Nodding syndrome

Evaluating epilepsy management in an onchocerciasis-endemic area: Case of Maridi, South Sudan

PURPOSE

The epilepsy prevalence in Maridi County, South Sudan, in 2018 was 43.8 (95% CI: 40.9-47.0) per 1000 persons; 85.2% of the identified persons with epilepsy (PWE) met the criteria of onchocerciasis-associated epilepsy. To address this health problem, an epilepsy clinic was established at Maridi County Hospital in 2020. In August 2023, the impact of the clinic on the lives of PWE and their families was evaluated.

METHODS

At the Maridi epilepsy clinic, data routinely collected by primary healthcare workers as part of patient care was reviewed. We also analyzed findings from two household surveys conducted in 2018 and 2022, which assessed the impact of the clinic on epilepsy care. Moreover, four households, each with four PWE, were visited in a high epilepsy prevalence area. PWE were examined by a neurologist, and in-depth interviews were conducted with family members.

RESULTS

The proportion of PWE on anti-seizure medication increased by 39.7% (95%CI: 35.3-44.2) between 2018 and 2022. The proportion of PWE reporting daily seizures decreased from 27.3% in 2018 to 5.3% in 2022. Of the 754 PWE seen in the clinic in July 2023, only 17 (2.3%) reported side effects. During household visits in July 2023, 13/173 (7.5%) of the visited PWE were found without remaining anti-seizure medication. A high level of epilepsy-related stigma was observed in all visited households.

CONCLUSION

The Maridi epilepsy clinic positively impacted the lives of PWE in Maridi. Similar initiatives should be accessible for all PWE living in onchocerciasis-endemic areas. Evidence-based information about OAE is needed to decrease misconceptions and epilepsy-related stigma.

Medical magnetic resonance imaging publications in Arab countries: A 25-year bibliometric analysis

Magnetic Resonance Imaging (MRI) is increasingly becoming a cornerstone in modern diagnostic healthcare, offering unparalleled capabilities in stroke, dementia, and cancer screening. Therefore, this study aims to map medical MRI literature affiliated with Arab countries, focusing on publication trends, top journals, author affiliations, study countries, and authors' collaboration, and keyword analysis. The scientific database used is the Scopus database. Microsoft Excel, VOSviewer software, and Biblioshiny for the Bibliometrix R package are the bibliometric tools used in this analysis. A total of 2592 publications were published between 1988 and 2022, with total citations of 22,115. Most of them were original articles (91,7%) and 89.9% were published in traditional journals. The number of total publications exhibited a steady increase over time, whereas total citations showed fluctuations, peaking in 2015 with 1571 citations for publications from that year. The most cited article was authored by Yaseen M. Arabi, receiving 286 citations. Saudi Arabia was the top active country. In addition, the most prolific author was Maha S Zaki, and the most prolific source was the "Egyptian Journal of Radiology and Nuclear Medicine". The most prolific affiliation was Cairo University. The "multiple sclerosis" and "case report" were the most trending keywords. The analysis revealed a significant growth in MRI research inside Arab countries, as shown by an increase in the total number of publications and international collaborations. Despite these developments, the results of this study suggest that there is still room for MRI research in the Arab region to advance. This can be achieved through increasing international collaboration and multidisciplinary work.

Long-term clinical course and treatment outcomes of individuals with Nodding Syndrome

Nodding Syndrome is a poorly understood epilepsy disorder in sub-Saharan Africa. The cause(s) of the disease, risk factors and long-term outcomes are unknown or controversial. The objectives of this study were to describe the long-term clinical course and treatment outcomes of individuals suffering from Nodding Syndrome. In addition, we aimed to provide a comprehensive characterization of the epileptological and social features of patients with Nodding Syndrome. From 11/2014 to 4/2015, we conducted a hospital-based, cross-sectional and observational study in Mahenge, Tanzania. Seventy-eight individuals (female:male ratio: 40:38, age at examination: 21.1 ± 6.39 (SD) years) have been enrolled, of whom 38 (49%) had also been examined in 2005 and in 2009. The 10-year clinical course analysis of this revisited subgroup revealed a calculated case fatality of 0.8-2.3%. Progressive physical or cognitive deterioration has not been observed in any of the 78 individuals and more than half of the people studied (38/69; 55%) managed to live and work independently. 14/78 individuals (18%) were seizure-free, (no head nodding, no other seizure types), 13 of whom were taking antiseizure medication. Phenytoin was more effective against head nodding seizures (14/19 (74%)) than monotherapy with other available antiseizure medication (phenobarbitone 12/25 (48%) and carbamazepine 7/22 (32%), p = 0.02, chi-square test). Our ten-year clinical outcome data show that Nodding Syndrome is not a fatal disease, however, the response to treatment is worse than in epilepsy patients in general. Phenytoin may be more effective than carbamazepine and phenobarbitone, but further studies are needed to confirm this observation.

Mapping, Associated Factors, and Pathophysiology of Nodding Syndrome in Africa: A Systematic Review

INTRODUCTION

Nodding syndrome (NS) remains a poorly understood disorder. For a long time, it has been thought to be restricted to East Africa; however, cases in Central Africa have been increasing over time. The objective of this systematic review (SR) was to provide a summary of the state of knowledge on NS to date.

METHODS

All original articles published on NS up to November 2021 were searched in four major databases and in the gray literature. Commentaries, editorials, book chapters, books, conference paper, qualitative studies that mentioned NS cases were also included. Data retrieved included study location (with GPS coordinates searched), year of study and publication, population characteristics, definition and diagnosis of NS, associated factors, and treatment if applicable. A meta-analysis of associated factors was performed where possible, and results were presented as odds ratios (ORs) and visualized as forest plots. Geographic information systems were used for cartographic representations. The quality of the articles included was assessed.

RESULTS

Of the 876 articles initially identified, 67 (corresponding to 59 studies) were included in the SR. NS is only present in Central and East Africa. Interestingly, there were reports of NS in Central Africa prior to 2010, earlier than previously thought. The way NS diagnosis was established varies according to studies, and the 2012 WHO classification was used in only 60% of the studies. Approximately 11% of the articles did not meet the quality requirements set for this review. In our meta-analysis, the main factor associated with NS was onchocerciasis (OR = 8.8 [4.8, 15.9]). However, the pathophysiology of the disease remains poorly understood. The lack of common anti-epileptic drugs is a significant barrier to the management of head nodding and associated epileptic seizures.

