Report of the first international workshop on onchocerciasis-associated epilepsy

Onchocerciasis-associated epilepsy: Charting a path forward

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.

Parasitic, bacterial, viral, immune-mediated, metabolic and nutritional factors associated with nodding syndrome

Nodding syndrome is a neglected, disabling and potentially fatal epileptic disorder of unknown aetiology affecting thousands of individuals mostly confined to Eastern sub-Saharan Africa. Previous studies have identified multiple associations-including Onchocerca volvulus, antileiomodin-1 antibodies, vitamin B6 deficiency and measles virus infection-yet, none is proven causal. We conducted a case-control study of children with early-stage nodding syndrome (symptom onset <1 year). Cases and controls were identified through a household survey in the Greater Mundri area in South Sudan. A wide range of parasitic, bacterial, viral, immune-mediated, metabolic and nutritional risk factors was investigated using conventional and state-of-the-art untargeted assays. Associations were examined by multiple logistic regression analysis, and a hypothetical causal model was constructed using structural equation modelling. Of 607 children with nodding syndrome, 72 with early-stage disease were included as cases and matched to 65 household- and 44 community controls. Mansonella perstans infection (odds ratio 7.04, 95% confidence interval 2.28-21.7), Necator americanus infection (odds ratio 2.33, 95% confidence interval 1.02-5.3), higher antimalarial seroreactivity (odds ratio 1.75, 95% confidence interval 1.20-2.57), higher vitamin E concentration (odds ratio 1.53 per standard deviation increase, 95% confidence interval 1.07-2.19) and lower vitamin B12 concentration (odds ratio 0.56 per standard deviation increase, 95% confidence interval 0.36-0.87) were associated with higher odds of nodding syndrome. In a structural equation model, we hypothesized that Mansonella perstans infection, higher vitamin E concentration and fewer viral exposures increased the risk of nodding syndrome while lower vitamin B12 concentration, Necator americanus and malaria infections resulted from having nodding syndrome. We found no evidence that Onchocerca volvulus, antileiomodin-1 antibodies, vitamin B6 and other factors were associated with nodding syndrome. Our results argue against several previous causal hypotheses including Onchocerca volvulus. Instead, nodding syndrome may be caused by a complex interplay between multiple pathogens and nutrient levels. Further studies need to confirm these associations and determine the direction of effect.

Comparison of Structural Changes in Nodding Syndrome and Other Epilepsies Associated With Onchocerca volvulus

BACKGROUND AND OBJECTIVE

Nodding syndrome (NS) is a unique childhood-onset epileptic disorder that occurs predominantly in several regions of sub-Saharan Africa. The disease has been associated with Onchocerca volvulus (Ov)-induced immune responses and possible cross-reactivity with host proteins. The aim of this study was to compare structural changes in the brain on MRI between NS and other forms of onchocerciasis-associated epilepsies (OAEs) and to relate structural changes to the Ov-induced immune responses and level of disability.

METHODS

Thirty-nine children with NS and 14 age-matched participants with other forms of OAE from an endemic region in Uganda underwent detailed clinical examination, serologic evaluation (including Ov-associated antibodies to Ov-16 and Hu-leiomodin-1) and quantitative volumetric analysis of brain MRIs (1.5 T scanner) using Neuroreader, a cloud-based software.

RESULTS

Cerebral and cerebellar atrophy were the predominant features in both NS and OAE. On quantitative volumetric analysis, participants with NS had larger ventricular volumes compared with participants with OAE, indicative of increased global cortical atrophy (p_corr = 0.036). Among children with NS, severe disability correlated with higher degree of atrophy in the gray matter volume (p_corr = 0.009) and cerebellar volume (p_corr = 0.009). NS cases had lower anti-Ov-16 IgG signal-to-noise ratios than the OAE cases (p < 0.01), but no difference in the levels of the Hu-leiomodin-1 antibodies (p = 0.64). The levels of Ov-associated antibodies did not relate to the degree of cerebral or cerebellar atrophy in either NS or OAE cases.

DISCUSSION

This is the first study to show that cerebral and cerebellar atrophy correlated with the severity of NS disability, providing an imaging marker for these endemic epileptic disorders that until now have remained poorly characterized. Both NS and OAE have cerebral and cerebellar atrophy, and the levels of Ov-associated antibodies do not seem to be related to the structural changes on MRI.

Onchocerciasis: Current knowledge and future goals

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.

