The impact of three-monthly age-targetted chemotherapy on Ascaris lumbricoides infection.

The impact of 3 chemotherapeutic regimens at 3-monthly intervals against Ascaris lumbricoides infection, targetted at under 15 years old children with and without initial mass chemotherapy, and at 2-12 years old children, was studied in three Myanmar [Burmese] rural communities over a period of 2 years. Computation was made of prevalence and intensity (worm burden) of Ascaris infection, and other parameters for estimation of basic reproductive rate (R0) of the parasite and of the proportion of target age group to be treated 3-monthly (g) by employing the mathematical model for targetted chemotherapy. The 3 treatment regimens were almost equally effective in reducing prevalence and intensity in both the targetted and non-targetted age groups. Ascaris transmission in each of the 3 communities was interrupted, as indicated by the values of mean worm burden per person. The findings are compared with those of other similar studies and the reasons for the impact are discussed. The possible impact in similar endemic areas of applying the mathematical model predictions for age-targetted chemotherapy in controlling ascariasis is also discussed.