Microbial quality and associated health risks of raw milk marketed in the Tanga region of Tanzania

Abstract

Objective To evaluate microbial quality and associated health risks of raw milk marketed in the Tanga region of Tanzania. Methods A microbial quality assessment of marketed raw milk was undertaken by evaluating 59 samples of milk from selling points (collecting centres =15), bicycle boys (12) and kiosks/restaurants (32) in Tanga city during April-May 2005. Quality and milk-borne hazards were assessed using a combination of tests in order to quantify the occurrence of Brucellosis (milk ring test), Escherichia coli ( E. coli) O157:H7 (culture), the coliform bacteria as well as standard plate count (SPC). Specific gravity (SG) determination was used as an indicator of adulteration. Results The mean coliform plate count (c.f.u/mL) of milk handled by bicycle boys (4.2 × 10 6) was significantly higher than that handled by collecting centres (3.0 × 10 6) and kiosk/restaurants (1.4 × 10 6), respectively ( P < 0.05). Of the 59 milk samples collected, 33 (56%) were Brucella milk ring test (MRT)-positive and 78% and 17% of the samples graded satisfactorily based on SG and coliform plate counts as prescribed by East African Community standards for raw milk. There was no verocytotoxigenic E. coli (VTEC) O157: H7 in any of the milk samples collected and analysed during the present study. Conclusions It can be concluded that raw market milk in the study area is of poor bacteriological quality and hazardous for human consumption. This highlights the need to implement good hygiene practices and effective monitoring from production through the delivery chain to the consumer. Further studies are needed for detection of toxins that are produced by E. coli, other pathogenic spore forming bacteria ( Bacillus spp. and Clostridium spp.) and other harmful microorganisms.