Refusal to take ivermectin: the associated 'risk' factors in Hoima district, Uganda

Community-directed treatment with ivermectin (CDTI), for the control of onchocerciasis, was launched in Uganda in 1997. In East Africa, as in other endemic areas, the refusal to take the drug reduces treatment coverage and therefore poses a serious threat to attempts to eliminate onchocerciasis as a disease of public-health importance. In early 2003, an attempt was therefore made to determine the factors associated with refusal to take ivermectin during mass treatment in 2002, by interviewing the individuals, from three Ugandan villages with CDTI, who had been eligible to receive ivermectin. The subject's socio-demographic characteristics, history of adverse reactions and participation in CDTI-related activities were explored, as potential 'risk' factors for refusing ivermectin in the treatment round in 2002. When odds ratios (OR) for refusal and their associated 95% confidence intervals (CI) were calculated, the villagers aged 18-35 years were found more likely to have received ivermectin in 2002 than their older counterparts (OR = 0.55; CI = 0.33-0.93). Individuals with an inter-current medical condition were also more likely to have received ivermectin in 2002 than the other villagers (OR = 0.56; CI = 0.32-0.99). Worryingly, the ingestion of ivermectin at any time before the 2002 treatment round was strongly associated with refusal to take ivermectin in that round (OR = 7.72; CI = 2.00-29.81), although there was no evidence that the adverse effects of treatment were significantly reducing coverage.