flow rate of the Bahr al Jabal at Mongalla is almost constant throughout the year and averages 1,048 m /s (37,000 cu ft/s). After Mongalla, the Bahr Al Jabal enters the enormous swamps of the Sudd region. More than half of the Nile's water is lost in this swamp to evaporation and transpiration . The average flow rate of

6667-595: The Nile. When in flood the Sobat carries a large amount of sediment, adding greatly to the White Nile's color. The Yellow Nile is a former tributary that connected the Ouaddaï highlands of eastern Chad to the Nile River Valley c.  8000 to c.  1000 BCE . Its remains are known as the Wadi Howar . The wadi passes through Gharb Darfur near the northern border with Chad and meets up with

6780-532: The Sudanese capital of Khartoum . The northern section of the river flows north almost entirely through the Nubian Desert to Cairo and its large delta , and the river flows into the Mediterranean Sea at Alexandria . Egyptian civilization and Sudanese kingdoms have depended on the river and its annual flooding since ancient times. Most of the population and cities of Egypt lie along those parts of

6893-425: The Sudanese stretches that meet at Khartoum . In the ancient Egyptian language , the Nile is called Ḥꜥpy (Hapy) or Jtrw (Iteru), meaning "river". In Coptic , the word ⲫⲓⲁⲣⲟ , pronounced piaro ( Sahidic ) or phiaro ( Bohairic ), means "the river" (lit. p(h).iar-o "the.canal-great"), and comes from the same ancient name. In Nobiin , the river is called Áman Dawū , meaning "the great water". In Luganda ,

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7006-554: The Sudd wetlands of South Sudan, the upper reaches of the White Nile remained largely unknown to the ancient Greeks and Romans. Vitruvius thought that source of the Nile was in Mauritania, on the "other" (south) side of the Atlas Mountains . Various expeditions failed to determine the river's source. Agatharchides records that in the time of Ptolemy II Philadelphus , a military expedition had penetrated far enough along

7119-490: The United States and Europe, see peak season from July to October. Peak season changes depending on geographic region and warmer and humid climates can see longer peak seasons. All ages are equally likely to be infected but there is a higher amount of death and neuroinvasive West Nile Virus in people 60–89 years old. People of older age are more likely to have adverse effects. There are several modes of transmission, but

7232-408: The White Nile at the tails of the swamps is about 510 m /s (18,000 cu ft/s). From here it meets with the Sobat River at Malakal . On an annual basis, the White Nile upstream of Malakal contributes about 15% of the total outflow of the Nile. The average flow of the White Nile at Lake Kawaki Malakal, just below the Sobat River, is 924 m /s (32,600 cu ft/s); the peak flow

7345-512: The White Nile contributes between 70% and 90% of the total discharge from the Nile. Below Renk , the White Nile enters Sudan, it flows north to Khartoum and meets the Blue Nile. The course of the Nile in Sudan is distinctive. It flows over six groups of cataracts , from the sixth at Sabaloka just north of Khartoum northward to Abu Hamad . The tectonic uplift of the Nubian Swell diverts

7458-606: The afterlife. The east was thought of as a place of birth and growth, and the west was considered the place of death, as the god Ra , the Sun, underwent birth, death, and resurrection each day as he crossed the sky. Thus, all tombs were west of the Nile, because the Egyptians believed that in order to enter the afterlife, they had to be buried on the side that symbolized death. As the Nile was such an important factor in Egyptian life,

7571-445: The aid of arthropods. The latter group is likely to have originated from the former, adapting to vertebrate-only transmission. Negarnaviricota belongs to the kingdom Orthornavirae , which encompasses all RNA viruses that encode RdRp, and the realm Riboviria , which includes Orthornavirae as well as all viruses that encode reverse transcriptase in the kingdom Pararnavirae . Negarnaviricota contains two subphyla, which contain

7684-482: The ancient calendar was even based on the three cycles of the Nile. These seasons, each consisting of four months of thirty days each, were called Akhet , Peret , and Shemu . Akhet, which means inundation, was the time of the year when the Nile flooded, leaving several layers of fertile soil behind, aiding in agricultural growth. Peret was the growing season, and Shemu, the last season, was the harvest season when there were no rains. Owing to their failure to penetrate

