Seroprevalence of West Nile Fever and Associated Risk Factors in Livestock of Afar Region, Northeast Ethiopia

TL;DR

This study found high West Nile virus exposure in livestock in Ethiopia's Afar region, with donkeys most affected, highlighting the need for surveillance and research.

Contribution

The study provides the first detailed seroprevalence data of WNV in Afar region livestock, revealing species-specific and environmental risk factors.

Findings

WNV seroprevalence was 50.7% across 736 livestock samples, with donkeys showing the highest rate at 76.1%.

Species was the most significant predictor of WNV seropositivity, with donkeys having a seven-fold higher chance than sheep.

Environmental factors like geography and temperature were key drivers of WNV transmission in the region.

Abstract

Our study assessed the seroprevalence of West Nile virus (WNV) infection in domestic animals in the Amibara and Haruka districts of Ethiopia’s Afar pastoral region, testing 736 serum samples from camels, cattle, donkeys, goats, and sheep. The overall seroprevalence of WNV IgG antibodies was 50.7%, with donkeys showing the highest prevalence (76.1%), followed by camels (69%), cattle (52%), goats (34.7%), and sheep (25.7%). These findings revealed a significantly higher prevalence compared with earlier studies in Ethiopia and other pastoral regions worldwide. Geographical differences, favorable vector breeding conditions, and temperature were identified as key factors influencing transmission dynamics. Risk factors such as species, sex, age, and location were examined, with species emerging as the most significant predictor of seropositivity. Female animals showed slightly higher seroprevalence, and older animals exhibited lower rates. The study underscores the importance of domestic livestock as sentinels for WNV surveillance, emphasizing the implications for both animal and human health in the region. These findings provide critical insights into the transmission of WNV, species-specific variations, and the environmental factors driving its prevalence in northeast Ethiopia.

Sub-Saharan Africa has long been prone to widespread mosquito-borne diseases affecting both humans and animals. However, the presence and impact of West Nile virus (WNV) among livestock in Ethiopia have not been thoroughly investigated. The objective of this study was to investigate the seroprevalence of West Nile virus in livestock in the Afar region using serological methods. A total of 736 serum samples were collected from 224 cattle, 155 camels, 144 sheep, 121 goats, and 92 donkeys in the Amibara and Haruka districts of the Afar region selected using haphazard sampling. Among 736 tested livestock serum samples, 50.7% (373/736) showed anti-WNV IgG antibodies evaluated using the ID screen® WNV competition multispecies ELISA kits (95% CI: 47–54.4%; p < 0.01). The seroprevalence was higher (p < 0.01) in donkeys (76.1%), followed by camels (69.1%), cattle (52.2%), goats (34.7%), and sheep (25.7%). The study showed a statistically significant difference of WNV seropositivity between species of animals AOR (1.5), 95% CI (1.038–2.212) (p < 0.01). Compared with sheep, donkeys had a seven-fold higher chance of being seropositive for WNV infection (OR: 6.447, 95% CI = 3.888–10.688) (p < 0.01). This study emphasizes how common WNV infection is in Ethiopia’s pastoral Afar region. It is imperative to consider consistent surveillance of WNV infection and prompt management of identified WNV disease in clinical practice. A clear need exists to build additional research capacity regarding WNV infections among both humans and animals.

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