West Nile virus infection in children

Abstract

West Nile virus (WNV) is an emerging flavivirus responsible for an increasing number of outbreaks of neuroinvasive disease in North America, Europe, and neighboring countries. Almost all WNV infections in humans are transmitted through the bite of infected mosquitoes. Transmission during pregnancy and through breastfeeding has been reported, but the risk seems to be very low. West Nile disease in children is less common (1–5% of all WNV cases) and associated with milder symptoms and better outcome than in elderly individuals, even though severe neuroinvasive disease and death have been reported also among children. However, the incidence of WNV infection and disease in children is probably underestimated and the disease spectrum is not fully understood because of lack of reporting and underdiagnosis in children. Infection is diagnosed by detection of WNV-specific antibodies in serum and WNV RNA in plasma and urine. Since no effective WNV-specific drugs are available, therapy is mainly supportive.

Keywords:

• breast milk
• diagnosis
• encephalitis
• epidemiology
• in utero infection
• prevention
• symptoms
• West Nile fever
• West Nile neuroinvasive disease
• West Nile virus

Financial & competing interests disclosure

This work was supported by the European Commission under FP7, project number 261426 (WINGS; Epidemiology, Diagnosis and Prevention of West Nile Virus in Europe). The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

Key issues

• Almost all West Nile virus (WNV) infections in both adults and children are transmitted through the bite of an infected mosquito, mainly of the Culex genus.

• Although anecdotal possible cases of WNV transmission in utero and by breast milk have been reported, the risk of WNV transmission to the fetus during pregnancy or to the infant through breastfeeding is very low.

• WNV infection is less frequently symptomatic in children than in adults. Pediatric cases of West Nile neuroinvasive disease (WNND) account for 2–5% of all cases of WNND. Clinical presentation of West Nile fever (WNF) and WNND in children is similar to the clinical presentation in adults, but symptoms are generally milder and are followed by complete recovery. Although rare, cases of death in children with WNND have been reported.

• The incidence of WNV infection and disease in children is probably underestimated and the disease spectrum is not fully understood because of lack of reporting and underdiagnosis in children.

• Diagnosis of WNV infection in children is based on the detection of WNV-specific IgM in serum or cerebrospinal fluid (CSF), confirmed by a neutralization assay, and/or by the detection of WNV RNA in plasma, CSF, or urine.

• Supportive therapy is the standard treatment for both children and adults with WNF or with WNND. Although anecdotal cases of clinical improvement have been reported with intravenous immunoglobulins or with WNV-specific immunoglobulins (WNIG) in patients with severe neuroinvasive disease, no effectiveness of WNIG has been reported in a randomized clinical trial.

Notes