7797-401: The antigenome and synthesizes a copy of the genome while using the antigenome as a template. Replication is executed while the genome is inside the nucleocapsid, and RdRp unveils the capsid and translocates along the genome during replication. As new nucleotide sequences are synthesized by RdRp, capsid proteins are assembled and encapsidate the newly replicate viral RNA. Transcribing mRNA from

7910-411: The camels' case, carriage. Water was vital to both people and livestock. The Nile was also a convenient and efficient means of transportation for people and goods. The Nile was also an important part of ancient Egyptian spiritual life. Hapi was the god of the annual floods, and both he and the pharaoh were thought to control the flooding. The Nile was considered to be a causeway from life to death and

8023-479: The central part of the basin may still be subsiding. The White Nile Rift system, although shallower than the Bahr el Arab rift , is about 9 kilometers (5.6 mi) deep. Geophysical exploration of the Blue Nile Rift System estimated the depth of the sediments to be 5–9 kilometers (3.1–5.6 mi). These basins were not interconnected until their subsidence ceased, and the rate of sediment deposition

8136-463: The course of the Blue Nile to determine that the summer floods were caused by heavy seasonal rainstorms in the Ethiopian Highlands, but no European of antiquity is known to have reached Lake Tana. The Tabula Rogeriana depicted the source as three lakes in 1154. Europeans began to learn about the origins of the Nile in the 14th century when the Pope sent monks as emissaries to Mongolia who passed India,

8249-492: The development of Egyptian civilization. Because the river overflowed its banks annually and deposited new layers of silt, the surrounding land was very fertile. The Ancient Egyptians cultivated and traded wheat, flax , papyrus and other crops around the Nile. Wheat was a crucial crop in the famine-plagued Middle East. This trading system secured Egypt's diplomatic relationships with other countries and contributed to economic stability. Far-reaching trade has been carried on along

8362-402: The dry season the natural discharge of the Blue Nile can be as low as 113 m /s (4,000 cu ft/s), although upstream dams regulate the flow of the river. During the wet season, the peak flow of the Blue Nile often exceeds 5,663 m /s (200,000 cu ft/s) in late August (a difference of a factor of 50). Before the placement of dams on the river the yearly discharge varied by

8475-412: The environment. For −ssRNA viruses, this allowed for a large number of invertebrate, and especially arthropod, viruses to be identified, which helped to provide insight into the evolutionary history of −ssRNA viruses. Based on phylogenetic analysis of RdRp showing that −ssRNA viruses were descended from a common ancestor, Negarnaviricota and its two subphyla were established in 2018, and it was placed into

8588-410: The etymology is disputed. Homer called the river Αἴγυπτος , Aiguptos , but in subsequent periods, Greek authors referred to its lower course as Neilos ; this term became generalized for the entire river system. Thus, the name may derive from Ancient Egyptian expression n ꜣ r ꜣ w-ḥ ꜣ w(t) (lit. 'the mouths of the front parts'), which referred specifically to the branches of the Nile transversing

8701-508: The first European to have visited the headwaters, modern writers give the credit to the Jesuit Pedro Páez . Páez's account of the source of the Nile is a long and vivid account of Ethiopia. It was published in full only in the early 20th century, although it was featured in works of Páez's contemporaries, including Baltazar Téllez, Athanasius Kircher and Johann Michael Vansleb . Europeans had been resident in Ethiopia since

8814-535: The first North American cases in 1999, the virus has been reported throughout the United States, Canada, Mexico, the Caribbean, and Central America. There have been human cases and equine cases, and many birds are infected. The Barbary macaque , Macaca sylvanus , was the first nonhuman primate to contract WNV. Both the American and Israeli strains are marked by high mortality rates in infected avian populations;

8927-624: The first known outbreak affected 18 animals in Hungary. Lineage 1 West Nile virus was detected in South Africa in 2010 in a mare and her aborted fetus ; previously, only lineage 2 West Nile virus had been detected in horses and humans in South Africa. Kunjin virus is a subtype of West Nile virus endemic to Oceania . A 2007 fatal case in a killer whale in Texas broadened the known host range of West Nile virus to include cetaceans . Since

9040-568: The fusion of the endosomal and viral membranes, allowing the genome to be released into the cytoplasm. Translation of the positive-sense single-stranded RNA occurs at the endoplasmic reticulum ; the RNA is translated into a polyprotein which is then cleaved by both host and viral proteases NS2B-NS3 to produce mature proteins. In order to replicate its genome, NS5, a RNA polymerase , forms a replication complex with other nonstructural proteins to produce an intermediary negative-sense single-stranded RNA ;

