Journal Article

Predicting the environmental suitability for onchocerciasis in Africa as an aid to elimination planning

Salah Eddin Karimi, Valery L. Feigin, Priya Rathi, Claudiu Herteliu, Salman Rawaf, Tarig B. Higazi, Catalina Liliana Andrei, Mohsen Bayati, Navid Manafi, Kelemu Tilahun Kibret, Martin Amogre Ayanore, Jae Il Shin, Temesgen Yihunie Akalu, Andrew T Olagunju, Khaled Khatab, Souranshu Chatterjee, B. Suresh Kumar Shetty, K M Shivakumar, Abedin Saghafipour, Abdullah Al Mamun, Seyed Sina Naghibi Irvani, Katie M Donkers, Vahid Yazdi-Feyzabadi, Mohsen Afarideh, Morteza Shamsizadeh, Fereshteh Ansari, Olalekan A. Uthman, Kiomars Sharafi, Mohammed Ibrahim Mohialdeen Gubari, Neda Kianipour, Yong Yu, Mahdi Bohluli, Fakher Rahim, Aziz Sheikh, Samath D Dharmaratne, Mu'awiyyah Babale Sufiyan, Huong Lan Thi Nguyen, Turki Alanzi, Natalie Maria Cormier, Naohiro Yonemoto, Abdollah Mohammadian-Hafshejani, Olatunji O. Adetokunboh, Behzad Karami Matin, Masood Ali Shaikh, Richard C. Franklin, Maysaa El Sayed Zaki, Chris A Schmidt, Nicola Luigi Bragazzi, Paula Moraga, Oliver J. Brady, Marcel Ausloos, Leila Zaki, Shanshan Li, Takahiro Tabuchi, Carlo La Vecchia, Zulfiqar A Bhutta, Giovanni Damiani, Anwar Faraj, Leila R Kalankes

2021

Overview

Recent evidence suggests that, in some foci, elimination of onchocerciasis from Africa may be feasible with mass drug administration (MDA) of ivermectin. To achieve continental elimination of transmission, mapping surveys will need to be conducted across all implementation units (IUs) for which endemicity status is currently unknown. Using boosted regression tree models with optimised hyperparameter selection, we estimated environmental suitability for onchocerciasis at the 5 × 5-km resolution across Africa. In order to classify IUs that include locations that are environmentally suitable, we used receiver operating characteristic (ROC) analysis to identify an optimal threshold for suitability concordant with locations where onchocerciasis has been previously detected. This threshold value was then used to classify IUs (more suitable or less suitable) based on the location within the IU with the largest mean prediction. Mean estimates of environmental suitability suggest large areas across West and Central Africa, as well as focal areas of East Africa, are suitable for onchocerciasis transmission, consistent with the presence of current control and elimination of transmission efforts. The ROC analysis identified a mean environmental suitability index of 0·71 as a threshold to classify based on the location with the largest mean prediction within the IU. Of the IUs considered for mapping surveys, 50·2% exceed this threshold for suitability in at least one 5 × 5-km location. The formidable scale of data collection required to map onchocerciasis endemicity across the African continent presents an opportunity to use spatial data to identify areas likely to be suitable for onchocerciasis transmission. National onchocerciasis elimination programmes may wish to consider prioritising these IUs for mapping surveys as human resources, laboratory capacity, and programmatic schedules may constrain survey implementation, and possibly delaying MDA initiation in areas that would ultimately qualify.

• Publisher: Public Library of Science (PLoS),Public Library of Science
• Subject: 06 Biological Sciences / 11 Medical and Health Sciences / Africa / Africa - epidemiology / Africa; Environment; Forecasting; Humans; Ivermectin; Mass Drug Administration; Onchocerciasis; ROC Curve; Disease Eradication / Arctic medicine. Tropical medicine / Biological Sciences / Biomedical and clinical sciences / Biopsy / Classification / Clinical Sciences / Computer and Information Sciences / Data collection / Data visualization / Datasets / Development and progression / Disease / Disease Eradication / Drug therapy / Elimination of transmission / Endemism / Engineering and Technology / Environment / Environmental health / Evaluation / Foci / Forecasting / Good Health and Well Being / Health sciences / Human resources / Humans / Implementation units (IUs) / Infection control / Ivermectin / Ivermectin - administration & dosage / Mapping / Mass Drug Administration / Mass drug administration (MDA) / Medical and Health Sciences / Medical research / Medicine and Health Sciences / Medicine, Experimental / Morbidity / Onchocerciasis / Onchocerciasis - drug therapy / Onchocerciasis - epidemiology / Onchocerciasis - transmission / Onchocerciasis ; Elimination planning ; Africa ; Implementation units ; Public health / People and Places / Polls & surveys / Programmes / Public aspects of medicine / RA1-1270 / RC955-962 / Receiver operating characteristic (ROC) / Regression analysis / Research and Analysis Methods / ROC Curve / Schedules / SDG 3 - Good Health and Well-being / Skin diseases / Spatial data / Surveying / Surveys / Transmission / Tropical diseases / Tropical Medicine / wa_395 / wc_695 / wc_765 / wc_885 / WR Dermatology