“…Thus, the present format of the Og4C3 antigen-detec tion ELISA, is unlikely to find a place in the commer cial field as a quick diagnostic assay for detection of Dirofilariasis, although this does not negate its relati vely good sensitivity and specificity when compared to VetRED, or its applicability in cases which require high sensitivity and specificity without time constraints on processing of samples. If we consider the prevalence of Dirofilariasis in this survey (39 %), one can assume that in the Townsville region, a general reduction in Dirofilariasis in the order of 16 % has occurred, in comparison to pre viously reported surveys were prevalence rates in the order of up to 90 % have been reported (Aubrey & Copeman, 1972;Blake & Overend, 1982;Boreham & Atwell, 1988;Bundensen et al, 1990;Carlisle, 1969;Carlisle & Atwell, 1985). The incidence of « occult » dogs also appears to be steadily rising, with 35 % of D. immitis positive cases found to be microfilariae negative in this survey.…”