Onchocerciasis-Associated Epilepsy with Head Nodding Seizures-Nodding Syndrome: A Case Series of 15 Patients from Western Uganda, 1994

Long-term observation and mortality of children with nodding syndrome in western Uganda, 1994 - 2018

PURPOSE

To assess long-term mortality and causes of death in children with nodding syndrome, an epileptic disorder of sub-Sahara Africa.

METHODS

Ten children with nodding syndrome were followed over 24 years. The mortality rate was determined as the number of deaths per 1000 person-years of observation. The standard mortality ratio (SMR) was calculated as the number of observed deaths divided by the number of expected deaths in the general population. Patients were started on phenobarbital and treatment response was monitored during the first 20 months of follow-up.

RESULTS

During an observation period of 89.8 person-years, eight patients had died, one patient was found alive, and one patient had been lost to follow-up. This corresponded to a mortality rate of 89.1 deaths per 1000 person-years and a SMR of 21.4 (95 % CI 6.6-36.2). Five deaths were related to status epilepticus, in two cases occurring after inadvertent drug withdrawal. All patients responded on phenobarbital with a reduction of seizure frequency but only four reached a seizure-free period of at least 6 months.

CONCLUSIONS

This long-term follow-up demonstrated high mortality in patients with nodding syndrome. Anti-seizure treatment with phenobarbital was of moderate efficacy. Abrupt interruption of phenobarbital was found leading to seizure aggravation, status epilepticus, and death. Our findings point out the importance of securing continuity of treatment access once anti-seizure therapy is included in health services in resource-poor settings. More rigorous observations and controlled studies are needed to improve the therapeutic options for nodding syndrome.

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: 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.

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.

Ecological assessment of Black Fly (Simuliumdamnosum, Sensulato) breeding sites in two tributaries of Ogun river, Ogun state, Nigeria

Onchocerciasis is a disease transmitted by blackfly vector of the genus Simuliumdamnosum complex having public and socio-economic consequences. The abundance of blackfly is directly linked to fluvial ecosystems in both tropical and non-tropical countries of the world. This study assessed the ecology of blackfly breeding sites in two tributaries of River Ogun located in Olokemeji and Lisa villages, Ogun State. A total of eighteen water samples were collected for physicochemical analysis during high rainfall (May, June and July), low rainfall (August, September and October) and dry season (November and December) with mean rainfall values of 163.17, 88.03 and 8.95 mm, respectively, in both tributaries. Physicochemical parameters such as temperature (^oC), electrical conductivity (EC), pH, total solids (TS), dissolved oxygen (DO), biochemical oxygen demand (BOD), total suspended solids (TSS), hardness (H), sulphate (SO₄), phosphate (PO₄), alkalinity, acidity, nitrate (NO₃) and total dissolved solids (TDS) were analysed using standard laboratory methods. Digestive enzymes were analysed using 1 g of frozen gut of Simulium larvae grounded with 20 ml of 0.067 g of potassium hydrogen and 20 ml of 0.1 M sodium reagent. A total of 766 and 482 samples of Simulium larvae were collected from Olokemeji and Lisa tributaries using Eppendorf tubes. The zooplanktons collected from Olokemeji and Lisa tributary were 904 and 802, while phytoplanktons collected from Olokemeji and Lisa tributary were 635 and 582 during the study period. Data obtained were analysed using both descriptive analysis and T-test. The results obtained for the physicochemical parameters were 28.7 °C, 137.5 µS/cm, 6.3, 248.1 mg/L, 58 mg/L, 108.8 mg/L, 90.8 mg/L, 2.24 mg/L, 2.24 mg/L, 30.76 mg/L, 42.35 mg/L, 1.99 mg/L, 2.07 mg/L and 2.55 mg/L for Temperature, EC, pH, TS, DO, BOD, TSS, H, SO₄, PO₄, alkalinity, acidity, NO₃ and TDS, respectively. There were significant (p < 0.05) differences between the means of EC, pH, TS, TDS, TSS and hardness of Lisa tributary, and water samples were also viewed under an electron microscope for zooplanktons and phytoplanktons. The values of species diversity which were greater than 0.5 indicated that the species were abundant and evenly distributed. There were significant (p < 0.05) differences between the tributaries in all the digestive enzymes except amylase content. The regression analysis between TSS, nitrate, sulphate, phosphate, acidity, hardness, TS, pH and Simulium larvae abundance showed a positive correlation, R² with values of 0.828, 0.994, 0.948, 0.933, 0.986, 0.997, 0.889 and 0.981, respectively. The R² values between Simulium larvae abundance with phytoplanktons and rainfall have values of 0.868 at p < 0.01 and 0.911 at p < 0.05.

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.

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.

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.

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.

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.

Onchocerciasis-associated epilepsy: another piece in the puzzle from the Mahenge mountains, southern Tanzania

In a study from the onchocerciasis-endemic area of Mahenge in southern Tanzania, Mmbando et al. [Inf Dis Poverty. 2018;7:64] demonstrate that in four selected villages the overall epilepsy prevalence was high, and significantly more elevated in the two villages of higher onchocerciasis endemicity compared to those of lower endemicity. This is replicating earlier findings from many other areas of tropical Africa. The authors are also providing data indicating that in the Mahenge focus, the prevalence of nodding syndrome may be related to that of onchocerciasis in the same way as epilepsy in general. The application of a clinical case definition for onchocerciasis-associated epilepsy (OAE) as used in the study of Mmbando et al. [Inf Dis Poverty. 2018;7:64] faces some difficulties; indeed, its precision in discerning cases of OAE from epilepsy due to other etiologies is not known, and it does not allow for a specific diagnosis in the individual patient. Because an operational surveillance tool for assessing the number of patients in the population could mean substantial advance for better estimating the burden of OAE, the proposed definition should be tried in different settings and its performance reviewed in the process.