Satellite mapping of Loa loa prevalence in relation to ivermectin use in west and central Africa

For many years, ivermectin has been widely distributed throughout west Africa for the safe and effective control of onchocerclasis. However, recent events in Loa-loa-endemic areas of Cameroon, where severe adverse reactions have occurred, now constrain the public-health use of this drug in the forest habitat of the L. loa vector. We have created a model of L. loa prevalence to identify areas where high endemicity may be associated with the occurrence of such reactions. The model results have been mapped and the areas of overlap between high L. loa prevalence and planned ivermectin distribution for onchocerciasis control identified.

Control of onchocerciasis in Nzerem-Ikpem, Nigeria: baseline prevalence and mass distribution of ivermectin

Data from a survey of endemicity of human onchocerciasis and subsequent mass distribution of ivermectin to control this disease in 9 villages of the Nzerem-Ikpem community in the Imo River basin of Nigeria are presented. Of the 1126 persons examined, 46.2% were positive for skin microfilarial, 29.2% for leopard skin, 34.2% for palpable subcutaneous nodules and 14.8% for various types of onchodermatitis. Ivermectin was distributed to a total of 1934 persons living in 233 households. The treatment coverage rate was 51%. 12.8% of those treated reported various mild reactions to the microfilaricide. Implications for community participation and long term sustenance of mass distribution programs are discussed.

Willingness to pay for the maintenance of equity in a local ivermectin distribution scheme in Toro, Northern Nigeria

The willingness to pay (WTP) for the maintenance of equity in a local ivermectin distribution scheme in the context of a community financing framework was determined in Toro, Northern Nigeria, using 214 randomly selected heads of households, or their representatives. Though WTP of the respondents for their own households was elicited, the focus of this paper is on WTP to maintain equity in a community financing scheme. Contingent valuation was used for the exercise, and WTP was elicited using an open-ended question. 97.2% of the respondents were in favour of allowing those that lack the ability to pay, to benefit from the scheme and the maximum WTP amounts they were willing to contribute annually so that those who lack the ability to pay could benefit from the scheme ranged from 5 Naira ($0. 06) to 100 Naira ($1.25). The mean WTP to maintain equity was 29.00 Naira ($0.36) while the median was 20.00 Naira ($0.25). This study shows that a community financing scheme for local ivermectin distribution will not be inequitable, since enough funds will be realised from well-to-do community members to cover the costs for those who are unable to pay.

The selection and validation of indicators for monitoring progress towards self-sustainment in community-directed, ivermectin-treatment programmes for onchocerciasis control in Uganda

A retrospective analysis was made of quantitative data on coverage obtained over 4 years of annual ivermectin treatment of the eligible populations (approximately 56,000 individuals) of 71 communities with endemic onchocerciasis in the Kabale, Kisoro and Rukungiri districts of Uganda. The objective was to formulate methods for defining sustainability in community-directed, ivermectin-treatment programmes (CDITP). Three dependent-variable scales of programme sustainability (PS), PS1, PS2, and PS3, were tested for statistical significance by analysis of variance. The inhabitants of a random sample of 230 households drawn from 23 communities [each containing one community leader and one community-based distributor (CBD)] were then invited to answer a questionnaire covering seven independent variables. These variables were analysed in regression and correlation models, with the PS scales as dependent variables. In the regression model, only one variable, selection of CBD by community members (P = 0.038), which scored 100% on the scale of programme-indicator sensitivity, passed as a useful indicator for predicting the sustainability and monitoring the sustainment of CDITP at the community level. The same variable was also selected in the correlation model (P = 0.028). Although two other variables--involvement of CBD in other primary-health-care activities (P = 0.0594) and provision of incentives for the CBD (P = 0.0558)--showed weak negative associations with sustainability in the correlation model, they did not exhibit a linear relationship with it and cannot therefore be used as valid indicators for predicting sustainability or monitoring sustainment.

Blackfly control: what choices after onchocerciasis?

Blackflies are reappearing in areas of West Africa where they used to be controlled with insecticides because they were vectors of the parasite Onchocerca volvulus. Even though they no longer transmit onchocerciasis in these areas they can hinder optimal land use through their biting behaviour. The authors discuss the problems associated with resuming the use of insecticides to control the blackfly and recommend that ground treatment be restricted to areas where it is likely to be effective on a continuing basis. In communities lacking technical and financial resources the only alternative consists of individual protection through the use of repellents or protective clothing.

Onchocerciasis control in Uganda

In 1990 a community-based programme of onchocerciasis control, involving the use of ivermectin, was introduced in Uganda. The problems confronting it are discussed and suggestions are made for making it sustainable.

Evaluation of community compliance with annual ivermectin treatment of onchocerciasis in Patigi, Nigeria

A low community acceptance and compliance with annual ivermectin treatment was recorded in Patigi, Nigeria where ivermectin is being distributed centrally in designated centres for the fifth time. The average community acceptance rate (ACAR) for the treatment period was 53.48% while the community compliance rate (CCR) of 1.9% of the total subjects interviewed was recorded. Absenteeism from treatment was a major reason for non-treatment (average, 34.6%). Inadequate and poor mobilisation was identified as a major reason for the low ivermectin acceptance and compliance with treatment in this community. An intensive mobilisation with health education messages with the inclusion of religious/traditional institutions is advocated.