Prevalence of epilepsy in Ndom Health District (Littoral Region, Cameroon) after long-term ivermectin-based preventive chemotherapy for the control of onchocerciasis

Assuming the causality relationship between Onchocerca volvulus infection and epilepsy onset, preventive chemotherapy for the control onchocerciasis can result to a significant impact on epilepsy burden. This study aimed at assessing the prevalence of epilepsy in an onchocerciasis endemic area under annual CDTI for 16 years. A cross-sectional survey was conducted in two communities (Kelleng and Nkonkwalla) located in the Ndom Health District (Littoral Region, Cameroon) to assess the prevalence of epilepsy using a standardized questionnaire for non-specialists in tropical areas. Data on the nuisance of onchocerciasis vector and distance of surveyed households to the river were also collected. Epilepsy status was collected from 367 participants (sex ratio (M/F): 1.13). The crude prevalence of epilepsy was estimated at 8.4 % (95 % CI: 5.8-11.8); the highest prevalence was found in females (13.8 %; 95 % CI: 8.8-20.3) compared to males (5.0 %; 95 % CI: 2.4-9.04)) (p-value = 0.02) and in Nkonkwalla (9.0 %; 95 % CI: 5.5-13.6) (p-value = 0.82) compared to Kelleng (7.7 %; 95 % CI: 4.06-13.13). After 16 years of CDTI in Kelleng, crude prevalence of epilepsy decreased from 10.2 % to 7.2 % (p-value = 0.19), whereas the age sex-standardized prevalence dropped from 13.5 % to 7.7 % between 2004 and 2020 (p-value = 0.05). The median age of epilepsy cases shifted from 24 (IQR: 20-30) in 2004 to 28 years (IQR: 23-34) in 2020. The shift in age-specific prevalence over the years suggests a decreasing incidence of epilepsy in areas under long-term CDTI and a significant impact of onchocerciasis control on the prevalence of epilepsy.

Onchocerciasis: Target product profiles of in vitro diagnostics to support onchocerciasis elimination mapping and mass drug administration stopping decisions

In June 2021, the World Health Organization (WHO), recognizing the need for new diagnostics to support the control and elimination of onchocerciasis, published the target product profiles (TPPs) of new tests that would support the two most immediate needs: (a) mapping onchocerciasis in areas of low prevalence and (b) deciding when to stop mass drug administration programs. In both instances, the test should ideally detect an antigen specific for live, adult O. volvulus female worms. The preferred format is a field-deployable rapid test. For mapping, the test needs to be ≥ 60% sensitive and ≥ 99.8% specific, while to support stopping decisions, the test must be ≥ 89% sensitive and ≥ 99.8% specific. The requirement for extremely high specificity is dictated by the need to detect with sufficient statistical confidence the low seroprevalence threshold set by WHO. Surveys designed to detect a 1–2% prevalence of a given biomarker, as is the case here, cannot tolerate more than 0.2% of false-positives. Otherwise, the background noise would drown out the signal. It is recognized that reaching and demonstrating such a stringent specificity criterion will be challenging, but test developers can expect to be assisted by national governments and implementing partners for adequately powered field validation.

River blindness, also known as onchocerciasis, affects 21 million people, predominantly in sub-Saharan Africa. For decades, the international community has fought this disease through mass drug administration (MDA) programs focused on controlling morbidity in areas of high prevalence. Now, as part of their 2021–2030 Roadmap for Neglected Tropical Diseases, the World Health Organization (WHO) has set an ambitious goal, shifting from controlling to eliminating onchocerciasis. This implies addressing areas of low infection prevalence. As a result, new diagnostics tools are required to identify and map areas of low onchocerciasis prevalence and to help decide where to initiate MDA. Similarly, new diagnostics are required to decide when the prevalence of onchocerciasis is sufficiently low to justify stopping MDA. A WHO-appointed independent panel, the Diagnostics Technical Advisory Group for Neglected Tropical Diseases, and its subgroup specific to onchocerciasis, have established the desired Target Product Profiles (TPPs) for such new tests. The TPPs were posted in June 2021 on the WHO website. This article describes the methodology used to produce the TPPs, with an emphasis on calculating the required sensitivity and specificity characteristics.

Macrophage migration inhibitory factor in Nodding syndrome

Nodding syndrome (NS) is a catastrophic and enigmatic childhood epilepsy, accompanied by multiple neurological impairments and neuroinflammation. Of all the infectious, environmental and psychological factors associated with NS, the major culprit is Onchocerca Volvulus (Ov)-a parasitic worm transmitted to human by blackflies. NS seems to be an 'Autoimmune Epilepsy' in light of the recent findings of deleterious autoimmune antibodies to Glutamate receptors and to Leiomodin-I in NS patients. Moreover, we recently found immunogenetic fingerprints in HLA peptide-binding grooves associate with protection or susceptibility to NS. Macrophage migration inhibitory factor (MIF) is an immune-regulatory cytokine playing a central role in modulating innate and adaptive immunity. MIF is also involved in various pathologies: infectious, autoimmune and neurodegenerative diseases, epilepsy and others. Herein, two functional polymorphisms in the MIF gene, a -794 CATT5-8 microsatellite repeat and a -173 G/C single-nucleotide polymorphism, were assessed in 49 NS patients and 51 healthy controls from South Sudan. We also measured MIF plasma levels in established NS patients and healthy controls. We discovered that the frequency of the high-expression MIF -173C containing genotype was significantly lower in NS patients compared to healthy controls. Interestingly however, MIF plasma levels were significantly elevated in NS patients than in healthy controls. We further demonstrated that the HLA protective and susceptibility associations are dominant over the MIF association with NS. Our findings suggest that MIF might have a dual role in NS. Genetically controlled high-expression MIF genotype is associated with disease protection. However, elevated MIF in the plasma may contribute to the detrimental autoimmunity, neuroinflammation and epilepsy.