9153-448: The genome by the viral enzyme RNA-dependent RNA polymerase (RdRp), also called RNA replicase, which is encoded by all −ssRNA viruses. Excluding viruses in the genus Tenuivirus and some in the family Chuviridae , all −ssRNA viruses have linear rather than circular genomes, and the genomes may be segmented or non-segmented. All −ssRNA genomes contain terminal inverted repeats , which are palindromic nucleotide sequences at each end of

9266-426: The genome follows the same directional pattern as producing the antigenome. At the leader sequence, RdRp synthesizes a 5-'end (usually pronounced "five prime end") triphosphate-leader RNA and either, in the case of the subphylum Haploviricotina , caps the 5'-end or, in the case of the subphylum Polyploviricotina , snatches a cap from a host mRNA and attaches it to the viral mRNA so that the mRNA can be translated by

9379-452: The genome. Replication of −ssRNA genomes is executed by RdRp, which initiates replication by binding to a leader sequence on the 3'-end (usually pronounced "three prime end") of the genome. RdRp then uses the negative sense genome as a template to synthesize a positive-sense antigenome. When replicating the antigenome, RdRp first binds to the trailer sequence on the 3'-end of the antigenome. Thereafter, RdRp ignores all transcription signals on

9492-459: The great lakes. Believing he had found the source of the Nile on seeing this "vast expanse of open water" for the first time, Speke named the lake after Queen Victoria . Burton, recovering from illness and resting further south on the shores of Lake Tanganyika , was outraged that Speke claimed to have proven his discovery to be the true source of the Nile when Burton regarded this as still unsettled. A quarrel ensued which sparked intense debate within

9605-410: The host cell's ribosomes . After capping the mRNA, RdRp initiates transcription at a gene start signal and later terminates transcription upon reaching a gene end signal. At the end of transcription, RdRp synthesizes a polyadenylated tail (poly (A) tail) consisting of hundreds of adenines in the mRNA's 3-end, which may be done by stuttering on a sequence of uracils . After the poly (A) tail

9718-414: The host cell. These attachment factors aid entry into the cell, however, binding to primary receptors is also necessary. Primary receptors include DC-SIGN , DC-SIGN-R, and the integrin α v β 3 . By binding to these primary receptors, WNV enters the cell through clathrin-mediated endocytosis . As a result of endocytosis, WNV enters the cell within an endosome . The acidity of the endosome catalyzes

9831-440: The infection, but others survive. The American robin ( Turdus migratorius ) and house sparrow ( Passer domesticus ) are thought to be among the most important reservoir species in N. American and European cities. Brown thrashers ( Toxostoma rufum ), gray catbirds ( Dumetella carolinensis ), northern cardinals ( Cardinalis cardinalis ), northern mockingbirds ( Mimus polyglottos ), wood thrushes ( Hylocichla mustelina ) and

9944-444: The lake's northern shore. Negative-sense single-stranded RNA virus See text Negative-strand RNA viruses ( −ssRNA viruses ) are a group of related viruses that have negative-sense , single-stranded genomes made of ribonucleic acid (RNA). They have genomes that act as complementary strands from which messenger RNA (mRNA) is synthesized by the viral enzyme RNA-dependent RNA polymerase (RdRp). During replication of

10057-609: The late 15th century, and one of them may have visited the headwaters even earlier without leaving a written trace. The Portuguese João Bermudes published the first description of the Tis Issat Falls in his 1565 memoirs, compared them to the Nile Falls alluded to in Cicero 's De Republica . Jerónimo Lobo describes the source of the Blue Nile, visiting shortly after Pedro Páez. Telles also uses his account. The White Nile

10170-580: The main Nile during the 70,000–80,000 years B.P. wet period. The White Nile system in Bahr El Arab and White Nile Rifts remained a closed lake until the connection of the Victoria Nile to the main system some 12,500 years ago during the African humid period . The Greek historian Herodotus wrote that "Egypt was the gift of the Nile". An unending source of sustenance, it played a crucial role in

