West nile fever A92.3

Smithburn et al., 1940

Infectious disease transmitted by mosquitoes with the West Nile fever virus (endemic arbovirosis).

West Nile virus, Flaviviridae family, belonging to the arboviruses.

Carriers are Culex, Aedes and Mansonia species. Of particular importance are Culex pipiens, Culex quinquefasciatus, Culex restuans, Culex salinarius and Culex talsalis.

The virus mainly infects birds (ravens, crows, etc.), which, however, do not fall ill; humans, horses and other mammals are also infected.

Rarely transmitted during organ transplants.

Spread to Africa, Middle East, Southern Europe, Russia, South India, South East Asia, North America.

Severe epidemic in New York in 1999. Approximately 27,000 cases have been reported in the USA since 1999 (as of 2007), 4600 in Canada. The epidemic in the USA in 2002 resulted in 4008 clinically manifest infections with 263 deaths. The 2005 epidemic in the USA resulted in 2000 cases of the disease (55 fatalities).

Incubation period: 3-12 days.

General symptoms: fever, headache, muscle and joint pain, nausea, vomiting, diarrhea, generalized lymphadenitis. Often eye involvement. Rarely, especially in children or immunosuppressed patients, severe courses with viral meningitis.

Integument: In 50% of cases maculopapular exanthema ( viral exanthema) (mainly extremities and trunk). Occasionally severe local itching in the area of the injection site, scratch excoriations, possibly superinfections.

Serum antibodies (ELISA, immunofluorescence); cultivation.

Dengue fever and other alpha and flavivirus.

Encephalitis, hepatitis, pancreatitis, myocarditis, high mortality.

Symptomatic. In very severe cases, IVIG may be necessary.

Patients with encephalitis often suffer from neurological late sequelae (about 50% of cases). The lethality rate in manifest encephalitis is 15-40% and mainly affects older patients, immunocompromised persons, children.

Mosquito protection and control.

It is assumed that Alexander the Great had already died of the West Nile virus. 1937 First description (and naming) by illness of a woman in Uganda who lived in the West Nile area.

1. Browne C et al.(2019) West Nile fever in Europe in 2018: an emerging problem or just an anomaly? Vet Rec 185:365-368
2. Gerhardt R (2006) West Nile virus in the United States (1999-2005). J Am Anim Hosp Assoc. 2006 May-Jun;42:170-177.
3. Smithburn KC, Hughes TP, Burke AW, Paul JH (1940) A neurotropic virus isolated from the blood of a native of Uganda. Am J Trop Med Hyg s1-20: 471-492