The prevalence of worm infections in the site is significantly lower than expected

Cheap and effective drugs called 'anthelmintics' are routinely administered to children in developing countries to eliminate infections by parasitic helminths. However, the effects of anthelmintic treatment on other pathogens (e.g., bacteria, viruses, protozoa) remain unknown. The aim of this study is to investigate the impact of anthelmintic treatment on the incidence of viral- and bacterial-induced diarrhea in school children in southern Vietnam. Diarrheal disease remains a substantial cause of morbidity and mortality in children in Vietnam, and these children are typically co-infected with intestinal helminths. As helminths and diarrheal pathogens infect the same intestinal niche, anthelmintic treatments may alter host immune responses and the composition of the gut microbiota in ways that affect infection and disease risks caused by diarrheal pathogens.

This study will recruit 350 helminth-infected and 350 helminth-uninfected children aged 6-15 years. Recruited children will be randomized to receive either anthelmintic or placebo treatment once every three months and will be monitored for incidences of diarrheal disease for 12 months. At the 12-month time point, all children will receive anthelmintic treatment. Blood and stool samples will be collected throughout the study and used for evaluation of anemia and host immune responses, and for classification of gut microbes and parasite detection, respectively. The interventional study proposed here will provide an important first test of whether anthelmintic treatments have any indirect effects on infections caused by diarrheal pathogens.

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.

Inclusion Criteria:

• Between 6-15 years of age
• Written informed consent from a parent or guardian
• Written assent from children >10 years of age

Exclusion Criteria:

• Subjects who do not fulfill any component of the inclusion criteria
• Subjects that are both hookworm-positive and anemic, as defined by the WHO guidelines