Reinfections and Incidence of Helminthiasis in Thailand, 1999-2000

Abstract

Abstract

A countrywide investigation to determine the helminthiasis infection situation in terms ofreinfection and incidence was carried out in 1999-2000. Liver fluke and hookworm were twomajor parasitic diseases for study.Samples consisted of 1,692 individuals living in 8 provinces, 62 villages throughout Thailand,obtained by semi-purposive sampling technique. All individuals had stool examinations in 1999. Ofthose samples, 835 were positive for liver flukes or hookworm eggs. The remaining 857 persons hadno liver flukes or hookworm eggs in their stools.Stool samples were collected from selected subjects, together with personal interviews to gatherinformation on individual bio-social and health-risk behaviors. Kato’s thick smear technique wasused for detection of helminth eggs and Katz’s modified thick smear technique used for egg counts.The results showed that the monthly reinfection rates (MRR) of liver flukes and hookworms were13.1% and 1.4%, respectively; whereas the monthly incidence rates (MIR) of liver flukes andhookworms were 12.4% and 1.4%, respectively. The findings also indicated notably high health-riskbehaviors for infection and transmission of the two helminths. With such high liver fluke reinfectionrates throughout the country, the prevalence of this disease will return to the same high level in onlyone year, while hookworm infection would possibly take a few years to return to its prior level.

Keywords : liver fluke infection, hookworm infection, prevalence rate, intensity, reinfection rate,incidence rate