Eliminating onchocerciasis within the Meme River Basin of Cameroon: A social-ecological approach to understanding everyday realities and health systems.

BACKGROUND: Onchocerciasis affects some of the world's most marginalized people, perpetuating poverty and inequalities. Mass Drug Administration (MDA) with Ivermectin has taken place within the Meme River basin region in Cameroon for over 15 years. Despite this, onchocerciasis is still prevalent in the region due to existing and emerging contextual challenges. Using a social-ecological approach we explore the everyday realities of communities, highlighting the challenges and potential solutions that could support Neglected Tropical Disease (NTD) programmes when transitioning from control to elimination of onchocerciasis in this highly endemic area and other similar communities. METHODOLOGY/PRINCIPAL FINDING: In-depth interviews (71) with community members and Community Drug Distributors (CDDs) were conducted to understand current knowledge, attitudes, and behaviours in relation to transmission, prevention and treatment of onchocerciasis. Through application of the social-ecological model, four key themes were identified: 1. Contextual factors on health promotion interventions (Onchocerciasis history and understanding of the disease, prevention and mitigation strategies and MDA experience); 2. Social determinants (poverty and livelihoods, economic and social impacts on CDD volunteers and stigma); 3. Environmental determinants (exposure, housing, occupation and poverty); and 4. health seeking pathways and decision making for treatment (access, cost and preferable treatment routes). We discuss these core and cross cutting themes (gender differences and community participation/ownership) in relation to intersectoral collaboration, gender equity and health systems support, making recommendations for NTD programmes within the context of integrated and interdisciplinary approaches. These include the need for; intersectional and gender analysis at the local level, addressing environmental dimensions of onchocerciasis through integrated and regular health promotion, vector control strategies and access to safe water sources; reflection and action that embeds responses to social and economic barriers to MDA; integrated case detection and management that is responsive to onchocerciasis symptoms and related stigma and a fair and just support network for CDDs. CONCLUSION/SIGNIFICANCE: NTD programmes need to respond to diverse community circumstances and behaviours. Communities are not a homogeneous risk group and treating them in this way will delay elimination. A deeper understanding of individual needs and their capacity to seek prevention and treatment must be considered if onchocerciasis is to be eliminated and the remaining impacts managed.

A multicenter, community-based, mixed methods assessment of the acceptability of a triple drug regimen for elimination of lymphatic filariasis.

BACKGROUND: Many countries will not reach elimination targets for lymphatic filariasis in 2020 using the two-drug treatment regimen (diethylcarbamazine citrate [DEC] and albendazole [DA]). A cluster-randomized, community-based safety study performed in Fiji, Haiti, India, Indonesia and Papua New Guinea tested the safety and efficacy of a new regimen of ivermectin, DEC and albendazole (IDA). METHODOLOGY/PRINCIPAL FINDINGS: To assess acceptability of IDA and DA, a mixed methods study was embedded within this community-based safety study. The study objective was to assess the acceptability of IDA versus DA. Community surveys were performed in each country with randomly selected participants (>14 years) from the safety study participant list in both DA and IDA arms. In depth interviews (IDI) and focus group discussions (FGD) assessed acceptability-related themes. In 1919 individuals, distribution of sex, microfilariae (Mf) presence and circulating filarial antigenemia (CFA), adverse events (AE) and age were similar across arms. A composite acceptability score summed the values from nine indicators (range 9-36). The median (22.5) score indicated threshold of acceptability. There was no difference in scores for IDA and DA regimens. Mean acceptability scores across both treatment arms were: Fiji 33.7 (95% CI: 33.1-34.3); Papua New Guinea 32.9 (95% CI: 31.9-33.8); Indonesia 30.6 (95% CI: 29.8-31.3); Haiti 28.6 (95% CI: 27.8-29.4); India 26.8 (95% CI: 25.6-28) (P<0.001). AE, Mf or CFA were not associated with acceptability. Qualitative research (27 FGD; 42 IDI) highlighted professionalism and appreciation for AE support. No major concerns were detected about number of tablets. Increased uptake of LF treatment by individuals who had never complied with MDA was observed. CONCLUSIONS/SIGNIFICANCE: IDA and DA regimens for LF elimination were highly and equally acceptable in individuals participating in the community-based safety study in Fiji, Haiti, India, Indonesia, and Papua New Guinea. Country variation in acceptability was significant. Acceptability of the professionalism of the treatment delivery was highlighted.

