a1 Departments of Parasitology, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand
a2 Microbiology, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand
a3 The Tropical Health Program, Queensland Institute of Medical Research, Bramston Terrace, Brisbane, Australia
Three techniques for estimating the intensity of Opisthorchis viverrini infection in individuals from a Northeast That community are compared. Egg counts were determined using a quantitative formalin/ethyl acetate technique, worm burdens were estimated by expulsion chemotherapy and antibody levels were measured by ELISA. Log-transformed worm and egg counts were closely correlated (r = 0·80), suggesting that both measurements provide good assessments of relative intensity of infection. However, no Opisthorchis worms were recovered from 34 people with high egg counts; probably due to problems with the expulsion technique in some individuals. Examination of egg production per fluke indicated that each fluke contributed an average of 180 eggs per gram (epg) of faeces and fecundity was negatively associated with total worm burden. Serum IgG levels correlated significantly with Opisthorchis egg count (r = 0·61) at two independent assessments. Although significant associations were observed between antibody levels and echinostome infection, analysis suggested that these reflected independent associations between these two variables and Opisthorchis infection and age. We conclude that all three measurements are useful for epidemiological studies.
(Received June 23 1990)
(Revised October 02 1990)
(Accepted October 02 1990)
* Reprint requests to Dr David Elkins, P.O. Box 108, Khon Kaen 40000, Thailand.