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Van Cutsem G, Siewe Fodjo JN, Hadermann A, Amaral LJ, Trevisan C, Pion S, Colebunders R. Onchocerciasis-associated epilepsy: Charting a path forward. Seizure 2024:S1059-1311(24)00123-7. [PMID: 38677953 DOI: 10.1016/j.seizure.2024.04.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Revised: 04/17/2024] [Accepted: 04/18/2024] [Indexed: 04/29/2024] Open
Abstract
This narrative review intends to inform neurologists and public health professionals about Onchocerciasis-Associated Epilepsy (OAE), a neglected public health problem in many remote onchocerciasis-endemic areas. For epidemiological purposes, we define OAE as sudden-onset of convulsive and non-convulsive seizure types, including head nodding seizures (nodding syndrome) in a previously healthy child aged 3 to 18 years in the absence of any other obvious cause for epilepsy, all happening within an area with high ongoing Onchocerca volvulus transmission. Several OAE pathophysiological mechanisms have been proposed, but none has been proven yet. Recent population-based studies showed that strengthening onchocerciasis elimination programs was followed by a significant reduction in the incidence of OAE and nodding syndrome. Treating epilepsy in onchocerciasis-endemic regions is challenging. More advocacy is needed to provide uninterrupted, free access to anti-seizure medication to persons with epilepsy in these remote, impoverished areas. It is crucial todevelop policies and increase funding for the prevention and treatment of OAE to reduce the associated burden of disease, notably via the establishment of morbidity management and disability prevention programs (MMDP). Moreover, effective collaboration between onchocerciasis elimination and mental health programs is imperative to alleviate the burden of OAE. This synergy promises reciprocal advantages and underscores the need for a comprehensive approach to address this multifaceted challenge.
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Affiliation(s)
- G Van Cutsem
- Department of Neurology, Centre Hospitalier de Luxembourg, Luxembourg; Faculty of Science, Technology and Medicine, University of Luxembourg, Luxembourg; Centre for Infectious Disease Epidemiology and Research, University of Cape Town, South Africa
| | - J N Siewe Fodjo
- Global Health Institute, University of Antwerp, Antwerp, Belgium
| | - A Hadermann
- Global Health Institute, University of Antwerp, Antwerp, Belgium
| | - L-J Amaral
- Global Health Institute, University of Antwerp, Antwerp, Belgium
| | - C Trevisan
- Department of Public Health, Institute of Tropical Medicine, Antwerp, Belgium
| | - S Pion
- Institute of Research for Sustainable Development, Montpelier, France
| | - R Colebunders
- Global Health Institute, University of Antwerp, Antwerp, Belgium.
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Hadermann A, Jada SR, Sebit WJ, Deng T, Bol YY, Siewe Fodjo JN, De Coninck L, Matthijnssens J, Mertens I, Polman K, Colebunders R. Onchocerciasis-associated epilepsy: an explorative case-control study with viral metagenomic analyses on Onchocerca volvulus. F1000Res 2023; 12:1262. [PMID: 38439783 PMCID: PMC10911407 DOI: 10.12688/f1000research.138774.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 12/06/2023] [Indexed: 03/06/2024] Open
Abstract
Background A high prevalence of onchocerciasis-associated epilepsy (OAE) has been observed in onchocerciasis-endemic areas with high ongoing Onchocerca volvulus transmission. However, the pathogenesis of OAE remains to be elucidated. We hypothesise that the O. volvulus virome could be involved in inducing epilepsy. With this study, we aim to describe the O. volvulus virome and identify potential neurotropic viruses linked to OAE. Methods In Maridi County, an onchocerciasis endemic area in South Sudan with a high prevalence of OAE, we will conduct an exploratory case-control study enrolling 40 persons aged 12 years and above with palpable onchocerciasis nodules. Cases will be participants with OAE (n=20), who will be age- and village-matched with controls without epilepsy (n=20). For each study participant, two skin snips at the iliac crest will be obtained to collect O. volvulus microfilariae, and one nodulectomy will be performed to obtain adult worms. A viral metagenomic study will be conducted on microfilariae and adult worms, and the O. volvulus virome of persons with and without OAE will be compared. The number, size, and localisation of onchocerciasis nodules in persons with and without OAE will be described. Moreover, the pre- and post-nodulectomy frequency of seizures in persons with OAE will be compared. Ethics and dissemination The protocol has been approved by the Ethics Committee of the University of Antwerp and the Ministry of Health of South Sudan. Findings will be disseminated nationally and internationally via meetings and peer-reviewed publications. Registration ClinicalTrials.gov registration NCT05868551 ( https://clinicaltrials.gov/study/NCT05868551). Protocol version 1.1, dated 09/05/2023.
