Other disease morbidity: Each study subject will be visited by a community health worker every week and will collect information by asking parents/guardian according to structured questionnaires about diarrheal disease, fever, cough etc. of the child retrospectively for previous seven days. They will work 6 days weekly and every one of them has to visit about 17 households per day for morbidity data collection. Parents/guardian will be advised to seek health care from study physician in study field office in case of any illness of the study child. The study physician will take history and will carry out physical examination and will give treatment to the sick child. If the child does not respond to the given treatment or if his/her condition deteriorates or if the child is seriously ill initially then he/she will be referred to the appropriate referral facilities for treatment, and treatment cost will not be carried out by the project. Asymptomatic E. histolytica infections will not be treated. But symptomatic E. histolytica infections will be treated according to the ICDDR, B Dhaka Hospital treatment guidelines