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

Cromwell, Elizabeth A. and Osborne, Joshua C. P. and Unnasch, Thomas R. and Basanez, Maria-Gloria and Gass, Katherine M. and Barbre, Kira A. and Hill, Elex and Johnson, Kimberly B. and Donkers, Katie M. and Shirude, Shreya and Schmidt, Chris A. and Adekanmbi, Victor and Adetokunboh, Olatunji O. and Afarideh, Mohsen and Ahmadpour, Ehsan and Ahmed, Muktar Beshir and Akalu, Temesgen Yihunie and Al-Aly, Ziyad and Alanezi, Fahad Mashhour and Alanzi, Turki M. and Alipour, Vahid and Andrei, Catalina Liliana and Ansari, Fereshteh and Ansha, Mustafa Geleto and Anvari, Davood and Appiah, Seth Christopher Yaw and Arabloo, Jalal and Arnold, Benjamin F. and Ausloos, Marcel and Ayanore, Martin Amogre and Baig, Atif Amin and Banach, Maciej and Barac, Aleksandra and Baernighausen, Till Winfried and Bayati, Mohsen and Bhattacharyya, Krittika and Bhutta, Zulfiqar A. and Bibi, Sadia and Bijani, Ali and Bohlouli, Somayeh and Bohluli, Mahdi and Brady, Oliver J. and Bragazzi, Nicola Luigi and Butt, Zahid A. and Carvalho, Felix and Chatterjee, Souranshu and Chattu, Vijay Kumar and Chattu, Soosanna Kumary and Cormier, Natalie Maria and Dahlawi, Saad M. A. and Damiani, Giovanni and Daoud, Farah and Darwesh, Aso Mohammad and Daryani, Ahmad and Deribe, Kebede and Dharmaratne, Samath Dhamminda and Diaz, Daniel and Do, Hoa Thi and El Sayed Zaki, Maysaa and El Tantawi, Maha and Elemineh, Demelash Abewa and Faraj, Anwar and Fasihi Harandi, Majid and Fatahi, Yousef and Feigin, Valery L. and Fernandes, Eduarda and Foigt, Nataliya A. and Foroutan, Masoud and Franklin, Richard Charles and Gubari, Mohammed Ibrahim Mohialdeen and Guido, Davide and Guo, Yuming and Haj-Mirzaian, Arvin and Hamagharib Abdullah, Kanaan and Hamidi, Samer and Herteliu, Claudiu and Hidru, Hagos Degefa de and Higazi, Tarig B. and Hossain, Naznin and Hosseinzadeh, Mehdi and Househ, Mowafa and Ilesanmi, Olayinka Stephen and Ilic, Milena D. and Ilic, Irena M. and Iqbal, Usman and Irvani, Seyed Sina Naghibi and Jha, Ravi Prakash and Joukar, Farahnaz and Jozwiak, Jacek Jerzy and Kabir, Zubair and Kalankesh, Leila R. and Kalhor, Rohollah and Karami Matin, Behzad and Karimi, Salah Eddin and Kasaeian, Amir and Kavetskyy, Taras and Kayode, Gbenga A. and Kazemi Karyani, Ali and Kelbore, Abraham Getachew and Keramati, Maryam and Khalilov, Rovshan and Khan, Ejaz Ahmad and Khan, Md Nuruzzaman Nuruzzaman and Khatab, Khaled and Khater, Mona M. and Kianipour, Neda and Kibret, Kelemu Tilahun and Kim, Yun Jin and Kosen, Soewarta and Krohn, Kris J. and Kusuma, Dian and La Vecchia, Carlo and Lansingh, Van Charles and Lee, Paul H. and LeGrand, Kate E. and Li, Shanshan and Longbottom, Joshua and Magdy Abd El Razek, Hassan and Magdy Abd El Razek, Muhammed and Maleki, Afshin and Mamun, Abdullah A. and Manafi, Ali and Manafi, Navid and Mansournia, Mohammad Ali and Martins-Melo, Francisco Rogerlandio and Mazidi, Mohsen and McAlinden, Colm and Meharie, Birhanu Geta and Mendoza, Walter and Mengesha, Endalkachew Worku and Mengistu, Desalegn Tadese and Mereta, Seid Tiku and Mestrovic, Tomislav and Miller, Ted R. and Miri, Mohammad and Moghadaszadeh, Masoud and Mohammadian-Hafshejani, Abdollah and Mohammadpourhodki, Reza and Mohammed, Shafiu and Mohammed, Salahuddin and Moradi, Masoud and Moradzadeh, Rahmatollah and Moraga, Paula and Mosser, Jonathan F. and Naderi, Mehdi and Nagarajan, Ahamarshan Jayaraman and Naik, Gurudatta and Negoi, Ionut and Nguyen, Cuong Tat and Nguyen, Huong Lan Thi and Nguyen, Trang Huyen and Nikbakhsh, Rajan and Oancea, Bogdan and Olagunju, Tinuke O. and Olagunju, Andrew T. and Omar Bali, Ahmed and Onwujekwe, Obinna E. and Pana, Adrian and Pourjafar, Hadi and Rahim, Fakher and Rahman, Mohammad Hifz Ur and Rathi, Priya and Rawaf, Salman and Rawaf, David Laith and Rawassizadeh, Reza and Resnikoff, Serge and Reta, Melese Abate and Rezapour, Aziz and Rubagotti, Enrico and Rubino, Salvatore and Sadeghi, Ehsan and Saghafipour, Abedin and Sajadi, S. Mohammad and Samy, Abdallah M. and Sarmiento-Suarez, Rodrigo and Sawhney, Monika and Schipp, Megan F. and Shaheen, Amira A. and Shaikh, Masood Ali and Shamsizadeh, Morteza and Sharafi, Kiomars and Sheikh, Aziz and Shetty, B. Suresh Kumar and Shin, Jae Il and Shivakumar, K. M. and Simonetti, Biagio and Singh, Jasvinder A. and Skiadaresi, Eirini and Soheili, Amin and Soltani, Shahin and Spurlock, Emma Elizabeth and Sufiyan, Mu'awiyyah Babale and Tabuchi, Takahiro and Tapak, Leili and Thompson, Robert L. and Thomson, Alan J. and Traini, Eugenio and Tran, Bach Xuan and Ullah, Irfan and Ullah, Saif and Uneke, Chigozie Jesse and Unnikrishnan, Bhaskaran and Uthman, Olalekan A. and Vinkeles Melchers, Natalie V. S. and Violante, Francesco S. and Wolde, Haileab Fekadu and Wonde, Tewodros Eshete and Yamada, Tomohide and Yaya, Sanni and Yazdi-Feyzabadi, Vahid and Yip, Paul and Yonemoto, Naohiro and Yousof, Hebat-Allah Salah A. and Yu, Chuanhua and Yu, Yong and Yusefzadeh, Hasan and Zaki, Leila and Zaman, Sojib Bin and Zamanian, Maryam and Zhang, Zhi-Jiang and Zhang, Yunquan and Ziapour, Arash and Hay, Simon I. and Pigott, David M. (2021) Predicting the environmental suitability for onchocerciasis in Africa as an aid to elimination planning. PLOS NEGLECTED TROPICAL DISEASES, 15 (7). ISSN 1935-2735

