Zero-inflated negative binomial regression of post ivermectin microfilarial density in ivermectin-naïve and multiply treated subjects.

*Results are presented as incidence rate ratios (IRR) for the negative binomial model. For quantitative variables (e.g. age), IRR is the ratio of mean O. volvulus microfilarial density when explanatory factor is [x+1] to mean microfilarial density when explanatory factor is [x] (holding all other variables constant). For qualitative variables (e.g. study group) the IRR is the ratio of mean microfilarial density for that category compared to the baseline category. ¶Baselines for categorical variables are Date of follow-up = D15 and Study group = ivermectin-naïve.