Effect of Onchocerciasis Elimination Measures on the Incidence of Epilepsy in Maridi, South Sudan (OAEMaridi)

Effect of Onchocerciasis Elimination Measures on the Incidence of Epilepsy in Maridi, South Sudan, a Three-year Prospective Study

For the first time using a prospective design, a study confirms the results of previous retrospective studies, which found that strengthening onchocerciasis elimination efforts decreases the incidence of epilepsy, including nodding syndrome. Therefore, this study confirms the solid epidemiological link between onchocerciasis and epilepsy.

This study also shows that a community-based "Slash and Clear" vector control method can effectively decrease blackfly biting rates and potentially decrease onchocerciasis transmission.

Moreover, this study shows that epilepsy is a major cause of death in onchocerciasis endemic areas with high ongoing transmission.

Study Overview

• Status: Completed
• Conditions: Epilepsy; Onchocerciasis
• Intervention / Treatment: Drug: bi-annual CDTI

Detailed Description

Background High onchocerciasis transmission predisposes communities in endemic areas to a high epilepsy burden. The 4·4% (95%CI:4·1-4·7%) epilepsy prevalence documented in 2018 in Maridi, South Sudan, motivated the strengthening of onchocerciasis elimination measures. We evaluated the effect of these interventions on the incidence of epilepsy, including nodding syndrome (NS).

Methods Annual community-directed treatment with ivermectin (CDTi) was implemented in 2019, temporarily interrupted in 2020 and reimplemented biannually in 2021. Additionally, a community-based "Slash and Clear" vector control method was initiated in 2019 at the Maridi dam. A two-stage house-to-house survey was conducted before (2018) and after (2022) implementing the interventions, consisting of initial screening by community workers to detect suspected cases of epilepsy, followed by confirmation of the diagnosis by a trained clinician.

Finding Overall, 17,652 and 14,402 individuals participated in the pre- and post-intervention surveys, respectively. The epilepsy incidence decreased from 313·0 (95% confidence intervals (CI):273·7-357·7) to 34·7 (95%CI:17·6-66·1) per 100,000 person-years. Similarly, the incidence of NS decreased from 120·4 (95%CI:96·7-149·6) to 10·4 (95%CI:2·7-33·2) per 100,000 person-years. Despite biannual CDTi, only 56·6% of the population took ivermectin in 2021. Mortality of persons with epilepsy accounted for 17·1% (95%CI:14·0-20·7%) of the overall number of deaths in the population.

Interpretation In onchocerciasis-endemic areas with high prevalence of epilepsy, strengthening onchocerciasis elimination interventions can decrease the incidence of epilepsy, including NS. Additional efforts are needed in Maridi, where epilepsy is a major cause of mortality, to increase CDTi coverage and sustain blackfly control.

• Study Type: Observational
• Enrollment (Actual): 17000

Contacts and Locations

Study Locations

• South Sudan
  • Central
    • Juba, Central, South Sudan, 140
      • Amref Health Africa

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child; Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Probability Sample

Study Population

The study was conducted in 44 villages from eight study areas in the central area of Maridi County: Hai-Gabat, Hai-Matara, Hai-Tarawa, Kazana-1, Kazana-2, Kwanga, Mudubai and Nagbaka.

Description

Inclusion Criteria:

• entire population of selected villages in Maridi County

Exclusion Criteria:

• No

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Population of selected villages in Maridi county; A total of 2,511 households containing 17,652 individuals were visited in 2018, and 2,254 households containing 14,402 individuals in 2022.	Drug: bi-annual CDTI; bi-annual community directed treatment with ivermectin (CDTI) and community-based "slash and clear" vector control intervention; Other Names: "slash and clear" vector control intervention

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
epilepsy incidence	Incidence of epilepsy including nodding syndrome	4 years

Collaborators and Investigators

• Sponsor: Universiteit Antwerpen
• Collaborators: Amref Health Africa
• Investigators: Principal Investigator: Jane Carter, MD, Amref Health Africa

Study record dates

Study Major Dates

• Study Start (Actual): March 1, 2018
• Primary Completion (Actual): January 31, 2023
• Study Completion (Actual): February 19, 2023

Study Registration Dates

• First Submitted: February 19, 2023
• First Submitted That Met QC Criteria: February 19, 2023
• First Posted (Actual): March 1, 2023

Study Record Updates

• Last Update Posted (Actual): November 30, 2023
• Last Update Submitted That Met QC Criteria: November 27, 2023
• Last Verified: November 1, 2023

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Skin Diseases; Infections; Parasitic Diseases; Skin Diseases, Parasitic; Skin Diseases, Infectious; Spirurida Infections; Secernentea Infections; Nematode Infections; Helminthiasis; Filariasis; Epilepsy; Onchocerciasis
• Other Study ID Numbers: Project Code AID 011898

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: After de-identification (text, tables, figures, and appendices), all individual participant data that underlie the results reported in this article will be made available immediately and indefinitely via the Zenodo repository following publication for anyone who wishes to access the data for any purpose.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No