Epilepsy in the Sanaga-Mbam valley, an onchocerciasis-endemic region in Cameroon: electroclinical and neuropsychological findings

OBJECTIVE

Epilepsy is highly prevalent in onchocerciasis-endemic African regions. Various types of epilepsy have been described in such regions based essentially on clinical characteristics.

METHODS

We conducted a clinical, neurophysiological and neuropsychological study of epilepsy in the onchocerciasis-endemic region of Ntui, Sanaga-Mbam area, Cameroon.

RESULTS

One hundred and eighty-seven persons with presumed epilepsy were recruited in an epilepsy clinic in Ntui. Epilepsy was clinically confirmed in 144 (79%) subjects, 69 (46.0%) of them met the onchocerciasis-associated epilepsy (OAE) criteria, and 51 of 106 tested (48.1%) presented Ov16 antibodies. Electroencephalograms (EEG) were recorded in 91 participants, of which 36 (33%) were considered abnormal and 27 of 36 (75%) revealed bifrontotemporal spike and slow waves. Concerning the neuropsychological evaluation, 29% showed severe global cognitive impairment, 28% severe episodic memory impairment, and 66% severe frontal cognitive impairment. Half of the persons with epilepsy (PWE) suffered from a mental disorder.

SIGNIFICANCE

In PWE in the Sanaga-Mbam area in Cameroon, we observed EEG patterns similar to those described among persons with OAE, including nodding syndrome in other onchocerciasis-endemic areas. Most PWE presented with severe cognitive impairment. We hypothesize that onchocerciasis may induce neurocognitive disorders and epilepsy via a mechanism that involves mainly the frontal and temporal regions of the brain.

First description of Nodding Syndrome in the Central African Republic

Background

The term Nodding Syndrome (NS) refers to an atypical and severe form of childhood epilepsy characterized by a repetitive head nodding (HN). The disease has been for a long time limited to East Africa, and the cause is still unknown. The objective of this study was to confirm the existence of NS cases in Central African Republic (CAR).

Methodology/Principal findings

This was a cross-sectional descriptive study in the general population. The identification of NS cases was conducted through a door-to-door survey in a village near Bangui along the Ubangui River. Based on Winkler’s 2008 and the World Health Organization (WHO)’s 2012 classifications, the confirmation of cases was done by a neurologist who also performed the electroencephalograms. No laboratory tests were done during this investigation. Treatment was offered to all patients. A total of 6,175 individuals was surveyed in 799 households. After reviewing the cases, we identified 5 NS cases in girls aged between 8 and 16. The age of onset of the seizures was between 5 and 12 years of age. Two cases were classified as "HN plus" according to Winkler’s 2008 classification. Four NS cases were classified as probable and one as confirmed according to the WHO’s 2012 classification. Three of them presented with developmental delay and cognitive decline, and one had an abnormally low height-for-age z-score. Electroencephalographic abnormalities were found in four patients.

Conclusions/Significance

Nodding Syndrome cases were described in CAR for the first time. Despite certain peculiarities, these cases are similar to those described elsewhere. Given that only a small part of the affected area was investigated, the study area along the Ubangui River needs to be expanded in order to investigate the association between Onchocerca volvulus and NS and also evaluate the real burden of NS in CAR.

Nodding Syndrome (NS) is a form of severe epilepsy that affects children in Africa. Thousands of children have been affected since its first description 60 years ago in East Africa, particularly Tanzania, South Sudan, and Uganda. Its evolution is marked by the appearance of many serious complications such as stunting, wasting, delayed sexual development, and psychiatric illness that can lead to death in some cases. Both the future of the affected children and the present of the adults in charge of them are hampered by an intolerable level of social and economic harm. Here, we describe new cases of NS that emerged in a context of extreme poverty in the Central African Republic (CAR). Because the area at risk of NS was partially investigated in this study, we urge to carry out a larger-scale study in order to assess the real burden of NS in CAR and draw the attention of public authorities.