DISCUSSION/CONCLUSION

The lack of an operational definition of NS is an obstacle to its diagnosis and, thus, to its appropriate treatment. Indeed, diagnostic difficulties might have led to false positives and false negatives which could have altered the picture of NS presented in this article. Treatment should take into account nutritional and psychological factors, as well as associated infections. Some risk factors deserve further investigation; therefore, we suggest a multicentric study with an etiological focus using a more operational definition of NS.

Nodding syndrome is unlikely to be an autoimmune reaction to leiomodin-1 after infection by Onchocerca volvulus

Nodding syndrome is a neurological disease of children in northern Uganda. Infection with the nematode parasite Onchocerca volvulus has been epidemiologically implicated as the cause of the disease. It has been proposed that an autoantibody directed against the human protein leiomodin-1 cross reacts with a tropomyosin-like nematode protein, thus suggesting that nodding syndrome is an autoimmune brain disease due to extra-cerebral parasitism. This hypothesis is dependent on constitutive neuronal expression of leiomodin-1. We tested this hypothesis by studying the distribution of leiomodin-1 in the normal human brain and other human tissues using immunohistochemistry. We found that immunostaining for leiomodin-1 follows a smooth muscle cell specific pattern. In the brain, it is confined to the smooth muscle cells of cerebral blood vessels and is not generally present in neurons or glia. However, immunoreactivity was identified in human Purkinje cell membrane and the body wall of C. elegans (as a proxy for Onchocerca volvulus) but only when immunostained with an antibody recognizing the N-terminal of leiomodin-1. Homology between leiomodin-1 and tropomodulin, specifically at the N-terminus, could explain why leiomodin-1 antibody cross reactivity between human Purkinje cells and C. elegans. However, we cannot provide proof confirming that the immunoreactivity in the membranes of Purkinje cells is specifically caused by the expression of tropomodulin. To overcome this limitation, further investigations using additional immunohistochemical and biochemical studies are required to corroborate our findings and provide more comprehensive evidence. Nevertheless, our findings do not support to the autoimmunity hypothesis involving Onchocerca volvulus and leiomodin-1. To gain a more comprehensive understanding of the cause and pathogenesis of NS, it is essential to explore alternative hypotheses.

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.

Epilepsy and nodding syndrome in association with an Onchocerca volvulus infection drive distinct immune profile patterns

Previous studies have described the association of onchocerciasis (caused by Onchocerca volvulus) with epilepsy, including nodding syndrome, although a clear etiological link is still missing. Cases are found in different African countries (Tanzania, South Sudan, Uganda, Democratic Republic of the Congo, Central African Republic and Cameroon). In our study we investigated immunological parameters (cytokine, chemokine, immunoglobulin levels) in individuals from the Mahenge area, Tanzania, presenting with either epilepsy or nodding syndrome with or without O. volvulus infection and compared them to O. volvulus negative individuals from the same endemic area lacking neurological disorders. Additionally, cell differentiation was performed using blood smears and systemic levels of neurodegeneration markers, leiomodin-1 and N-acetyltyramine-O, β-glucuronide (NATOG) were determined. Our findings revealed that cytokines, most chemokines and neurodegeneration markers were comparable between both groups presenting with epilepsy or nodding syndrome. However, we observed elevated eosinophil percentages within the O. volvulus positive epilepsy/nodding syndrome patients accompanied with increased eosinophilic cationic protein (ECP) and antigen-specific IgG levels in comparison to those without an O. volvulus infection. Furthermore, highest levels of NATOG were found in O. volvulus positive nodding syndrome patients. These findings highlight that the detection of distinct biomarkers might be useful for a differential diagnosis of epilepsy and nodding syndrome in O. volvulus endemic areas. Trial-registration: NCT03653975.

Nodding syndrome, a case-control study in Mahenge, Tanzania: Onchocerca volvulus and not Mansonella perstans as a risk factor

BACKGROUND

Nodding syndrome (NS) has been consistently associated with onchocerciasis. Nevertheless, a positive association between NS and a Mansonella perstans infection was found in South Sudan. We aimed to determine whether the latter parasite could be a risk factor for NS in Mahenge.

METHODS

Cases of epilepsy were identified in villages affected by NS in Mahenge, Tanzania, and matched with controls without epilepsy of the same sex, age and village. We examined blood films of cases and controls to identify M. perstans infections. The participants were also asked for sociodemographic and epilepsy information, examined for palpable onchocercal nodules and onchocerciasis-related skin lesions and tested for anti-Onchocerca volvulus antibodies (Ov16 IgG4) by ELISA. Clinical characteristics of cases and controls, O. volvulus exposure status and relevant sociodemographic variables were assessed by a conditional logistic regression model for NS and epilepsy status matched for age, sex and village.

RESULTS

A total of 113 epilepsy cases and 132 controls were enrolled, of which, respectively, 56 (49.6%) and 64 (48.5%) were men. The median age in cases and controls was 28.0 (IQR: 22.0-35.0) and 27.0 (IQR: 21.0-33.3) years. Of the persons with epilepsy, 43 (38.1%) met the probable NS criteria and 106 (93.8%) had onchocerciasis-associated epilepsy (OAE). M. perstans infection was absent in all participants, while Ov16 seroprevalence was positively associated with probable NS (odds ratio (OR): 5.05, 95%CI: 1.79-14.27) and overall epilepsy (OR: 2.03, 95%CI: 1-07-3.86). Moreover, onchocerciasis-related skin manifestations were only found in the cases (n = 7, p = 0.0040), including persons with probable NS (n = 4, p = 0.0033). Residing longer in the village and having a family history of seizures were positively correlated with Ov16 status and made persons at higher odds for epilepsy, including probable NS.

CONCLUSION

In contrast to O. volvulus, M. perstans is most likely not endemic to Mahenge and, therefore, cannot be a co-factor for NS in the area. Hence, this filaria is unlikely to be the primary and sole causal factor in the development of NS. The main risk factor for NS remains onchocerciasis.

Case definitions for onchocerciasis-associated epilepsy and nodding syndrome: A focused review

Onchocerciasis-associated epilepsy (OAE) is an important but neglected public health problem in onchocerciasis-endemic areas with insufficient or inadequate onchocerciasis control. Hence, there is a need for an internationally accepted, easy-to-use epidemiological case definition of OAE to identify areas of high Onchocerca volvulus transmission and disease burden requiring treatment and prevention interventions. By including OAE as a manifestation of onchocerciasis, we will considerably improve the accuracy of the overall onchocerciasis disease burden, which is currently underestimated. Hopefully, this will lead to increased interest and funding for onchocerciasis research and control interventions, notably the implementation of more effective elimination measures and treatment and support for affected individuals and their families.

