Modelling of onchocerciasis-associated skin and ocular disease and the impact of ivermectin treatment
File(s)
Published version
Author(s)
Type
Journal Article
Abstract
Background
Despite decades of control interventions in sub-Saharan Africa, morbidity associated with Onchocerca volvulus infection still exerts a substantial burden of disease, arising from cutaneous, ocular and neurological manifestations.
Methods
We developed and integrated a morbidity sub-model into our previously published individual-based, stochastic transmission model, EPIONCHO-IBM, including both reversible (severe itch, reactive skin disease (RSD)), and irreversible (skin atrophy, depigmentation, hanging groin) cutaneous sequelae, and eye disease (blindness, visual impairment). We modelled the relationship between onchocerciasis skin disease (OSD) and infection prevalence using pre-intervention data from northern Nigeria, and between onchocerciasis ocular disease (OOD) and infection intensity using data from the Onchocerciasis Control Programme in West Africa. We simulated the impact of ivermectin mass drug administration (MDA) upon OSD and OOD using data from Cameroon, Central African Republic, Nigeria, Sudan and Uganda.
Results
Modelled age-specific OSD and OOD prevalence at baseline align well with reported prevalence estimates across the simulated range of endemicity levels but underestimate irreversible OSD in older age groups. Under MDA, we capture trends in infection prevalence, severe itch and irreversible OSD but underestimate reductions in RSD and blindness prevalence.
Conclusions
Integrating morbidity outcomes into transmission dynamics modelling will help improve estimates of onchocerciasis disease burden and inform the effectiveness and cost-effectiveness of current and alternative interventions.
Despite decades of control interventions in sub-Saharan Africa, morbidity associated with Onchocerca volvulus infection still exerts a substantial burden of disease, arising from cutaneous, ocular and neurological manifestations.
Methods
We developed and integrated a morbidity sub-model into our previously published individual-based, stochastic transmission model, EPIONCHO-IBM, including both reversible (severe itch, reactive skin disease (RSD)), and irreversible (skin atrophy, depigmentation, hanging groin) cutaneous sequelae, and eye disease (blindness, visual impairment). We modelled the relationship between onchocerciasis skin disease (OSD) and infection prevalence using pre-intervention data from northern Nigeria, and between onchocerciasis ocular disease (OOD) and infection intensity using data from the Onchocerciasis Control Programme in West Africa. We simulated the impact of ivermectin mass drug administration (MDA) upon OSD and OOD using data from Cameroon, Central African Republic, Nigeria, Sudan and Uganda.
Results
Modelled age-specific OSD and OOD prevalence at baseline align well with reported prevalence estimates across the simulated range of endemicity levels but underestimate irreversible OSD in older age groups. Under MDA, we capture trends in infection prevalence, severe itch and irreversible OSD but underestimate reductions in RSD and blindness prevalence.
Conclusions
Integrating morbidity outcomes into transmission dynamics modelling will help improve estimates of onchocerciasis disease burden and inform the effectiveness and cost-effectiveness of current and alternative interventions.
Date Issued
2026-04-09
Date Acceptance
2026-02-16
Citation
Communications Medicine, 2026, 6
ISSN
2730-664X
Publisher
Nature Portfolio
Journal / Book Title
Communications Medicine
Volume
6
Copyright Statement
© The Author(s) 2026. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
License URL
Identifier
10.1038/s43856-026-01464-2
Subjects
onchocerciasis
morbidity
modelling
ivermectin
sub-Saharan Africa
Publication Status
Published
Article Number
ARTN 198
Date Publish Online
2026-03-02