Seroprevalence and associated risk factors of equine herpesvirus type-1/-4 in selected districts of Northwest Amhara, Ethiopia.

Serological testing of equines in Northwest Amhara, Ethiopia revealed a high prevalence of equine herpesvirus type-1 and type-4 (EHV-1/-4), with significant differences in infection rates based on species, age, sex, and physiological status.

Study Objectives and Methods

• The study aimed to estimate the prevalence, distribution, and associated epidemiological risk factors of EHV-1/-4 infections among equines in selected districts of Northwest Amhara Region, Ethiopia.
• A total of 460 serum samples were collected from horses and donkeys using a multistage cluster sampling technique.
• Antibody detection was performed using a competitive Enzyme-linked immunosorbent assay (cELISA), a laboratory test that identifies specific antibodies indicating prior exposure to EHV-1/-4 viruses.
• Risk factors such as species, age, sex, and physiological status (e.g., lactating, pregnant) of equines were recorded and analyzed.
• Statistical analysis was conducted using R software (version 4.3.1) to identify significant associations between these risk factors and EHV seroprevalence.

Key Findings

• The overall seroprevalence of EHV-1/-4 antibodies among equids was 65.9%, indicating widespread exposure to these viruses in the study area.
• Geographical variability was observed: the Wogera district had the highest prevalence (86.1%) while Debark showed the lowest (47.4%).
• Species difference: Donkeys showed a significantly higher likelihood of infection compared to horses, with odds of 2.019 times greater.
• Age differences: Equids aged 3–8 years had the highest prevalence; those under 3 years had the lowest. This age-related prevalence difference was statistically significant.
• Sex differences: Female equines were 1.73 times more likely to be infected than males, a statistically significant difference.
• Physiological status: Lactating equids had the highest seroprevalence (81.6%), followed by pregnant (74.6%) and dry (66.4%) animals, suggesting physiological stress or immune modulation may influence susceptibility.

Interpretation and Implications

• The high overall seroprevalence indicates that EHV-1/-4 are endemic and widely distributed among equine populations in Northwest Amhara.
• Significant differences based on species, age, sex, and physiological status suggest these factors contribute to infection risk and should be considered when designing control measures.
• Higher rates in donkeys might relate to differences in management, exposure, or innate susceptibility compared to horses.
• Age-associated risk reflects that animals in prime working age (3–8 years) might be more exposed due to increased activity or longer duration of exposure.
• Lactating and pregnant females showing increased prevalence suggests reproductive status impacts immune defenses, warranting focused health management in these groups.
• Overall, the findings emphasize the need for targeted preventive strategies such as vaccination programs, improved biosecurity, and awareness campaigns to limit viral transmission in equine populations.

Conclusion

• The study documents a substantial burden of EHV-1/-4 infection among equines in the Northwest Amhara region, with important epidemiological risk factors identified.
• These findings provide essential baseline data to inform control and prevention efforts aimed at reducing equine herpesvirus infections and associated health impacts in Ethiopia.