Crimean‐Congo Haemorrhagic Fever Virus Exposure in Horses and Donkeys in Border Livestock Markets of Nigeria

Abstract

INTRODUCTION: Crimean-Congo haemorrhagic fever virus (CCHFV) is a tick-borne zoonotic pathogen of major public health importance in Africa. Although CCHFV exposure has been reported in several livestock species in Nigeria, data on equids remain limited despite their extensive involvement in livestock movement and trade. This study assessed CCHFV seroprevalence in horses and donkeys in major international livestock markets in northern Nigeria and examined factors associated with exposure. METHODS: From June 2023 to July 2024, a longitudinal sero-surveillance study was conducted in three high-volume livestock markets in northern Nigeria. Serum samples from 808 equids (305 horses and 503 donkeys) were tested for CCHFV-specific IgG antibodies using a commercial multi-species ELISA. Data on age, sex, origin and tick infestation status were collected. Seroprevalence was estimated with 95% confidence intervals, and associations were evaluated using univariable analyses and multilevel binomial logistic regression accounting for market-state clustering. RESULTS: Overall CCHFV seroprevalence was 23.1% (95% CI: 20.3%-26.2%). Horses had a significantly higher seroprevalence (52.1%, 95% CI: 46.3%-58.0%) than donkeys (5.7%, 95% CI: 3.7%-8.1%) (p < 0.001). In univariable analyses, seropositivity in horses was associated with age and sex, whereas no significant associations were observed in donkeys. In the multilevel model, species and age remained independently associated with seropositivity; horses had substantially higher odds than donkeys (OR = 20.91, 95% CI: 11.14-39.24), and odds increased with age (OR = 1.17 per year, 95% CI: 1.06-1.29). CONCLUSIONS: CCHFV exposure is widespread among equids in northern Nigeria, particularly in horses. These findings support the potential value of horses as sentinel species for CCHFV surveillance in livestock trade corridors. SUMMARY: Crimean-Congo haemorrhagic fever virus (CCHFV) is a tick-borne zoonotic virus of public health importance in Africa, yet data on equids in Nigeria remain limited. We assessed CCHFV seroprevalence in horses and donkeys sampled at major international livestock markets in northern Nigeria. Serum samples from 808 equids were tested using a commercial multi-species ELISA. Overall seroprevalence was 23.1% (95% CI: 20.3%-26.2%), with higher seroprevalence in horses (52.1%) than in donkeys (5.7%). In multilevel analyses, species and age were independently associated with seropositivity, while sex, tick infestation status and animal origin were not. These findings indicate widespread CCHFV exposure among equids and suggest that horses may serve as useful sentinel animals for monitoring CCHFV circulation in livestock trade corridors.