Schmallenberg virus exposure in camels and donkeys: Potential reservoirs for trans-border spread in the Nigeria-Sahel region

Livestock trade and altered migration patterns have influenced the spread of transboundary animal diseases (TADs). Schmallenberg virus (SBV), an emerging arboviral pathogen transmitted by biting midges, causes severe birth defects and abortions, transient fever, diarrhea, and reduced milk production in ruminants, exemplifying a global threat to domestic livestock populations. This study investigated the exposure of camels and donkeys to SBV and identified potential risk factors that may influence introduction and spread. A total of 460 serum samples from camels (n=230) and donkeys (n=230) were screened for SBV antibodies using a commercial enzyme-linked immunosorbent assay (ELISA), and data on potential risk factors were collected. The observed seroprevalence of SBV was 56.5% in camels and 11.3% in donkeys. Univariate analysis demonstrated a significantly higher seroprevalence in older camels (P = 0.008; odds ratio (OR) = 2.3; 95% confidence interval (CI): 1.25-4.27) and donkeys (P = 0.004; OR = 3.41; 95% CI: 1.48-7.97). Seropositivity was not significantly influenced by sex, management system, or mixed species rearing. Multivariable analysis revealed geographic clustering of infection risk, with significantly higher odds of seropositivity in camels from Zangon Daura (OR = 4.73; 95% CI: 1.33-20.4) and donkeys from Sule Tankarkar (OR = 4.46; 95% CI: 1.20-17.9). Our findings suggest that camels and donkeys are exposed to SBV and might serve as reservoirs and potential sources for spread within the region. Further molecular studies are recommended for a deeper understanding of SBV transmission dynamics.