prevalence A total of 250 hemolymph pooled samples from 750 organisms (50 pools per hatchery) were analyzed in thisstudy. Viral prevalence of each commercial hatchery wasestimated by using the online pooled prevalence for fixedpool size and tests with known sensitivity and specificity(method 4, which assumes a fixed pool size and that test sensitivity and specificity are known exactly) of the Epi-tools epidemiological calculators