Risk factors associated with failing pre-transmission assessment surveys (pre-TAS) in lymphatic filariasis elimination programs: Results of a multi-country analysis.

Achieving elimination of lymphatic filariasis (LF) as a public health problem requires a minimum of five effective rounds of mass drug administration (MDA) and demonstrating low prevalence in subsequent assessments. The first assessments recommended by the World Health Organization (WHO) are sentinel and spot-check sites-referred to as pre-transmission assessment surveys (pre-TAS)-in each implementation unit after MDA. If pre-TAS shows that prevalence in each site has been lowered to less than 1% microfilaremia or less than 2% antigenemia, the implementation unit conducts a TAS to determine whether MDA can be stopped. Failure to pass pre-TAS means that further rounds of MDA are required. This study aims to understand factors influencing pre-TAS results using existing programmatic data from 554 implementation units, of which 74 (13%) failed, in 13 countries. Secondary data analysis was completed using existing data from Bangladesh, Benin, Burkina Faso, Cameroon, Ghana, Haiti, Indonesia, Mali, Nepal, Niger, Sierra Leone, Tanzania, and Uganda. Additional covariate data were obtained from spatial raster data sets. Bivariate analysis and multilinear regression were performed to establish potential relationships between variables and the pre-TAS result. Higher baseline prevalence and lower elevation were significant in the regression model. Variables statistically significantly associated with failure (p-value ≤0.05) in the bivariate analyses included baseline prevalence at or above 5% or 10%, use of Filariasis Test Strips (FTS), primary vector of Culex, treatment with diethylcarbamazine-albendazole, higher elevation, higher population density, higher enhanced vegetation index (EVI), higher annual rainfall, and 6 or more rounds of MDA. This paper reports for the first time factors associated with pre-TAS results from a multi-country analysis. This information can help countries more effectively forecast program activities, such as the potential need for more rounds of MDA, and prioritize resources to ensure adequate coverage of all persons in areas at highest risk of failing pre-TAS.

Economic performance and cost-effectiveness of using a DEC-salt social enterprise for eliminating the major neglected tropical disease, lymphatic filariasis.

BACKGROUND: Salt fortified with the drug, diethylcarbamazine (DEC), and introduced into a competitive market has the potential to overcome the obstacles associated with tablet-based Lymphatic Filariasis (LF) elimination programs. Questions remain, however, regarding the economic viability, production capacity, and effectiveness of this strategy as a sustainable means to bring about LF elimination in resource poor settings. METHODOLOGY AND PRINCIPAL FINDINGS: We evaluated the performance and effectiveness of a novel social enterprise-based approach developed and tested in Léogâne, Haiti, as a strategy to sustainably and cost-efficiently distribute DEC-medicated salt into a competitive market at quantities sufficient to bring about the elimination of LF. We undertook a cost-revenue analysis to evaluate the production capability and financial feasibility of the developed DEC salt social enterprise, and a modeling study centered on applying a dynamic mathematical model localized to reflect local LF transmission dynamics to evaluate the cost-effectiveness of using this intervention versus standard annual Mass Drug Administration (MDA) for eliminating LF in Léogâne. We show that the salt enterprise because of its mixed product business strategy may have already reached the production capacity for delivering sufficient quantities of edible DEC-medicated salt to bring about LF transmission in the Léogâne study setting. Due to increasing revenues obtained from the sale of DEC salt over time, expansion of its delivery in the population, and greater cumulative impact on the survival of worms leading to shorter timelines to extinction, this strategy could also represent a significantly more cost-effective option than annual DEC tablet-based MDA for accomplishing LF elimination. SIGNIFICANCE: A social enterprise approach can offer an innovative market-based strategy by which edible salt fortified with DEC could be distributed to communities both on a financially sustainable basis and at sufficient quantity to eliminate LF. Deployment of similarly fashioned intervention strategies would improve current efforts to successfully accomplish the goal of LF elimination, particularly in difficult-to-control settings.

Comprehensive Assessment of a Hotspot with Persistent Bancroftian Filariasis in Coastal Sri Lanka.