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Affiliation(s)
- Amber Hadermann
- Global Health Institute, University of Antwerp, Antwerp, 2610, Belgium
| | | | - Wilson J. Sebit
- Public Health Laboratory, Ministry of Health South Sudan, Juba, South Sudan
| | | | - Yak Y. Bol
- Neglected Tropical Diseases Unit, Ministry of Health South Sudan, Juba, South Sudan
| | | | - Lander De Coninck
- Laboratory of Viral Metagenomics, KU Leuven, Leuven, Flanders, 3000, Belgium
| | - Jelle Matthijnssens
- Laboratory of Viral Metagenomics, KU Leuven, Leuven, Flanders, 3000, Belgium
| | - Inge Mertens
- Health Unit, VITO (Vlaamse Instelling voor Technologisch Onderzoek), Mol, 2400, Belgium
- Centre for Proteomics, University of Atwerp, Antwerp, Belgium
| | - Katja Polman
- Department of Health Sciences, VU Amsterdam, Amsterdam, 1081, The Netherlands
- Department Public Health, Institute of Tropical Medicine, Antwerp, 2600, Belgium
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Bhwana D, Amaral LJ, Mhina A, Matine P, Francis F, Siewe Fodjo JN, Mmbando BP, Colebunders R. Impact of a bi-annual community-directed treatment with ivermectin programme on the incidence of epilepsy in an onchocerciasis-endemic area of Mahenge, Tanzania: A population-based prospective study. PLoS Negl Trop Dis 2023; 17:e0011178. [PMID: 37379350 DOI: 10.1371/journal.pntd.0011178] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 06/10/2023] [Indexed: 06/30/2023] Open
Abstract
BACKGROUND Community-directed treatment with ivermectin (CDTi) is used to eliminate onchocerciasis. However, despite 25 years of annual CDTi in Mahenge, Tanzania, the prevalence of onchocerciasis and onchocerciasis-associated epilepsy remained high in certain rural villages. Therefore, in 2019, bi-annual CDTi was introduced in the area. This study assessed the impact of the programme on the incidence of epilepsy in four villages. METHODOLOGY Door-to-door epilepsy surveys were conducted prior to (2017/18) and after (2021) implementing a bi-annual CDTi program. All household members were screened for epilepsy symptoms using a validated questionnaire, and suspected cases were examined by a medical doctor to confirm/reject the diagnosis of epilepsy. The prevalence and annual incidence of epilepsy, including nodding syndrome, were calculated with 95% Wilson confidence intervals with continuity correction. The latter was also done for CDTi coverage in 2016 and 2021. RESULTS Precisely 5,444 and 6,598 persons were screened for epilepsy before and after implementing the intervention. The CDTi coverage of the overall population was 82.3% (95%CI: 81.3-83.2%) in 2021 and sustained in both distribution rounds (81.5% and 76.8%). The coverage was particularly high in children and teenagers aged 6 to 18 years (93.2%, 95%CI: 92.1-94.2%). The epilepsy prevalence remained similar: 3.3% (95%CI: 2.9-3.9%) in 2017/18 versus 3.1% (95%CI: 2.7-3.5%) in 2021. However, the incidence of epilepsy declined from 177.6 (95%CI: 121.2-258.5) in 2015-2017 and 2016-2018 to 45.5 (95%CI: 22.2-89.7) in 2019-2021 per 100,000 persons-years. The incidence of probable nodding syndrome varied from 18.4 (95%CI: 4.7-58.5) to 5.1 (95%CI: 0.3-32.8). None of the nine incidence cases of epilepsy for which information on ivermectin intake was available took ivermectin in the year they developed their first seizures. CONCLUSION A bi-annual CDTi programme should be implemented in areas with high prevalence of onchocerciasis and epilepsy. High CDTi coverage among children is particularly important to prevent onchocerciasis-associated epilepsy.
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Affiliation(s)
- Dan Bhwana
- National Institute of Medical Research, Tanga, Tanzania
| | | | - Athanas Mhina
- National Institute of Medical Research, Tanga, Tanzania
| | - Paul Matine
- National Institute of Medical Research, Tanga, Tanzania
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Frallonardo L, Di Gennaro F, Panico GG, Novara R, Pallara E, Cotugno S, Guido G, De Vita E, Ricciardi A, Totaro V, Camporeale M, De Iaco G, Bavaro DF, Lattanzio R, Patti G, Brindicci G, Papagni R, Pellegrino C, Santoro CR, Segala FV, Putoto G, Nicastri E, Saracino A. Onchocerciasis: Current knowledge and future goals. FRONTIERS IN TROPICAL DISEASES 2022. [DOI: 10.3389/fitd.2022.986884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Human Onchocerciasis, caused by infection by the filarial nematode Onchocerca volvulus, is a neglected public health disease that affects millions of people in the endemic regions of sub-Saharan Africa and Latin America. It is also called river blindness because the Blackflies that transmit infection breeds in rapidly flowing fresh water streams and rivers. This review features state-of-the-art data on the parasite, its endobacteria Wolbachia, the prevalence of the infection and its geographical distribution, its diagnostics, the interaction between the parasite and its host, and the pathology of Onchocerciasis. By development and optimization of the control measures, transmission by the vector has been interrupted in foci of countries in the Americas (Colombia, Ecuador, Mexico, and Guatemala)and inSudan, followed by Onchocerciasis eliminations. The current state and future perspectives for vector control and elimination strategy are described.
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Angwafor SA, Bell GS, Ngarka L, Otte W, Tabah EN, Nfor LN, Njamnshi TN, Njamnshi AK, Sander JW. Incidence and prevalence of epilepsy and associated factors in a health district in North-West Cameroon: A population survey. Epilepsy Behav 2021; 121:108048. [PMID: 34083120 DOI: 10.1016/j.yebeh.2021.108048] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 04/28/2021] [Accepted: 04/28/2021] [Indexed: 11/25/2022]
Abstract
This population-based cross-sectional survey with a follow-up case-control study assessed the prevalence, incidence, and risk factors for epilepsy in a rural health district in the North-West Region of Cameroon. Community-based epilepsy screening targeted all inhabitants, six years and older, in all 16 health areas in the Batibo Health District. During door-to-door visits, trained fieldworkers used a validated questionnaire to interview consenting household heads to screen for epilepsy in eligible residents. Trained physicians subsequently assessed people with suspected seizures. After clinical assessment, they confirmed or refuted the diagnosis and estimated the date of epilepsy onset. A trained nurse interviewed people with epilepsy and randomly selected healthy individuals, obtaining relevant demographic details and information on exposure to risk factors for epilepsy. Out of 36,282 residents screened, 524 had active epilepsy. The age-standardized prevalence of active epilepsy was 33.9/1,000 (95% CI: 31.0-37.1/1,000). We estimated the one-year age-standardized epilepsy incidence at 171/100,000 (95%CI: 114.0-254.6). Active epilepsy prevalence varied widely between health areas, ranging between 12 and 75 per 1,000. The peak age-specific prevalence was in the 25-34 age group. In adults, multivariate analysis showed that having a relative with epilepsy was positively associated with epilepsy. Epilepsy characteristics in this population, geographical heterogeneity, and the age-specific prevalence pattern suggest that endemic neurocysticercosis and onchocerciasis may be implicated. Further investigations are warranted to establish the full range of risk factors for epilepsy in this population.
