The West Nile virus (WNV) is a mosquito-borne flavivirus that has been a significant health concern around the world. This virus was first isolated in a woman in the West Nile district of Uganda in 1937 and has since caused multiple human and animal disease outbreaks in all continents except Antarctica.1,2,3 WNV has a complex lifecycle involving a cycle of transmission between birds and mosquitos, particularly the Culex species.1,4 In the wild, birds are the definitive reservoir and host for WNV, amplifying the virus and passing it onto mosquitos.1,3 A mosquito bites an infected bird, contracts the infection, and transmits it to another bird or mammal through their bite, incidentally infecting humans.3,5 When acquired by humans, 80 % of cases are asymptomatic while approximately 20 % develop a mild fever called WNV fever, which usually resolves on its own. About 1 % can become West Nile neuroinvasive disease (WNND), causing serious neurological complications such as encephalitis, meningitis, and acute flaccid paralysis.6, 7, 8

Surprisingly, the first major outbreak of WNV was detected in the United States in 1999 during an epidemic of meningoencephalitis in New York. This strain of WNV caused 62 cases of WNV meningoencephalitis, at least 59 hospitalized cases, and 7 deaths.3 In the years 1999-2001, WNV spread throughout the eastern hemisphere and even the Southern portions of Canada while simultaneously pushing west. Eventually in 2004, Southern California and Arizona had the highest WNV activity in the nation.3 These statistics show the startling efficiency of arboviruses if given suitable vectors, hosts, and climate. Human infections typically occur in summer or fall in temperate and subtropical regions.4 The states currently with the highest incidence of WNV are Texas, Arizona, and California due to warm weather that allows mosquitos to thrive.3,9 Outbreaks have occurred in colder climates as well due to factors such as decreased mosquito control effort and lack of awareness of disease.10 Currently, WNV boasts the highest number of arboviral related neurological disease in North America and caused four times more incidences of neuroinvasive disease than all other arboviruses combined.3,4 The Centers for Disease Control and Prevention (CDC) reported that in 2024, there were 491 confirmed cases of West Nile virus across 39 states, with 342 classified as neuroinvasive. The CDC also noted that approximately 10 % of severe WNV cases result in death.11 The elderly and immunocompromised individuals are particularly susceptible to the virus; they are more likely to contract WNV, develop neuroinvasive disease, and have worse clinical outcomes.1,5,8,12

Though first discovered in Africa and spread to the US, WNV has spread globally from individual reports to full outbreaks in various countries. A demographic study of WNV conducted over most of Europe from 2006 to 2021 on 2916 registered cases of WNND showed significant impact of gender and age on WNV transmission and severity. Out of the 2916 cases, about two-thirds were male and the odds of developing WNND after being infected with WNV is 27 % higher in males than in females.13 Moreover, this study observed an average age across all participants infected with WNV to be 64.9 years and a positive association between older age and developing WNV compared to other disease. Patients older than 50 had a three times increased chance of developing West Nile encephalitis compared to West Nile fever, and those over 65 had a 16 to 50 times increased risk of WNND.14,15

While primarily impacting adults, WNV infection in children makes up about 4 % of neuroinvasive cases annually.5 The disease is less common in children but can still result in severe outcomes such as neuroinvasion and death.16 There were 2397 cases of WNV infection in patients younger than 19 years of age reported to the CDC from 1999 to 2016 with 34 % of which were neuroinvasive.10 WNV incidence in children is underrepresented and imprecise as data is underreported. WNV is a now a public health concern worldwide, but its impact is undoubtedly higher in low-income regions of the world. A variety of socioeconomic, environmental, and infrastructural factors play into the increased effect of WNV in these regions. The first cases of neuroinvasive WNV in India were reported in 2013-2016, later than most countries. However, children seem to succumb to the virus more frequently in India, with multiple cases of WNV isolated from brain tissue of children who died due to WNV encephalitis.17 These cases demonstrate a contradictory trend from the usual cases of older adults that only takes place in lower-income, WNV endemic regions. These findings suggest differences between regions that cause a larger impact on the pediatric populations in lower income regions. This article aims to provide an updated overview of West Nile Virus from a pediatric neurology standpoint on the characteristics, systemic and neurological symptoms, and treatment of West Nile Virus especially in low-income regions where it is most burdensome.