During the month of May, 2012, the Central Rift veterinary unit was greatly involved in laboratory analysis of buffaloes and cattle serum samples meant for bovine tuberculosis disease surveillance and research on wildlife species in the Masai Mara ecosystem. The samples were submitted to International Livestock Research Institute (ILRI), Nairobi and were analyzed in a level II biosafety laboratory. The samples were tested using gamma interferon test (Bovigam) for Mycobacterium bovis infection in animals. Biopsy tissue samples were collected from 10 non-migratory wildebeests in Oloolaimutiak area of Masai Mara. These samples were collected using biopsy darts alone without capture or immobilization of the wildebeests. Tissue samples will be used to test for genetic diversity among the wildebeests populations in the Mara-Serengeti ecosystem and other parts of Kenya.
Bovine tuberculosis Gamma interferon IFN-γ test (Bovigam) at ILRI.
Bovine tuberculosis in wildlife is a potential source of infection for domestic livestock and humans (Cleaveland et al., 2002; Michel, 2002). The disease is a threat to valuable and endangered wildlife species and has resulted in mortality and morbidity in African buffalo (Syncerus caffer; Keet et. al., 1996), lion (Panthera leo; Keet et. al., 2000b), and cheetah (Acinonyx jubatus; de Lisle et. al., 2002), in Kruger National Park, South Africa. The disease is believed to be spreading from South Africa towards East Africa through wildlife and livestock movements. This study is meant to detect any possible bovine tuberculosis infection in buffaloes and cattle of Masai Mara and Amboseli, and to validate some of the recently developed diagnostic tests particularly STAT-PAK and (Bovigam) tests for use in Kenya.
The gamma-interferon assay test (Bovigam) is a rapid blood-based assay of cell mediated immunity (CMI) for diagnosis of bovine tuberculosis in bovid species e.g buffaloes, cattle and other ruminants (Rothel et. al.,1990). The test is based on the release of IFN-γ from sensitized lymphocytes during a 1624-hour incubation period with avian-PPD and bovine-PPD. Bovine purified protein derivatives (PPD) and avian (PPD) are mixed with lymphocytes in whole blood and incubated for 16-24 hours so that lymphocytes can be stimulated to produce gamma interferon (IFN-γ) lymphokine. Blood plasma is then collected from above the cultures and assayed for gamma interferon production using monoclonal antibody-based sandwich enzyme immunoassay (EIA) kit (Jones et. al., 1992). Results are obtained by comparison of gamma interferon (IFN-γ) production following stimulation with avian-PPD and bovine-PPD.
A positive test is indicated by an increase in mean optical density of bovine-PPD plasma of atleast 0.1 units greater than avian-PPD and nil control antigen. Lymphocytes from buffaloes or cattle which are not infected with Mycobacteria bovis do not produce gamma interferon. Detection of higher levels of gamma interferon (IFN-γ) in blood plasma indicates the presence of M. bovis antibodies in the animal. The test can detect early bovine tuberculosis infections in animals before they become a source of infection for other animals and contaminate the environment, (Gormley E. et. al,. 2006). The test is easier to apply in wildlife as it requires only one capture as opposed to tuberculin skin test that requires a second capture when reading the results.
Twelve buffaloes serum samples were tested by gamma-interferon assay test (Bovigam) at ILRI but all results were negative for Mycobacteria bovis infection indicating that the Mara buffaloes could be free from bovine tuberculosis. However, further sampling and laboratory analysis are still on-going to confirm the disease status.
Collection of genetic tissue samples from wildebeests in Mara
Biopsy tissue samples were collected from 10 adult wildebeests using biopsy darts. The animals were randomly selected from a herd of about 60 wildebeests in Oloolaimutiak area of Masai Mara. The samples were then preserved in absolute ethanol solution awaiting genetic analysis. These will be analyzed together with other samples collected earlier. This investigation will provide useful information on genetic relationships among various wildebeest populations in Kenya.
Rescue of orphaned hyena cub from Ongata Naado area in Narok
A young male hyena cub of about 1 week old was rescued from the field by school children of Ongata Naado primary school in Narok. They were not able to trace its mother and reported the case to KWS Narok station to collect the cub from the school. The veterinary team from Narok responded and rescued the cub. It was extremely weak and dehydrated; it was then fed on milk and water orally. Unfortunately it died of hypovolemic shock and hypoglyceamia while being transported to Nairobi animal orphanage.
During the month of May, there were no reports of wildlife injury cases resulting from human-wildlife conflicts that required veterinary intervention. We wish to acknowledge the support of the David Sheldrick Wildlife Trust towards provision of wildlife veterinary services in Masai Mara ecosystem this has significantly contributed to the general wildlife conservation in these areas which are facing the challenge of human-wildlife conflict and loss of wildlife habitat.
Report by: Dr. Domnic Mijele
Return to the Field Report List