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Affiliation(s)
- Samuel A Angwafor
- NIHR University College London Hospitals Biomedical Research Centre, UCL Queen Square Institute of Neurology, London WC1N 3BG and Chalfont Centre for Epilepsy, Chalfont St Peter, Bucks SL9 0RJ, United Kingdom; Faculty of Health Sciences, University of Bamenda, Cameroon
| | - Gail S Bell
- NIHR University College London Hospitals Biomedical Research Centre, UCL Queen Square Institute of Neurology, London WC1N 3BG and Chalfont Centre for Epilepsy, Chalfont St Peter, Bucks SL9 0RJ, United Kingdom
| | - Leonard Ngarka
- Neurology Department, Central Hospital Yaoundé/Faculty of Medicine and Biomedical Sciences (FMBS), The University of Yaoundé I, Yaoundé, Cameroon; Brain Research Africa Initiative (BRAIN), Yaoundé, Cameroon/Geneva, Switzerland
| | - Willem Otte
- Department of Pediatric Neurology, UMC Utrecht Brain Center, University Medical Center Utrecht and Utrecht University, Utrecht, Netherlands
| | - Earnest N Tabah
- Department of Public Health, Faculty of Medicine and Biomedical Sciences, University Of Dschang, Cameroon & Department of Disease Control, Ministry of Public Health, Yaounde, Cameroon
| | - Leonard N Nfor
- Neurology Department, Central Hospital Yaoundé/Faculty of Medicine and Biomedical Sciences (FMBS), The University of Yaoundé I, Yaoundé, Cameroon; Brain Research Africa Initiative (BRAIN), Yaoundé, Cameroon/Geneva, Switzerland
| | - Theophilus N Njamnshi
- Department of Medical Laboratory Science, School of Health and Medical Science, Kumbo, Catholic University of Cameroon, Bamenda, Cameroon
| | - Alfred K Njamnshi
- Neurology Department, Central Hospital Yaoundé/Faculty of Medicine and Biomedical Sciences (FMBS), The University of Yaoundé I, Yaoundé, Cameroon; Brain Research Africa Initiative (BRAIN), Yaoundé, Cameroon/Geneva, Switzerland.
| | - Josemir W Sander
- NIHR University College London Hospitals Biomedical Research Centre, UCL Queen Square Institute of Neurology, London WC1N 3BG and Chalfont Centre for Epilepsy, Chalfont St Peter, Bucks SL9 0RJ, United Kingdom; Stichting Epilepsie Instelligen Nederland (SEIN), Heemstede, Netherlands
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Luna J, Metanmo S, Boumediene F, Mbelesso P, Auditeau E, Ajzenberg D, Preux PM. Onchocerciasis in tropical neurology: A scoping review. J Neurol Sci 2021; 421:117314. [PMID: 33493958 DOI: 10.1016/j.jns.2021.117314] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 01/05/2021] [Accepted: 01/06/2021] [Indexed: 11/18/2022]
Abstract
BACKGROUND Onchocerciasis is a serious problem in tropical areas. The role of the parasite as a factor associated with neurological diseases needs to be addressed because it might involve a reduction of the risk via elimination strategies. We performed a systematic scoping review to identify available studies on this association and put into perspective the different methodological approaches for interpreting the evidence. METHODOLOGY A literature search was conducted using MEDLINE (Pubmed) through October 1, 2020. We included all the studies evaluating the association between onchocerciasis and four neurological diseases (epilepsy, nodding syndrome, Nakalanga syndrome, and encephalitis) in tropical countries. A descriptive and critical summary of the results was conducted to provide an overview of the findings. RESULTS Overall, 161 articles were identified in the literature search. After full-length examination, we included twelve articles for epilepsy and three for nodding syndrome. Two meta-analyses of case-control studies found a modest strength of the association between O. volvulus and epilepsy. Recent meta-analyses and original studies support a significant association. Epidemiological studies suggest an association between onchocerciasis and nodding syndrome, however, the level of evidence from case-control studies was relatively low. No measure of association was reported for Nakalanga syndrome. There was no specific study on the association between O. volvulus and encephalitis. CONCLUSION The association between onchocerciasis and epilepsy seems increasingly likely. However, there are still many unanswered questions about the different clinical presentations of this epilepsy. Strong international collaboration is essential to improve our understanding of risk factors and physiopathological mechanisms of these intriguing conditions.
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Affiliation(s)
- Jaime Luna
- INSERM, Univ. Limoges, CHU Limoges, IRD, U1094 Tropical Neuroepidemiology, Institute of Epidemiology and Tropical Neurology, GEIST, Limoges, France
| | - Salvatore Metanmo
- INSERM, Univ. Limoges, CHU Limoges, IRD, U1094 Tropical Neuroepidemiology, Institute of Epidemiology and Tropical Neurology, GEIST, Limoges, France
| | - Farid Boumediene
- INSERM, Univ. Limoges, CHU Limoges, IRD, U1094 Tropical Neuroepidemiology, Institute of Epidemiology and Tropical Neurology, GEIST, Limoges, France
| | - Pascal Mbelesso
- Department of Neurology, Amitié Hospital, Bangui, Central African Republic
| | - Emilie Auditeau
- INSERM, Univ. Limoges, CHU Limoges, IRD, U1094 Tropical Neuroepidemiology, Institute of Epidemiology and Tropical Neurology, GEIST, Limoges, France
| | - Daniel Ajzenberg
- INSERM, Univ. Limoges, CHU Limoges, IRD, U1094 Tropical Neuroepidemiology, Institute of Epidemiology and Tropical Neurology, GEIST, Limoges, France
| | - Pierre-Marie Preux
- INSERM, Univ. Limoges, CHU Limoges, IRD, U1094 Tropical Neuroepidemiology, Institute of Epidemiology and Tropical Neurology, GEIST, Limoges, France.
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Colebunders R, Njamnshi AK, Menon S, Newton CR, Hotterbeekx A, Preux PM, Hopkins A, Vaillant M, Siewe Fodjo JN. Onchocerca volvulus and epilepsy: A comprehensive review using the Bradford Hill criteria for causation. PLoS Negl Trop Dis 2021; 15:e0008965. [PMID: 33411705 PMCID: PMC7790236 DOI: 10.1371/journal.pntd.0008965] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND The possibility that onchocerciasis may cause epilepsy has been suggested for a long time, but thus far, an etiological link has not been universally accepted. The objective of this review is to critically appraise the relationship between Onchocerca volvulus and epilepsy and subsequently apply the Bradford Hill criteria to further evaluate the likelihood of a causal association. METHODS PubMed and gray literature published until September 15, 2020, were searched and findings from original research were synthesized. Adherence to the 9 Bradford Hill criteria in the context of onchocerciasis and epilepsy was determined to assess whether the criteria are met to strengthen the evidence base for a causal link between infection with O. volvulus and epilepsy, including the nodding syndrome. RESULTS Onchocerciasis as a risk factor for epilepsy meets the following Bradford Hill criteria for causality: strength of the association, consistency, temporality, and biological gradient. There is weaker evidence supporting causality based on the specificity, plausibility, coherence, and analogy criteria. There is little experimental evidence. Considering the Bradford Hill criteria, available data suggest that under certain conditions (high microfilarial load, timing of infection, and perhaps genetic predisposition), onchocerciasis is likely to cause epilepsy including nodding and Nakalanga syndromes. CONCLUSION Applying the Bradford Hill criteria suggests consistent epidemiological evidence that O. volvulus infection is a trigger of epilepsy. However, the pathophysiological mechanisms responsible for seizure induction still need to be elucidated.