Onchocerciasis-associated epilepsy: an update and future perspectives

Onchocerciasis-associated epilepsy (OAE) is an important neglected public health problem in areas with high ongoing onchocerciasis transmission. The risk that children in such areas develop epilepsy is related to their Onchocerca volvulus microfilarial (mf) load. Before the implementation of mass treatment with ivermectin, microfilariae were detected in cerebrospinal fluid (CSF). More recently, neither O. volvulus microfilariae nor DNA were detected in CSF or brain tissue; however, these samples were obtained years after seizure onset. It is possible that during fever-induced increased blood-brain barrier permeability, microfilariae enter the brain and, upon dying, cause an inflammatory reaction inducing seizures. Including OAE in the onchocerciasis disease burden estimation may mobilise extra resources for onchocerciasis disease elimination and treatment/care of OAE-affected persons/families.

Nodding Syndrome: Clinical Characteristics, Risks Factors, Access to Treatment, and Perceptions in the Greater Mundri Area, South Sudan

We conducted a house-to-house survey in the Mundri, Western Equatoria state of South Sudan to investigate the clinical characteristics, risk factors, access to treatment and perceptions about nodding syndrome (NS). In total, 224 NS cases with median age of seizure onset of 10 years were identified. Head nodding only was reported in 50 (22.3%) cases, and head nodding plus other types of seizures in 174 (77.7%) cases. Wasting, stunted growth, delayed sexual development and speech and behavioral abnormalities were observed in 17 (23.6%), 16 (22.2%), 9 (17.3%), 14 (19.4%) and 4 (5.6%) cases, respectively. The consumption of rat meat, but not other bushmeat was associated with an increased risk of NS (OR 9.31, 95% CI 1.27-406.51). Children with NS were more likely to have taken ivermectin in the last 5 years (OR 2.40, 95% CI 1.33-4.43). NS cases were less likely to share a bedroom with other children (OR 0.06, 95% CI 0.02-0.16) or adults (OR 0.27, 95% CI 0.13-0.56). In conclusion, rat meat consumption is an unlikely risk factor for NS, and ivermectin intake was more common among NS cases than controls. Importantly, we documented that children with NS are stigmatized because of the misconception that NS is transmitted through direct contact.

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.

Preliminary seroprevalence study of neurotropic virus antibodies in Nodding syndrome

Nodding syndrome (NS) is a mostly East African pediatric epileptiform encephalopathy of unknown etiology that shares some clinical features with measles-associated subacute sclerosing panencephalitis (SSPE) and progressive rubella panencephalitis. Two independent studies in northern Uganda identified an association between NS and prior measles infection, while an earlier study in South Sudan found an inverse association. We report preliminary serologic analyses of antibodies to measles (MV), rubella (RV), HSV-1, and CMV viruses in northern Ugandan children with NS and Household (HC) and Community (CC) Controls. Only MV-positive titers were significantly different (3-fold and > 2-fold) in NS relative to HC and HC + CC, respectively. While these results are consistent with greater prior measles infection in Ugandan persons with NS, further studies are needed to determine whether Measles virus (MV) plays any role in the etiology and pathogenesis of NS. Resolving this issue will be invaluable for the thousands of children at risk for this devastating yet often neglected condition.

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Nodding syndrome (NS) is an enigmatic pediatric epileptiform encephalopathy.

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We report an association between NS and measles virus (MV)-positive titers.

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Further studies should assess whether MV plays any role in the etiology of NS.

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.

'There Were Moments We Wished She Could Just Die': The Highly Gendered Burden of Nodding Syndrome in Northern Uganda

Nodding Syndrome (NS) occurs within a wide spectrum of epilepsies seen in onchocerciasis endemic areas of sub-Saharan Africa. It has debilitating consequences on affected individuals and increases the socio-economic, physical and psychological burden on care-givers and their households, diminishing their standing within the community. Social science research on the disproportionate burden of the disease on females is limited. Based on ethnographic research over 3 years in northern Uganda, we explored the burden of being ill and care-giving for persons with NS from a gendered perspective. We found that NS-affected females were at greater risk of physical and psychological abuse, sexual violence, unwanted pregnancies, sexually transmitted infections and stigma, in a context of deteriorating socio-economic conditions. Primary care-givers of the NS-affected, mostly women, struggled to make ends meet and were subjected to stigma and abandonment. Targeted interventions, including legal protection for affected females, stigma reduction, and psycho-social and financial support are needed.

Epidemiology of nodding syndrome in the Greater Mundri area, South Sudan: Prevalence, spatial pattern and environmental risk factors

Background

Nodding syndrome (NS) is a progressive neurological disease that has been described in several sub-Saharan African counties, but South Sudan is considered the most affected. However, knowledge about the exact burden and the epidemiological risk factors of NS in South Sudan is lacking.

Objective

To determine the prevalence, distribution and epidemiological risk factors of NS in the Greater Mundri area, the epicenter of NS in South Sudan.

Methods

A NS prevalence house-to-house survey was conducted in multiple villages between February 2018 and November 2019. Geographical distribution and clustering of NS cases was identified using spatial and binomial regression analysis. Epidemiological risk factors of NS were identified using univariate and multivariate models.

Results

Of the 22,411 persons surveyed in 92 villages, 607 (2.7%) persons with NS were identified, of which 114 (19%) were new-onset cases. The highest prevalence was found in Diko village with a prevalence of 13.7%. NS showed a significant spatial pattern with clustering of cases between adjacent households and along rivers. Risks factors for NS include all behaviors around rivers (drinking, cooking, handwashing and bathing) and exposure to poultry. On the other hand, ownership of mobile phone decreased the risk of NS. Many other factors, including prior ivermectin treatment and internal displacement were not associated with NS.

Conclusion

Our study demonstrates a very high burden of the NS disease in the Greater Mundri area, strengthens the association with rivers, and identified possible new clues for an underlying cause.

The position of geochemical variables as causal co-factors of diseases of unknown aetiology

Abstract

The term diseases of unknown aetiology (DUA) or idiopathic diseases is used to describe diseases that are of uncertain or unknown cause or origin. Among plausible geoenvironmental co-factors in causation of DUA, this article focusses on the entry of trace elements, including metals and metalloids into humans, and their involvement in humoral and cellular immune responses, representing potentially toxic agents with implications as co-factors for certain DUA. Several trace elements/metals/metalloids (micronutrients) play vital roles as co-factors for essential enzymes and antioxidant molecules, thus, conferring protection against disease. However, inborn errors of trace element/metal/metalloid metabolisms can occur to produce toxicity, such as when there are basic defects in the element transport mechanism. Ultimately, it is the amount of trace element, metal or metalloid that is taken up, its mode of accumulation in human tissues, and related geomedical attributes such as the chemical form and bioavailability that decisively determine whether the exerted effects are toxic or beneficial. Several case descriptions of DUA that are common worldwide are given to illustrate our knowledge so far of how trace element/metal/metalloid interactions in the immune system may engender its dysregulation and be implicated as causal co-factors of DUA.