The Sri Lankan Anti-Filariasis campaign distributed five rounds of mass drug administration (MDA with diethylcarbamazine plus albendazole) to some 10 million people in eight districts between 2002 and 2006. Sri Lanka was recognized by the WHO for having eliminated lymphatic filariasis (LF) as a public health problem in 2016. However, recent studies by our group documented pockets with persistent LF in coastal Sri Lanka, especially in Galle district. The present study was performed to reexamine an area previously identified as a potential hotspot for persistent LF (Balapitiya Public Health Inspector area, population 17,500). A community survey documented high rates for circulating filarial antigenemia (3%, confidence interval [CI]: 1.8-4.9) and microfilaremia (1%, CI: 0.5-2.5%). Circulating filarial antigenemia rates were 2.8-fold higher in males than females. High prevalence was also observed for anti-filarial antibodies in young children (5.7%, CI: 3.7-8.4%) and for filarial DNA in vector mosquitoes (5.2%, CI: 4.2-6.3%). Spatial data showed that persistent LF was dispersed across the entire study area. Other studies showed that persistent LF was not limited to Balapitiya and not solved by additional rounds of MDA. Molecular xenomonitoring studies conducted in 2016 in 22 of 168 Public Health Midwife areas in the coastal Galle evaluation unit (approximate population 600,000) found that 179 of 660 (27%) pools of Culex collected from all areas were positive for Wuchereria bancrofti DNA by quantitative polymerase chain reaction; the estimated infection rate in mosquitoes was 1.26%, CI: 1.0-1.5%. Interventions other than routine MDA will be required to remove LF hotspots in Balapitiya and in other areas in coastal Sri Lanka.

Can community-based integrated vector control hasten the process of LF elimination?

Community-based integrated vector control (IVC) using polystyrene beads (EPS) and pyrethroid impregnated curtains (PIC) as an adjunct to mass drug administration (MDA) was implemented for lymphatic filariasis elimination, in the filaria endemic villages of Tirukoilur, south India. In all the villages, MDA was carried out by the state health machinery, as part of the national filariasis elimination programme. Thirty-six difficult-to-control villages were grouped as, viz, MDA alone, MDA + EPS and MDA + EPS + PIC arms. Implementation and monitoring of IVC was carried out by the community. After 3 years of IVC, higher reductions in filariometric indices were observed in both the community and vector population. Decline in antigenaemia prevalence was higher in MDA + IVC as compared to MDA alone arm. Vector density dropped significantly (P < 0.05) in both the IVC arms, and nil transmission was observed during post-IVC period. Almost 53.8 and 75.8 % of the cesspits in MDA + EPS and MDA + EPS + PIC arms were closed by the householders, due to the enhanced awareness on vector breeding. The paper presents the key elements of IVC implementation through social mobilization in a LF prevalent area. Thus, community-based IVC strategy can hasten LF elimination, as it reduced the transmission and filariometric indices significantly. Indices were maintained at low level with nil transmission, by the community through IVC tools.

Awareness and coverage of mass drug administration for elimination of lymphatic filariasis: a community based cross sectional study in Nepal.

Lymphatic filariasis (LF) is among the major public health problems in Nepal. The disease is a major cause of morbidities primarily, lymphedema of legs and hydrocele and it impedes socio economic development in many endemic areas of the country. This study is aimed at exploring the understanding of people about mass drug administration (MDA) of the said disease and the status of compliance of MDA in Nepal. This study is a cross sectional study carried out among 894 household samples in three of the sixty LF endemic districts. The selected districts were Dhading, Kapilvastu and Kailali. The sentinel surveillance of sites in three districts constituted the sampling frame at the first stage. The peripheral health care centers in the sentinel sites constituted the sampling frame at the second stage of sampling. The coverage of MDA was 95.5 %. However, the compliance was less. Only 71.6 % of the respondents who took the drugs from health workers swallowed the diethyl carbamazine (DEC) completely, other did not swallow. In the present study, majority of respondents reported that they had heard or seen persons with side effects of DEC in their community. A total of 20 % of respondents reported that they had side effects after having DEC and only 3.9 % of these side effects were treated. The Female Community Health volunteers (FCHVs), health workers and radio/Television (TV) were the chief sources of MDA related information. This study recommends for a concerted public health action combining effective drug delivery mechanism and sound public awareness campaigns. The community people need to be made aware beforehand about the location, time of drug distribution. Also public awareness of the DEC should be conducted so that people would trust it and comply with the drug regime. Along with the health workers and radio/TV that has been used traditionally, we recommend mobilization of FCHVs in the public awareness campaigns the MDA campaigns.

