On allowing for diagnostic imperfections in assessing effectiveness of treatment for Schistosomiasis.

Some possible effects of misdiagnosis for Schistosomiasis in epidemiological measurements are investigated. With greater chances of misdiagnosis for lower prevalence levels, expectations of control programmes might be reassessed. As prevalence decreases, the fraction of missed positives over all apparent negatives need not uniformly decrease. In control situations even perfect treatment rates may produce very small changes in prevalence and other indices of infectivity level.