Neuroscience education and research in Cameroon: Current status and future direction

Neurological disorders comprise 20% of hospital admissions in Cameroon. The burden of neurological disorders is increasing, especially in children and the elderly. However, there are very few neurologists, psychiatrists, gerontologists and neuropsychologists trained in the treatment of neurological disorders in Cameroon and there are very few facilities for training in basic and clinical neuroscience. Although non-governmental organizations such as the International Brain Research Organization (IBRO), International Society of Neurochemistry (ISN), and Teaching and Research in Natural Sciences for Development (TReND) in Africa have stepped in to provide short training courses and workshops in neuroscience, these are neither sufficient to train African neuroscientists nor to build the capacity to train neuroscience researchers and clinicians. There has also been little support from universities and the government for such training. While some participants of these schools have managed to form collaborations with foreign researchers and have been invited to study abroad, this does not facilitate the training of neuroscientists in Cameroon. Moreover, the research infrastructure for training in neuroscience remains limited. This is reflected in the low research output from Cameroonian universities in the field. In this review, we describe the burden of neurological disorders in Cameroon and outline the outstanding efforts of local scientists to develop the discipline of neuroscience, which is still an emerging field in Cameroon. We identify key actionable steps towards the improvement of the scientific capacity in neuroscience in Cameroon: (1) develop targeted neuroscience training programs in all major universities in Cameroon; (2) implement a thriving scientific environment supported by international collaborations; (3) focus on the leadership and the mentorship of both local and senior neuroscientists; (4) develop public awareness and information of policy makers to increase governmental funding for neuroscience research.

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Improving scientific capacity to tackle the neurological diseases burden in Cameroon is urgent.

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Neuroscience schools and advocated researchers shape the future of neuroscience in Cameroon.

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Public-private partnerships are required for sustainable country impact of neuroscience schools.

Onchocerciasis in tropical neurology: A scoping review

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.

Epilepsy-associated neurocognitive disorders (EAND) in an onchocerciasis-endemic rural community in Cameroon: A population-based case-control study

BACKGROUND

Epilepsy affects at least 50 million individuals worldwide, especially in sub-Saharan Africa (sSA). Cognitive impairment is common in people with epilepsy (PWE) yet, little is known on the burden of cognitive impairment in people with epilepsy in sSA. This study was thus designed to assess cognitive impairment in PWE or epilepsy-associated neurocognitive disorders (EAND) in a rural population in Cameroon.

METHODS

This was a case-control study including PWE and age/sex-matched healthy controls from July to September 2017 in Bilomo, a village in the Mbam and Kim Division. The Montreal Cognitive Assessment (MoCA), International HIV Dementia Scale (IHDS), Dubois' Five Word testing, Frontal Assessment Battery (FAB), Isaac's Set Test and the Clock drawing test were administered to the study participants to evaluate global and specific cognitive functions.

RESULTS

Eighty participants were included (40 cases and 40 controls) with a mean age of 25.78 years. Using the MoCA, 87.5% of cases had cognitive impairment, against 37.5% of controls (p < 0.001; OR 11.67; CI 3.40-45.09). Using the IHDS, the prevalence of global cognitive impairment was 84.6% among the cases against 40% for the controls (p = <0.001; OR 7.07; CI 2.29-29.19). Specifically, executive function deficits (92.5% of cases vs 40.0% of controls p = <0.001 OR = 18.50 CI; 4.48-105.08) and decreased verbal fluency (100% of cases against 45% of controls p < 0.001) were the most affected cognitive domains. Longer duration of epilepsy and higher seizure frequency were associated with global cognitive impairment. Low level of education was associated with both decreased verbal fluency and executive dysfunction while a longer stay in Bilomo correlated with poor results on the Isaac's Set Test.

CONCLUSION

The prevalence of cognitive impairment appears to be much higher in PWE in the Mbam valley, particularly decreased executive function and verbal fluency, than in people without epilepsy. Longer disease duration, higher seizure frequency, low level of education and length of stay in Bilomo are associated with poorer cognitive performance. More studies are needed to refine evaluation tools to better characterize and manage EAND in sSA.

Nodding syndrome: bridging the gap-a scoping review protocol

INTRODUCTION

Nodding syndrome (NS) is an encephalopathy of unknown origin that affects children aged between 3 and 15 years old. Cases have been reported since the 1950 in Tanzania and South Sudan, the most heavily affected population is the Acholi community in Uganda. In response to the high incidence of the disease, the Ugandan Government has developed a management algorithm, but access to such measures in affected communities is limited. There is little funding for research on the disease, consequently, few studies have been conducted to date. Nevertheless, the number of scientific publications on NS has increased since 2013, reporting several aetiological hypotheses, management algorithms and cases of stigmatisation; however, none has obtained conclusive results.This document describes a protocol for a scoping review of NS to date aimed at obtaining a broad overview of the disease. The results will identify gaps in knowledge in order to better guide future research, intervention strategies, health policies in areas at risk and cooperation and development programmes.

