Listeria Contamination of Raw Bovine Milk and the Factors Influencing Its Occurrence in Greater Luweero District, Uganda

Aim: To establish the occurrence of Listeria contamination of raw bovine milk and the contributory factors in Greater Luweero.

Methods: A cross-sectional study was carried out during 2013; in Luweero, Nakaseke and Nakasongola districts, in Central Uganda. All the 16 milk collecting centers in the study area were sampled and the supplying farms identified for trace back. A total of 100 bulk raw milk samples, each representing a farm, were analysed using the VIDAS® Listeria monocytogenes II (LMO2) enzyme-linked fluorescent immunoassay (ELFA) kit (BioMérieux, Durham NC, USA). The supplying farms were systematically random sampled; and the managers together with those of the milk collecting centers were interviewed to establish the management practices and environmental risk factors associated with Listeria contamination of the milk.

Results: High level of Listeria contamination of raw milk from farms (72%); knowledge gap and significant non-adherence to milk trade guidelines (50% and 31.25%; and 88% and 39% among milk collecting center and farm managers, respectively) were encountered. Among the factors influencing occurrence of Listeria in raw milk, the significant ones (P=.05) included improper hygienic practices; such as poor faecal disposal, improper cleaning of milking utensils and of hands before milking; and non-adherence to Dairy Development Authority (DDA) guidelines; lack of access to dairy extension services; and absence of farm entry restriction and biosecurity measures.

Conclusions: There is a high occurrence of Listeria contaminated raw bovine milk from farms in Greater Luweero district. The risk factors that were significantly associated with the contamination can be minimized through sensitization and training of farmers and center managers. Listeriosis is of great public health significance, hence effective inspections to assess compliance to guidelines for quality and safety is recommended. Establishing Listeria monocytogenes carrier status of cattle; and microbial levels in milk will inform on policies for prevention of contamination.