Article highlights

The importance of a proper understanding of geochemical perturbations in human metabolisms is emphasisedIt is proferred that such an understanding would aid greatly in the decipherment of diseases of unknown aetiology (DUA)The thesis presented may pave the way towards better diagnosis and therapy of DUA.

Nodding syndrome: A key role for sources of nutrition?

Nodding Syndrome (NS) has occurred among severely food-stressed communities in northern Uganda and several other East African populations that, with their forced physical displacement, have resorted to nutritional support from available wild plants and fungi, some of which have neurotoxic potential. Among the latter is an agaric mushroom with an unknown content of hydrazine-generating agaritine, namely Agaricus bingensis, the unusually wide consumption of which may relate to the low serum levels of vitamin B6 in Ugandan NS subjects relative to controls. Hydrazine-related compounds induce patterns of DNA damage that promote neuropathological changes (tauopathy) reminiscent of those associated with established NS. While the cause of this childhood brain disease is unknown, we encourage increased attention to the role of malnutrition and B6 hypovitaminosis in the etiology of this devastating brain disease.

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Idiopathic epileptic encephalopathy with tauopathy (Nodding syndrome) impacts East African children

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Associated factors include nematode infection, food insecurity, and food use of wild plants and fungi

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Food use of hydrazinic fungi induces B6 hypovitaminosis, which may be marked in Nodding syndrome

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Vitamin B6 deficiency promotes tau phosphorylation in mouse models of human tauopathy

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Hydrazine generates carbon free radicals associated with DNA-damage and neurodegenerative disease

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Increased research attention to nutritional practices associated with Nodding syndrome is merited.

Ictal Electroencephalographic Characteristics of Nodding Syndrome: A Comparative Case-Series from South Sudan, Tanzania, and Uganda

Nodding syndrome (NS) is a poorly understood form of childhood‐onset epilepsy that is characterized by the pathognomonic ictal phenomenon of repetitive vertical head drops. To evaluate the underlying ictal neurophysiology, ictal EEG features were evaluated in nine participants with confirmed NS from South Sudan, Tanzania, and Uganda and ictal presence of high frequency gamma oscillations on scalp EEG were assessed. Ictal EEG during the head nodding episode predominantly showed generalized slow waves or sharp‐and‐slow wave complexes followed by electrodecrement. Augmentation of gamma activity (30–70 Hz) was seen during the head nodding episode in all the participants. We confirm that head nodding episodes in persons with NS from the three geographically distinct regions in sub‐Saharan Africa share the common features of slow waves with electrodecrement and superimposed gamma activity. ANN NEUROL 2022;92:75–80

Post-Infectious Autoimmunity in the Central (CNS) and Peripheral (PNS) Nervous Systems: An African Perspective

The direct impact and sequelae of infections in children and adults result in significant morbidity and mortality especially when they involve the central (CNS) or peripheral nervous system (PNS). The historical understanding of the pathophysiology has been mostly focused on the direct impact of the various pathogens through neural tissue invasion. However, with the better understanding of neuroimmunology, there is a rapidly growing realization of the contribution of the innate and adaptive host immune responses in the pathogenesis of many CNS and PNS diseases. The balance between the protective and pathologic sequelae of immunity is fragile and can easily be tipped towards harm for the host. The matter of immune privilege and surveillance of the CNS/PNS compartments and the role of the blood-brain barrier (BBB) and blood nerve barrier (BNB) makes this even more complex. Our understanding of the pathogenesis of many post-infectious manifestations of various microbial agents remains elusive, especially in the diverse African setting. Our exploration and better understanding of the neuroimmunology of some of the infectious diseases that we encounter in the continent will go a long way into helping us to improve their management and therefore lessen the burden. Africa is diverse and uniquely poised because of the mix of the classic, well described, autoimmune disease entities and the specifically "tropical" conditions. This review explores the current understanding of some of the para- and post-infectious autoimmune manifestations of CNS and PNS diseases in the African context. We highlight the clinical presentations, diagnosis and treatment of these neurological disorders and underscore the knowledge gaps and perspectives for future research using disease models of conditions that we see in the continent, some of which are not uniquely African and, where relevant, include discussion of the proposed mechanisms underlying pathogen-induced autoimmunity. This review covers the following conditions as models and highlight those in which a relationship with COVID-19 infection has been reported: a) Acute Necrotizing Encephalopathy; b) Measles-associated encephalopathies; c) Human Immunodeficiency Virus (HIV) neuroimmune disorders, and particularly the difficulties associated with classical post-infectious autoimmune disorders such as the Guillain-Barré syndrome in the context of HIV and other infections. Finally, we describe NMDA-R encephalitis, which can be post-HSV encephalitis, summarise other antibody-mediated CNS diseases and describe myasthenia gravis as the classic antibody-mediated disease but with special features in Africa.

Nodding Syndrome: A Scoping Review

Nodding syndrome (NS) is a debilitating yet often neglected neurological disease affecting thousands of children in several sub-Saharan African countries. The cause of NS remains unknown, and effective treatment options are lacking. Moreover, knowledge regarding NS is scarce and is based on a limited number of publications, with no comprehensive overview published to date. Therefore, the aim of this scoping review was to summarise the current evidence and identify existing knowledge gaps in order to help clinicians, scientists, and policymakers develop guidelines for prioritising this severe condition. We searched the Medline (Ovid), Embase (Ovid), Scopus, and Global Health Library databases in accordance with the PRISMA extension for scoping review guidance and in accordance with the Joanna Briggs Institute guidelines and methodology for a scoping review, using keywords describing NS. We then extracted and presented the original data regarding the epidemiology, aetiology, pathophysiology, clinical features, diagnosis, management, and outcomes of NS, as well as community perceptions and the psychosocial and economic impact of NS. Out of 1470 identified articles, a total of 69 were included in this scoping review. Major gaps exist in understanding the aetiology and pathogenesis of NS. Future research is urgently needed not only to address these gaps, but also to study the treatment options, epidemiology, and psychosocial and economic impacts of NS. Innovative interventions and rehabilitation programmes designed to address the psychosocial and economic burdens associated with NS are also urgently needed.