10283-431: The measles virus and the mumps virus . Many diseases caused by −ssRNA viruses have been known throughout history, including hantavirus infection, measles, and rabies. In modern history, some such as Ebola and influenza have caused deadly disease outbreaks. The vesicular stomatitis virus , first isolated in 1925 and one of the first animal viruses to be studied because it could be studied well in cell cultures ,

10396-477: The membrane have yet to be identified. The lipid membrane has many roles in viral infection , including acting as signaling molecules and enhancing entry into the cell. Cholesterol, in particular, plays an integral part in WNV entering a host cell. The two viral envelope proteins, E and M, are inserted into the membrane. The RNA genome is bound to capsid (C) proteins, which are 105 amino-acid residues long, to form

10509-424: The most common cause of infection in humans is by being bitten by an infected mosquito. Other modes of transmission include blood transfusion, organ transplantation, breast-feeding, transplacental transmission, and laboratory acquisition. These alternative modes of transmission are extremely rare. Prevention efforts against WNV mainly focus on preventing human contact with and being bitten by infected mosquitoes. This

10622-460: The negative-sense strand serves as a template for synthesis of the final positive-sense RNA. Once the positive-sense RNA has been synthesized, the capsid protein, C, encloses the RNA strands into immature virions. The rest of the virus is assembled along the endoplasmic reticulum and through the Golgi apparatus , and results in non-infectious immature virions. The E protein is then glycosylated and prM

10735-513: The original sources of indigo dye . Another may be Nymphaea caerulea , known as "The Sacred Blue Lily of the Nile", which was found scattered over Tutankhamun 's corpse when it was excavated in 1922. Another possible etymology derives from the Semitic term Nahal , meaning "river". Old Libyan has the term lilu , meaning water (in modern Berber ilel ⵉⵍⴻⵍ means sea ). With a total length of about 6,650 km (4,130 mi) between

10848-467: The phylum are recognized. Negative-strand RNA viruses are closely associated with arthropods and can be informally divided between those that are reliant on arthropods for transmission and those that are descended from arthropod viruses but can now replicate in vertebrates without the aid of arthropods. Prominent arthropod-borne −ssRNA viruses include the Rift Valley fever virus and the tomato spotted wilt virus . Notable vertebrate −ssRNA viruses include

10961-470: The presence of dead birds—especially Corvidae —can be an early indicator of the arrival of the virus. The natural hosts for WNV are birds and mosquitoes. Over 300 different species of bird have been shown to be infected with the virus. Some birds, including the American crow ( Corvus brachyrhynchos ), blue jay ( Cyanocitta cristata ) and greater sage-grouse ( Centrocercus urophasianus ), are killed by

11074-575: The present course of the Nile in Egypt and Sudan. Rushdi Said postulates that Egypt supplied most of the waters of the Nile during the early part of its history. The other theory is that the drainage from Ethiopia via rivers equivalent to the Blue Nile, the Atbara and the Takazze flowed to the Mediterranean via the Egyptian Nile since well back into Tertiary times. Salama suggests that during

11187-462: The region of Lake Victoria and the Mediterranean Sea , the Nile is among the longest rivers on Earth. The drainage basin of the Nile covers 3,254,555 square kilometers (1,256,591 sq mi), about 10% of the area of Africa. Compared to other major rivers, though, the Nile carries little water (5% of that of the Congo River , for example). The Nile basin is complex, and because of this,

11300-402: The risk for WNV. Similarly, rainfall may also drive mosquito replication rates and affect the seasonality and geographic variations of the virus. Studies show an association between heavy precipitation and higher incidence of reported WNV. Likewise, wind is another environmental factor that serves as a dispersal mechanism for mosquitoes. Mosquitoes have extremely wide environmental tolerances and

11413-685: The river is called Kiira or Kiyira . In Runyoro , it is called Kihiira . In Egyptian Arabic , the Nile is called en-Nīl , while in Standard Arabic it is called an-Nīl . In Biblical Hebrew , it is הַיְאוֹר ‎, Ha-Ye'or or הַשִׁיחוֹר ‎, Ha-Shiḥor . The English name Nile and the Arabic names en-Nîl and an-Nîl both derive from the Latin Nilus and the Ancient Greek Νεῖλος . Beyond that, however,

