Parasitic Infections in a Fishing Community, Lao Pdr

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. (FBT) in Southeast Asia with respect to the number of infected people and the associated morbidity (WHO, 1995). The North and northeastern parts of Thailand, adjacent to the Lao People’s Democratic Republic (PDR), have been a major focus of infection. The baseline patterns of parasite distribution are well-documented (Jongsuksuntigul and Imsomboon, 2003; Sithithaworn and Haswell-Elkins, 2003). In northeastern Thailand, the prevalence and intensity of liver fluke infection correlates with SOUTHEAST ASIAN J TROP MED PUBLIC HEALTH 1084 Vol 37 No. 6 November 2006 the incidence of cholangiocarcinoma (cancer of the biliary tract) (Vatanasapt et al, 1990; Sithithaworn et al, 1994; Sriamporn et al, 2004). While information on the distribution of O. viverrini in other endemic countries, such as Cambodia and Vietnam, is limited, evidence for the infection in Lao PDR was available almost a decade ago, notably in communities around Nam Ngum reservoir, in the Keoudom and Thulakhom districts of Vientiane (Giboda et al, 1991a,b). Fish collected from the Num Ngum reservoir and other areas in Vientiane were also reported to harbor several types of trematode metacercariae, including O. viverrini (Ditrich et al, 1990). In addition to Vientiane, the infection was reported in Khummoune (Kobayashi et al, 1996; Vannachone et al, 1998; Kobayashi et al, 2000) and Chumpasak Provinces (Chai and Hongvanthong, 1998). A recent nation-wide survey of primary school children showed an extensive distribution of the parasite in the country and a high prevalence was found in Khummoune and other southern regions, particularly those along the Mekong River (Rim et al, 2003). This study was a part of a collaborative project between the Food and Agriculture Organization (FAO) and the Lao PDR Government on improved utilization, quality and safety of fish and fishery products. The target area was around the Nam Ngum reservoir, the main fishing area in the Lao PDR. This study aimed to determine the current epidemiological patterns of parasitic infection in a fishing community in the Nam Ngum area. MATERIALS AND METHODS Description of the study area and sample popu-