METHODS AND ANALYSIS

To identify the relevant data, we will conduct a literature search using the electronic databases PubMed/Medline, Embase, Social Science Citation Index Scopus, Scientific Electronic Library Online (SciELO), Literatura Latinoamericana y del Caribe en Ciencias de la Salud (LILACS), Social Science Citation Index Expanded and The Cochrane Library. We will also include grey literature. The search strategy will be designed by a librarian.Two members of the team will work independently to identify studies for inclusion and perform data extraction. The search results will be assessed by two independent reviewers and data from the included studies will be charted and summarised in duplicate. The data will be summarised in tables and figures to present the research landscape and describe and map gaps.

ETHICS AND DISSEMINATION

Ethical approval is not required. The scoping review will adhere to the Preferred Reporting Items for Systematic Reviews andMeta-Analyses-ScR guidelines. The results will be disseminated at scientific congresses and meetings.

Protection or susceptibility to devastating childhood epilepsy: Nodding Syndrome associates with immunogenetic fingerprints in the HLA binding groove

Nodding syndrome (NS) is a devastating and enigmatic childhood epilepsy. NS is accompanied by multiple neurological impairments and neuroinflammation, and associated with the parasite Onchocerca volvulus (Ov) and other environmental factors. Moreover, NS seems to be an ‘Autoimmune Epilepsy’ since: 1. ~50% of NS patients have neurotoxic cross-reactive Ov/Leimodin-I autoimmune antibodies. 2. Our recently published findings: Most (~86%) of NS patients have glutamate-receptor AMPA-GluR3B peptide autoimmune antibodies that bind, induce Reactive Oxygen Species, and kill both neural cells and T cells. Furthermore, NS patient’s IgG induce seizures, brain multiple damage alike occurring in brains of NS patients, and elevation of T cells and activated microglia and astrocytes, in brains of normal mice. Human Leukocyte antigen (HLA) class I and II molecules are critical for initiating effective beneficial immunity against foreign microorganisms and contributing to proper brain function, but also predispose to detrimental autoimmunity against self-peptides. We analyzed seven HLA loci, either by next-generation-sequencing or Sequence-Specific-Oligonucleotide-Probe, in 48 NS patients and 51 healthy controls from South Sudan. We discovered that NS associates significantly with both protective HLA haplotype: HLA-B*42:01, C*17:01, DRB1*03:02, DQB1*04:02 and DQA1*04:01, and susceptible motif: Ala24, Glu63 and Phe67, in the HLA-B peptide-binding groove. These amino acids create a hydrophobic and sterically closed peptide-binding HLA pocket, favoring proline residue. Our findings suggest that immunogenetic fingerprints in HLA peptide-binding grooves tentatively associate with protection or susceptibility to NS. Accordingly, different HLA molecules may explain why under similar environmental factors, only some children, within the same families, tribes and districts, develop NS, while others do not.

Nodding syndrome (NS) is a devastating and mysterious neurological disorder affecting 5–15 years old children, primarily in Sudan, Uganda and Tanzania. NS strongly associates with an infection with the parasitic worm Oncocherca Volvulus (Ov), transmitted by the black fly, affecting many people worldwide. Moreover, NS is most probably an 'Autoimmune Epilepsy', especially in view of our recent findings that NS patient’s autoimmune GluR3B antibodies induce ROS and kill both neural cells and T cells. NS patient’s IgG also induce seizures, multiple brain damage and inflammation-inducing cells in the brain. HLA class I genes are expressed on the surface of all nucleated cells and present peptides to cytotoxic CD8⁺ T cells. HLA class II genes are expressed mainly on the surface of antigen presenting cells and present peptides to helper CD4+ T cells. Analysis of HLA of South-Sudanese NS patients and healthy controls revealed that that few amino acids in HLA peptide-binding grooves associate with either protection or susceptibility to NS. Theses amino acids could be critical in NS by affecting beneficial immunity and/or detrimental autoimmunity.

