First detection of West Nile virus seropositivity in horses in southern Iraq

West Nile virus (WNV) circulates between birds and mosquitoes, with horses and humans as incidental dead-end hosts. Despite documented cases in neighboring countries and human cases in southern Iraq, no previous studies have investigated WNV in Iraqi horses.

To determine the seroprevalence of WNV in horses from three southern Iraqi governorates (Thi-Qar, Misan, and Basrah) between March and June 2024.

Blood samples were collected from 236 horses regardless of age, sex, or health status. Serum samples were analyzed using commercial competitive enzyme-linked immunosorbent assay kits to detect specific anti-Pr E IgG and IgM antibodies.

The overall IgG seropositivity rate was 30.08%, with similar rates reported for Misan (30.66%), Basrah (30.12%), and Thi-Qar (29.48%). IgM seropositivity was 11.86% overall, with 14.67%, 7.22%, and 14.1% in Misan, Basrah, and Thi-Qar, respectively. No statistically significant differences were observed among governorates (p > 0.05). Females had a slightly increased positivity rate (42.7%) when placed alongside males (38%), and with respect to age, the positivity rates for three distinct age categories: 1 to 2 years (no.64), 2 to 5 years (no.135), and above 5 years (no.37) were recorded as 45.31%, 41.48%, and 37.83%, respectively.

This is the first study to demonstrate WNV seropositivity in Iraqi horses, revealing active virus circulation in southern Iraq, particularly in marshland areas suitable for mosquito vectors and migratory birds. The findings highlight the need for surveillance programs and preventive measures to control WNV transmission throughout the region.