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      Epilepsy in Onchocerciasis Endemic Areas: Systematic Review and Meta-analysis of Population-Based Surveys

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          We sought to evaluate the relationship between onchocerciasis prevalence and that of epilepsy using available data collected at community level.


          We conducted a systematic review and meta-regression of available data.

          Data Sources

          Electronic and paper records on subject area ever produced up to February 2008.

          Review Methods

          We searched for population-based studies reporting on the prevalence of epilepsy in communities for which onchocerciasis prevalence was available or could be estimated. Two authors independently assessed eligibility and study quality and extracted data. The estimation of point prevalence of onchocerciasis was standardized across studies using appropriate correction factors. Variation in epilepsy prevalence was then analyzed as a function of onchocerciasis endemicity using random-effect logistic models.


          Eight studies from west (Benin and Nigeria), central (Cameroon and Central African Republic) and east Africa (Uganda, Tanzania and Burundi) met the criteria for inclusion and analysis. Ninety-one communities with a total population of 79,270 individuals screened for epilepsy were included in the analysis. The prevalence of epilepsy ranged from 0 to 8.7% whereas that of onchocerciasis ranged from 5.2 to 100%. Variation in epilepsy prevalence was consistent with a logistic function of onchocerciasis prevalence, with epilepsy prevalence being increased, on average, by 0.4% for each 10% increase in onchocerciasis prevalence.


          These results give further evidence that onchocerciasis is associated with epilepsy and that the disease burden of onchocerciasis might have to be re-estimated by taking into account this relationship.

          Author Summary

          Epilepsy is particularly common in tropical areas. One main reason is that many endemic infections have neurological consequences. In addition, the medical, social and demographic burden of epilepsy remains substantial in these countries where it is often seen as a contagious condition and where the aetiology is often undetermined. For several decades, field researchers had reported some overlapping between the geographical distributions of epilepsy and onchocerciasis, a parasitic disease caused by the filarial worm Onchocerca volvulus which afflicts some 40 million persons worldwide. Here, we conducted a statistical analysis of all the data available on the relationship between the two conditions to determine whether the proportion of people suffering from epilepsy in a community could be related to the frequency of onchocerciasis. The combined results of the eight studies carried out in west, central and east Africa indicate a close epidemiological association between the two diseases. Should a causative relationship be demonstrated, onchocerciasis, which is known as “river blindness” because of its most serious sequela and the distribution of its vectors, could thus also be called “river epilepsy”. More research is needed to determine the mechanisms explaining this association and to assess the burden of onchocerciasis-associated epilepsy.

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          Most cited references 39

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          Pathogenesis, clinical features, and neurological outcome of cerebral malaria.

          Cerebral malaria is the most severe neurological complication of Plasmodium falciparum malaria. Even though this type of malaria is most common in children living in sub-Saharan Africa, it should be considered in anybody with impaired consciousness that has recently travelled in a malaria-endemic area. Cerebral malaria has few specific features, but there are differences in clinical presentation between African children and non-immune adults. Subsequent neurological impairments are also most common and severe in children. Sequestration of infected erythrocytes within cerebral blood vessels seems to be an essential component of the pathogenesis. However, other factors such as convulsions, acidosis, or hypoglycaemia can impair consciousness. In this review, we describe the clinical features and epidemiology of cerebral malaria. We highlight recent insights provided by ex-vivo work on sequestration and examination of pathological specimens. We also summarise recent studies of persisting neurocognitive impairments in children who survive cerebral malaria and suggest areas for further research.
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            Covariance structure selection in general mixed models

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              Guidelines for epidemiologic studies on epilepsy. Commission on Epidemiology and Prognosis, International League Against Epilepsy.


                Author and article information

                Role: Editor
                PLoS Negl Trop Dis
                PLoS Neglected Tropical Diseases
                Public Library of Science (San Francisco, USA )
                June 2009
                16 June 2009
                : 3
                : 6
                [1 ]Unité Mixte de Recherche 145, Institut de Recherche pour le Développement (IRD) and University of Montpellier 1, Montpellier, France
                [2 ]Basic Health Services Kabarole & Bundbugyo Districts, Fort Portal, Uganda
                [3 ]Institut d'Epidémiologie Neurologique et de Neurologie Tropicale (EA3174), Faculté de Médecine, Limoges, France
                [4 ]Office of HIV, STD and Hepatitis C Services, Arizona Department of Health Services, Phoenix, Arizona, United States of America
                [5 ]134 Chemin du Recredoz, Divonne les Bains, France
                [6 ]Peramiho Mission Hospital, Peramiho, United Republic of Tanzania (URT)
                [7 ]Diocèse de Bouar, Bouar, Central African Republic (CAR)
                [8 ]Department of Public Health Sciences, University of Alberta, Edmonton, Alberta, Canada
                The University of Nottingham, United Kingdom
                Author notes

                Conceived and designed the experiments: SDSP MB. Analyzed the data: SDSP FBT AC. Contributed reagents/materials/analysis tools: MMT SEOM AS IB WK PMP MB. Wrote the paper: SDSP CK MMT SEOM WK MB.

                Pion et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
                Page count
                Pages: 9
                Research Article
                Infectious Diseases/Helminth Infections
                Infectious Diseases/Neglected Tropical Diseases
                Neurological Disorders/Epilepsy

                Infectious disease & Microbiology


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