Impact of a bi-annual community-directed treatment with ivermectin programme on the incidence of epilepsy in an onchocerciasis-endemic area of Mahenge, Tanzania: A population-based prospective study

Epilepsy in low- to middle-income countries

PURPOSE OF REVIEW

Epilepsy disproportionately affects those in low- and middle-income countries (LMICs) where diagnostic and treatment gaps persist.We highlight key recent developments and showcase practical opportunities to improve epilepsy care in resource limited settings.

RECENT FINDINGS

In LMICs, cultural, socioeconomic and infrastructural factors drive the epilepsy treatment gap. Robust implementation of the WHO Intersectoral Global Action Plan (WHO IGAP) and Mental Health Gap Action Program (mhGAP), for example, will reduce the epilepsy education gap. Engaging traditional healers and other key community leaders should lessen stigma. The Epilepsy Diagnostic Companion, a culture specific tool that helps identify convulsive seizures, can expedite epilepsy diagnosis at primary care level. Novel, robust 3-D printable EEG headsets prototypes that can be deployed in remote rural communities have been piloted with encouraging results. Levetiracetam has been added to the WHO Essential Medicines List (EML), paving way to safer, less teratogenic antiseizure medications (ASMs). Epilepsy surgery programs in carefully selected patients potentially offer cheap, effective and potentially curative treatments, including in LMICs.

SUMMARY

Apps, EEG prototypes, better access to ASMs and implementation of WHO iGAP offer current, tangible opportunities to improve epilepsy care in LMICs. Bidirectional learning must be facilitated to also help hard to reach communities in high-income settings.

Recognising the neurological burden of onchocerciasis: the need to include onchocerciasis-associated epilepsy in onchocerciasis global health metrics

BACKGROUND

Historically, onchocerciasis has been recognised for its dermatological and ophthalmological manifestations, such as blindness. However, growing epidemiological evidence indicates that onchocerciasis is also associated with neurological complications, particularly onchocerciasis-associated epilepsy (OAE). These complications are not currently reflected in disease burden estimates and associated disability-adjusted life years (DALYs) for onchocerciasis.

MAIN TEXT

The most recent global burden of disease estimates for onchocerciasis in 2019 reported 1.23 million DALYs without accounting for OAE. Yet, a preliminary study suggested that 128,000 years of life lost to disability (YLD, a key component of DALYs) may be attributable to epilepsy in onchocerciasis-endemic areas of East and Central Africa. This figure, which would represent over 13% of the total onchocerciasis morbidity burden and 10% of the global epilepsy morbidity burden, is likely still an underestimation. Current disability weights for epilepsy YLD estimation may not fully capture the spectrum of OAE, which often involves nodding syndrome, developmental delays, motor disabilities, cognitive impairments and stigma. In regions where access to antiseizure medication treatment is sparse, poorly controlled seizures can exacerbate disability and lead to premature mortality. Targeted integrated strategies-combining onchocerciasis control measures with improved epilepsy care-could help address these critical gaps.

CONCLUSIONS

Recognising OAE as part of the disease burden associated with onchocerciasis may encourage global health stakeholders to allocate resources for targeted interventions, thereby refining disease burden estimates, reducing disability, averting premature deaths and improving overall health outcomes.

Community-based epilepsy care in an onchocerciasis-endemic area: A 3-year cohort study in Mahenge, Tanzania

OBJECTIVE

In onchocerciasis-endemic areas, limited access to antiseizure medications (ASMs) contributes to a high epilepsy burden. This study evaluated the impact of a community-based epilepsy care program in Mahenge, Tanzania, an onchocerciasis-endemic area with high epilepsy prevalence.

METHODS

A baseline survey (2017-2018) identified persons with epilepsy (PWE) in four rural villages. Subsequently, PWE were invited to enroll in the epilepsy treatment program (2019-2022), where trained community health workers (CHWs) screened for epilepsy, promoted ivermectin intake to treat onchocerciasis, distributed ASMs, and monitored seizure frequency and ASM adherence monthly under supervision from the project clinician trained in epilepsy diagnosis and treatment. A concluding survey (2022) collected sociodemographic data and participants' status as alive, deceased, or lost to follow-up. Mixed-effects negative binomial regression analyzed risk factors for weekly seizure incidence rate.

