In 1937, the case of West Nile virus, WNV, contagion was first identified in West Nile, Uganda (Khairallah et al. , 2007). Since then, cases of normal adults, soldiers, and children with mild febrile condition were reported in African nations and Israel. In 1957, an outbreak happened in a nursing home in Israel, which caused death and neurologic infections (Khairallah et al. , 2007). In the middle decade of 1990s, the West Nile virus had a widespread outbreak in Asia, Europe, Africa, and the Middle East (Khairallah et al. , 2007).
Although a wide virulence of West Nile virus has not yet been foreseen in the United States, the national West Nile virus surveillance team has been annually reporting for documented cases of meningitis and encephalitis brought by the West Nile virus. Outbreaks were commonly associated with animal host such as avian mortality in Israel and in the United States before human West Nile virus cases had been reported (Khairallah et al. , 2007). In 2003, WNV has been circulated in the 46 nations of the United States (Gottfried, Quinn, and Jones, 2005).
The WNV can impart medical conditions to the infected patients from mild fibrile to neurologic disease and even death (Gottfried, Quinn, and Jones, 2005). An estimate of one in very five patients, in a Connecticut and New York survey, was in fibrile condition (Gottfried, Quinn, and Jones, 2005). The 68 cases of WNV human infections in New York City during 1999 led to the death of seven infected individuals (Grinev et al. , 2008). From thereon, the epidemic consistently occurred annually with approximately 23,975 total infected individuals and about 962 deaths until 2006 (Grinev et al.
, 2008). Further, in 2002–2003 human WNV outbreaks in North America, new modes of transmission were reported, which involved blood transfusion, organ donation, mother-child, and through other human-human interactions (Grinev et al. , 2008). Literature Review West Nile Virus is a flavivirus similar to the viral antigen of Japanese encephalitis and Saint Louis viruses (Levinson, 2006). It has been prevalent in Africa but has brought pestilence as well in Asian and European continents.
The Culex mosquitoes are blamed for the transmission of WNV among wild birds in Asia, Africa, southern Europe, and in the Middle East (Levinson, 2006). In addition, WNV is a typical cause of febrile condition that usually develops into encephalitis, meningitis, and other sever-related illness without the direct involvement of the central nervous system, especially among the older-aged patients (Levinson, 2006). On the other hand, the febrile-myalgic conditions imparted by WNV differ from other fever types due to lymphadenopathy and maculopapular trunk rashes.
Along with these, arthralgia, sore throat, headache, vomiting, ocular pain, nausea, and vomiting may occur simultaneously with WNV infections (Levinson, 2006). Also, in Africa, WNV has been associated with severe hepatic necrosis. Meanwhile, WNV is classified under the same flaviviruses’ phylogenetic group like Rocio, Japanese encephalitis, and Murray valley viruses (Levinson, 2006). Rocio and Murray valley viruses are consistently transmitted between birds and mosquitoes resulting to a Japanese encephalitis-like condition.
Whereas the Murray valley virus caused a periodic threat of epidemia in Australia, the Rocio virus made a consecutive outbreak during 1975–1977 in a local community of Brazil (Levinson, 2006). The West Nile virus intruded New York City in 1999 and eventually found its way towards the rest of the northeastern areas of the United States, leaving about 60 cases of encephalitis and aseptic meningitis on infected individuals as well as avian death among the rare zoo birds, crows, and other species (Levinson, 2006).
Then, WNV gained a widespread virulence all over the states and even in Mexico and Canada. Culex pipiens remained as the major WNV vector in the northeastern part of the United States, but the involvement of other Culex species were also noted as the blue jays compete with crows as host and subjects of infection in the rest of the country (Levinson, 2006).
Annually, in the United States, approximately 1000–3000 encephalitis patients with around100–300 deaths have been consistently reported (Levinson, 2006). Furthermore, one in every 100 cases of infections has the central nervous system affected while the rest involved suffered from West Nile fever (Levinson, 2006). Also, sequelae, death, and encephalitis were typically observed in patients with a previous central nervous system disease along with diabetes history (Levinson, 2006).