Introduction
The West Nile Virus is a human neurotropic pathogen that causes encephalitis and West Nile fever. The virus was introduced to the Western Hemisphere in the summer of late 1999. Several persons had been infected with the virus in New York and the infection spread to over 12 states by 2000. The virus dominates most of North America in areas with mosquito species. Over 2 million people were infected with WNV between 1999 and 2010. 13,00 of these cases were reported to have been fatal to a point of death. The motive of this review is to confer and summarize the infection, its symptoms, and treatment.
The Pathogen
West Nile Virus belongs to one genre of the family Flaviviridae. This family is of three genera; hepaciviruses, flaviviruses, and pestiviruses. The first one includes hepatitis b and C viruses. The second genus includes yellow fever virus and dengue virus. Pestiviruses include viruses that affect animals, especially hoofed mammals. The flavivirus genus comprises around 70 viruses that are divided into two groups: tick-borne and mosquito-borne. The JE serocomplex/encephalitic clade and the non-encephalitic clade are two types of mosquito-borne viruses. The WNV and the Japanese encephalitis virus are sorted into JE serocomplex of the mosquito-borne viruses. The non-encephalitic group includes YFV and DENV.
Structure of the virus
The WNV contains a single-strand positive RNA genome. It is an enveloped virion. The particular genome is made up of a single open reading frame without any polyadenylation extension. The viral RNA translates to a single polyprotein that is cleaved by both the host and the viral proteases (Eshetu et al., 2020). This results in the capsid, pre membrane and envelope structural form, and a non-structural form of seven proteins. This environment favors the formation and assembly of the positive-stranded RNA enveloped in an icosahedra capsid of about 50 nm.
The Disease Infection
As stated earlier, WNV causes West Nile fever, and its infections and geographical distribution depend highly on the presence of favorable conditions for the Culex mosquito, which is the mosquito vector that transmits the disease. The WNV is transmitted to humans by the bite of an infected female mosquito. Mosquitoes get infected with the virus when they bite an infected bird. The virus has been shown to be most closely linked to crows and jays. At least 110 different bird species have been identified as being infected with the virus, which is quite a large number.
The West Nile Virus cannot be transmitted from person to person. However, it has spread in a few instances as a consequence of organ donation programs. According to medical specialists, the organ donor contracted the virus via a blood transfusion. The infection was discovered in all of the blood samples collected. The risk of developing West Nile virus after having a blood transfusion is much lower than the risk of not undergoing any procedure that needs a blood transfusion. The culex mosquito heavily feeds on blood from mammals and avian which makes it the preferred transmission vector. Most people infected with the virus do not show symptoms other than fever (Stojanov 2018). One in every five infections bears such symptoms as body aches, headaches, rashes, vomiting, and diarrhea. The incubation period for the virus infection is believed to be 2 to 14 days. Most people would ask if WNV is communicable but research affirms that the infection can only be acquired through a mosquito bite, and only if the mosquito had bitten an infected mammal or bird. WNV has no vaccine to prevent or reduce its infections and like all mosquito-borne infections, WNV is controlled by ensuring protection against mosquito bites. Using medicated mosquito net, repellants, and wearing long-sleeved clothing in heavily infested areas (MacDonald et al., 2019). Up until now, the virus infection has had no specific treatment, but most people are known to recover fully from the infection. The infection is highly managed clinically, with the administration of antibiotics and painkillers where patients have persisting meningeal pains and headaches. Vomiting and nausea are managed through antiemetic therapy and rehydration.
In 1937, a lady living in Uganda’s West Nile area was found to have the West Nile Virus (WNV). Nile delta area crows and columbiform birds were the first ones to show signs of this disease. It wasn’t until 1997 that the more virulent strain of WNV was shown to be fatal to various bird species in Israel, including those that were susceptible to encephalitis and paralysis. Over the last half-century, WNV infections in humans have been observed in several regions across the world.
WNV strains common in Israel and Tunisia were introduced into New York in 1999, triggering a major and dramatic epidemic that swept throughout USA in the years that followed (Ronca, Ruff & Murray, 2021). Vector-borne virus importation and establishment beyond their native environment pose a severe threat to world populations as demonstrated by the WNV epidemic in the United States from 1999–2010.
The most severe outbreaks happened in Russia, Israel, Romania, USA and Greece. The epidemics occurred along key bird migration routes. WNV was once prevalent in parts of Africa, West Asia, Europe, Australia and in the Middle East. Since its first appearance in the US in 1999, the virus has spread around the globe, from Canada to Venezuela.
Conclusion
West Nile Virus is a mosquito-borne disease that is not common. It has been known to exist in the Northern Hemisphere since the 1990s. it is not a killer disease, has no vaccine but can be controlled easily. Infected individuals usually recover fully, and where it persists, symptoms of body fatigue and headaches are exhibited.
Reference
Eshetu, D., Kifle, T., Agaje, B. G., & Hirigo, A. T. (2020). Seropositivity of west nile virus among acute febrile patients in southern ethiopia. Infection and Drug Resistance, 13, 1491.
McDonald, E., Martin, S. W., Landry, K., Gould, C. V., Lehman, J., Fischer, M., & Lindsey, N. P. (2019). West Nile virus and other domestic nationally notifiable arboviral diseases—United States, 2018. American Journal of Transplantation, 19(10), 2949-2954.
Ronca, S. E., Ruff, J. C., & Murray, K. O. (2021). A 20-year historical review of West Nile virus since its initial emergence in North America: Has West Nile virus become a neglected tropical disease?. PLoS Neglected Tropical Diseases, 15(5), e0009190.
Ronca, S. E., Ruff, J. C., & Murray, K. O. (2021). A 20-year historical review of West Nile virus since its initial emergence in North America: Has West Nile virus become a neglected tropical disease?. PLoS Neglected Tropical Diseases, 15(5), e0009190.
Vielle, N. J., Zumkehr, B., García-Nicolás, O., Blank, F., Stojanov, M., Musso, D., … & Alves, M. P. (2018). Silent infection of human dendritic cells by African and Asian strains of Zika virus. Scientific reports, 8(1), 1-12.
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