Seroprevalence, risk factors and spatial distribution of West Nile virus in Jordan.

Background: This is the first countrywide study of the seroprevalence, risk factors and spatial distribution of West Nile virus (WNV) in Jordan.

Methods: A cross-sectional sample of 801 participants was administered a comprehensive questionnaire survey and tested for WNV immunoglobulin G antibodies.

Results: The point seroprevalence rate for WNV infection was 8.61% (95% confidence interval 6.8 to 10.8). Multivariate regression analysis demonstrated that sex, age, climate, income and drinking water source were significantly associated with seropositivity (p≤0.05). Males had 1.73 greater odds of infection compared with females. Compared with 15 to 29-year-olds, adults 30-49 y old and adults ≥50 y old had 2.0 and 3.1 greater odds of infection, respectively. Individuals living in the Jordan Valley and Badia had 22.2 and 7.2 times greater odds of infection, respectively, compared with individuals living in the highlands. Households with an income of <US$750/month had 1.8 greater odds of infection compared with those with higher household incomes. Individuals using spring lakes as a drinking water source had 5.1 greater odds of infection than people who used water from any other source.

Conclusions: This study demonstrates that WNV is circulating in Jordan and should be considered as a differential diagnosis in medical cases presenting with nervous system symptoms, especially for older populations living in the Jordan Valley and Badia areas.