The impact of lymphatic filariasis on labour inputs in southern India: results of a multi-site study.

A multi-site study was undertaken, in the rural areas of three districts in Tamil Nadu state, in southern India, to examine the impact of acute and chronic forms of lymphatic filariasis, caused by infection with Wuchereria bancrofti, on labour inputs. More than half of the acute episodes of adenolymphangitis (ADL) observed in the study communities caused total disability. The mean (S.D.) time that each ADL case was able to allocate to economic activity each day during these acute episodes was much less than seen in the controls matched for sex, age and occupation [0.97 (2.36) v. 4.48 (3.82) h; P < 0.01]. The acute disease also severely affected domestic activities, with female ADL cases spending only 1.54 (2.12) h/day on domestic activity, compared with 4.18 (2.61) h by controls. The subjects with chronic filariasis also spent significantly less time in economic activity than their matched controls [4.40 (3.79) v. 5.13 (3.83) h/day; P < 0.01). Although the acute episodes have a dramatic effect on the productivity of the affected individual, the labour loss caused by chronic disease is more serious, as the manifestations of chronic disease mostly affect the most productive age-groups, persist for life and are mostly irreversible. The adverse impact of acute and chronic filariasis was observed in males and females, farmers and non-farmers and during the rainy, winter and summer seasons. It is estimated that about 3.8% of the potential labour inputs of the men and 0.77% of those of the women were lost because of lymphatic filariasis. In addition to this loss, the total economic burden of the disease must include the costs of treatment and other health care and of the resources spent on control programmes. Estimates of the disease burden are likely to be useful in determining the costs and benefits of the recently launched campaign to eliminate lymphatic filariasis.