Cost and cost effectiveness of mass diethylcarbamazine chemotherapy for the control of bancroftian filariasis: comparison of four strategies in Tanzania.

This study examines the costs and cost effectiveness of four different mass diethylcarbamazine (DEC) chemotherapy regimens-standard dose, semi-annual single dose, low monthly dose and DEC-medicated salt-in reducing microfilarial (mf) prevalence at the community level. Costs were estimated for each intervention in relation to both ingredient and activity, by the derivation and use of detailed itemized cost menus. The most expensive and most effective strategy in reducing community mf prevalence over 2 years was DEC salt intervention, followed in order of costs by the standard, low monthly and semi-annual DEC strategies. The most cost effective strategy was the low monthly DEC treatment. Cost and sensitivity analyses, however, suggest that the optimal choice of mass DEC strategy for reducing mf is very sensitive to programme design parameters. In particular, the results demonstrate that if the salt delivery structure is simplified, DEC salt has the potential to be the dominant intervention for filariasis control. The results suggest that economies of scale considerations might militate against the adoption of this intervention for large-scale applications, unless perhaps offset by its potential for cost recovery by direct patient purchase. Further analyses require a more realistic evaluation of filariasis intervention effectiveness by addressing changes in infection intensity and by accounting for the population dynamics of parasite transmission and control.