Foot and mouth disease (FMD) epidemiology in small ruminants by identifying antibodies for non-structural and structural proteins with a sequential screening approach: A cross-sectional study

Abstract

Foot and Mouth Disease (FMD) is a transboundary animal disease that causes major economic losses to the livestock industry in developing countries like Pakistan. In this cross-sectional study, a total of n = 315 serum samples were collected from 92 FMD unvaccinated sheep and goats flocks among three districts (Chakwal, Dera Ghazi Khan, and Jhang) of Punjab province, Pakistan. These serum samples were subjected to FMD NSP (3ABC) ELISA test to estimate the seroprevalence of FMD NSP antibodies due to previous infection, and the results showed the overall seroprevalence of NSP antibodies as 31% (95% CI, 26–36) at the animal and 50% (95% CI, 42–59) at flock level. The univariate analysis showed that the introduction of new animals in a flock was found as a potential risk factor OR: 10 (95% CI: 1.4–74) for FMD NSP antibody positivity in small ruminants (sheep and goats). In the final logistic regression model district and the age of animals were found as statistically significant (p = <0.05) risk factors for FMD NSP seropositivity in small ruminants. Among the positive FMD NSP sera, 90 samples were screened for serotype-specific FMD SP antibodies (O, A, Asia-1) by SPCE FMD SP antibodies ELISA tests. The SP antibodies ELISA results showed that 71% (64/90) NSP-seropositive samples were also found positive by at least one SP antibodies ELISA test. The descriptive analysis revealed serotype “O” as the most prevalent serotype with an overall prevalence of 44% (40/90), however, the other serotypes (A and Asia-1) were also identified from all the study districts. The descriptive analysis and ANOVA results showed that the samples with higher mean percentage positive (PP) values for the NSP ELISA test are significantly more positive for FMD SP antibodies ELISA test in a sequential testing approach. In spite of the small sample size, this study provides valuable insight into the epidemiology of FMD in small ruminants.