RESULTS

Of 206 participants, 77.7% reported bilateral tonic-clonic seizures, and 32.0% reported focal seizures. More than one third (38.5%) were suspected of having nodding syndrome. Weekly seizure frequency decreased significantly from a mean of 1.9 seizures (interquartile range [IQR] = 0-2) at enrollment to .4 seizures (IQR = 0-0) at the last follow-up (Wilcoxon test p < .0001), with significantly improved ASM adherence (57.5%-94.7%, McNemar test p < .0001). Factors associated with lower weekly seizure incidence included longer program participation, ASM adherence, carbamazepine use compared to phenobarbital, and ivermectin intake in 2022. ASM adverse events were associated with increased seizure frequency. The mortality rate was 32.7 deaths per 1000 person-years, with most deceased not fully adhering to ASM (88%) and having epilepsy-related causes of death (60%).

SIGNIFICANCE

The community-based program using CHWs was associated with a significant reduction in seizure frequency and improved ASM adherence. In onchocerciasis-endemic areas, it should be investigated whether carbamazepine should be a preferred ASM in PWE. Ivermectin's impact on seizure frequency merits further investigation in onchocerciasis-endemic areas. Community-based epilepsy care is a promising strategy for scaling up epilepsy care in rural areas in Africa.

The Spectrum of Ocular Diseases in the Onchocerciasis-Endemic Focus of Raga in South Sudan

Introduction

Raga County is an onchocerciasis-endemic area in the Western Bahr El Ghazal state of South Sudan, known to have a high prevalence of blindness. The objective of this study was to determine the causes of eye disease and blindness in Raga County as well as to assess the relationship of eye diseases with other prevalent conditions like onchocerciasis and epilepsy.

Methods

We reviewed unpublished pre-community directed treatment with ivermectin (CDTI) data about eye disease and onchocerciasis in Western Bahr El Ghazal including Raga. In addition, a cross-sectional study was conducted from 21st March to 2nd April 2023 in 11 villages in Raga County. Participants were persons with blindness or other eye/vision problems, recruited via a community-based approach. Two senior ophthalmic clinical officers, supervised by an experienced ophthalmologist, performed the following assessments on participants: visual acuity measurement with Snellen Charts, anterior chamber examination with a loupe, and fundoscopy to assess the posterior segment with direct and indirect ophthalmoscopes.

Results

Pre-CDTI data showed that the most severe vision problems in villages with a high prevalence of O. volvulus infection were caused by onchocerciasis eye disease. During the 2023 survey, in total, 1559 persons (3,118 eyes) were examined (mean age: 47 ± 19.2 years, 58.4% male). The most frequent eye diagnosis was allergic conjunctivitis, observed in 1453 (46.6%) eyes of the participants. The main causes of blindness were onchocerciasis-related blindness (22.6%, caused by onchocerciasis chorioretinitis (9.4%), sclerosing keratitis, punctate keratitis (5.6%), and onchocerciasis optic neuropathy (7.6%)), and cataract (9.3%). A significantly higher proportion of persons with epilepsy presented with clinical signs of onchocerciasis including blindness (53.2%), compared to persons without epilepsy (32.5%) (p = 0.0007).

Conclusion

Despite years of CDTI, the main causes of blindness in Raga County remain onchocerciasis-related blindness observed in 22.6% and cataract observed in 9.3% of the study participants. The study confirmed an epidemiological association between onchocerciasis and epilepsy.

Epidemiology of epilepsy in Wulu County, an onchocerciasis-endemic area in South Sudan

Background

We sought to investigate the epidemiology of epilepsy in Wulu County (Lakes State, South Sudan), and document the onchocerciasis transmission status in the study villages.

Methods

In February 2024, a community-based epilepsy study was conducted Wulu County and participants were surveyed via a door-to-door approach in five villages, namely: Kombi, Makundi Center, Tonjo, War-Pac, and Woko. All village residents were asked about ivermectin intake during the 2023 round of community-directed treatment with ivermectin (CDTI). In addition, children aged 3-9 years were tested for Ov16 antibodies using a rapid diagnostic test. Epilepsy diagnosis in screened individuals was confirmed by a physician.