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Affiliation(s)
- Robert Colebunders
- Global Health Institute, University of Antwerp, Antwerp, Belgium
- * E-mail:
| | - Alfred K. Njamnshi
- Neurology Department, Yaoundé Central Hospital, Yaoundé, Cameroon
- Faculty of Medicine and Biomedical Sciences, University of Yaoundé I, Yaoundé Cameroon
- Brain Research Africa Initiative (BRAIN), Yaoundé, Cameroon
| | - Sonia Menon
- Global Health Institute, University of Antwerp, Antwerp, Belgium
| | - Charles R. Newton
- Department of Psychiatry, University of Oxford, Oxford, United Kingdom
| | - An Hotterbeekx
- Global Health Institute, University of Antwerp, Antwerp, Belgium
| | - Pierre-Marie Preux
- Institute of Epidemiology and Tropical Neurology, INSERM UMR1094, University of Limoges, Limoges, France
| | - Adrian Hopkins
- Neglected and Disabling Diseases of Poverty Consultant, Kent, United Kingdom
| | - Michel Vaillant
- Competence Center in Methodology and Statistics, Luxembourg Institute of Health, Strassen, Luxembourg
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Siewe Fodjo JN, Remme JHF, Preux PM, Colebunders R. Meta-analysis of epilepsy prevalence in West Africa and its relationship with onchocerciasis endemicity and control. Int Health 2020; 12:192-202. [PMID: 32141502 PMCID: PMC7320426 DOI: 10.1093/inthealth/ihaa012] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 02/04/2020] [Accepted: 02/19/2020] [Indexed: 01/28/2023] Open
Abstract
Background A high prevalence and incidence of epilepsy has been reported in onchocerciasis-endemic regions in Central and East Africa. There is compelling epidemiological evidence suggesting that this high burden is caused by onchocerciasis-associated epilepsy (OAE). We hypothesized that OAE had also occured in West African onchocerciasis foci. Methods We searched PubMed, the African Journals Online platform and grey literature for population-based epilepsy studies in West African countries. Epilepsy and onchocerciasis prevalence data were extracted. The pre-control onchocerciasis endemicity in the study sites was estimated from historical data of onchocerciasis control programmes. The prevalence of epilepsy in different sites was analysed, taking into account onchocerciasis endemicity and the duration of control. Results The pooled prevalence of epilepsy in the West African study sites was 13.14 per 1000 (95% confidence interval 11.28–15.00). Higher pre-control endemicity and a shorter duration of onchocerciasis control were both associated with increased epilepsy prevalence (p<0.001). Two studies in Ivory Coast that provided detailed descriptions of persons with epilepsy in onchocerciasis-endemic settings revealed that most of them had features of OAE (73.7% and 83.3%, respectively). Conclusions Our findings suggest that before and during the early years of implementing onchocerciasis control in West Africa, high onchocerciasis endemicity resulted in a high prevalence of OAE and that subsequent control efforts significantly reduced the prevalence of OAE.
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Affiliation(s)
| | | | - Pierre-Marie Preux
- INSERM, University of Limoges, CHU Limoges, UMR 1094, Tropical Neuroepidemiology, Institute of Neuroepidemiology and Tropical Neurology, GEIST, 87000 Limoges, France
| | - Robert Colebunders
- Global Health Institute, University of Antwerp, Doornstraat 331, 2610 Antwerp, Belgium
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Vanhamme L, Souopgui J, Ghogomu S, Ngale Njume F. The Functional Parasitic Worm Secretome: Mapping the Place of Onchocerca volvulus Excretory Secretory Products. Pathogens 2020; 9:pathogens9110975. [PMID: 33238479 PMCID: PMC7709020 DOI: 10.3390/pathogens9110975] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 11/17/2020] [Accepted: 11/18/2020] [Indexed: 01/15/2023] Open
Abstract
Nematodes constitute a very successful phylum, especially in terms of parasitism. Inside their mammalian hosts, parasitic nematodes mainly dwell in the digestive tract (geohelminths) or in the vascular system (filariae). One of their main characteristics is their long sojourn inside the body where they are accessible to the immune system. Several strategies are used by parasites in order to counteract the immune attacks. One of them is the expression of molecules interfering with the function of the immune system. Excretory-secretory products (ESPs) pertain to this category. This is, however, not their only biological function, as they seem also involved in other mechanisms such as pathogenicity or parasitic cycle (molting, for example). We will mainly focus on filariae ESPs with an emphasis on data available regarding Onchocerca volvulus, but we will also refer to a few relevant/illustrative examples related to other worm categories when necessary (geohelminth nematodes, trematodes or cestodes). We first present Onchocerca volvulus, mainly focusing on the aspects of this organism that seem relevant when it comes to ESPs: life cycle, manifestations of the sickness, immunosuppression, diagnosis and treatment. We then elaborate on the function and use of ESPs in these aspects.
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Affiliation(s)
- Luc Vanhamme
- Department of Molecular Biology, Institute of Biology and Molecular Medicine, IBMM, Université Libre de Bruxelles, Rue des Professeurs Jeener et Brachet 12, 6041 Gosselies, Belgium; (J.S.); (F.N.N.)
- Correspondence:
| | - Jacob Souopgui
- Department of Molecular Biology, Institute of Biology and Molecular Medicine, IBMM, Université Libre de Bruxelles, Rue des Professeurs Jeener et Brachet 12, 6041 Gosselies, Belgium; (J.S.); (F.N.N.)
| | - Stephen Ghogomu
- Molecular and Cell Biology Laboratory, Biotechnology Unit, University of Buea, Buea P.O Box 63, Cameroon;
| | - Ferdinand Ngale Njume
- Department of Molecular Biology, Institute of Biology and Molecular Medicine, IBMM, Université Libre de Bruxelles, Rue des Professeurs Jeener et Brachet 12, 6041 Gosselies, Belgium; (J.S.); (F.N.N.)