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.

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.

Epilepsy in Onchocerca volvulus Sero-Positive Patients From Northern Uganda-Clinical, EEG and Brain Imaging Features

Globally, epilepsy is the most common chronic neurological disorder. The incidence in sub-Saharan Africa is 2-3 times higher than that in high income countries. Infection by Onchocerca volvulus may be an underlying risk factor for the high burden and based upon epidemiological associations, has been proposed to cause a group of disorders—Onchocerca associated epilepsies (OAE) like nodding syndrome (NS). To improve our understanding of the disease spectrum, we described the clinical, electroencephalographic (EEG) and magnetic resonance imaging (MRI) features of children with epilepsy and sero-positive for Onchocerca volvulus (possible OAEs other than nodding syndrome). Twenty-nine children and adolescents with non-nodding syndrome OAE in northern Uganda were enrolled. A diagnosis of OAE was made in patients with epilepsy and seizure onset after age 3 years, no reported exposure to perinatal severe febrile illness or traumatic brain injury, no syndromic epilepsy diagnosis and a positive Ov-16 ELISA test. Detailed clinical evaluation including psychiatric, diagnostic EEG, a diagnostic brain MRI (in 10 patients) and laboratory testing were performed. Twenty participants (69%) were male. The mean age was 15.9 (standard deviation [SD] 1.9) years while the mean age at seizure onset was 9.8 (SD 2.9) years. All reported normal early childhood development. The most common clinical presentation was a tonic-clonic seizure. The median number of seizures was 2 (IQR 1–4) in the previous month. No specific musculoskeletal changes, or cranial nerve palsies were reported, neither were any vision, hearing and speech difficulties observed. The interictal EEG was abnormal in the majority with slow wave background activity in 52% (15/29) while 41% (12/29) had focal epileptiform activity. The brain MRI showed mild to moderate cerebellar atrophy and varying degrees of atrophy of the frontal, parietal and occipital lobes. The clinical spectrum of epilepsies associated with Onchocerca may be broader than previously described. In addition, focal onset tonic-clonic seizures, cortical and cerebellar atrophy may be important brain imaging and clinical features.

Case-Control Study of Nodding Syndrome in Acholiland: Urinary Multi-Mycotoxin Screening

This case-control study adds to the growing body of knowledge on the medical, nutritional, and environmental factors associated with Nodding Syndrome (NS), a seizure disorder of children and adolescents in northern Uganda. Past research described a significant association between NS and prior history of measles infection, dependence on emergency food and, at head nodding onset, subsistence on moldy maize, which has the potential to harbor mycotoxins. We used LC-MS/MS to screen for current mycotoxin loads by evaluating nine analytes in urine samples from age-and-gender matched NS cases (n = 50) and Community Controls (CC, n = 50). The presence of the three mycotoxins identified in the screening was not significantly different between the two groups, so samples were combined to generate an overall view of exposure in this community during the study. Compared against subsequently run standards, α-zearalenol (43 ± 103 µg/L in 15 samples > limit of quantitation (LOQ); 0 (0/359) µg/L), T-2 toxin (39 ± 81 µg/L in 72 samples > LOQ; 0 (0/425) µg/L) and aflatoxin M1 (4 ± 10 µg/L in 15 samples > LOQ; 0 (0/45) µg/L) were detected and calculated as the average concentration ± SD; median (min/max). Ninety-five percent of the samples had at least one urinary mycotoxin; 87% were positive for two of the three compounds detected. While mycotoxin loads at NS onset years ago are and will remain unknown, this study showed that children with and without NS currently harbor foodborne mycotoxins, including those associated with maize.

Nodding syndrome research revisited

Nodding syndrome is one of several forms of onchocerciasis-associated epilepsy (OAE) seen among children in areas formerly hyperendemic for the transmission of Onchocerca volvulus. These forms of epilepsy are highly prevalent and clustered in certain villages located close to blackfly (Diptera: Simuliidae) breeding sites. OAE presents with a wide spectrum of seizures, including generalized tonic-clonic and head nodding seizures, impaired cognitive function, growth stunting and delayed puberty. In 2014, the present authors published a perspective paper in this journal which hypothesized that nodding syndrome may be caused by either a neurotropic virus transmitted by blackflies or an endosymbiont present within the O. volvulus parasite. Seven years later, this critical review presents progress in nodding syndrome research, and assesses whether it is still plausible that a neurotropic virus or endosymbiont could be the cause.

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.

Onchocerca volvulus and epilepsy: A comprehensive review using the Bradford Hill criteria for causation

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.

Case Report: Nakalanga Syndrome Revisited: Long-Term Follow-Up of a Patient Living in Western Uganda, 1994-2018

Nakalanga syndrome is a childhood developmental disorder that has been reported from various parts of sub-Saharan Africa with the major sign of retarded growth, regularly combined with physical deformities, impaired mental and pubertal development, and epilepsy. We present a follow-up over a 24-year period of a patient living in the Itwara onchocerciasis focus of western Uganda. We demonstrate the strong similarity of Nakalanga syndrome to the more recently described Nodding syndrome, and we discuss the possible causation of both disorders by onchocerciasis. We suggest that the growing knowledge about the tight interconnections between Nakalanga and nodding syndrome, other forms of epilepsy, and onchocerciasis should be taken into consideration in a revised classification system.

Putative Autoantigen Leiomodin-1 Is Expressed in the Human Brain and in the Membrane Fraction of Newly Formed Neurons

Nodding syndrome is a pediatric epilepsy disorder associated with Onchocerca volvulus infection, but the mechanism driving this relationship is unclear. One hypothesis proposes that parasite-induced immune responses cross-react with human leiomodin-1 resulting in immune-mediated central nervous system (CNS) damage. However, as leiomodin-1 expression and epitope availability in human neurons remains uncharacterized, the relevance of leiomodin-1 autoimmunity is unknown. Leiomodin-1 transcript expression was assessed in silico using publicly available ribonucleic acid (RNA) sequencing databases and in tissue by in situ hybridization and quantitative polymerase chain reaction. Abundance and subcellular localization were examined by cell fractionation and immunoblotting. Leiomodin-1 transcripts were expressed in cells of the CNS, including neurons and astrocytes. Protein was detectable from all brain regions examined as well as from representative cell lines and in vitro differentiated neurons and astrocytes. Leiomodin-1 was expressed on the membrane of newly formed neurons, but not neural progenitor cells or mature neurons. Importantly, leiomodin-1 antibodies were only toxic to cells expressing leiomodin-1 on the membrane. Our findings provide evidence that leiomodin-1 is expressed in human neurons and glia. Furthermore, we show membrane expression mediates leiomodin-1 antibody toxicity, suggesting these antibodies may play a role in pathogenesis.

