A survey of zoonotic diseases in trade cattle slaughtered at Tanga city abattoir:a cause of public health concern

Objective:To estimate the prevalence of hydatidosis,cysticercosis,tuberculosis,leptospirosis,brucellosis and toxoplasmosis in slaughtered bovine stock(aged≥3 years)at Tanga city abattoir,Tanzania.Methods:Prevalence estimation of the five zoonotic diseases was undertaken through an active abattoir and sero-survey was carried out in Tanga city,during the period of January 2002and March 2004.Serum samples collected from a sub-sample(n=51)of the slaughter stock were serologically screened for antibodies against brucellosis,leptospirosis and toxoplasmosis using Rose Bengal plate test,microscopic agglutination test(for 5 serovars of Leptospira interrogans)and Eiken latex agglutination test,respectively.The same animals were tested for tuberculosis using the single intradermal tuberculin test.Results:Post mortem examination of 12 444 slaughter cattle(10 790 short horn zebu and 1 654 graded)over a period of twenty two months,showed a prevalence of 1.56%(194)for hydatidosis,1.49%(185)for cysticercosis and 0.32%(40)for tuberculosis.In all three zoonoses,a statistically significant difference in infection rates was noted between the short horn zebu and graded breeds(P<0.05).The overall seroprevalences of animals with brucellosis,toxoplasmosis and leptospirosis antibodies were found to be 12%,12%and 51%,respectively.The most common leptospiral antibodies detected were those against antigens of serovars Leptospira hardjo(29%),Leptospira tarassovi(18%),Leptospira bataviae(4%)and Leptospira pomona(0%).With regard to tuberculosis,10%(n=5)of the animals tested were classified as non-specific reactors or inconclusive.Conclusions:The study findings suggest that brucellosis,toxoplasmosis and leptospirosis are prevalent in Tanga and provide definitive evidence of slaughtered stock exposure to these zoonotic agents with concurrent public health consequences.

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

Objective:To evaluate micmbial 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 milkborne 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 coliforra 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.