The most common soil transmitted helminthic infections(STHI) includes infection with Ascaris lumbricoides, Trichuris trichiura, and Hookworm. Growth retardation, malnutrition, anemia, impaired cognitive function and immunosuppression are main manifestations in children. Even within the developing world, wide differences exist in prevalence rates. The poorest countries have higher levels of STHI than those with a lower incidence of poverty. According to an estimate made by the WHO, the prevalence of A. lumbricoides, T. trichiura and Hookworm in South Asia was 27%, 20% and 16% respectively. Given that the prevalence of STHI in urban slums in Bangladesh is much higher than the other parts of the world and Asia and that there are major health and socio-economic consequences of such infections, it is important that we come up with effective means of reducing the prevalence of such infections. 60-80% of preschool children in urban slums of Bangladesh are infected with these STHI due to poor hygiene . At present deworming at six months interval is recommended but the effectiveness of this regimen of dewormig is questionable.

2. Hypothesis: Ante-helminthic treatment at every three month is more effective than ante-helminthic treatment at every six months to reduce soil transmitted helminthic infection, to reduce diarrheal and respiratory illness to improve nutritional status in preschool children.

3.Objective: The main objectives of the proposed study is to compare the relative efficacy of two different ante-helminthic treatment regimens to reduce the prevalence of STHI, diarrheal diseases, respiratory illness and to improve nutritional status in children 4. Design: The population of the study will be preschool children aged 2-5 year and will be selected randomly from an urban of Dhaka. They will be divided into two groups randomly. One group will get ante-helminthic at every three months interval and the other groups will get at six months interval for one year. Stool samples will be collected at the baseline and after three months completing one-year treatment of the above mentioned regimen. Blood haemoglobulin and nutritional status will also be measured at baseline and after three months of completion of treatment as mentioned above. The treatment will be 400 mg of Albendazole in a single dose.

5. Potential Impact: The findings of the research can be implemented by the government and non-government organization.