Toward the elimination of lymphatic filariasis by 2020: treatment update and impact assessment for the endgame.

Lymphatic filariasis (LF) is an important public health problem endemic in 73 countries, where it is a major cause of acute and chronic morbidity and a significant impediment to socioeconomic development. It is targeted for elimination by 2020, through preventive chemotherapy using albendazole in combination with either ivermectin or diethylcarbamazine citrate. Preventive chemotherapy enables the regular and coordinated administration of safe, single-dose medications delivered through mass drug administration (MDA). Many countries are now scaling down MDA activities after achieving 100% geographic coverage and instituting monitoring and evaluation procedures to establish the impact of several consecutive rounds of MDA and determine if transmission has been interrupted. At the same time, countries yet to initiate MDA for elimination of LF will adopt improved mapping and coverage assessment protocols to accelerate the efforts for achieving global elimination by 2020. This review provides an update on treatment for LF and describes the current global status of the elimination efforts, transmission control processes and strategies for measuring impact and continuing surveillance after MDA has ceased.

Costs of integrated mass drug administration for neglected tropical diseases in Haiti.

We conducted a cost analysis of Haiti's Ministry of Public Health and Population neglected tropical disease program, Projet des Maladies Tropicales Negligées and collected data for 9 of 55 communes participating in the May 2008-April 2009 mass drug administration (MDA). The Projet des Maladies Tropicales Negligées Program partnered with IMA World Health and Hôpital Ste. Croix to implement MDA for treatment of lymphatic filariasis and soil-transmitted helminthiasis by using once a year treatment with albendazole and diethylcarbamazine in a population of approximately 8 million persons. Methods included analyzing partner financial records and conducting retrospective surveys of personnel. In the nine communes, 633,261 persons were treated at a cost of U.S. $0.64 per person, which included the cost of donated drugs, and at a cost of U.S. $0.42 per person treated, when excluding donated drug costs. The MDA for lymphatic filariasis in Haiti began in 2000, with the treatment of 105,750 persons at a cost per person of U.S. $2.23. The decrease in cost per person treated is the result of cumulative implementation experience and economies of scale.

Improving community participation to eliminate lymphatic filariasis in American Samoa.

In 2000, the American Samoa Department of Health initiated a campaign of annual mass drug administration (MDA) with albendazole and diethylcarbamazine (DEC) to eliminate transmission of filariasis. Drug coverage was well below prescribed targets in the first three campaigns, ranging from 24 to 52% of the total population. Evaluation findings from a variety of formative research methods identified opportunities to improve MDA coverage and ensuing program modifications resulted in increased drug coverage of 65-71% in the following four annual distributions. Partnering with churches for drug distribution and using multiple media channels for health promotion led to sustained program improvements. With the increased emphasis on the use of mass distribution for delivery of drugs for a number of neglected tropical diseases, other programs may benefit from a similar approach.

Strengthening of mass drug administration implementation is required to eliminate lymphatic filariasis from India: an evaluation study.

BACKGROUND & OBJECTIVES: The mass drug administration (MDA) is one of the strategies to eliminate lymphatic filariasis in India. Eleven districts are endemic for the disease in Madhya Pradesh state of India, which conduct MDA activities annually. A mid-term evaluation was conducted with the objectives to review the progress of the single dose of di-ethyl-carbamazine (DEC) administration, and to understand the functioning of the programme to recommend mid-term amendments. METHODS: A qualitative cross-sectional study was conducted in three endemic districts of Madhya Pradesh between July and October 2007. The teams of faculty members from medical college visited the study districts and collected data by desk review, indepth interviews, on site observations, and from the community. RESULTS: The filaria units in these districts were understaffed. There were no night clinics in two out of the three districts. The sufficient number of trainings for MDA were conducted without any mechanism for quality assurance. There was erratic and inadequate supply of DEC tablets, leading to the postponement of MDA activity, twice. The evaluated coverage with DEC tablets was much lower than that reported by the district officials. The tablet intake was not ensured by the distributors and the compliance rate was in the range of 60-70%. The IEC activities were conducted in limited areas, and there were prevailing myths and misconceptions, contributing to low compliance rate. There was no proper recording of the data on filariasis with gross mismatch at district headquarters and peripheral health facilities. A proportion of community members developed side effects following DEC tablet intake and had to visit private health facilities for treatment. INTERPRETATION & CONCLUSION: This evaluation study noted that MDA is restricted to tablet distribution only and the major issues of implementation in compliance, health education, side effect and morbidity management, and the logistics were not being given due attention. The implementation should be strengthened immediately in the MDA programme in India to achieve the goal of LF elimination by 2015.