Meta-analysis of epilepsy prevalence in West Africa and its relationship with onchocerciasis endemicity and control

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.

The Functional Parasitic Worm Secretome: Mapping the Place of Onchocerca volvulus Excretory Secretory Products

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.

Genetic Contributions to Acquired Epilepsies

Whether genetic factors contribute to acquired epilepsies has long been controversial. Supporters observe that, among individuals exposed to seemingly the same brain insult, only a minority develops unprovoked seizures. Yet, only in relatively recent years have studies started to build a case for genetic contributions. Here, we appraise this emerging evidence, by providing a critical review of studies published in the field.

Zoonotic Implications of Onchocerca Species on Human Health

The genus Onchocerca includes several species associated with ungulates as hosts, although some have been identified in canids, felids, and humans. Onchocerca species have a wide geographical distribution, and the disease they produce, onchocerciasis, is generally seen in adult individuals because of its large prepatency period. In recent years, Onchocerca species infecting animals have been found as subcutaneous nodules or invading the ocular tissues of humans; the species involved are O. lupi, O. dewittei japonica, O. jakutensis, O. gutturosa, and O. cervicalis. These findings generally involve immature adult female worms, with no evidence of being fertile. However, a few cases with fertile O. lupi, O. dewittei japonica, and O. jakutensis worms have been identified recently in humans. These are relevant because they indicate that the parasite’s life cycle was completed in the new host—humans. In this work, we discuss the establishment of zoonotic Onchocerca infections in humans, and the possibility of these infections to produce symptoms similar to human onchocerciasis, such as dermatitis, ocular damage, and epilepsy. Zoonotic onchocerciasis is thought to be an emerging human parasitic disease, with the need to take measures such as One Health Strategies, in order to identify and control new cases in humans.

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.

Changes in epilepsy burden after onchocerciasis elimination in a hyperendemic focus of western Uganda: a comparison of two population-based, cross-sectional studies

BACKGROUND

In 1994, prevalence and incidence of epilepsy were high in the Itwara onchocerciasis focus (western Uganda), and cases of nodding and Nakalanga syndrome were documented. Onchocerciasis transmission was interrupted successfully in 2001. 17 years later, we re-investigated the epilepsy burden in this area.

METHODS

From Dec 11 to Dec 15, 2018, a door-to-door survey was done in the three villages (Kabende Centre, Masongora South, and Rwesenene) with the highest epilepsy rates in 1994 to identify people with suspected epilepsy. Epilepsy diagnoses were confirmed by an interview and physical examination by a study clinician. The prevalence and incidence of epilepsy were measured using methods consistent with those used in 1994. Results from 2018 were compared with those from 1994.

FINDINGS

The overall crude prevalence of epilepsy in the study villages decreased from 3·0% (35 of 1169) in 1994 to 1·2% (27 of 2325) in 2018 (p=0·0002), with a concomitant decrease in the proportion of people with epilepsy with unknown cause (p=0·037). Between 1994 and 2018, the overall incidence of epilepsy decreased from 418 cases per 100 000 person-years (95% CI 265-626) to 73 new cases per 100 000 person-years (32-114; p<0·0001); this reduction was more pronounced for cases having the first seizure between ages 3 years and 18 years (p<0·0001). No new case of nodding or Nakalanga syndromes had occurred since the interruption of onchocerciasis transmission.

INTERPRETATION

Our findings support the existence of a negative association between onchocerciasis elimination and epilepsy burden in previously hyperendemic areas. Therefore, onchocerciasis elimination efforts should be intensified in endemic regions with a high prevalence of epilepsy, which might reduce the burden of epilepsy.

FUNDING

Flemish University Development Cooperation and the European Research Council.

Neuroinflammation and Not Tauopathy Is a Predominant Pathological Signature of Nodding Syndrome

Nodding syndrome (NS) is an epileptic disorder occurring in children in African onchocerciasis endemic regions. Here, we describe the pathological changes in 9 individuals from northern Uganda who died with NS (n = 5) or other forms of onchocerciasis-associated epilepsy (OAE) (n = 4). Postmortem examinations were performed and clinical information was obtained. Formalin-fixed brain samples were stained by hematoxylin and eosin and immunohistochemistry was used to stain astrocytes (GFAP), macrophages (CD68), ubiquitin, α-synuclein, p62, TDP-43, amyloid β, and tau (AT8). The cerebellum showed atrophy and loss of Purkinje cells with hyperplasia of the Bergmann glia. Gliosis and features of past ventriculitis and/or meningitis were observed in all but 1 participant. CD68-positive macrophage clusters were observed in all cases in various degrees. Immunohistochemistry for amyloid β, α-synuclein, or TDP-43 was negative. Mild to sparse AT8-positive neurofibrillary tangle-like structures and threads were observed in 4/5 NS and 2/4 OAE cases, preferentially in the frontal and parietal cortex, thalamic- and hypothalamic regions, mesencephalon and corpus callosum. Persons who died with NS and other forms of OAE presented similar pathological changes but no generalized tauopathy, suggesting that NS and other forms of OAE are different clinical presentations of a same disease with a common etiology.

The Pathogenesis of Nodding Syndrome

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.

Prevalence and incidence of nodding syndrome and other forms of epilepsy in onchocerciasis-endemic areas in northern Uganda after the implementation of onchocerciasis control measures

Background

Around 2007, a nodding syndrome (NS) epidemic appeared in onchocerciasis-endemic districts of northern Uganda, where ivermectin mass distribution had never been implemented. This study evaluated the effect of community-directed treatment with ivermectin (CDTI) and ground larviciding of rivers initiated after 2009 and 2012 respectively, on the epidemiology of NS and other forms of epilepsy (OFE) in some districts of northern Uganda.

Methods

In 2012, a population-based community survey of NS/epilepsy was carried out by the Ugandan Ministry of Health in Kitgum and Pader districts. In August 2017, we conducted a new survey in selected villages of these districts and compared our findings with the 2012 data. In addition, two villages in Moyo district (where CDTI was ongoing since 1993) served as comparative onchocerciasis-endemic sites in which larviciding had never been implemented. The comparison between 2012 and 2017 prevalence and cumulative incidence were done using the Fisher’s and Pearson’s Chi-square tests at 95% level of significance.

