Seropositivity and risk factors of Brucella infection in small ruminants that had history of recent abortion in the afar region of north-eastern Ethiopia

Abstract

Background: Brucellosis is one of the most important reproductive disease causes abortion and breeding failure in small ruminants and also causes severe systemic diseases in exposed humans. In Ethiopia, several studies of seroprevalence shows the magnitude and distribution of brucellosis both in animals and humans vary in different geographical localities. However, except few studies in Ethiopia all these serological studies was limited to RBPT and CFT, so far not supplemented with a varities of serological tests like ELISA to detect brucella infection, which is increase the likehood of detecting infected individulas and also improve the reliability of epidemiological data for appropriate control strategies. Hence, the present study was conducted in Amibara district of Afar Region, Ethiopia to detect the seropositivity and risk factor of Brucella infection in small ruminants that had history of recent abortion using mRBPT, cELISA and CFT. Materials and methods: Sera were collected from 226 animals (195 goats and 31sheep) and assessed for seropositivity of Brucella infection using modified Rose Bengal Plate Test (mRBPT), Complement Fixation Test (CFT) and competitive Enzyme Linked Immuno Sorbent Assay (cELISA).Results : In this study the over all seroprevalence was 12.0% (27 out of 226), 7.5% (17 out of 226) and 26.6% (60 out of 226) by mRBPT, CFT and cELISA, respectively. Out of 27 sera which were reactive by mRBPT, 17 (63.0%) were also reactive by (CFT). Out of the 17 sera which were reactive by CFT and mRBPT, 14 (82.4%) were reactive by cELISA. Out of the 29 sera which were non-reactive both by mRBPT and CFT, 10 (34.5%) were found to be reactive by cELISA. Out of the 226 sera which were tested both by mRBPT and cELISA, 20 (8.9%) were reactive by both tests, while 159 (70.4%) were non-reactive by both tests. The percentage of test agreement (79.2%) between mRBPT and cELISA was poor (k= 0.353). A high seropositivity for Brucella infection was significantly associated with the presence of retained placenta in the study animals (adjusted OR= 2.2, 95%CI, 1.1-4.4, P=0.030) as detected by cELISA. Conclusion: The findings of this study could suggest that brucellosis is main cause of abortion and breeding failure in small ruminants that had histry of recent abortion in the pastoral communities’ andwarrants the need for proactive measures to reduce its economic impact and risk of zoonotic transmission. This study indicates that cELISA based seroepidemiological survey increase the likehood of detecting infected individulas of brucellosis and also would be useful to provide reliable evidence for Brucella infection in small ruminants compared to mRBPT.