Association between intestinal parasitic infections and type of sanitation system in rural El Salvador Lana F. Corrales 1 , Ricardo Izurieta 2 and Christine L. Moe 1 1 Hubert Department of Global Health, Emory University, Rollins School of Public Health, Atlanta, GA, USA 2 Department of Global Health, University of South Florida College of Public Health, Tampa, FL, USA Summary objective To identify demographic, behavioural and environmental determinants of intestinal parasitic infection, evaluate the impact of a variety of dry sanitation systems on intestinal parasitic infection, and evaluate the safety of using stored biosolids in agriculture in order to guide future sanitation interventions in rural areas of El Salvador. methods Interviews were conducted with 109 households in eight communities where double-vaulted and solar urine-diverting desiccating latrines, pit latrines or no latrines were used. Faecal samples from 499 individuals were tested for enteric helminths and protozoa. results Users of solar desiccating latrines had the lowest prevalence of enteric parasite infection. Double-vault, urine-diverting desiccating latrines effectively reduced the transmission of some patho- gens, but may not achieve the conditions sufficient for the complete destruction of the more environ- mentally persistent pathogens, Ascaris lumbricoides and Trichuris trichiura. Contact with inadequately treated latrine biosolids was associated with an increased risk of Ascaris infection. conclusions Solar latrines were associated with the overall lowest prevalence of enteric parasitic infections. Members of households where latrine biosolids were used in agriculture had a higher pre- valence of infection than those where biosolids were buried. We therefore recommend the promotion of solar latrines in rural areas of El Salvador over other dry sanitation systems, and recommend that stored biosolids not be used in agriculture. keywords sanitation, ecological sanitation, latrines, geohelminths, Ascaris, biosolids Introduction Intestinal parasitic infections are among the most prevalent infections worldwide, with an estimated 3.5 billion people infected and 450 million ill (WHO 2001). While mortality from enteric helminths and protozoa is relatively low, morbidity and the indirect effects of apparently asympto- matic infections have a substantial impact on health and quality of life. The World Bank (1993) estimates the global burden of disease from geohelminth infections (A. lumb- ricoides, T. trichiura and hookworm) to be 2.4 million DALYs. In Latin America, the Pan American Health Organization (PAHO) (1997) estimates that helminth infections affect between 20% and 30% of the general population, with prevalences as high as 60–80% in endemic areas. Intestinal protozoan infections are even more prevalent. Geohelminths and enteric protozoa are readily passed from person to person via the faecal-oral route, either directly, through contact with contaminated hands, or indirectly, via contamination of food, water, or the environment. Sanitation reduces the dispersal of faeces in the environment and thus reduces the transmission of faecal-oral infections (Feachem et al. 1983). Reviews of the impact of sanitation on diarrhoeal disease estimate that sanitation interventions reduce diarrhoea morbidity in young children from 22% to 36% (Esrey et al. 1991; Fewtrell et al. 2005). Currently, UNICEF & WHO (2004) estimate that 2.6 billion people worldwide lack access to adequate sanitation. Roughly 15% of the urban population and nearly 50% of the rural population of El Salvador do not have access to sanitation (Ministry of Health of El Salvador 1998). In many areas, pit latrines cannot be constructed due to rocky or hard soil, lack of space, or a high ground water table. Since the early 1990s, USAID, UNICEF and the Ministry of Health have promoted the construction of thousands of alternative, ecologically sustainable latrine models designed to contain human excreta while producing a soil conditioner that can be used in agriculture. Two models of ‘eco-san’ latrines found in El Salvador are the double-vault desiccating latrine [known in Latin America as Tropical Medicine and International Health doi:10.1111/j.1365-3156.2006.01737.x volume 11 no 12 pp 1821–1831 december 2006 ª 2006 Blackwell Publishing Ltd 1821