Impact of single dose of diethylcarbamazine and other antifilarial drug combinations on bancroftian filarial infection variables: assessment after 2 years.

The impact of single dose mass drug administration of diethylcarbamazine (DEC), DEC with albendazole (ALB), and ivermectin (IVR) with albendazole, was examined on the human bancroftian filarial infections in village scale trials in south India, from a follow-up study after 2 years. The treatment arms administered with DEC alone and DEC+ALB demonstrated long-term benefits in reducing microfilaraemia significantly (P<0.05), while antigenaemia reduction was negligible. The arm with ALB+IVR did not show such reductions. Among the antigenaemic and microfilaraemic individuals, 87% became amicrofilaraemic in DEC+ALB arm, which were higher than that observed in the other 2 treatment arms. Among amicrofilaraemics (but Ag+), nearly 35% cleared of infection in DEC+ALB, while 26% and 6% in DEC alone and IVR+ALB arms, respectively. The drug combination DEC+ALB was observed to demonstrate a significant impact in reducing filarial infection even after 2 years post treatment.

Independent assessment of Mass Drug Administration in filariasis affected Surat city.

The Mass Drug Administration (MDA) done in Surat city (Gujarat) during 2005, revealed good impact on infection and infectivity in mosquitoes and also on microfilaria rate & mean infection density. The overall impact seen was 23% on mf rate, 28% on mean mf density, 65% on infection rate and 50% on infectivity rate in vectors. Indigenous population contribution to microfilaria cases was 9.7%, whereas migratory population contributed 72.2%; predominant 51.9% from Orissa and 20.3% from U.P. Of the total 3640 persons interviewed for MDA compliance in seven zones of the Surat city revealed that actual drug consumption was 76.7% (2792/3640). Another 11.9% although took the drug but did not consume and 11.4% refused. Important reasons for consuming was fear to get the disease (40.7%) and for not consuming; 'will consume after meal' (6.9%), too many tablets (1.7%), seek consent from doctor (1.5%), lack of awareness (1.4%) etc. Refusal was mainly due to the reason as respondents felt apparently healthy. Assessment of IEC activities suggested that main awareness was created by media (local or national TV, banners or handbills, local news papers or mike announcement) alongwith some impact made through NGO's. These observations clearly indicated the utility of effective health education for optimum community participation and shown that it was crucial for successful community based elimination campaign. However some gray areas also suggest the scope for further improvements.

The Leogane, Haiti demonstration project: decreased microfilaremia and program costs after three years of mass drug administration.

To support the global program to eliminate lymphatic filariasis (LF), well-monitored demonstration projects are important for defining the relationship between coverage and reductions in microfilaremia. We are using mass treatment with diethylcarbamazine (DEC) and albendazole in an effort to eliminate LF from Leogane, Haiti. Wuchereria bancrofti microfilaremia prevalence at baseline ranged from 0.8% to 15.9% in four sentinel sites. After three rounds of DEC-albendazole mass drug administration (MDA), both microfilaremia prevalence and intensity decreased dramatically. Mild and moderate adverse reactions after treatment were common, especially after the first MDA, but decreased after subsequent MDAs. Drug coverage for the first year was estimated to be 72%, but concerns about adverse reactions appeared to decrease drug coverage in the second MDA. As a result of community education efforts that focused on providing a greater understanding of adverse reactions, coverage increased dramatically for the third round. Program efficiency increased substantially; the costs per person treated for three rounds of MDA were 2.23 US dollars, 1.96 US dollars, and 1.30 US dollars per person, respectively. The Leogane experience highlights the importance of adapting community education and mobilization campaigns to achieve and maintain good coverage.

A randomized clinical trial to compare the efficacy of three treatment regimens along with footcare in the morbidity management of filarial lymphoedema.

