Factors associated with occurrence of Listeria monocytogenes in raw milk from cattle in greater Luweero District.

Abstract

Listeria monocytogenes is not only a human food-borne pathogen, but also causes disease in a number of animal species, most commonly in farm ruminants. The pathogen is important when considering public health and it causes severe illnesses associated with the contamination of various categories of foods, including dairy products. In Greater Luweero (Luweero, Nakaseke and Nakasongola districts), in Uganda, dairy production is one of the major agricultural activities with a large proportion of milk consumed locally in unpasteurized form, while the rest is sold to milk collecting centres and processing plants. Hence, there was need to study occurrence of L. monocytogenes in raw milk and the associated factors in order to map out mitigation measures for the problem. The research was conducted from February 2013 to April 2013. The main objective was to obtain information on the occurrence of Listeria monocytogenes in raw cattle milk from the three districts in order to map out mitigation measures for controlling the food-borne illnesses. The specific objectives were: to determine the prevalence of Listeria monocytogenes in raw cattle milk and identifying farm management practices that were responsible for contamination of milk with Listeria monocytogenes, establishment of existing knowledge and adherence to guidelines and rules set by Dairy Development Authority. The research was a cross-sectional study at collecting centers and farm level. The milk samples were collected for microbiological analysis while the management practices and environmental risk factors for the contamination of milk were established using questionnaires and a checklist. Listeria monocytogenes was detected in 72% of raw milk samples and the factors that were associated with the contamination included improper faecal matter disposal, use of untreated water sources, use of un-boiled water without disinfectants and soap in cleaning utensils and hands before milking, lack of established milking parlours and absence of farm entry restriction and biosecurity measures. Of the 16 milk collection centre managers, (50%) knew the guidelines and had copies of the document though 62.5% never adhered to them while majority of the farm managers (88%, n=100) knew the guidelines; but 55.7% were not adhering to the guidelines or partially neglected some. There was a high prevalence of Listeria monocytogenes contamination of milk on farms; and knowledge gap regarding milk trade guidelines, and significant non-adherence to guidelines were encountered. Hence, there is need to sensitize and train farmers concerning the guidelines, effective Ministry of Agriculture, Animal Industry and Fisheries Veterinary and Dairy Development Authority inspections and undertaking studies to assess the carrier status of cattle for a possibility of establishing the L. monocytogenes shedders; and the admissible levels of the pathogens in milk therefore reduce on the level of milk contamination as well as assessing the human listeriosis disease burden in Uganda with identification of prevailing risk factors for this zoonosis.