Intestinal Helminthiasis in Southern Vietnam

A program to control intestinal helminth infections, based on stool surveys, mass treatment of children below 17 years, improvement of sanitation and health education was performed between 1997 and 1999 in Phan Tien, an ethnic minority community in mountainous southern Vietnam. Before intervention, 28.6% of children excreted eggs of at least one parasite, hookworm being the most common (23%), followed by Trichuris trichiura (1.9%), Hymenolepis nana (1.9%), Enterobius vermicularis (0.9%), Ascaris lumbricoides (0.5%), and multiple kinds of helminthes (0.5%). Strongyloides stercoralis was never detected. Poor sanitation and personal hygiene, and walking barefoot were considered the main risk factors for intestinal helminth infections. The success of 400 mg albendazole single dose mass treatment was initially frustrated by the poor quality of the drug formulation used, only containing half of the indicated amount of albendazole. Using another formulation quickly reduced the hookworm infection rate. Praziquantel was used to treat H. nana infections. After three years of intervention, intestinal helminth infections were reduced to 3.3% (p<0.0001). We conclude that interventions combining health education, improvement of sanitation and mass treatment effectively control intestinal helminth infections, but the quality of the drugs used is an important factor. al, 1997) but usually IHI evolves slowly and gradually and remains asymptomatic or mildly symptomatic. Consequently, the detection and treatment of IHI are often neglected, giving way to a large burden of silent infection, especially in children. This may result in chronic anemia, reduced physical fitness and activity, impaired school performance, increased susceptibility to infection, and retarded growth in children (Dallman et al, 1980; Stephenson, 1987; Pollitt et al, 1989; Soewondo, 1995). To assess the prevalences of infection by the different intestinal helminthes in Phan Tien, and to determine the appropriate interventions, repeated surveys were conducted from 1997 onwards. MATERIALS AND METHODS Population and study site Phan Tien, an ethnic minority community, is situated in Bac Binh District, in the mountainous part of Binh Thuan Province, in southern Vietnam. In three years (Apirl 1997-DecemSOUTHEAST ASIAN J TROP MED PUBLIC HEALTH 624 Vol 36 No. 3 May 2005 ber1999) the population increased from 907 to 1,083 subjects, by immigration and a high birth rate (3.2% per year), approximately half of the population being younger than 15 years. Subsistence agriculture and forest work, such as logging wood, was the main source of income of this commune. There was no health care facility before 1994 and no electricity before 2000. Houses in Phan Tien are mainly made of clay walls and thatched roofs, without toilets or bathrooms. Animals and human excrements were disseminated in and around the village. Walking barefoot was common in Phan Tien, especially for infants and young children. People and cattle shared a small river surrounding the village as their water source for consumption, washing and agricultural irrigation. The capacity of three wells, drilled in 1994 with the aid of UNICEF, was insufficient. Two of them broke down in 1996 so that many inhabitants kept consuming river water. The rainy season runs from late April through November, followed by a dry season during which the river drops to very low levels and the water becomes turbid. The ambient temperature ranges from 20o to 35oC and humidity is high. This study comprised annually repeated stool examinations of all children younger than 17 years in Phan Tien, during an intervention program from April 1997 to December 1999. There were no exclusion criteria. Feces examination surveys The feces examination surveys were synchronized with malaria surveys at the end of the rainy season, but in 1997 two surveys were done, in April, at the end of the dry season, and in December, at the end of the wet season. Empty plastic containers were distributed to families with children of pre-school age. The older children received the containers at school. By checking the population registration it was ensured that all children received a container and were instructed to return a fresh stool specimen. Fresh stool samples were immediately examined by the Willis and Kato-Katz thick smear techniques (Beaver et al, 1984; WHO, 1992). The agar plate method was used to detect Strongyloides stercoralis (Arakaki et al, 1990). Any intestinal helminth infection was specified by infecting species.