Results

A total of 2138 individuals in 390 households were interviewed. In the selected villages of Kitgum and Pader, there was no significant decrease in prevalence of NS and OFE between 2012 and 2017. However, the cumulative incidence of all forms of epilepsy decreased from 1165 to 130 per 100 000 persons per year (P = 0.002); that of NS decreased from 490 to 43 per 100 000 persons per year (P = 0.037); and for OFE from 675 to 87 per 100 000 persons per year (P = 0.024). The median age of affected persons (NS and OFE) shifted from 13.5 (IQR: 11.0–15.0) years in 2012 to 18.0 (IQR: 15.0–20.3) years in 2017; P <  0.001. The age-standardized prevalence of OFE in Moyo in 2017 was 4.6%, similar to 4.5% in Kitgum and Pader.

Conclusions

Our findings support the growing evidence of a relationship between infection by Onchocerca volvulus and some types of childhood epilepsy, and suggest that a combination of bi-annual mass distribution of ivermectin and ground larviciding of rivers is an effective strategy to prevent NS and OFE in onchocerciasis-hyperendemic areas.

"Those who died are the ones that are cured". Walking the political tightrope of Nodding Syndrome in northern Uganda: Emerging challenges for research and policy

Background

Nodding Syndrome was first reported from Tanzania in the 1960s but appeared as an epidemic in Northern Uganda in the 1990s during the LRA civil war. It is characterized by repetitive head nodding, often followed by other types of seizures, developmental retardation and growth faltering with onset occurring in children aged 5–15 years. More than 50 years after the first reports, the aetiology remains unknown and there is still no cure. The recent hypothesis that Nodding Syndrome is caused by onchocerciasis also increases the relevance of onchocerciasis control. Northern Uganda, with its unique socio-political history, adds challenges to the prevention and treatment for Nodding Syndrome. This article aims to show how and why Nodding Syndrome has been politicised in Uganda; how this politicisation has affected health interventions including research and dissemination; and, the possible implications this can have for disease prevention and treatment.

Methodology

Ethnographic research methods were used triangulating in-depth interviews, focus group discussions, informal conversations and participant observation, for an understanding of the various stakeholders’ perceptions of Nodding Syndrome and how these perceptions impact future interventions for prevention, treatment and disease control.

Principal findings

Distrust towards the government was a sentiment that had developed in Northern Uganda over several decades of war and was particularly linked to the political control and ethnic divisions between the north and south. This coincided with the sudden appearance of Nodding Syndrome, an unknown epidemic disease of which the cause could not be clearly identified and optimal treatment had not clearly been established. Additionally, the dissemination of the inconclusive results of research conducted in the area lacked sufficient community involvement which further fueled this political distrust. Disease perceptions revolved around rumours that the entire Acholi ethnic group of the north would be annihilated, or that international researchers were making money by stealing study samples. This discouraged some community members from participating in research or from accepting the mass drug administration of ivermectin for prevention and treatment of onchocerciasis. Such rumour and distrust led to suspicions concerning the integrity of the disseminated results, which may negatively impact future disease management and control interventions.

Conclusions and recommendations

Trust must be built up gradually through transparency and by de-politicising interventions. This can be done by engaging the community at regular intervals during research and data collection and the dissemination of results in addition to involvement during service delivery for prevention and treatment. Maintaining a regular feedback loop with the community will help control rumours, build trust, and improve the preparations for adequate dissemination.

Nodding Syndrome, a form of epilepsy that occurs in onchocerciasis-endemic areas has affected about 3000 children in Northern Uganda where the epidemic emerged at the time of the civil war. Although an association with onchocerciasis has been established, the disease etiology has not yet been identified. In conjunction with the area’s history of war, political conflict and ethnic divides, many affected people were suspicious of government health interventions and scientific studies. Furthermore, ambiguities around the disease etiology leaves room for several interpretations, which in addition to distrust leads to rumours, that may hinder future interventions. In view of improving adherence to health interventions, this article explains the socio-political nature of Nodding Syndrome in Northern Uganda. We show how and why this disease has been politicised in Uganda; how this politicisation has affected research and dissemination; and, the implications this has for disease control. The insights presented will be critical for reducing resistance to research, to treatment and to the dissemination of knowledge which is necessary for the prevention and control of Nodding Syndrome and onchocerciasis in Northern Uganda.

Nodding Syndrome: The Unresolved Mystery of a Pediatric Disease in Sub-Saharan Africa

Nodding syndrome is a mysterious neurologic illness of unknown etiology, presenting with distinctive clinical features often at early age. Currently, it affects children in restricted geographical areas in South Sudan, Northern Uganda and Southern Tanzania and is associated with high mortality and morbidity, especially in the children with severe disease. In this paper, we will give an outline of what is known about nodding syndrome with respect to epidemiology, clinical presentation, etiology and treatment. In addition, a possible approach to resolving the mystery is presented.

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.

Electronic supplementary material

The online version of this article (10.1186/s40249-019-0544-6) contains supplementary material, which is available to authorized users.

Doxycycline for the treatment of nodding syndrome (DONS); the study protocol of a phase II randomised controlled trial

BACKGROUND

Nodding syndrome is a poorly understood neurological disorder of unknown aetiology, affecting several thousand children in Africa. There has been a consistent epidemiological association with infection by the filarial parasite, Onchocerca volvulus and antibodies to leiomodin and DJ-1, cross-reacting with O.volvulus proteins, have been reported. We hypothesized that nodding syndrome is a neuro-inflammatory disorder, induced by antibodies to O.volvulus or its symbiont, Wolbachia, cross-reacting with human neuron proteins and that doxycycline, which kills Onchocerca through effects on Wolbachia, may be used as treatment.

METHODS

This will be a two-arm, double-blind, placebo-controlled, randomised phase II trial of doxycycline 100 mg daily for six weeks in 230 participants. Participants will be patients' ages≥8 years with nodding syndrome. They will receive standard of care supportive treatment. All will be hospitalised for 1-2 weeks during which time baseline measurements including clinical assessments, EEG, cognitive and laboratory testing will be performed and antiepileptic drug doses rationalised. Participants will then be randomised to either oral doxycycline (Azudox®, Kampala Pharmaceutical Industries) 100 mg daily or placebo. Treatment will be initiated in hospital and continued at home. Participants will be visited at home at 2, 4 and 6 weeks for adherence monitoring. Study outcomes will be assessed at 6, 12, 18 and 24-month visits. Analysis will be by intention to treat. The primary efficacy outcome measure will be the proportion of patients testing positive and the levels or titires of antibodies to host neuron proteins (HNPs) and/or leiomodin at 24 months. Secondary outcome measures will include effect of the intervention on seizure control, inflammatory markers, cognitive function, disease severity and quality of life.