- Molecular and Cell Biology Laboratory, Biotechnology Unit, University of Buea, Buea P.O Box 63, Cameroon;
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Johnson TP, Sejvar J, Nutman TB, Nath A. The Pathogenesis of Nodding Syndrome. ANNUAL REVIEW OF PATHOLOGY-MECHANISMS OF DISEASE 2020; 15:395-417. [PMID: 31977293 DOI: 10.1146/annurev-pathmechdis-012419-032748] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Nodding syndrome is a rare, enigmatic form of pediatric epilepsy that has occurred in an epidemic fashion beginning in the early 2000s in geographically distinct regions of Africa. Despite extensive investigation, the etiology of nodding syndrome remains unclear, although much progress has been made in understanding the pathogenesis of the disease, as well as in treatment and prevention. Nodding syndrome is recognized as a defined disease entity, but it is likely one manifestation along a continuum of Onchocerca volvulus-associated neurological complications. This review examines the epidemiology of nodding syndrome and its association with environmental factors. It provides a critical analysis of the data that support or contradict the leading hypotheses of the etiologies underlying the pathogenesis of the syndrome. It also highlights the important progress made in treating and preventing this devastating neurological disease and prioritizes important areas for future research.
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Affiliation(s)
- Tory P Johnson
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA
| | - James Sejvar
- Division of High-Consequence Pathogens and Pathology, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia 30329-4027, USA
| | - Thomas B Nutman
- Helminth Immunology Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Avindra Nath
- Section of Infections of the Nervous System, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA;
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Vinkeles Melchers NVS, Mollenkopf S, Colebunders R, Edlinger M, Coffeng LE, Irani J, Zola T, Siewe JN, de Vlas SJ, Winkler AS, Stolk WA. Burden of onchocerciasis-associated epilepsy: first estimates and research priorities. Infect Dis Poverty 2018; 7:101. [PMID: 30253788 PMCID: PMC6156959 DOI: 10.1186/s40249-018-0481-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Accepted: 08/30/2018] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Since the 1990s, evidence has accumulated of an increased prevalence of epilepsy in onchocerciasis-endemic areas in Africa as compared to onchocerciasis-free areas. Although the causal relationship between onchocerciasis and epilepsy has yet to be proven, there is likely an association. Here we discuss the need for disease burden estimates of onchocerciasis-associated epilepsy (OAE), provide them, detail how such estimates should be refined, and discuss the socioeconomic impact of OAE, including a cost-estimate for anti-epileptic drugs. MAIN BODY Providing OAE burden estimates may aid prevention of epilepsy in onchocerciasis- endemic areas by inciting and informing collaboration between onchocerciasis control programmes and mental health services. Epilepsy not only massively impacts the health of those affected, but it also carries a high socioeconomic burden for the households and communities involved. We used previously published geospatial estimates of onchocerciasis in Africa and a separately published logistic regression model quantifying the association between onchocerciasis and epilepsy to estimate the number of OAE cases. We then applied disability weights for epilepsy to quantify the burden in terms of years of life lived with disability (YLD) and estimate the cost of treatment. We estimate that in 2015 roughly 117 000 people were affected by OAE across onchocerciasis-endemic areas previously under the African Programme for Onchocerciases control (APOC) mandate where OAE has ever been reported or suspected, and another 264 000 persons in onchocerciasis-endemic areas where OAE has never been investigated before. The total number of YLDs due to OAE was 39 300 and 88 700 in these areas respectively, based on a weighted mean disability weight of 0.336. The burden of OAE is approximately 13% of the total YLDs attributable to onchocerciasis and 10% of total YLDs attributable to epilepsy. We estimated that by 2015 the total costs of treatment with anti-epileptic drug for OAE cases would have been a minimum of 12.4 million US$. CONCLUSIONS These estimates suggest a considerable health, social and economic burden of OAE in Africa. The treatment and care for people with epilepsy, especially in hyperendemic onchocerciasis areas with high epilepsy prevalence thus requires more financial and human resources.
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Affiliation(s)
- Natalie V S Vinkeles Melchers
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, P.O. box 2040, 3000, CA, Rotterdam, The Netherlands.
| | - Sarah Mollenkopf
- Institute for Health Metrics and Evaluation, University of Washington, 2301 5th Avenue, Suite 600, Seattle, WA, 98121, USA
| | | | - Michael Edlinger
- Department of Medical Statistics, Informatics, and Health Economics, Medical University Innsbruck, Vienna, Austria
| | - Luc E Coffeng
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, P.O. box 2040, 3000, CA, Rotterdam, The Netherlands
| | - Julia Irani
- Department of Public Health, Institute of Tropical Medicine Antwerp, Nationalestraat 155, 2000, Antwerp, Belgium
| | - Trésor Zola
- Department of Tropical Medicine, University of Kinshasa, Kinshasa, Democratic Republic of the Congo
| | - Joseph N Siewe
- Global Health Institute, University of Antwerp, Antwerp, Belgium
| | - Sake J de Vlas
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, P.O. box 2040, 3000, CA, Rotterdam, The Netherlands
| | - Andrea S Winkler
- Centre for Global Health, Institute for Health and Society, Oslo, Norway.,Center for Global Health, Department of Neurology, Technical University of Munich, Munich, Germany
| | - Wilma A Stolk
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, P.O. box 2040, 3000, CA, Rotterdam, The Netherlands
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Colebunders R, Basáñez MG, Siling K, Post RJ, Rotsaert A, Mmbando B, Suykerbuyk P, Hopkins A. From river blindness control to elimination: bridge over troubled water. Infect Dis Poverty 2018; 7:21. [PMID: 29587844 PMCID: PMC5872540 DOI: 10.1186/s40249-018-0406-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Accepted: 03/12/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND An estimated 25 million people are currently infected with onchocerciasis (a parasitic infection caused by the filarial nematode Onchocerca volvulus and transmitted by Simulium vectors), and 99% of these are in sub-Saharan Africa. The African Programme for Onchocerciasis Control closed in December 2015 and the World Health Organization has established a new structure, the Expanded Special Project for the Elimination of Neglected Tropical Diseases for the coordination of technical support for activities focused on five neglected tropical diseases in Africa, including onchocerciasis elimination. AIMS In this paper we argue that despite the delineation of a reasonably well-defined elimination strategy, its implementation will present particular difficulties in practice. We aim to highlight these in an attempt to ensure that they are well understood and that effective plans can be laid to solve them by the countries concerned and their international partners. CONCLUSIONS A specific concern is the burden of disease caused by onchocerciasis-associated epilepsy in hyperendemic zones situated in countries experiencing difficulties in strengthening their onchocerciasis control programmes. These difficulties should be identified and programmes supported during the transition from morbidity control to interruption of transmission and elimination.
