INCIDENCE OF SALMONELLA SPP. IN SEWAGE AND SEMIURBAN WASTE-WATER TREATED BY POND OXIDATION METHOD AT THE UNIVERSITY-OF-THE-NORTH

The study was carried out to determine the incidence of Salmonella spp . in sewage and semi-urban waste water treated by the pond oxidation s ystem, using a Salmonella-specific DNA probe. The Salmonella specific DNA probe was labelled following the digoxigenin (DIG) standard random primed DNA labelling technique. For the detection system, both the DI G calorimetric and chemiluminescent detection systems were used. When a total of 803 samples, collected from the four oxidation ponds A, B, C, and D, the irrigation water, overflow polluted water, the stream an d the borehole; were screened using a Salmonella DNA probe, 96.4% of t he samples from oxidation Pond A, 51% from Pond B, 25.0% from Pond C, and 71.0% from Pond D, were Salmonella positive. The results also show ed that 44.1% of the water samples from irrigation water, 69.9% of ove rflow polluted water samples and 83% of stream water samples collected from pools were positive for Salmonella presence. An overall positivi ty rate of 56% on all the samples tested, was observed. Significantly, no Salmonella positive samples were observed when water samples were collected from the one borehole which serviced the villagers living ar ound the oxidation ponds. It may be concluded from these results that the treatment of sewage and semi-urban waste water, using the oxidatio n pond methods at the University of the North did not efficiently remo ve pathogenic bacteria such as Salmonella from treated effluent. The d irect or indirect use of the pond oxidation treated effluent may const itute a major source of contamination for human salmonellosis. It is r ecommended that the use of the pond oxidation treated effluent for the irrigation of the sports fields at the University of the North not be practised as it may be a source of Salmonella infection among the stu dents that use the sports fields. It may also be concluded that the bo rehole water used by the Mamotintane Villagers is safe potable water s ince no Salmonella contamination was observed. Furthermore, the overfl ow water and the stream water used by the villagers livestock could be a major source of Salmonella contamination to their livestock. The Un iversity of the North should use a pond oxidation system that has a hi gh pathogen removal efficiency in order to improve on the health of th e people and their livestock.