11526-618: The river south-west for over 300 km, following the structure of the Central African Shear Zone embracing the Bayuda Desert . At Al Dabbah it resumes its northward course towards the first cataract at Aswan forming the S-shaped Great Bend of the Nile mentioned by Eratosthenes . In the north of Sudan, the river enters Lake Nasser (known in Sudan as Lake Nubia), the larger part of which

11639-532: The riverbed sufficiently for the river to overflow westward into a depression to create Lake Moeris . Lake Tanganyika drained northwards into the Nile until the Virunga Volcanoes blocked its course in Rwanda. The Nile was much longer at that time, with its furthest headwaters in northern Zambia. The currently existing Nile first flowed during the former parts of the Würm glaciation period. Affad 23

11752-407: The scientific community and interest by other explorers keen to either confirm or refute Speke's discovery. British explorer and missionary David Livingstone pushed too far west and entered the Congo River system instead. It was ultimately Welsh-American explorer Henry Morton Stanley who confirmed Speke's discovery, circumnavigating Lake Victoria and reporting the great outflow at Ripon Falls on

11865-588: The sea level rose at the end of the most recent ice age , the stream which is now the northern Nile captured the ancestral Nile near Asyut . This change in climate also led to the current extents of the Sahara desert, around 3400 BCE. The Giza pyramid complex originally overlooked a branch of the Nile that no longer exists. This branch was highest during the African Humid Period . The existing Nile has five earlier phases: Flowing north from

11978-468: The subphylum Haploviricotina are nonsegmented, whereas segmentation is universal in Polyploviricotina . Phylogenetic analysis based on RdRp shows that −ssRNA viruses are descended from a common ancestor and that they are likely a sister clade of reoviruses , which are dsRNA viruses. Within the phylum, there are two clear branches, assigned to two subphyla, based on whether RdRp synthesizes

12091-511: The survival and reproduction rates of mosquitoes, suitable habitats, distribution, and abundance. Ambient temperatures drive mosquito replication rates and transmission of WNV by affecting the peak season of mosquitoes and geographic variations. For example, increased temperatures can affect the rate of virus replication, speed up the virus evolution rate, and viral transmission efficiency. Furthermore, higher winter temperatures and warmer spring may lead to larger summer mosquito populations, increasing

12204-425: The viral genome, RdRp synthesizes a positive-sense antigenome that it uses as a template to create genomic negative-sense RNA. Negative-strand RNA viruses also share a number of other characteristics: most contain a viral envelope that surrounds the capsid, which encases the viral genome, −ssRNA virus genomes are usually linear, and it is common for their genome to be segmented. Negative-strand RNA viruses constitute

12317-517: The virus: they do not usually develop a high enough level of virus in the blood ( viremia ) to infect another mosquito feeding on them and carry on the transmission cycle; some birds are also dead-end hosts. In the normal rural or enzootic transmission cycle, the virus alternates between the bird reservoir and the mosquito vector. It can also be transmitted between birds via direct contact, by eating an infected bird carcass or by drinking infected water. Vertical transmission between female and offspring

12430-560: The western shores of the lake and flows at first to the west until just south of Masindi Port , where the river turns north, then makes a great half circle to the east and north to Karuma Falls . For the remaining part, it flows westerly through the Murchison Falls until it reaches the northern shores of Lake Albert where it forms a significant river delta. Lake Albert is on the border of the Democratic Republic of

12543-574: Was enough to fill and connect them. The Egyptian Nile connected to the Sudanese Nile, which captures the Ethiopian and Equatorial headwaters during the current stages of tectonic activity in the Eastern, Central and Sudanese Rift systems. The connection of the different Niles occurred during cyclic wet periods. The Atbarah overflowed its closed basin during the wet periods that occurred about 100,000 to 120,000 years ago. The Blue Nile connected to

12656-597: Was even less understood. The ancients mistakenly believed that the Niger River represented the upper reaches of the White Nile. For example, Pliny the Elder writes that the Nile had its origins "in a mountain of lower Mauretania ", flowed above ground for "many days" distance, then went underground, reappeared as a large lake in the territories of the Masaesyli , then sank again below the desert to flow underground "for

12769-403: Was identified as an −ssRNA virus, which was unique at the time because other RNA viruses that had been discovered were positive sense. In the early 21st century, the bovine disease rinderpest , caused by −ssRNA rinderpest virus, became the second disease to be eradicated, after smallpox , caused by a DNA virus. In the 21st century, viral metagenomics has become common to identify viruses in

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