Filariasis is a major public health problem with an estimated 750 million people exposed to risk of infection and 80 million cases in the world. India accounts for about 50% of the at-risk population and about 60% of all cases (1). Diethylcarbamazine (DEC) has been the drug of choice and is known for its excellent microfilaricidal activity (2-4). Different methods of drug delivery--6 mg/kg/day for 12 days (5, 6) for selected cases or mass, spaced doses in different regimens (1, 2, 7-11)--have been attempted with varying degrees of impact. Dec-medicated salt has been used for control of lymphatic filariasis in India (12, 13); the largest trial was carried out in Karaikal and the immediate and delayed epidemiological impacts have been reported (14). This article describes the implementation process in Karaikal and presents the epidemiological assessment data.
Materials and methods
Karaikal lies in the Union Territory of Pondicherry,, 290 km south of Madras on the eastern coast of South India. According to the 1981 census, the population was 119 978 in an area of 160 square kilometers, including the urban municipal zone and five communes (semi-urban and rural). This area has been endemic for Wuchereria bancrofti for several decades and the National Filariasis Control Programme (NFCP) of India started a control unit in 1970. Routine control measures based on selective chemotherapy and antilarval measures have been in operation in the urban area since then.
For a period of 4 years from January 1982 a community-based trial of mass consumption of Dec-medicated salt (0.1%-O.2%) was carried out to evaluate its efficacy and impact on epidemiological and transmission parameters. This trial was implemented jointly by the NFCP and the Directorate of Health and Family Welfare, government of Pondicherry Union Territory.
The following epidemiological and entomological data were collected:
-- human infection prevalence (microfilaria rate in
--vector infection prevalence (vector infection and infectivity rates in
Data on the pre-intervention epidemiological parameters were obtained from the local filariasis control unit of the NFCP for the 10-year period, 1972-81. These data had been collected using standard guidelines by the NFCP (15). In January 1982, surveys were carried out to collect the immediate pre-intervention data on human and vector infection status. Data during the intervention (1982-86) and in the post-intervention period (1986-93) on the same parameters were collected by the local NFCP unit.
Details of the salt-manufacturing units within the study area and of outside sources to meet the local requirements, along with the entry routes, and the mechanisms of distribution of salt from the manufacturing sites to the consumers were studied. Based on these data, a plan was drawn up for the production, quality control and distribution of Dec-medicated salt to the target population.
Role of local authorities and the community
After the programme's inauguration by the then Minister for Health and Family Welfare of Pondicherry in January 1982, a series of meetings were held in the communes and municipal zones with the local health and administrative authorities, field health staff, local political office-bearers, opinion leaders, village Panchayat members and social workers to explain the salient features of the medicated-salt programme and its benefits. They were told that the Dec-medicated salt was non-toxic with no harmful effects on prepared foods and shown how to identify the marks indicating Dec-medicated salt. The community was motivated through door-to-door visits and group discussions to explain the programme. Slides (35mm) describing the programme and requesting public cooperation were projected in local cinemas, which are popular in South India. Publicity was given through public address systems on mobile vehicles and using specially designed banners. …