Seroprevalence of brucellosis in small ruminants and related risk behaviours among humans in different husbandry systems in Mali.

Abstract

Mali has a high pastoral potential with diverse coexisting production systems ranging from traditional (nomadic, transhumant, sedentary) to commercial (fattening and dairy production) production systems. Each of those systems is characterised by close interactions between animals and humans, increasing the potential risk of transmission of zoonotic diseases. The nature of contact network suggests that the risks may vary according to species, production systems and behaviors. However, the study of the link between small ruminants and zoonotic diseases has received limited attention in Mali. The objective of this study was to assess brucellosis seroprevalence and determine how the husbandry systems and human behaviour expose animal and human to infection risk. A cross-sectional study using cluster sampling was conducted in three regions in Mali. Blood was collected from 860 small ruminants. The sera obtained were analysed using both Rose Bengal and cELISA tests. In addition, 119 farmers were interviewed using a structured questionnaire in order to identify the characteristics of farms as well as the risk behaviors of respondents. Husbandry systems were dominated by agro-pastoral systems followed by pastoral systems. The commercial farms (peri-urban and urban) represent a small proportion. Small ruminant individual seroprevalence was 4.1% [2.8-5.6% (95% CI)]. Herd seroprevalence was estimated at 25.2% [17.7-33.9% (95% CI)]. Peri-urban farming system was more affected with seroprevalence of 38.1% [18.1-61.5 (95% CI)], followed by pastoral farming system (24.3% [11.7-41.2 (95% CI)]). Identified risk behaviors of brucellosis transmission to animals were: exchange of reproductive males (30.2%); improper disposal of placentas in the farms (31.1%); and keeping aborted females in the herd (69.7%). For humans, risk factors were: close and prolonged contact with animals (51.2%); consumption of unpasteurized dairy products (26.9%); and assisting female animals during delivery without any protection (40.3%). This study observed a high seroprevalence of brucellosis in small ruminants and also identified risky practices that allow cross transmission between the two populations. This calls for control strategy using a multi-sectoral and multidimensional approach.