Relationship between faecal egg count and worm burden of Opisthorchis viverrini in human autopsy cases

Abstract

The relationship between faecal examination for egg output and worm burden of Opisthorchis viverrini in man of 181 autopsy cases from Northeast Thailand is described. Diagnosis of the parasite infection by stool examination for the presence of eggs was less sensitive than the worm recovery technique. Using Stoll's dilution and formalin-ether technique, no eggs were detected in the faeces of 20 cases harbouring low worm burdens (less than 20 worms). The quantitative faecal egg count by Stoll's dilution technique showed a strikingly close positive correlation with the number of worms recovered (r = 0.96, P less than 0.001) indicating a strong linear association between eggs per gram of faeces (epg) and worm burden. The number of epg per worm was inversely correlated to the worm burden (P less than 0.001), suggesting that density-dependent constraints on fecundity could operate to restrict egg output in heavy infections. The accuracy of egg counts for estimating worm burden and its relevance to parasite epidemiological research are discussed.

Bovine fasciolosis: prevalence, relationship between faecal egg count and worm burden and its economic impact due to liver condemnation at Rudsar abattoir, Northern Iran

“…When the density of the worms was high, the egg production was high. Similar results in a study on Opisthorchis viverrini were obtained by Sithithaworn et al (1991).…”

Diversity of human intestinal helminthiasis in Lao PDR

“…Very similar linear regression lines were described in Thailand. 33,34 Hence, we can confirm that egg counts are a valid proxy measure for intensity of infection with O. viverrini. In addition, similar to Elkins et al, 33 we also found a decreasing fecundity of O. viverrini with increasing worm burden, a phenomenon that may reflect density-dependent constraints on fecundity.…”

“…In addition, similar to Elkins et al, 33 we also found a decreasing fecundity of O. viverrini with increasing worm burden, a phenomenon that may reflect density-dependent constraints on fecundity. 34,35 Our validation of a commonly employed faecal concentration technique with results of the purging examination, the latter serving as a diagnostic 'gold standard', showed high sensitivity and specificity for diagnosis both of O. viverrini and MIFs. Our findings therefore support the use of FECT in future studies emphasising parasite speciesspecific diagnosis.…”

Improvement of PCR for Detection of Opisthorchis viverrini DNA in Human Stool Samples

“…The finding of PCR positive results in egg-negative samples is in concordance with the monoclonal-antibody-based coproantigen detection method, which also demonstrated positive reactions in eggnegative cases (11). Moreover, in an autopsy study, only 30% of the people who harbored fewer than 10 adult O. viverrini worms excreted eggs that were detectable in their feces while the majority of them (70%) were egg negative (13). That we obtained PCR-positive results with apparently egg-negative samples suggests that diagnosis by our PCR method is more sensitive than the fecal examination method, particularly in the light infection group.…”