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Author summary As of 2018, it was unknown if onchocerciasis transmission occurred among approximately 2 400 implementation units (IUs; typically, second administrative-level units, such as districts) considered potentially endemic. These IUs have either never been surveyed for onchocerciasis or historical data are not sufficient to define contemporary endemicity status. Given the large number of IUs for which baseline data collection is likely required to achieve continental elimination, there is a need to prioritise areas for surveys to ensure that those suitable for endemic transmission, and therefore potentially eligible for mass drug administration, are able to initiate interventions as soon as possible. We used boosted regression trees to predict environmental suitability for onchocerciasis, with corresponding measures of uncertainty. We summarized the fine scale spatial predictions at the IU level by using receiver operating characteristic (ROC) curve analysis to identify a threshold that maximized agreement with the occurrence locations to identify IUs that may warrant prioritisation for mapping surveys. This analysis suggests that approximately half of the IUs considered for surveys could be classified as environmentally suitable for onchocerciasis. In order to develop an elimination strategy, many national onchocerciasis elimination programmes (NOEPs) need a mechanism to synthesise historical data to define priority areas for surveys. 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 x 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 center dot 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 center dot 2% exceed this threshold for suitability in at least one 5 x 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.

Item Type: Article
Subjects: WR Dermatology
Divisions: Faculty of Health > Department of Epidemiology
Depositing User: zeynab . bagheri
Date Deposited: 04 Sep 2021 09:37
Last Modified: 04 Sep 2021 09:37

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