Variation across studies may occur for several biological and
methodological reasons. This premise could not directly be tested
on the PCR-based prevalence data, since study-specific effects dueto method sensitivity and population-specific attributes cannot be
separated. However, using data from microscopic studies, the
degree to which the maximum optical magnification and the
number of microscopic fields screened affected observed prevalence in the same species could be assessed. The corresponding
statistical models revealed a positive relationship between
Plasmodiumspp. prevalence and the number of microscopic fields
screened when other study-specific and species-specific effects
were held constant in a GLMM (Table I). For species in the other
3 parasite genera, no significant indication for method sensitivity
was found to affect observed prevalence (Table I).