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Title: The occurrence of brucella organism contamination in raw milk marketed within Nakuru town and its environs
Authors: Achitsa, Mukulo, Margaret
Keywords: Milk
Issue Date: Aug-2006
Publisher: Egerton University
Abstract: Milk is an excellent medium for growth of a great variety of microorganisms, both saprophytes and pathogens. Brucellosis is one of the zoonoses transmitted through consumption of raw contaminated milk. Bmcellae cause abortion in animals and a severe zoonosis in human beings, characterized by fever, sweats, anorexia, fatigue, malaise, weight loss, and depression. This study was designed to investigate the incidence of Brucella species in raw milk in Nakuru municipality and its environs, and the link between raw milk and the rise in the incidences of human brucellosis. Milk samples were obtained randomly from selling points and from dairy animals from randomly selected herds were tested for the presence of antibodies and Brucella organisms. The Milk Ring Test (MRT) was used to test for the presence of Brucella antibodies in milk. Blood samples from the dairy animals were tested using Rose Bengal Plate Test (RBPT), Serum Agglutination Test (SAT) and Compliment Fixation Test (CFT). Vaginal swabs and milk from RBPT-positive animals were cultured for Brucella. Milk deliberately contaminated with Brucella organisms was divided into three experimental groups; the first was fermented spontaneously, the second using mala and the last using yoghurt starter culture bacteria. The acidity, pH levels and Brucella counts of the above milk was taken after specific time intervals of fermentation. Deliberately contaminated milk was also subjected to various heat treatments and tested to determine its safety. The results generated were analyzed using Analysis of variance (ANOVA) was done by General Linear Procedure of SPSS version 11.5 and mean separation done by Duncan’s Multiple Range Test (DMRT) at p = 0.05. All milk sampled from the infonnal market tested negative on MRT. A total of 36 animals (5.9%) out of 608 animals that were sampled were Brucella-positive. Cultures of swabs and milk were the surest method to confim presence of Bmcella in dairy animals. A pH of 3.9 and below was confirmed to kill Brucella in fennenting milk. However, fermented milk at this pH was not acceptable by most palates. No Brucella survived batch pasteurization of contaminated milk and home boiling while stirring. Milk spiked at lO7 colony forming units (cfu) of Brucella/ml, and boiled without stirring had survivors. It is recommended that milk should be boiled at 93°C and held for 3-5 minutes while stirring, before consumption or fennentation. The recommendations made are expected to improve safety of milk for all consumers and to create awareness amongst the public, academia, policy makers and small-scale milk traders. This information can be used to formulate policies that will assist in controlling brucellosis and other milk bome zoonoses.
Appears in Collections:Faculty of Health Sciences

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