Mapping the burden of onchocercal skin disease

Onchocerciasis is a neglected tropical disease caused by a nematode parasite, Onchocerca volvulus, and transmitted by bites of Simulium blackflies which breed near fast-flowing rivers. In humans, thousands of microfilariae (immature worms) migrate to the skin and eyes where they cause pathology. Historically, much research was devoted to the serious effect of blindness, from which the disease earns its alternative name of 'river blindness'. Mapping the burden of onchocercal skin disease (OSD) was expedited by the development of a clinical classification and grading system that facilitated comparison of data from different countries. After successful field testing in Nigeria, the classification scheme was used in a multicountry study in seven endemic sites, to estimate the true burden of OSD across Africa. High levels of OSD were found, affecting 28% of the population. A new control programme, the African Programme for Onchocerciasis Control (APOC) was launched in 20 countries using annual doses of ivermectin, donated by Merck & Co., Inc. The multicountry study also found a close correlation between the levels of itching and OSD with the level of endemicity, as determined by the prevalence of onchocercal nodules. This enabled APOC to use Rapid Epidemiological Mapping of Onchocerciasis, which entailed identifying likely vector breeding sites near rivers, then sampling 50 adult males in nearby villages to determine the prevalence of nodules and delineate which villages required treatment. Onchocerciasis is now targeted for elimination in Africa, and the challenge is to complete Onchocerciasis Elimination Mapping of hypoendemic areas using serology.

Ivermectin as an adjuvant to anti-epileptic treatment in persons with onchocerciasis-associated epilepsy: A randomized proof-of-concept clinical trial

INTRODUCTION

Recent findings from onchocerciasis-endemic foci uphold that increasing ivermectin coverage reduces the epilepsy incidence, and anecdotal evidence suggests seizure frequency reduction in persons with onchocerciasis-associated epilepsy, when treated with ivermectin. We conducted a randomized clinical trial to assess whether ivermectin treatment decreases seizure frequency.

METHODS

A proof-of-concept randomized clinical trial was conducted in the Logo health zone in the Ituri province, Democratic Republic of Congo, to compare seizure frequencies in onchocerciasis-infected persons with epilepsy (PWE) randomized to one of two treatment arms: the anti-epileptic drug phenobarbital supplemented with ivermectin, versus phenobarbital alone. The primary endpoint was defined as the probability of being seizure-free at month 4. A secondary endpoint was defined as >50% reduction in seizure frequency at month 4, compared to baseline. Both endpoints were analyzed using multiple logistic regression. In longitudinal analysis, the probability of seizure freedom during the follow-up period was assessed for both treatment arms by fitting a logistic regression model using generalized estimating equations (GEE).

RESULTS

Ninety PWE enrolled between October and November 2017 were eligible for analysis. A multiple logistic regression analysis showed a borderline association between ivermectin treatment and being seizure-free at month 4 (OR: 1.652, 95% CI 0.975-2.799; p = 0.062). There was no significant difference in the probability of experiencing >50% reduction of the seizure frequency at month 4 between the two treatment arms. Also, treatment with ivermectin did not significantly increase the odds of being seizure-free during the individual follow-up visits.

CONCLUSION

Whether ivermectin has an added value in reducing the frequency of seizures in PWE treated with AED remains to be determined. A larger study in persons with OAE on a stable AED regimen and in persons with recent epilepsy onset should be considered to further investigate the potential beneficial effect of ivermectin treatment in persons with OAE.

TRIAL REGISTRATION

Registration: www.clinicaltrials.gov; NCT03052998.

Onchocerciasis (river blindness): larva-induced eczema (onchodermatitis) from an important oculocutaneous tropical disease spilling over into North America and Europe

Onchocerciasis is a leading cause of blindness in the world. It may be seen in temperate climates of the United States and Europe in immigrants and travelers from endemic regions, often linked to poverty and war. One should be aware of an incubation period that can be up to 15 months. In its early stage and throughout its course, onchocerciasis has noteworthy skin findings, facilitating diagnosis, as onchodermatitis resembles common eczema with variable degrees of papular, lichenoid, atrophic, and pigmentary alterations, features not suggestive if one is unaware of an individual's immigration and travel history. The same concept applies for the encysted worms (onchocercomas), as they tend to appear as common skin cysts and benign neoplasms. New methods can be employed to increase diagnostic sensitivity and specificity. Ivermectin is the gold standard of therapy, the use of which has almost miraculously eliminated this disease from large areas of the earth. However, its effect remains isolated to microfilariae and can be devastating in those coinfected with Loa loa. Recently, the symbiotic relationship between adult worms and Wolbachia bacteria has been discovered and, with it, the possibility of adding doxycycline as a treatment option. We also discuss coinfection with HIV and other diseases.

Stigma and epilepsy in onchocerciasis-endemic regions in Africa: a review and recommendations from the onchocerciasis-associated epilepsy working group

BACKGROUND

In onchocerciasis-endemic areas, particularly in those with a sub-optimal onchocerciasis control programme, a high prevalence of epilepsy is observed. Both onchocerciasis and epilepsy are stigmatizing conditions. The first international workshop on onchocerciasis-associated epilepsy (OAE) was held in Antwerp, Belgium (12-14 October 2017) and during this meeting, an OAE alliance was established. In this paper, we review what is known about epilepsy-associated stigma in onchocerciasis-endemic regions, and present the recommendations of the OAE alliance working group on stigma.

