Brucellosis in livestock in and near the Maasai Mara national reserve in Kenya : seroprevalence and possible impact on animal and human welfare

University essay from SLU/Dept. of Clinical Sciences

Abstract: Brucellosis is caused by bacteria from the genus Brucella. The disease occurs worldwide and is of major importance in domestic animals, both for socio-economic reasons and because of the impact on animal and human welfare. Disease control programs in low-income countries are either inadequate or non-existent; a reason why brucellosis has got the chance of being as widely spread as it is as present. Not only does Brucella infect domestic animals, it also occurs in wildlife species, thus there is a risk of transmission between wild animals and domestic livestock in areas where these animal groups get in contact with each other. Many Brucella species in animals are proven to have the ability to also infect humans, causing human brucellosis, with different degrees of severity. The Maasai Mara ecosystem, in Narok County Kenya, is part of the arid and semi-arid lands which form about 80% of Kenya’s landmass that support wildlife and livestock farming. Approximately, 68% of Narok County is rangelands with conservancies such as Lemek, Mara North, Koiyaki, Mara-Naboisho, Ol Kinyei, Olare Orok, Motorogi and Olarro which offer prime grazing for ranching and livestock production. While crop failure is common in many arid and semi-arid areas, livestock farming assumes a significant role. Maasai Mara is a well-known area, housing one of the most famous national reserves in Kenya and is surrounded by pastoral landscapes that are shared between wildlife, livestock and people. Such wildlife-livestock overlap may expose livestock to novel pathogens of wildlife origin and consequently reduce the food security of the Maasai pastoralists who derive their livelihood from livestock farming. A majority of livestock keepers in and around Maasai Mara depend entirely on livestock production for their livelihood and families’ survival. By living in an area like the Maasai Mara, pastoralists have to settle for a limited agricultural practice due to wildlife occupying large areas, and also endure their livestock commingling with wildlife in search for pasture land and water sources, throughout the year. By mixing wildlife and livestock there is an increased danger of disease transmission, and the presence of zoonotic diseases, such as brucellosis, around the Maasai Mara may serve as a source of cross-transmission of disease not only between wildlife and livestock but also between livestock and humans. The aim of this study was to investigate the seroprevalence of Brucella spp. in cattle in wildlife/livestock interfaces. A questionnaire was handed out to all participating farmers, including questions about animal keeping and management, experiences of wildlife contact and observed symptoms of disease in both livestock and people handling livestock, etc. Blood samples were collected from 225 cattle, from three villages with different distances to the Maasai Mara, and that engage in different strategies for grazing, allowing the animals to come in contact to wildlife to various extent. The purpose was to examine whether different farming strategies and the distance to wildlife-dense areas affect the incidence of infectious diseases. Antibodies against Brucella abortus was found, using ELISA, in 12.44% of the 225 sampled animals, with more females being infected than males (15% and 5%). Cattle from farms closer to Maasai Mara had a significantly higher prevalence of antibodies against Brucella spp. in serum (7.03 times higher odds of Brucella infection in Mara Rianta compared to Endoinyo Narasha, p=0.003), suggesting that a closer contact with wildlife may pose a risk of being afflicted by infectious diseases to a greater extent. Symptoms consistent with brucellosis were reported to occur in both humans and animals. By studying the seroprevalence of a contagious and zoonotic disease as brucellosis, one may gain understanding of the disease extent as a whole, help identify mitigation strategies, and thereby improve both health and economic circumstances for affected farmers.

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