Selective treatment and targeted chemotherapy: effect on prevalence and intensity of infection for two intestinal helminths in Nepalese children.

The study examines the effect of mebendazole distribution (2 x 100 mg x 3 days) either as mass chemotherapy targeted to children 1 to 10 years old, or selective treatment of heavily infected children, over a two year period in sixteen rural villages of Nepal. Eight villages were covered with six monthly mass chemotherapy, provided by Community Health Volunteers, other eight with yearly selective treatment of heavily infected children based on clinical signs. Prevalence and intensity of infection, indirectly measured as the number of eggs per gram of faeces, were measured for A. lumbricoides and hookworms utilising the Kato thick-smear technique. At the end of two year intervention, the effect of both activities was similar on worm prevalence with a slightly significant difference (p < 0.05) on worm load in favour of mass chemotherapy. Furthermore a greater effect of mebendazole was reported, regardless of the type of intervention, on hookworms present at baseline with a lower prevalence (23.4%) than A. lumbricoides (47.6%). The study suggests that clinical diagnosis of heavily infected children may be a feasible way to direct selective treatment. Baseline prevalence seems to influence effectiveness of control programs. Further studies are needed to substantiate these observations.