MAIN BODY

For this scoping review, literature searches were performed on the electronic databases PubMed, Scopus and Science Direct using the search terms "epilepsy AND onchocerciasis AND stigma". Hand searches were also undertaken using Google Scholar, and in total seven papers were identified that addressed epilepsy-related stigma in an onchocercisasis-endemic area. Due to the limited number of published research papers on epilepsy-associated stigma in onchocerciasis-endemic areas, other relevant literature that describes important aspects related to stigma is discussed. The thematic presentation of this scoping review follows key insights on the barriers to alleviating the social consequences of stigma in highly affected onchocerciasis-endemic areas, which were established by experts during the working group on stigma and discrimination at the first international workshop on OAE. These themes are: knowledge gaps, perceived disease aetiology, access to education, marriage restrictions, psycho-social well-being, burden on the care-giver and treatment seeking behaviour. Based on the literature and expert discussions during the OAE working group on stigma, this paper describes important issues regarding epilepsy-related stigma in onchocerciasis-endemic regions and recommends interventions that are needed to reduce stigma and discrimination for the improvement of the psycho-social well-being of persons with epilepsy.

CONCLUSIONS

Educating healthcare workers and communities about OAE, strengthening onchocerciasis elimination programs, decreasing the anti-epileptic treatment gap, improving the care of epilepsy-related injuries, and prioritising epilepsy research is the way forward to decreasing the stigma associated with epilepsy in onchocerciasis-endemic regions.

High prevalence of epilepsy in an onchocerciasis endemic health zone in the Democratic Republic of the Congo, despite 14 years of community-directed treatment with ivermectin: A mixed-method assessment

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A high epilepsy prevalence in the Aketi health zone was observed despite 14 years of community-directed treatment with ivermectin.

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The high prevalence of OV16 antibodies in children is indicative of high ongoing onchocerciasis transmission.

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High onchocerciasis transmission is the consequence of high exposure to blackflies and low intake of ivermectin.

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Head nodding seizures were observed in 13.8% of the persons with epilepsy.

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Ivermectin coverage needs to be increased and bi-annual distribution should be considered.

Objectives

To investigate the reasons for the high prevalence of epilepsy (>6%) discovered in 2015 in the Aketi health zone in the north of the Democratic Republic of the Congo.

Methods

Persons with epilepsy (PWE) diagnosed in a door-to-door survey in 2015 were traced and re-examined in 2017 by a neurologist. Confirmed PWE were paired with matched controls. For onchocerciasis assessment, children 7–10 years old were tested for IgG4 Onchocerca volvulus (OV16) antibodies, a rapid epidemiological mapping of onchocerciasis (REMO) study was performed, and ivermectin coverage was investigated.

Results

Forty-three (61.4%) previously diagnosed PWE were traced; the neurologist confirmed the epilepsy diagnosis in all of them. The overall OV16 positivity rate was 64.5%. Poor ivermectin coverage (55.9%) and a high prevalence of onchocercal nodules (>70%) were observed. The prevalence of epilepsy was 5.7% in Aketi rural town, with nine PWE (13.8%) experiencing head nodding seizures. A case-control study showed that PWE had lower body weight and higher ivermectin coverage in 2017 than healthy controls.

Conclusions

The high prevalence of epilepsy in the Aketi health zone, despite 14 years of community-directed treatment with ivermectin (CDTI), was found to be associated with high onchocerciasis transmission and low ivermectin use. An awareness programme to increase ivermectin coverage and the introduction of a bi-annual CDTI programme should be considered.

Comprehensive management of epilepsy in onchocerciasis-endemic areas: lessons learnt from community-based surveys

BACKGROUND

Onchocerciasis-endemic regions are known to have a high epilepsy prevalence. Limited resources in these areas and poor access to healthcare by persons with epilepsy (PWE) result in a wide anti-epileptic treatment gap, poor seizure control and a high burden of seizure-related complications. Recent community-based surveys highlight the need for epilepsy management strategies suitable for remote onchocerciasis-endemic villages to ensure better health outcomes for PWE. In this paper, we propose a feasible approach to manage PWE in such settings.

MAIN TEXT

Improved management of PWE in onchocerciasis-endemic areas may be achieved by decentralizing epilepsy care. Simplified approaches for the diagnosis and treatment of epilepsy may be used by non-physicians, under the supervision of physicians or specialists. To reduce the treatment gap, a regular supply of subsidized anti-epileptic drugs (AED) appropriate for different types of onchocerciasis-associated epilepsy should be instituted. Setting up a community-based epilepsy surveillance system will enable early diagnosis and treatment of PWE thereby preventing complications. Community awareness programs on epilepsy must be implemented to reduce stigma and facilitate the social rehabilitation of PWE. Finally, strengthening onchocerciasis elimination programs by optimizing community-directed treatment with ivermectin (CDTI) and considering alternative treatment strategies might reduce the incidence of epilepsy.