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Affiliation(s)
| | - Maria-Gloria Basáñez
- London Centre for Neglected Tropical Disease Research, Imperial College London, London, UK
| | - Katja Siling
- Institute of Tropical Medicine, Antwerp, Belgium
- London School of Hygiene & Tropical Medicine, London, UK
| | - Rory J. Post
- London School of Hygiene & Tropical Medicine, London, UK
- Liverpool John Moores University, Liverpool, UK
| | - Anke Rotsaert
- Global Health Institute, University of Antwerp, Antwerp, Belgium
| | - Bruno Mmbando
- National Institute for Medical Research, Tanga, Tanzania
| | | | - Adrian Hopkins
- Neglected and Disabling diseases of Poverty Consultant, Gravesend, Kent, UK
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Walsh S, Donnan J, Fortin Y, Sikora L, Morrissey A, Collins K, MacDonald D. A systematic review of the risks factors associated with the onset and natural progression of epilepsy. Neurotoxicology 2017; 61:64-77. [DOI: 10.1016/j.neuro.2016.03.011] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Accepted: 03/14/2016] [Indexed: 01/08/2023]
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Colebunders R, Njamnshi AK, van Oijen M, Mukendi D, Kashama JM, Mandro M, Gumisiriza N, Preux PM, Suykerbuyk P, Idro R. Onchocerciasis-associated epilepsy: From recent epidemiological and clinical findings to policy implications. Epilepsia Open 2017; 2:145-152. [PMID: 29588943 PMCID: PMC5719844 DOI: 10.1002/epi4.12054] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/15/2017] [Indexed: 11/12/2022] Open
Abstract
A high prevalence of epilepsy is reported in many onchocerciasis‐endemic regions. In this paper we discuss recent epidemiological and clinical aspects as well as public health implications of onchocerciasis‐associated epilepsy (OAE) and propose a strategy to reduce the burden of disease. OAE probably presents in a variety of clinical manifestations, including the nodding syndrome and the Nakalanga syndrome. The most common clinical presentation, however, is generalized (primarily tonic‐clonic) seizures. A characteristic of OAE is the onset of seizures between the ages of 3 and 18 years and clustering in certain families and villages close to rapid‐flowing black‐fly‐infested rivers. A strategy combining active surveillance for epilepsy with early treatment with antiepileptic drugs and prevention of onchocerciasis by increasing the geographical and therapeutic coverage of community‐directed treatment with ivermectin (CDTi) may considerably decrease the burden of disease.
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Affiliation(s)
| | - Alfred K Njamnshi
- Neurology Department Central Hospital Yaoundé Faculty of Medicine and Biomedical Sciences the University of Yaoundé IYaoundé IRepublic of Cameroon
| | - Marieke van Oijen
- Global Health Institute University of Antwerp Antwerp Belgium.,Department of Neurology Academic Medical Center Amsterdam the Netherlands
| | - Deby Mukendi
- Neuro-psycho-pathological Centre University of Kinshasa Kinshasa Democratic Republic of the Congo
| | - Jean Marie Kashama
- Neuro-psycho-pathological Centre University of Kinshasa Kinshasa Democratic Republic of the Congo
| | - Michel Mandro
- Provincial division of Health of Ituri Ministery of Health Bunia Democratic Republic of the Congo
| | | | | | | | - Richard Idro
- College of Health Sciences Makerere University Kampala Uganda.,Nuffield Department of Medicine Centre for Tropical Medicine and Global Health University of Oxford Oxford United Kingdom
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Kaiser C, Rubaale T, Tukesiga E, Kipp W, Asaba G. Nodding syndrome, western Uganda, 1994. Am J Trop Med Hyg 2015; 93:198-202. [PMID: 25918208 PMCID: PMC4497897 DOI: 10.4269/ajtmh.14-0838] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2014] [Accepted: 03/15/2015] [Indexed: 11/07/2022] Open
Abstract
Nodding syndrome (NS) is a poorly understood condition, which was delineated in 2008 as a new epilepsy syndrome. So far, confirmed cases of NS have been observed in three circumscribed African areas: southern Tanzania, southern Sudan, and northern Uganda. Case-control studies have provided evidence of an association between NS and infection with Onchocerca volvulus, but the causation of NS is still not fully clarified. We report a case of a 15-year old boy with head nodding seizures and other characteristic features of NS from an onchocerciasis endemic area in western Uganda, with no contiguity to the hitherto known areas. We suggest that the existence of NS should be systematically investigated in other areas.
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Affiliation(s)
- Christoph Kaiser
- Basic Health Services, Kabarole and Bundibugyo Districts, Fort Portal, Uganda; Vector Control Unit, Ministry of Health, Fort Portal, Uganda; Department of Public Health Sciences, University of Alberta, Edmonton, Canada
| | - Tom Rubaale
- Basic Health Services, Kabarole and Bundibugyo Districts, Fort Portal, Uganda; Vector Control Unit, Ministry of Health, Fort Portal, Uganda; Department of Public Health Sciences, University of Alberta, Edmonton, Canada
| | - Ephraim Tukesiga
- Basic Health Services, Kabarole and Bundibugyo Districts, Fort Portal, Uganda; Vector Control Unit, Ministry of Health, Fort Portal, Uganda; Department of Public Health Sciences, University of Alberta, Edmonton, Canada
| | - Walter Kipp
- Basic Health Services, Kabarole and Bundibugyo Districts, Fort Portal, Uganda; Vector Control Unit, Ministry of Health, Fort Portal, Uganda; Department of Public Health Sciences, University of Alberta, Edmonton, Canada
| | - George Asaba
- Basic Health Services, Kabarole and Bundibugyo Districts, Fort Portal, Uganda; Vector Control Unit, Ministry of Health, Fort Portal, Uganda; Department of Public Health Sciences, University of Alberta, Edmonton, Canada
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Ae-Ngibise KA, Akpalu B, Ngugi A, Akpalu A, Agbokey F, Adjei P, Punguyire D, Bottomley C, Newton C, Owusu-Agyei S. Prevalence and risk factors for Active Convulsive Epilepsy in Kintampo, Ghana. Pan Afr Med J 2015; 21:29. [PMID: 26401223 PMCID: PMC4561141 DOI: 10.11604/pamj.2015.21.29.6084] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Accepted: 04/22/2015] [Indexed: 11/11/2022] Open
Abstract
INTRODUCTION Epilepsy is common in sub-Saharan Africa, but there is little data in West Africa, to develop public health measures for epilepsy in this region. METHODS We conducted a three-stage cross-sectional survey to determine the prevalence and risk factors for active convulsive epilepsy (ACE), and estimated the treatment gap in Kintampo situated in the middle of Ghana. RESULTS 249 people with ACE were identified in a study population of 113,796 individuals. After adjusting for attrition and the sensitivity of the screening method, the prevalence of ACE was 10.1/1000 (95% Confidence Interval (95% CI) 9.5-10.7). In children aged <18 years, risk factors for ACE were: family history of seizures (OR=3.31; 95% CI: 1.83-5.96), abnormal delivery (OR=2.99; 95% CI: 1.07-8.34), problems after birth (OR=3.51; 95% CI: 1.02-12.06), and exposure to Onchocerca volvulus (OR=2.32; 95% CI: 1.12-4.78). In adults, a family history of seizures (OR=1.83; 95% CI: 1.05-3.20), never attended school (OR=11.68; 95% CI: 4.80-28.40), cassava consumption (OR=3.92; 95% CI: 1.14-13.54), pork consumption (OR=1.68; 95% CI: 1.09-2.58), history of snoring at least 3 nights per week (OR=3.40: 95% CI: 1.56-7.41), exposure to Toxoplasma gondii (OR=1.99; 95% CI: 1.15-3.45) and Onchocerca volvulus (OR=2.09: 95% CI: 1.29-3.40) were significant risk factors for the development of ACE. The self-reported treatment gap was 86.9% (95% CI: 83.5%-90.3%). CONCLUSION ACE is common within the middle belt of Ghana and could be reduced with improved obstetric care and prevention of parasite infestations such as Onchocerca volvulus and Toxoplasma gondii.
