Milk Contamination and Prevalence of Escherichia coli O157:H7 in Kwara State, Nigeria

Introduction: Milk handling and milking practices in the Nigerian informal sector are done commonly without observing hygienic practices of vended cattle milk, and this is a threat to food safety and public health. However, empirical evidence to confirm quality of milk produced by local processors is lacking.

Purpose: A cross-sectional study was carried out to determine the quality and prevalence of Escherichia coli O157 in raw cattle milk processed and vended in Kwara state, Nigeria.

Methods: Total aerobic plate count (TAPC), Total coliform count (TCC), Methylene blue reductase test (MBRT), and California mastitis test (CMT) were carried out to determine the quality and wholesomeness of randomly collected raw cattle milk (n=552), across various markets (n=10) in the major zones (Central, North, and South) of the state. Isolation of E. coli was done using standard microbiological procedures while presence of the E. coli O157: H7 was confirmed with serology.

Results: Mean TAPC ranged from logcfu 8.5±1.4 to log cfu 11.5±0.6 while all TCC were higher than log cfu five. CMT revealed that 58.5% and 41.5% of milk samples were positive and negative respectively for mastitis causing organisms. The overall prevalence of E. coli was 38.3% and 1.3% for E. coli O157:H7. The prevalence (43.2%) of isolated E. coli was significantly higher (P<0.05) in the North than other zones.

Significance: Our study determined the presence of pathogenic E. coli and largely poor quality of vended raw milk in the markets. In view of public safety, the need to demonstrate a high level of hygienic practice during milk processing and enlightenment of processors on the need for standard hygiene is required.