Seroprevalence of SARS-CoV-2 in Livestock in Sarawak, East Malaysia

Abstract

Livestock remain an understudied component of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) ecology in Southeast Asia despite close and frequent contact with humans in smallholder farming systems. This cross-sectional study investigated the seroprevalence of SARS-CoV-2 neutralizing antibodies in livestock in Sarawak, Malaysian Borneo. Archived plasma samples collected between June and September 2024 from 180 livestock animals, including pigs, cattle, buffalo, sheep, and goats, were obtained from the Sarawak Veterinary Diagnostic Service Laboratory and tested using the GenScript cPASS surrogate virus neutralization test (sVNT), a species-independent assay detecting antibodies that block the SARS-CoV-2 spike receptor-binding domain (RBD)–ACE2 interaction. Overall, 19.4% (35/180) of samples were seropositive using the manufacturer-recommended cut-off. Seroprevalence varied significantly by species, with the highest prevalence observed in goats (48.6%), followed by sheep (28.6%), cattle (11.4%), buffalo (8.3%), and pigs (2.6%), and also differed by sampling location but not by age group or sex. Most positive samples exhibited low-level inhibition values near the assay cut-off, suggesting weak or transient neutralizing antibody responses. Multivariable logistic regression identified species as the primary factor independently associated with seropositivity. Collectively, these findings are consistent with sporadic spillback exposure of SARS-CoV-2 from humans into livestock in Sarawak, without evidence of widespread or sustained transmission among livestock populations. Periodic, risk-based surveillance of livestock remains warranted to monitor potential changes in host susceptibility as SARS-CoV-2 continues to evolve.