The progression of lymphoedema to elephantiasis associated with increased incidence of episodic adeno-lymphangitis (ADL) is of great concern, as it causes physical suffering, permanent disability and economic loss to lymphatic filariasis patients. This randomized clinical trial aimed to assess the efficacy in terms of reduction of oedema and ADL frequency of three treatment regimens among lymphoedema patients from Orissa, India. The regimens were: (I) oral penicillin--one tablet of 800 000 U penicillin G potassium twice daily for 12 days--repeated every 3 months for 1 year; (II) diethylcarbamazine--6 mg/kg bodyweight for 12 days-repeated every 3 months for 1 year; and (III) topical antiseptic, i.e. betadine ointment. Foot care was part of all regimens. All three drug regimens are efficacious in reducing oedema and frequency of ADL episodes. Although the efficacy was slightly higher in regimen I, the difference was not significant. About half of all patients had reduced oedema after the 90 days of treatment, with oedema reduction of 75-100% in 20%. A major proportion of the remaining patients had oedema reduced by less than 25%. The proportion of people whose oedema reduced was slightly but not significantly lower in regimen II. anova revealed that lymphoedema reduction varied according to grade; being greatest at grade 1 lymphoedema, followed by grade 2. All three regimens significantly reduced ADL frequency after 1 year of treatment. This may be because of foot care as well as use of antibiotics. The estimated costs of treatment per patient for a period of 3 months are US$2.4, 1.5 and 4.0 respectively for regimen I, II and III. Thus affordable treatments with simple antibiotics and foot care can give substantial relief to the patients and reverse early lymphoedema.

A rapid method to assess the coverage of the mass drug administration of diethylcarbamazine in the program to eliminate lymphatic filariasis in India.

A rapid method to assess the coverage of mass drug administration (MDA) in the program to eliminate lymphatic filariasis needs to be developed for monitoring and evaluation of the program. This study attempted to develop and test a method of rapid assessment of coverage by using the existing resources of the program. This is based on the data obtained from the randomly selected health workers and drug distributors involved in the drug distribution process and the data of a household coverage survey of the program. The MDA coverage rate obtained through the evaluation survey was highly correlated with the rates obtained from health workers and drug distributors as a rapid assessment. Thus, MDA coverages assessed through health workers and drug distributors can give a good coverage estimate. The involvement of the existing human resources of the program in this rapid method of assessing MDA coverage was cost-effective.

Cost of mass annual single dose diethylcarbamazine distribution for the large scale control of lymphatic filariasis.

Economic analysis of the revised strategy to control lymphatic filariasis with mass annual single dose diethylcarbamazine (DEC) at 6 mg/kg body weight launched in one of the districts of Tamil Nadu in 1996 was carried out. This exploratory study, proposed for five years in 13 districts under 7 states on a pilot scale through the Department of Public Health is an additional input of the existing National Filaria Control Programme in India. A retrospective costing exercise was undertaken systematically from the provider's perspective following the completion of the first round of drug distribution. The major activities and cost components were identified and itemized cost menu was prepared to estimate the direct (financial) and indirect (opportunity) cost related to the implementation of the Programme. The total financial cost of this Programme to cover 22.7 lakh population in the district was Rs. 22.05 lakhs. The opportunity cost of labour and capital investment was calculated to be Rs. 7.98 lakhs. The total per capita cost was Rs. 1.32, with Rs. 0.97 and Rs. 0.35 as financial and opportunity cost respectively. Based on these estimates, the implementation cost of the Programme at Primary Health Centre (PHC) level was calculated and projected for five years. The additional financial cost for the existing health care system is estimated to be Rs. 27,800 per PHC every year. DEC tablets (50 mg) was the major cost component and sensitivity analysis showed that the cost of the Programme could be minimized by 20 per cent by switching over to 100 mg tablets. The analysis indicates that this Programme is a low-cost option and the results are discussed in view of its operational feasibility and epidemiological impact.

Mass administration of DEC-medicated salt for filariasis control in the endemic population of Karaikal, south India: implementation and impact assessment.

DEC (diethylcarbamazine)-medicated salt, at a concentration of 0.1 to 0.2 mg per 100 mg, was given to the entire population of Karaikal (119 978) in South India for a 4-year period from 1982. The per capita consumption of DEC in medicated salt was 13.3 grams for the entire period. The prevalence of microfilaraemia declined significantly from 4.5% in 1982 to 0.14% in 1985 and 0.4% in 1993. Vector infection declined from 0.6% in 1982 to zero after two years. The mechanism of preparation and regulated distribution of DEC-medicated salt in the locality is presented. Long-term follow-up suggests that DEC-medicated salt distribution is cheap, safe and efficient for the elimination of filariasis.