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Evaluation of the diethylcarbamazine patch to evaluate onchocerciasis endemicity in Central Africa
Gladys Ozoh1, Michel Boussinesq, Anne-Cécile Zoung-Kanyi Bissek
1Department of Dermatology, College of Medicine, University of Nigeria, Enugu, Nigeria.
Insights
The diethylcarbamazine (DEC) patch test effectively assesses onchocerciasis (river blindness) endemicity in Central African children. This diagnostic tool correlates well with infection levels, aiding control program monitoring.
Area of Science:
- Tropical medicine
- Infectious disease epidemiology
- Parasitology
Background:
- Onchocerciasis, or river blindness, remains a significant public health concern in many African regions.
- Accurate assessment of disease endemicity is crucial for effective control strategies under programs like the African Programme for Onchocerciasis Control.
- Existing diagnostic methods may require refinement or validation in diverse geographical settings.
Purpose of the Study:
- To evaluate the utility of the diethylcarbamazine (DEC) patch test for determining onchocerciasis endemicity levels.
- To assess the DEC patch test's applicability in Central African foci as part of baseline data collection.
- To compare DEC patch test results with established indicators of onchocerciasis prevalence.
Main Methods:
- A cohort of 226 untreated children aged 3-5 years from endemic areas in Cameroon, Gabon, and the Central African Republic were tested.
- Graded skin reactions to the DEC patch test were meticulously observed and analyzed.
- Test results were compared against the prevalence of onchocercal nodules and reactive skin disease within the study communities.
Main Results:
- Positive reactions to the DEC patch test varied significantly, ranging from 25.0% to 77.1% among the tested children.
- A strong positive correlation was observed between DEC patch test positivity and the prevalence of onchocercal nodules.
- These findings indicate a direct relationship between test results and the level of onchocerciasis endemicity.
Conclusions:
- The DEC patch test is a valuable tool for assessing onchocerciasis endemicity in Central Africa, extending its utility beyond West African foci.
- The test can be effectively employed to monitor the intensity of Onchocerca volvulus transmission.
- This diagnostic approach supports the ongoing efforts of the African Programme for Onchocerciasis Control.
Objective:
As part of a baseline data collection for assessing the impact of the African Programme for Onchocerciasis Control, to evaluate the diethylcarbamazine (DEC) patch test in determining the endemicity of onchocerciasis.
Method:
A total of 226 untreated children aged 3-5, living in four selected endemic foci, in Cameroon, Gabon and Central African Republic, were tested. Observed graded skin reactions to the patch were analysed and compared with the prevalence of onchocercal nodules and reactive skin disease in the corresponding community.
Results:
The proportion of children who tested positive ranged from 25.0% to 77.1%. The values were closely correlated with the prevalence of nodules, i.e. the level of endemicity for onchocerciasis.
Conclusion:
The DEC patch test, which has been so far used only in West African foci of onchocerciasis, can also constitute a valuable tool to evaluate the levels of endemicity of onchocerciasis in Central Africa, and to follow-up the intensity of transmission of Onchocerca volvulus.
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