Quantitative risk modelling of human rabies in Ghana and Nigeria associated with West/Central African dog-trade.

backgroundThe practice of dog trade and butchery for human consumption is documented in some countries in Africa. Increasing demand for dog meat has resulted in increased transboundary movements of trade-dogs, which creates opportunities for the potential transmission of rabies. This study estimated the probability of rabies virus introduction into the dog slaughter environment, exposure among dog butchers, and the effectiveness of risk mitigation measures in Ghana and Nigeria.

methodsWe developed Quantitative Risk Analysis models for Ghana and Nigeria due to active within-country and transborder dog trade in both countries. The models quantified the risk of acquiring rabies among dog butchers in these countries and evaluated risk mitigation options, including butchers' vaccination, education, use of personal protective equipment (PPE), and dog vaccination. The models were parameterized based on data from published reports on activities related to dog trade and butchery and live interviews with butchers in selected dog markets. Experts' opinions were used for data triangulation, and sensitivity analyses were performed for variables in the models.

resultsEncounters with rabid dogs were much higher with the inclusion of transboundary dogs compared to in-country dogs only. This increased the probability estimates of rabies infection among butchers by 66.2% (6.5 to 10.8/850 butchers/yr) and 238.2% (16.5 to 55.8/1,750 butchers/yr) in Ghana and Nigeria, respectively. The probability of bite and consequent infection risk were key drivers of uncertainty in the models. Vaccination of 70% of the dog population as recommended by the World Health Organization could reduce butcher infections by 62% and 70% in Ghana and Nigeria, respectively. In comparison, appropriate post-exposure vaccination of butchers would reduce infections by 100% in both countries. Where optimal dog vaccination and subsidized butcher vaccination are nonexistent due to cost and other logistics, continuous butcher education combined with enforced use of PPE could drastically reduce exposure risk.

conclusionCreating awareness of the importance of dog trade and butchering as potential occupational sources of rabies transmission, and regulation of dog trade in affected countries are critical for the realization of the global target of "Zero Dog-Mediated Human Rabies by 2030".