Epidemiology of food-borne trematodes and other parasite infections in a fishing community on the Nam Ngum reservoir, Lao PDR

Abstract

Food-borne trematodes (FBT) are important causes of parasitic infections in many Asian countries. Parasitological surveys in Xai Udom, a small fishing community on the Nam Ngum reservoir, Lao People's Democratic Republic, revealed an overall parasitic infection rate in May 1999 of 68.8% (n=173) and in December 1999 of 65.9% (n=261). The liver fluke, Opisthorchis viverrini accounted for most of the infections (prevalences of 53.8% and 42.1%, during the first and second surveys, respectively). The prevalence and intensity showed increasing trends with age. Minute intestinal flukes were also present but with relatively low infection rates (3.8-10.9%). The second common group of parasites comprised soil-transmitted nematodes, Trichuris trichiura. Ascaris lumbricoides, hookworm and Strongyloides stercoralis, with prevalences of 22.4 and 17.6%, 20.8 and 8.0%, 16.8 and 13.4%, and 4.0 and 15.3% (first and second surveys, respectively). Most people had no or only light infections, with a few people having heavy infections. Coexisting intestinal protozoa were Giardia lamblia (5.2 and 4.9%) and Entamoeba coli (6.9 and 6.5%). Concurrent tapeworm infections were Taenia (1.7 and 1.1%) and Hymenolepis nana (0.7 and 0.6%) (first and second surveys, respectively). Despite the availability of effective anthelmintic drugs, the results of our study reaffirm that FBT are still a major health threat in this fishing area of Lao PDR, similar to a decade ago.