Results

We surveyed 1355 persons in the five study sites. The overall CDTI coverage in 2023 was 67.4 %. Fifty-five persons with epilepsy (PWE) were identified (prevalence 4.1 %) and a history of nodding seizures was noted in 11/55 (20 %) PWE. The mean age of PWE was 21.5 ± 9.6 years, with 32 (58.2 %) being males. Epilepsy onset frequently occurred under 5 years of age (38.6 % of cases). In two PWE, seizure onset occurred during the past 12 months (annual incidence: 147.6 per 100,000 persons). Twenty-nine PWE (52.7 %) were taking anti-seizure medicines, but only five were taking them daily. Overall, Ov16 seroprevalence in children aged 3-9 years (n = 119) was 15.1 % and differed across villages, peaking at 30.9 % in Woko village where epilepsy prevalence was also highest (7.1 %). Of the 35 recorded deaths during the past two years, 9 (25.7 %) occurred in PWE. Annual estimates for epilepsy mortality and fatality rates were 323.7 per 100,000 persons and 7031.3 per 100,000 PWE, respectively.

Conclusion

High epilepsy prevalence was found in Wulu, particularly in villages with persistent onchocerciasis transmission. Frequent epilepsy onset among under-fives suggests that perinatal/early childhood etiologies are common. Appropriate measures should be instituted to prevent and treat epilepsy in Wulu villages.

Attitudes and perceptions towards epilepsy in an onchocerciasis-endemic region of Tanzania: a mixed approach to determine the magnitude and driving factors

BACKGROUND

Epilepsy remains a significant public health concern in Tanzania, with affected individuals enduring stigma, whether through actions or perceptions. Myths, misunderstandings, and misconceptions about epilepsy have persisted due to a multitude of factors. Here, we assessed attitudes and perceptions toward epilepsy in Mahenge.

METHODS

A cross-sectional study utilising a mixed-methods approach was undertaken in eight villages in the Ulanga district of Mahenge, integrating a semi-structured questionnaire and focus group discussions (FGDs). The questionnaire involved 778 community members, and 15 FGDs were conducted (seven groups with people with epilepsy and eight without). Descriptive statistics, chi-square, and logistic regression were used for quantitative analysis, while we used NVivo version 14 for thematic analysis of qualitative data.

RESULTS

Of 778 participants, over half were women (425, 54.6%) with a median age of 41 years (IQR: 30-55) and most had completed primary education (79.9%). The majority of participants were aware of epilepsy (96.8%), yet they displayed low knowledge (51%), negative attitudes (45.5%), and perceptions (42.1%) towards the disorder. A low level of understanding was significantly associated with negative attitudes (Adjusted Odds Ratio [AOR] = 1.89, 95%CI: 1.41-2.53) and perceptions (AOR = 3.22, 95%CI: 2.05-5.04) towards epilepsy. In the qualitative analysis, often hereditary factors and infections were named as causes of epilepsy, along with misconceptions involving witchcraft and divine punishment. There was also a misconception about the contagiousness of epilepsy. Traditional healers were often the initial point of treatment. Epilepsy-related stigma was evident, with individuals with epilepsy facing derogatory labels, social isolation, and barriers to education. Lastly, there was a lack of understanding regarding a possible association between epilepsy and onchocerciasis.

CONCLUSIONS

Despite high awareness of epilepsy, there is insufficient understanding, negative attitudes, and perceptions, including misconceptions and stigma about this neurologic condition. Community-based education programmes are essential for promoting proper healthcare-seeking behaviour and dispelling myths.

Prevalence of onchocerciasis and epilepsy in a Tanzanian region after a prolonged community-directed treatment with ivermectin

INTRODUCTION

Epidemiological evidence suggests that Onchocerca volvulus is associated with epilepsy, although the exact pathophysiological mechanism is unknown. Mahenge is an endemic focus of onchocerciasis, with the longest-running ivermectin treatment intervention in Tanzania. We assessed the prevalence of onchocerciasis and epilepsy after 25 years of control using ivermectin.

