A population dynamic approach to the cost-effectiveness analysis of mass anthelmintic treatment: effects of treatment frequency on Ascaris infection.

This study examines the cost-effectiveness of different frequencies of mass chemotherapy in reducing helminth infection and morbidity at the community level. The cost-effectiveness framework utilities a dynamic model of helminth transmission which permits the effectiveness of treatment to be expressed as some long-term reduction in infection and disease. Cost analysis is incorporated into this framework using an itemized cost menu and cost data from an actual control programme. The cost-effectiveness of mass treatment is investigated using epidemiological measures considered appropriate to Ascaris lumbricoides infection in both a high and low transmission area. The optimal strategy for control is shown to be dependent on the control objectives, the rate of transmission, and existing budget constraints. The analysis suggests that if the aim of control is to reduce morbidity due to ascariasis and mass treatment is the approach selected, then it is more cost-effective to intervene in a high transmission area than in a low transmission area, and that relatively long intervals between treatments offer the most cost-effective strategy.