Patterns of emergence and circulation of West Nile Virus in Algeria

In recent years, many countries have experienced increased outbreaks of vector-borne diseases, such as West Nile virus (WNV). WNV is primarily transmitted to humans by the bite of infected Culex mosquitoes and has an enzoonotic transmission cycle involving birds. In Algeria, serological evidence of WNV in humans dates back to the 1970s, but circulation patterns are poorly characterized. To address this, we conduct a cross-sectional seroprevalence survey of WNV in humans and fit serocatalytic models to the data. We also analyze data on severe WNV cases. In this study, we report a seroprevalence of 16.7%. We identify age, region, and residence type as risk factors for infection. We also show that patterns of spread in two provinces in the south are consistent with low level endemic risk over decades, while those from three provinces in the north are all consistent with single outbreaks that occurred within the last 10-15 years. An outbreak may have occurred in Oran in 2010 and in Jijel and Tizi Ouzou near the time of data collection in 2017 and 2018, respectively. Investigation of potential drivers of viral establishment, along with continued surveillance of WNV cases, especially in the northern provinces, is warranted.