METHODS

This was a population-based cross-sectional study in 34 villages in Mahenge in 2021. Community health workers conducted door-to-door household surveys to enumerate the population and screen for individuals suspected of epilepsy using a standardised questionnaire. Trained physicians confirmed epilepsy. Children aged 6-11 years were screened for onchocerciasis antibodies using the Ov16 rapid test. Villages were stratified into three altitude levels (low [<400], medium [400-950], and high [>950 meters above sea level]) as a proxy for rapids, which black flies favour for breeding sites. Incidence of epilepsy was estimated as a ratio of new cases in the year preceding the survey per 100,000 population.

RESULTS

56,604 individuals (median age 20.2 years, 51.1% females) were surveyed. Onchocerciasis prevalence in children was 11.8% and was highest in villages at medium (21.7%) and lowest in low altitudes (3.2%), p<0.001. Self-reported use of ivermectin was 88.4%. Epilepsy prevalence was 21.1 (95%CI: 19.9-22.3) cases per 1000 persons and was highest in medium (29.5%) and lowest in the lowlands (12.7%). The odds ratio (OR) of having epilepsy was significantly higher in females (OR = 1.22, 95%CI: 1.08-1.38), middle altitudes (OR = 2.34 [95%CI: 2.04-2.68]), and in individuals positive for OV16 (OR = 1.98 [95%CI:1.57-2.50]). The incidence of epilepsy a year before the survey was 117 (95%CI: 99.7-160.4) cases per 100,000 person-years.

CONCLUSION

Despite ivermectin use for 25 years, the prevalence of onchocerciasis and epilepsy remains high. It is crucial to strengthen bi-annual ivermectin treatment and initiate interventions targeting vectors to control onchocerciasis and epilepsy in the area.

Onchocerciasis-associated epilepsy: Charting a path forward

This narrative review intends to inform neurologists and public health professionals about Onchocerciasis-Associated Epilepsy (OAE), a neglected public health problem in many remote onchocerciasis-endemic areas. For epidemiological purposes, we define OAE as sudden-onset of convulsive and non-convulsive seizure types, including head nodding seizures (nodding syndrome) in a previously healthy child aged 3 to 18 years in the absence of any other obvious cause for epilepsy, all happening within an area with high ongoing Onchocerca volvulus transmission. Several OAE pathophysiological mechanisms have been proposed, but none has been proven yet. Recent population-based studies showed that strengthening onchocerciasis elimination programs was followed by a significant reduction in the incidence of OAE and nodding syndrome. Treating epilepsy in onchocerciasis-endemic regions is challenging. More advocacy is needed to provide uninterrupted, free access to anti-seizure medication to persons with epilepsy in these remote, impoverished areas. It is crucial todevelop policies and increase funding for the prevention and treatment of OAE to reduce the associated burden of disease, notably via the establishment of morbidity management and disability prevention programs (MMDP). Moreover, effective collaboration between onchocerciasis elimination and mental health programs is imperative to alleviate the burden of OAE. This synergy promises reciprocal advantages and underscores the need for a comprehensive approach to address this multifaceted challenge.

Impact of annual community-directed treatment with ivermectin on the incidence of epilepsy in Mvolo, a two-year prospective study

OBJECTIVES

The potential impact of cumulative community-directed treatment with ivermectin (CDTI) on epilepsy epidemiology in Mvolo County, South Sudan, an onchocerciasis-endemic area with high epilepsy prevalence, was investigated. Annual CDTI was introduced in 2002 in Mvolo, with interruptions in 2016 and 2020.

METHODS

Comprehensive house-to-house surveys in Mvolo (June 2020 and 2022) identified cases of epilepsy, including probable nodding syndrome (pNS). Community workers screened households in selected sites for suspected epilepsy, and medical doctors confirmed the diagnosis and determined the year of seizure onset. The incidence of epilepsy, including pNS, was analysed using 95% confidence intervals (CIs). Data on ivermectin intake and onchocerciasis-associated manifestations (itching and blindness) were collected.

