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The ubiquitous contamination of environmental lead (Pb) remains a worldwide threat.Improper Pb mine waste disposal from an abandoned lead-zinc mine has recently unearthed a widespread Pb poisoning in children in Kabwe Zambia. Although the adverse effects of Pb on human health have begun to receive attention, the ecotoxicological effects on aquatic vertebrates still need further investigation. In addition, there is paucity in the knowledge on the behavioural and molecular subcellular responses in larval zebrafish exposed to Pb within the range of environmental relevant concentration (average 3 µg/L with maximum of 94 µg/L) on aquatic organisms such as zebrafish. The adverse effects of environmentally relevant levels of Pb on larval zebrafish was evaluated by measuring swimming behaviour under alternating dark and light conditions. Larval zebrafish acutely exposed to environmentally relevant Pb exhibited neuro-behavioural alteration including enhanced hyperactivity under light conditions evidenced by increased distanced covered and speed compared to the control. The alteration of entire behavioral profiles was further associated with the disturbed expression patterns of mRNA level of key genes associated with antioxidant (HO-1, Ucp-2 and CoxI), proapoptotic gene (TP53), and antiapoptotic gene (Bcl-2). To our knowledge, this is the first report on the effects of environmentally relevant Pb levels from Kabwe, Zambia and their adverse neurobehavioural effects and subcellular molecular oxidative responses in larval zebrafish acutely exposed within a 30 minutes period. The current results would be beneficial in our understanding of the effects of low Pb levels acutely discharged into an aquatic environment and the life of aquatic organisms.

Aim:To determine the prevalence of tuberculosis among traditional milking cows in southern Zambia and isolation of Mycobacterium spp from the tuberculin positive cow's milk. Materials and Methods:A total of 1,025 cows originating from traditional cattle sector, in Mapepe, Magoye, Monze, Batoka, GART-Batoka, Kalomo areas of Zambia, supplying major quantity of milk to milk processors, were tested for bovine tuberculosis using single comparative intra-dermal tuberculin test during 2011 and 2012. Milk samples obtained from 16 bovine tuberculin reactor cows were cultured for isolation of Mycobacterium spp and those showing growth of Mycobacterium spp. were identified through biochemical tests of the culture. Further confirmation and species differentiation of the Mycobacterium spp. isolates was done using the loop-mediated isothermal amplification system and multiplexpolymerase chain reaction Results: 27 (2.6%) of the cows tested were found tuberculin reactors, 9 cows (0.87 %) gave inconclusive reaction and 989 (96.48%) were non-reactors. Three milk samples (18.7%) out of the 16 tuberculin reactor cow's milk when cultured and upon molecular analysis, were found positive for presence of M. bovis indicating these positive cows were shedding M. bovis in their milk. Conclusion:The isolation of M. bovis in freshly drawn milk from the tuberculin positive reactor cows is being reported for the first time in Zambia. Bovine tuberculosis is an animal and human health risk in the traditional dairy herds supplying milk to the Zambian population especially in the informal market and needs attention of the public health and veterinary authorities.