Active Circulation of Middle East Respiratory Syndrome Coronavirus at the Camel-Human-Environment Interface in Nigeria: Evidence from One Health Surveillance

Background

Middle East Respiratory Syndrome Coronavirus (MERS-CoV) is one of the coronaviruses of greatest concern for global public health. MERS-CoV remains on the World Health Organization watch list because of its pandemic potential. The primary reservoir for MERS-CoV is the dromedary camel (Camelus dromedarius), with over 80% of the global population residing in Africa, yet surveillance remains critically limited. With growing human-animal interactions and the rising demand for camel meat and dairy products, understanding the zoonotic exposure risks, particularly among high-risk occupational groups, is critical for global health security. This study, therefore, investigated MERS-CoV exposure and its active circulation at the animal-human-environment interface in Nigeria, using One Health surveillance.

Methods

Between 2024 and 2025, nasopharyngeal swabs and blood samples (n = 479 each) were collected from dromedary camels at slaughter. Plasma samples (n = 272) were collected from abattoir workers. Environmental swabs (n = 38) were collected from abattoir hard surfaces. Serum and plasma samples were screened for MERS-CoV antibodies using camel- and human-specific commercial ELISA and virus neutralization tests (VNT). Swab samples were screened by RT-qPCR to detect MERS-CoV RNA, followed by whole-genome sequencing of positive samples.

Results

Evidence of MERS-CoV was detected across animal, human, and environmental samples. Among camels, seropositivity was 75.78%, with 91.33% (137/150) of the randomly selected samples confirmed by VNT. Viral RNA was detected in 13.9% of camel samples. In abattoir workers, seropositivity was 9.56%, with viral RNA in 2.20% of plasma samples. Environmental testing showed 2.63% MERS-CoV RNA from abattoir surfaces. Whole-genome sequencing positioned Nigerian MERS-CoV strains with those from Ethiopia and others in Clade C.

Conclusion

In Nigeria, MERS-CoV subclinical circulation is under-reported. This finding provides evidence of asymptomatic human infection and environmental contamination likely from camel saliva or excretions, and points to ongoing silent spillover. This highlights the need for strengthened biosecurity measures for camel handlers, continued genomic surveillance, and expanded integrated surveillance in the livestock population.