Sero-prevalence and an outbreak investigation of foot and mouth disease with isolation and identification of circulating virus from cattle in selected districts of Oromia and Amhara Regional States, Ethiopia

Abstract Foot-and-Mouth Disease (FMD) is a highly contagious transboundary viral disease of cloven-hoofed animals. It is one of the most economically important animal diseases in developing countries, including Ethiopia. A cross-sectional study was conducted from March 2022 to February 2023 to estimate seroprevalence, isolate, and molecularly detect foot-and-mouth disease virus circulating in selected districts of the Oromia and Amhara regional states, Ethiopia. Multistage sampling was conducted to select the required sample size of cattle for the sero-prevalence study, and purposive sampling was used to collect field epithelial tissues and oropharyngeal fluid samples for FMDV isolation and molecular detection. A total of 654 cattle serum samples were collected and tested for antibodies against FMDV using 3ABC-ELISA. The result showed an overall seroprevalence of FMDV of 27.2% (CI = 24.0%-30.0%). The multivariable logistic regression analysis revealed that FMDV seropositivity was significantly ( P < 0.05) affected by factors such as districts, production system, herd size, and age. Cattle that were kept in large herd sizes were 2.2 times more likely to be infected with FMDV than those in small herds (OR = 2.2, 95% CI = 1.3–3.8). The odds of being positive for FMDV were also 4 times higher in cattle in the extensive production systems than in intensive production systems. From 25 epithelial tissues, which were inoculated into monolayer BHK-21 cell lines, 19 (76%) samples exhibited FMDV cytopathic effect, and viruses were isolated. In this study, three serotypes, serotype O (50%), SAT2 (42.86%), and serotype A (7.14%), were identified using antigen detection ELISA. Out of 29 samples tested by rRT-PCR, 17(58.6%) were positive for the FMDV genome with Ct values ranging from 18 to 34.1. The current study findings revealed that FMD was prevalent in the study districts. Thus, the control strategy should be designed in such a way that it includes early reporting of disease outbreaks, regular sero-surveillance, and effective targeted vaccination. Further study on sequencing and characterizing the circulating virus to a lineage level is also recommended.