CONCLUSIONS

A community-based approach with task-shifting of epilepsy care from specialists to non-physician health workers will reduce epilepsy-associated morbidity. Increased advocacy and collaboration with various stakeholders is needed to establish a sustainable, cost-effective chronic care model for epilepsy that will significantly improve the quality of life of PWE in onchocerciasis-endemic regions.

Nodding syndrome research, lessons learned from the NSETHIO project

BACKGROUND

Until recently, nodding syndrome (NS) was considered as a mysterious disease of unknown etiology. A link between onchocerciasis and epilepsy was suspected for a long time. However, onchocerciasis was not considered as the cause of NS because NS was believed to occur only in onchocerciasis-endemic regions in Uganda, South Sudan, and Tanzania. In October 2015, with funding from the European Research Council, the NSETHIO group launched a trans-disciplinary, multi-country research project to identify the cause of NS and to study the link between onchocerciasis and epilepsy.

METHODS

We reviewed NSETHIO activities as well as all published papers, and compared project findings with results of previous research on NS.

RESULTS

Findings from the NSETHIO project showed that NS is only one of the clinical manifestations in the wide spectrum of onchocerciasis-associated epilepsy (OAE) that could be prevented by strengthening onchocerciasis elimination programs. NSETHIO demonstrated that OAE is an important neglected public health problem in onchocerciasis-endemic areas with no or a sub-optimally functioning onchocerciasis control strategies.

CONCLUSIONS

Today there is overwhelming evidence that NS together with the Nakalanga syndrome is clinical presentations of OAE, a condition that could be prevented by strengthening onchocerciasis elimination programs. While research needs to continue to elucidate the pathophysiological mechanisms causing NS, new strategies to accelerate onchocerciasis elimination coupled with community-based surveillance and treatment programs for epilepsy are urgently needed in areas of high Onchocerca volvulus transmission.

Neurological manifestations in Onchocerca volvulus infection: A review

Human onchocerciasis, caused by infection by the filarial nematode Onchocerca volvulus, is a major neglected public health problem that affects millions of people in the endemic regions of sub-Saharan Africa and Latin America. Onchocerciasis is known to be associated with skin and eye disease and more recently, neurological features have been recognized as a major manifestation. Especially the latter poses a severe burden on affected individuals and their families. Although definite studies are awaited, preliminary evidence suggests that neurological disease may include the nodding syndrome, Nakalanga syndrome and epilepsy but to date, the exact pathophysiological mechanisms remain unclear. Currently, the only way to prevent Onchocera volvulus associated disease is through interventions that target the elimination of onchocerciasis through community distribution of ivermectin and larviciding the breeding sites of the Similium or blackfly vector in rivers. In this review, we discuss the epidemiology, potential pathological mechanisms as well as prevention and treatment strategies of onchocerciasis, focusing on the neurological disease.

Is nodding syndrome in northern Uganda linked to consumption of mycotoxin contaminated food grains?

OBJECTIVE

Nodding syndrome (NS) is a type of epilepsy characterized by repeated head-nodding seizures that appear in previously healthy children between 3 and 18 years of age. In 2012, during a WHO International Meeting on NS in Kampala, Uganda, it was recommended that fungal contamination of foods should be investigated as a possible cause of the disease. We therefore aimed to assess whether consumption of fungal mycotoxins contributes to NS development.

RESULTS

We detected similar high levels of total aflatoxin and ochratoxin in mostly millet, sorghum, maize and groundnuts in both households with and without children with NS. Furthermore, there was no significant association between concentrations of total aflatoxin, ochratoxin and doxynivalenol and the presence of children with NS in households. In conclusion, our results show no supporting evidence for the association of NS with consumption of mycotoxins in contaminated foods.

Onchodermatitis: Where Are We Now?

Onchocerciasis causes debilitating pruritus and rashes as well as visual impairment and blindness. Prior to control measures, eye disease was particularly prominent in savanna areas of sub-Saharan Africa whilst skin disease was more common across rainforest regions of tropical Africa. Mass drug distribution with ivermectin is changing the global scene of onchocerciasis. There has been successful progressive elimination in Central and Southern American countries and the World Health Organization has set a target for elimination in Africa of 2025. This literature review was conducted to examine progress regarding onchocercal skin disease. PubMed searches were performed using keywords 'onchocerciasis', 'onchodermatitis' and 'onchocercal skin disease' over the past eight years. Articles in English, or with an English abstract, were assessed for relevance, including any pertinent references within the articles. Recent progress in awareness of, understanding and treatment of onchocercal skin disease is reviewed with particular emphasis on publications within the past five years. The global burden of onchodermatitis is progressively reducing and is no longer seen in children in many formerly endemic foci.