RESULTS

The surveys covered 15,755 (2020) and 15,092 (2022) individuals, identifying 809 (5.2%, 95% CI: 4.8-5.5%) and 672 (4.5%, 95% CI: 4.1-4.8%) epilepsy cases, respectively. Each survey reported that a third of the surveyed population experienced skin itching, and 3% were blind. Epilepsy incidence per 100,000 person-years gradually declined, from 326.5 (95% CI: 266.8-399.1) in 2013-2015 to 96.6 (95% CI: 65.5-141.7) in 2019-2021. Similarly, pNS incidence per 100,000 person-years decreased from 151.7 (95% CI: 112.7-203.4) to 27.0 (95% CI: 12.5-55.5). Coverage of CDTI was suboptimal, reaching only 64.0% of participants in 2019 and falling to 24.1% in 2021 following an interruption in 2020 due to COVID-19 restrictions. Additionally, while 99.4% of cases had active epilepsy in 2022, less than a quarter of these had access to antiseizure medication.

CONCLUSIONS

The observed decrease in epilepsy incidence despite suboptimal CDTI coverage highlights the potential impact of onchocerciasis control efforts and underscores the need to strengthen these efforts in Mvolo County and across South Sudan. As a proactive measure, Mvolo and neighbouring counties are transitioning to biannual CDTI. Furthermore, the substantial epilepsy treatment gap in Mvolo should be addressed.

Integration of onchocerciasis morbidity management and disability prevention services in the healthcare system in Tanzania: a call for action and recommendations

Onchocerciasis is among the Neglected Tropical Diseases (NTDs) responsible for dermatological, ophthalmological, and neurological manifestations. With the ongoing burden of onchocerciasis clinical manifestations, morbidity management, and disability prevention services are required to alleviate the suffering of the affected populations. Unfortunately, despite the ongoing transmission of onchocerciasis, morbidity management, and disability prevention services are limited in Tanzania. Therefore, this article highlights the concept of onchocerciasis morbidity management and disability prevention, along with the significance of its adoption in the healthcare system in Tanzania. We further provide recommendations on where and how to start.

Disability assessment among persons with epilepsy in Mahenge, an onchocerciasis-endemic area in Tanzania: A cross-sectional study

BACKGROUND

A high prevalence of epilepsy has been observed in the onchocerciasis-endemic focus of Mahenge, Tanzania. This study sought to assess the degree of disability experienced by persons with epilepsy (PWE) in Mahenge and identify associations with sociodemographic and clinical features.

METHOD

This cross-sectional study was conducted in Mahenge, Tanzania, between February and July 2020. PWE were recruited from the Mahenge epilepsy clinic and four neighbouring rural villages (Mdindo, Mzogezi, Mzelezi and Sali). Data were collected using the 36-item version of the World Health Organization Disability Assessment Schedule 2.0 (WHODAS 2.0) questionnaire for adults. For children aged 5-17 years, we used the Module on Child Functioning developed by UNICEF and the Washington Group. Questionnaires were administered by trained research assistants. Descriptive statistics were performed, and multivariable analyses (gamma and logistic regressions) were conducted.

RESULTS

A total of 321 adults (45.5% males) and 48 children (55.3% males) with epilepsy participated. The overall median WHODAS 2.0 score was 4.8% (IQR: 0.9-18.9). The most affected disability domain was 'participating in the society' (median score: 12.5%, IQR: 0-29.2). Fifteen (31.3%) of the children with epilepsy had a disability in at least one domain of the child functioning module, with the 'accepting change' domain harbouring the highest proportion of disabled children (12.5%). Higher seizure frequency and longer epilepsy duration were associated with more disability.

CONCLUSION

PWE in Mahenge experience variable degrees of disability. The affected domains indicate the need for societal rehabilitation of PWE in various community and/or social activities. Peer-support groups were instituted at the study sites to address these needs.

The onchocerciasis hypothesis of nodding syndrome

Nodding syndrome (NS) is a phenotypic presentation of onchocerciasis-associated epilepsy (OAE). OAE is an important public health problem in areas with high ongoing Onchocerca volvulus transmission. OAE, including NS, is preventable by strengthening onchocerciasis elimination programs. The presence of tau in OAE postmortem brains could be the consequence of neuroinflammation directly or indirectly induced by O. volvulus. Omics research is needed to investigate whether O. volvulus worms contain a neurotropic virus.