Lymphatic filariasis affects 119 million people living in 73 countries, with India accounting for 40% of the global prevalence of infection. Despite its debilitating effects, lym- phatic filariasis is given very low control priority. One of the reasons for this is paucity of information on the economic burden of the disease. Recent studies in rural areas of south India have shown that the treatment costs and loss of work time due to the disease are considerable. Based on the results of these studies, Kapa Ramaiah et al. here estimate the annual economic loss because of lymphatic filariasis for India and discuss the implications of their findings. Lymphatic filariasis (LF) is second only to malaria as the most important vector-borne disease in India. The disease is endemic in 18 states or Union territories, including the populous states of Uttar Pradesh and Bihar. Approximately 420 million people reside in en- demic areas and 48.11 million are infected. Bancroftian filariasis, caused by Wuchereria bancrofti and transmit- ted by the tropical house mosquito Culex quinquefasciatus, accounts for 95% of the total lymphatic filariasis cases in India 1 . Bancroftian filariasis is prevalent in both urban and rural areas, the majority of cases occurring among the poor. Although mortality is uncommon, morbidity associated with this infection can be considerable and lifelong. Because of these factors, LF escapes the attention of planners, governments and the media. All rural and many urban areas in India lack any antifilar- ial measures and only 11% of the endemic popu- lation is protected by the National Filaria Control Programme (NFCP)*. The advent of new and easy-to-implement control strategies for filariasis, such as annual, single-dose mass chemotherapy with antifilarial drugs 2 , and the re- cent World Health Assembly resolution to eliminate LF as a public health problem 3 , have generated re- newed hopes for the control of this disease. To provide further impetus to the ongoing control efforts, and to support future campaigns to eliminate filariasis 4 , precise information on the prevalence, social and eco- nomic burden and costs of control of the disease is nec- essary. Such information may encourage increased in- vestment in filariasis control programmes by planners, Non-Governmental Organizations (NGOs), industry and other donors. Estimates of health burden suggest that LF is responsible for over 1% of all disability adjusted life years (DALYs) † lost due to infectious and parasitic diseases, and that 44% of DALYs lost, worldwide, be- cause of this disease, occur in India 5 . However, under- lying all these estimates is a poor understanding of the epidemiology and burden of this disease 6 . This lack of knowledge on the social and economic impact stimu- lated simultaneous multi-country research studies by WHO/TDR in 1992. Using the results of the studies undertaken in India on both treatment expenditure by patients (direct costs) and labour time lost (indirect costs), we report here on the estimates of the economic burden of lymphatic filariasis in India. Prevalence of lymphatic filariasis The clinical course of LF includes three distinct phases: asymptomatic microfilaraemia, acute episodes of adenolymphangitis (ADL), and chronic disease (ir- reversible swelling of lower and/or upper limbs in men and women and hydrocele in men), which is often superimposed with repeated ADL. There were 20.32 mil- lion chronic cases in India in 1996, 79% occurring in males 1 . However, estimates of the number of cases of acute disease are not available in the literature, pri- marily because of the paucity of epidemiological data. Using detailed data from a recent study in south India 7 , we have estimated, for the first time, the number of ADL episodes per year for males and females in India (Table 1). Our estimates suggest that, in total, 40.65 million ADL episodes are suffered per year in India, 60% of which are suffered by males. Economic loss due to lymphatic filariasis Estimates of the economic loss due to LF in India are based on studies in rural areas, where two-thirds of people affected live. The annual economic burden is estimated on the basis of prevalence of chronic and acute disease, costs of treatment to the patient, loss of working days because of illness, and the prevailing wage rates. In all cases, these variables are differenti- ated by sex. The study population for the estimation of labour loss comprised the dominant segments of the work force in India (agricultural labourers, weavers and construction workers), living in seven villages in Tamil Nadu, south India. The study on treatment costs was undertaken in two of these villages. Although acute episodes of ADL can cripple af- fected individuals for up to five days, patients sought treatment in only 43.9% of the cases of ADL, with only 26.8% of them incurring expenditure 8 . By contrast, 74.7% of patients suffering from chronic disease sought Focus Parasitology Today, vol. 16, no. 6, 2000 251 0169-4758/00/$ – see front matter © 2000 Elsevier Science Ltd. All rights reserved. PII: S0169-4758(00)01643-4 *Sharma et al., eds. (1995) National Filaria Control Programme, India, Operational Manual. The Directorate, National Malaria Eradication Program, Delhi-110 054 The Economic Burden of Lymphatic Filariasis in India K.D. Ramaiah, P .K. Das, E. Michael and H. Guyatt Kapa D. Ramaiah and Pradeep K. Das are at the Vector Control Research Centre, Medical Complex, Indira Nagar, Pondicherry-605 006, India. Edwin Michael and Helen L. Guyatt are at The Wellcome Centre for the Epidemiology of Infectious Disease, Department of Zoology, University of Oxford, South Parks Road, Oxford, UK OX1 3FY. Tel: +91 413 372422, Fax: +91 413 372041, e-mail: mosquito@md2.vsnl.net.in †DALY measures the disease burden in terms of future span of disability-free life lost and reflects a composite measure of mortality and morbidity effects. It was introduced by the World Bank in 1993 as a standardized and uniform approach to comparing the public health importance of various diseases and conditions