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Affiliation(s)
- Kenneth Ayuurebobi Ae-Ngibise
- Kintampo Health Research Centre, Ghana Health Service, Kintampo, Ghana ; Studies of the Epidemiology of Epilepsy in Demographic Surveillance Systems (SEEDS)-INDEPTH Network Accra, Ghana
| | - Bright Akpalu
- Kintampo Health Research Centre, Ghana Health Service, Kintampo, Ghana ; Studies of the Epidemiology of Epilepsy in Demographic Surveillance Systems (SEEDS)-INDEPTH Network Accra, Ghana
| | - Anthony Ngugi
- Studies of the Epidemiology of Epilepsy in Demographic Surveillance Systems (SEEDS)-INDEPTH Network Accra, Ghana ; KEMRI/Wellcome Trust Research Programme, The Centre of Geographical Medicine Research- Coast, Kilifi, Kenya ; Population Health Sciences/Research Support Unit, Faculty of Health Sciences, Aga Khan University- East Africa, Nairobi, Kenya
| | - Albert Akpalu
- Department of Medicine, Korle Bu Teaching Hospital, Ghana
| | - Francis Agbokey
- Kintampo Health Research Centre, Ghana Health Service, Kintampo, Ghana ; Studies of the Epidemiology of Epilepsy in Demographic Surveillance Systems (SEEDS)-INDEPTH Network Accra, Ghana
| | - Patrick Adjei
- Department of Medicine, Korle Bu Teaching Hospital, Ghana
| | | | - Christian Bottomley
- MRC Tropical Epidemiology Group, London School of Hygiene and Tropical Medicine, UK
| | - Charles Newton
- Studies of the Epidemiology of Epilepsy in Demographic Surveillance Systems (SEEDS)-INDEPTH Network Accra, Ghana ; KEMRI/Wellcome Trust Research Programme, The Centre of Geographical Medicine Research- Coast, Kilifi, Kenya ; Department of Psychiatry, University of Oxford, United Kingdom
| | - Seth Owusu-Agyei
- Kintampo Health Research Centre, Ghana Health Service, Kintampo, Ghana ; Studies of the Epidemiology of Epilepsy in Demographic Surveillance Systems (SEEDS)-INDEPTH Network Accra, Ghana
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Ba-Diop A, Marin B, Druet-Cabanac M, Ngoungou EB, Newton CR, Preux PM. Epidemiology, causes, and treatment of epilepsy in sub-Saharan Africa. Lancet Neurol 2014; 13:1029-44. [PMID: 25231525 PMCID: PMC5497080 DOI: 10.1016/s1474-4422(14)70114-0] [Citation(s) in RCA: 188] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
SUMMARY Epilepsy is a common neurological disease in tropical countries, particularly in sub-Saharan Africa. Previous work on epilepsy in sub-Saharan Africa has shown that many cases are severe, partly a result of some specific causes, that it carries a stigma, and that it is not adequately treated in many cases. Many studies on the epidemiology, aetiology, and management of epilepsy in sub-Saharan Africa have been reported in the past 10 years. The prevalence estimated from door-to-door studies is almost double that in Asia, Europe, and North America. The most commonly implicated risk factors are birth trauma, CNS infections, and traumatic brain injury. About 60% of patients with epilepsy receive no antiepileptic treatment, largely for economic and social reasons. Further epidemiological studies should be a priority to improve understanding of possible risk factors and thereby the prevention of epilepsy in Africa, and action should be taken to improve access to treatment.
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Affiliation(s)
- Awa Ba-Diop
- INSERM UMR1094, Tropical Neuroepidemiology, and Institute of Neuroepidemiology and Tropical Neurology, School of Medicine, University of Limoges, Limoges, France
| | - Benoît Marin
- INSERM UMR1094, Tropical Neuroepidemiology, and Institute of Neuroepidemiology and Tropical Neurology, School of Medicine, University of Limoges, Limoges, France; CEBIMER: Center of Epidemiology, Biostatitics, and Research Methodology, CHU Limoges, France
| | - Michel Druet-Cabanac
- INSERM UMR1094, Tropical Neuroepidemiology, and Institute of Neuroepidemiology and Tropical Neurology, School of Medicine, University of Limoges, Limoges, France
| | - Edgard B Ngoungou
- INSERM UMR1094, Tropical Neuroepidemiology, and Institute of Neuroepidemiology and Tropical Neurology, School of Medicine, University of Limoges, Limoges, France; Unit of Neuroepidemiology and Tropical Infectious Diseases, Department of Epidemiology, Biostatistics, University of Health Sciences, Libreville, Gabon
| | - Charles R Newton
- KEMRI/Wellcome Trust Collaborative Programme, Centre for Geographical Medicine, Kilifi, Kenya; Department of Psychiatry, University of Oxford, Oxford, UK
| | - Pierre-Marie Preux
- INSERM UMR1094, Tropical Neuroepidemiology, and Institute of Neuroepidemiology and Tropical Neurology, School of Medicine, University of Limoges, Limoges, France; CEBIMER: Center of Epidemiology, Biostatitics, and Research Methodology, CHU Limoges, France.
