This study is a randomized, double-blind, placebo-controlled trial to evaluate the effects of 400 mg albendazole treatment against placebo on the incidence of diarrheal disease caused by viral and bacterial pathogens in school children in southern Vietnam. Children will be enrolled from three primary schools in Cu Chi district in Ho Chi Minh City, Vietnam. Children will be screened for infections by the four most common soil-transmitted helminths, Ascaris lumbricoides, Trichuris trichiura, Necator americanus, and Ancylostoma duodenale. Infected and uninfected individuals will be recruited into the study and randomized to either receive albendazole treatment once every three months for 12 months, or to placebo once every three months for 9 months, after which albendazole treatment will be given at month 12, in accordance with the current deworming schedule in Cu Chi district. A questionnaire regarding the participant's demographics, his/her daily habits, and potential sources of infection will be administered at baseline. Weekly active and passive surveillance of diarrheal cases will be conducted throughout the study, and a health questionnaire will be administered during all cases of diarrhea and at the end of the study.