DISCUSSION

This trial postulates that targeting O.volvulus through drugs which kill Wolbachia can modify the pathogenic processes in nodding syndrome and improve outcomes. Findings from this study are expected to substantially improve the understanding and treatment of nodding syndrome.

TRIAL REGISTRATION

Registered with clinicaltrials.gov ID: NCT02850913 on 1st August, 2016.

Low prevalence of epilepsy and onchocerciasis after more than 20 years of ivermectin treatment in the Imo River Basin in Nigeria

Background

High epilepsy prevalence and incidence have been reported in areas with high onchocerciasis transmission. Recent findings suggest that proper community-directed treatment with ivermectin (CDTI) is potentially able to prevent onchocerciasis-associated epilepsy (OAE). We assessed the epilepsy prevalence and onchocerciasis transmission in two Nigerian villages following more than 20 years of CDTI.

Methods

A cross-sectional door-to-door survey was performed in two villages in the Imo River Basin reported to be mesoendomic for onchocerciasis (Umuoparaodu and Umuezeala). Individuals were screened for epilepsy using a validated 5-item questionnaire. Persons suspected to have epilepsy were examined by a neurologist or a physician with training in epilepsy for confirmation. Onchocerciasis was investigated via skin snip microscopy and rapid diagnostic tests for Ov16 antibodies. Results were compared with previous findings from the Imo river basin.

Results

A total of 843 individuals from 257 households in the two villages were encountered. We detected four persons with epilepsy (PWE) giving a crude epilepsy prevalence of 0.5%. This finding differs from observations reported 14 years ago which showed an epilepsy prevalence of 2.8% in the neighbouring village of Umulolo (P = 0.0001), and 1.2% from 13 villages in the Imo river basin (P = 0.07). The seroprevalence of Ov16 antibodies was found to be 0%. Only 4.6% of skin snips were positive compared to 26.8% in previous surveys (P < 0.0001). Ivermectin mass distribution coverage in the study sites in 2017 was 79.7%.

Conclusions

A low epilepsy and onchocerciasis prevalence was observed following more than 20 years of CDTI in the Imo River Basin. Absence of Ov16 antibodies indicates minimal transmission of onchocerciasis. These results contrast with observations from areas of high onchocerciasis transmission, where epilepsy prevalence and incidence remain high. Findings from this study suggest that sustained efforts could eventually achieve elimination of onchocerciasis in these villages.

Electronic supplementary material

The online version of this article (10.1186/s40249-019-0517-9) contains supplementary material, which is available to authorized users.

Baseline characterization of epilepsy in an onchocerciasis endemic area of the Democratic Republic of Congo

Increased epilepsy prevalence is reported in onchocerciasis (OC) endemic areas and is associated with the occurrence of distinct syndromes such as nodding disease and Nakalanga syndrome. To date, a causal relationship between OC and epilepsy is still a matter of controversy. We conducted a case-control study of participants with epilepsy and age- and gender-matched presumably healthy controls to elucidate the relationships between OC and epilepsy and explore the role of inflammation and growth factors in an OC endemic area in the Democratic Republic of Congo (DRC). Eighty-two participants with epilepsy (mean age ± SD: 23.2 ± 8.7 years) and 27 controls (mean age ± SD: 22.3 ± 12.0 years) underwent snip skin biopsies to determine Onchocerca volvulus infection status. Serum concentrations of cytokines, chemokines, and growth factors were measured using a Luminex Multiplex Assay kit. Children <19 years of age underwent neurocognitive assessments using the Kaufman Assessment Battery for Children, 2^nd edition (KABC-II). Overall, epilepsy was associated with OC (OR = 4.51, z = 3.11, p = 0.0019), and children with OC were more likely to be severely stunted (OR = 11.67, z = 2.62, p = 0.0087). The relationship between epilepsy and OC was no longer significant (z = 1.27, p = 0.20) when stunting was included as a correcting covariate. Epilepsy was associated with poor KABC-II test scores, high serum levels of IL-17, and low levels of IL-1RA, IL-8, and EGF. KABC-II testing scores correlated with serum levels of IL-10, MCP-1 and HGF. Familial history of epilepsy occurred frequently. Future studies should consider cytokines and/or growth factors when assessing susceptibility to epilepsy in OC endemic areas. Additional investigations, preferentially in low-prevalence OC areas, may provide further insights into the concept, risk, and burden of river epilepsy.

The effect of bi-annual community-directed treatment with ivermectin on the incidence of epilepsy in onchocerciasis endemic villages in South Sudan: a study protocol

BACKGROUND

Nodding syndrome (NS) is a devastating epileptic illness of unknown aetiology mainly affecting children 5-15 years of age. Head nodding distinguishes NS from other forms of epilepsy. Other manifestations of the illness include mental and physical growth retardation. Many children die as a result of falling in fires or drowning. Recently, it was shown that NS is only one of the phenotypic presentations of onchocerciasis associated epilepsy (OAE). Despite the strong epidemiological association between epilepsy and onchocerciasis, the causal mechanism is unknown. After implementation of bi-annual community directed treatment with ivermectin (CDTi) and larviciding of rivers in northern Uganda, new cases of NS have ceased, while new cases continue to emerge in South Sudanese onchocerciasis-endemic areas with an interrupted CDTi programme. This study is designed to evaluate the potential effects of bi-annual CDTi on reducing the incidence of NS/OAE in onchocerciasis-endemic areas in South Sudan.

METHODS

A pre-intervention door-to-door population-based household survey will be conducted in selected onchocerciasis-endemic villages in Mundri and Maridi Counties, which have a high prevalence of epilepsy. Using a validated questionnaire, the entire village will be screened by community research assistants for suspected epilepsy cases. Suspected cases will be interviewed and examined by a trained clinical officer or medical doctor who will confirm or reject the diagnosis of epilepsy. Bi-annual CDTi will be implemented in the villages and a surveillance system for epilepsy set up. By implementing an epilepsy onchocerciasis awareness campaign we expect to obtain > 90% CDTi coverage of eligible individuals. The door-to-door survey will be repeated two years after the baseline survey. The incidence of NS/OAE will be compared before and after bi-annual CDTi.

DISCUSSION

Our study is the first population-based study to evaluate the effect of bi-annual CDTi to reduce the incidence of NS/OAE. If the study demonstrates such a reduction, these findings are expected to motivate communities in onchocerciasis-endemic regions to participate in CDTi, and will encourage policy makers, funders and other stakeholders to increase their efforts to eliminate onchocerciasis.