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Dowell SF, Sejvar JJ, Riek L, Vandemaele KAH, Lamunu M, Kuesel AC, Schmutzhard E, Matuja W, Bunga S, Foltz J, Nutman TB, Winkler AS, Mbonye AK. Nodding syndrome. Emerg Infect Dis 2014; 19:1374-84. [PMID: 23965548 PMCID: PMC3810928 DOI: 10.3201/eid1909.130401] [Citation(s) in RCA: 100] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
An epidemic illness characterized by head nodding associated with onchocerciasis has been described in eastern Africa since the early 1960s; we summarize published reports and recent studies. Onset of nodding occurs in previously healthy 5-15-year-old children and is often triggered by eating or cold temperatures and accompanied by cognitive impairment. Its incidence has increased in Uganda and South Sudan over the past 10 years. Four case-control studies identified modest and inconsistent associations. There were nonspecific lesions seen by magnetic resonance imaging, no cerebrospinal fluid inflammation, and markedly abnormal electroencephalography results. Nodding episodes are atonic seizures. Testing has failed to demonstrate associations with trypanosomiasis, cysticercosis, loiasis, lymphatic filariasis, cerebral malaria, measles, prion disease, or novel pathogens; or deficiencies of folate, cobalamin, pyridoxine, retinol, or zinc; or toxicity from mercury, copper, or homocysteine. There is a consistent enigmatic association with onchocerciasis detected by skin snip or serologic analysis. Nodding syndrome is an unexplained epidemic epilepsy.
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Affiliation(s)
- Scott F Dowell
- Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA.
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Bhalla D, Dumas M, Preux PM. Neurological manifestations of filarial infections. HANDBOOK OF CLINICAL NEUROLOGY 2013; 114:235-42. [PMID: 23829914 DOI: 10.1016/b978-0-444-53490-3.00018-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/17/2023]
Abstract
Filarial infections cause a huge public health burden wherever they are endemic. These filaria may locate anywhere in the human body. Their manifestations and pathogenic mechanisms, except the most common ones, are rarely investigated systematically. Their neurological manifestations, however, are being increasingly recognized particularly with onchocerciasis or Loa loa infections, Wuchereria bancrofti, or Mansonella perstans. The risk of developing these manifestations may also increase in cases that harbor multiple filariasis or coinfections, for instance as with Plasmodium. The microfilaria of Onchocerca and Loa loa are seen in cerebrospinal fluid. The pathogenesis of neurological manifestations of these infections is complex; however, pathogenic reactions may be caused by mechanical disruption, e.g., degeneration often followed by granulomas, causing fibrosis or mass effects on other tissues, vascular lesions, e.g., vascular block of cerebral vessels, or disordered inflammatory responses resulting in meningitis, encephalitis or localized inflammatory responses. The chances of having neurological manifestations may also depend upon the frequency and"heaviness"of infection over a lifetime. Hence, this type of infection should no longer be considered a disease of the commonly affected areas but one that may produce systemic effects or other manifestations, and these should be considered in populations where they are endemic.
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Affiliation(s)
- Devender Bhalla
- INSERM UMR 1094, Tropical Neuroepidemiology, Limoges, France; University of Limoges, School of Medicine, Institute of Neuroepidemiology and Tropical Neurology, CNRS FR 3503 GEIST, Limoges, France; Centre Hospitalier Universitaire, Limoges, France
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Kaiser C, Pion SDS, Boussinesq M. Case-control studies on the relationship between onchocerciasis and epilepsy: systematic review and meta-analysis. PLoS Negl Trop Dis 2013; 7:e2147. [PMID: 23556028 PMCID: PMC3610636 DOI: 10.1371/journal.pntd.0002147] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2012] [Accepted: 02/20/2013] [Indexed: 11/18/2022] Open
Abstract
OBJECTIVE A systematic review and meta-analysis of all available case-control studies on the relationship between onchocerciasis and epilepsy. Because age and level of onchocerciasis endemicity in the area of residence are major determinants for infection, an additional analysis was performed, restricted to studies achieving control of these confounding factors. DATA SOURCES Medical databases, the "African Neurology Database, Institute of Neuroepidemiology and Tropical Neurology, Limoges," reference lists of relevant articles, commercial search engines, up to May 2012. METHODS We searched for studies examining infection status with Onchocerca volvulus in persons with epilepsy (PWE) and without epilepsy (PWOE) providing data suitable for the calculation of pooled odds ratios (ORp) and/or standardized mean differences (SMD) using random-effects models. RESULTS Eleven studies providing data of qualitative skin biopsies for diagnosis of onchocerciasis were identified. Combined analysis on the total sample of 876 PWE and 4712 PWOE resulted in an ORp of 2.49 (95% confidence interval (95%CI): 1.61-3.86, p<0.001). When this analysis was restricted to those studies achieving control for age, residence and sex (367 PWE, 624 PWOE), an ORp of 1.29 (95% CI: 0.93-1.79; p = 0.139) was found. Presence of nodules for diagnosis of onchocerciasis was analyzed in four studies (225 PWE, 189 PWOE; ORp 1.74; 95%CI: 0.94-3.20; p<0.076), including two studies of the restricted analysis (106 PWE, 106 PWOE; ORp 2.81; 95%CI: 1.57-5.00; p<0.001). One study examined quantitative microfilariae counts in patients without preceding microfilaricidal treatment and demonstrated significantly higher counts in PWE than in PWOE. INTERPRETATION Our results strengthen the hypothesis that, in onchocerciasis foci, epilepsy and infection with O. volvulus are associated. Analysis of indicators giving information on infection intensity, namely nodule palpation and quantitative microfilaria count in untreated patients, support the hypothesis that intensity of infection with O. volvulus is involved in the etiology of epilepsy.
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Affiliation(s)
- Christoph Kaiser
- Basic Health Services Kabarole & Bundibugyo Districts, Fort Portal, Uganda.
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Affiliation(s)
- Gretchen L Birbeck
- International Neurologic and Psychiatric Epidemiology Program (INPEP), Michigan State University, MI 48824, USA.
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Pion SDS, Boussinesq M. Significant association between epilepsy and presence of onchocercal nodules: case-control study in Cameroon. Am J Trop Med Hyg 2012; 86:557. [PMID: 22403337 PMCID: PMC3284382 DOI: 10.4269/ajtmh.2012.11-0603a] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
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