Seroprevalence of peste des petit ruminants in small ruminants in Koinadugu district, Sierra Leone

Abstract

Background: Peste des petits ruminants (PPR) is an infectious viral disease that impacts small ruminants. Globally, 62.5% of small ruminants are at risk of PPR, with an estimated impact of two billion United States dollars. In 2022, PPR vaccination campaigns administered 24,230 doses (< 50% of the population) to small ruminants in Koinadugu district, Sierra Leone. However, in 2023, the district reported 600 PPR cases and 250 deaths, according to the National Integrated Animal Disease Surveillance Reporting System database. Currently, the prevalence of PPR remains unknown in the district. Therefore, the study aimed to determine the PPR seroprevalence among small ruminants in the Koinadugu district.

Methods: A cross-sectional study on small ruminants was conducted in Koinadugu district from May to October 2024. Multi-stage sampling selected chiefdoms and study animals using balloting. Sera were analysed at the Central Veterinary Laboratory using the blocking ELISA kit from the African Union Pan-African Veterinary Vaccine Center. Ethical approvals were obtained from the Sierra Leone Ethics and Scientific Review Committee SLSERC 018/02/2024, the Faculty of Veterinary Science Research Ethics Committee (REC026-24), and the Animal Ethics Committee (AEC026-24) at the University of Pretoria. Electronic data in Microsoft Excel was analysed using STATA version 16. PPR seroprevalence in small ruminants was assessed using a chi-square test at the 5% significance level.

Results: A total of 211 blood samples were collected, of which 131 (62.09%) were from goats and 80 (37.91%) were from sheep. Ninety-one (91) serum samples tested positive for PPRV antibodies, yielding an overall prevalence of 43.0%. The majority of the sampled small ruminants were goats (n = 131, 62.09%), female (n = 161, 76.30%), and a local breed (n = 156, 73.93%). The animals sampled from the Sengbeh chiefdom were 153 (72.51%) compared to the Yagala chiefdom (n = 58, 27.49%). Regarding the chi-square test of association, age (X2 4.4902, P < 0.034) and chiefdom (X2 16.3471, P < 0.001) were significantly associated with PPR infection. However, sex, species, and breed types were not significantly associated with PPR infection.

Conclusion: Peste des petits ruminants antibodies are common among small ruminants in the Koinadugu district. Age and chiefdoms are associated with their presence. Sierra Leone's government should strengthen PPR control and collaboration with the private sector and neighbouring countries.