Dataset Information

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

ABSTRACT: 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.

SUBMITTER: Cromwell EA

PROVIDER: S-EPMC8318275 | biostudies-literature | 2021 Jul

REPOSITORIES: biostudies-literature

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

Cromwell Elizabeth A EA Osborne Joshua C P JCP Unnasch Thomas R TR Basáñez Maria-Gloria MG Gass Katherine M KM Barbre Kira A KA Hill Elex E Johnson Kimberly B KB Donkers Katie M KM Shirude Shreya S Schmidt Chris A CA Adekanmbi Victor V Adetokunboh Olatunji O OO Afarideh Mohsen M Ahmadpour Ehsan E Ahmed Muktar Beshir MB Akalu Temesgen Yihunie TY Al-Aly Ziyad Z Alanezi Fahad Mashhour FM Alanzi Turki M TM Alipour Vahid V Andrei Catalina Liliana CL Ansari Fereshteh F Ansha Mustafa Geleto MG Anvari Davood D Appiah Seth Christopher Yaw SCY Arabloo Jalal J Arnold Benjamin F BF Ausloos Marcel M Ayanore Martin Amogre MA Baig Atif Amin AA Banach Maciej M Barac Aleksandra A Bärnighausen Till Winfried TW Bayati Mohsen M Bhattacharyya Krittika K Bhutta Zulfiqar A ZA Bibi Sadia S Bijani Ali A Bohlouli Somayeh S Bohluli Mahdi M Brady Oliver J OJ Bragazzi Nicola Luigi NL Butt Zahid A ZA Carvalho Felix F Chatterjee Souranshu S Chattu Vijay Kumar VK Chattu Soosanna Kumary SK Cormier Natalie Maria NM Dahlawi Saad M A SMA Damiani Giovanni G Daoud Farah F Darwesh Aso Mohammad AM Daryani Ahmad A Deribe Kebede K Dharmaratne Samath Dhamminda SD Diaz Daniel D Do Hoa Thi HT El Sayed Zaki Maysaa M El Tantawi Maha M Elemineh Demelash Abewa DA Faraj Anwar A Fasihi Harandi Majid M Fatahi Yousef Y Feigin Valery L VL Fernandes Eduarda E Foigt Nataliya A NA Foroutan Masoud M Franklin Richard Charles RC Gubari Mohammed Ibrahim Mohialdeen MIM Guido Davide D Guo Yuming Y Haj-Mirzaian Arvin A Hamagharib Abdullah Kanaan K Hamidi Samer S Herteliu Claudiu C Hidru Hagos Degefa de HD Higazi Tarig B TB Hossain Naznin N Hosseinzadeh Mehdi M Househ Mowafa M Ilesanmi Olayinka Stephen OS Ilic Milena D MD Ilic Irena M IM Iqbal Usman U Irvani Seyed Sina Naghibi SSN Jha Ravi Prakash RP Joukar Farahnaz F Jozwiak Jacek Jerzy JJ Kabir Zubair Z Kalankesh Leila R LR Kalhor Rohollah R Karami Matin Behzad B Karimi Salah Eddin SE Kasaeian Amir A Kavetskyy Taras T Kayode Gbenga A GA Kazemi Karyani Ali A Kelbore Abraham Getachew AG Keramati Maryam M Khalilov Rovshan R Khan Ejaz Ahmad EA Khan Md Nuruzzaman Nuruzzaman MNN Khatab Khaled K Khater Mona M MM Kianipour Neda N Kibret Kelemu Tilahun KT Kim Yun Jin YJ Kosen Soewarta S Krohn Kris J KJ Kusuma Dian D La Vecchia Carlo C Lansingh Van Charles VC Lee Paul H PH LeGrand Kate E KE Li Shanshan S Longbottom Joshua J Magdy Abd El Razek Hassan H Magdy Abd El Razek Muhammed M Maleki Afshin A Mamun Abdullah A AA Manafi Ali A Manafi Navid N Mansournia Mohammad Ali MA Martins-Melo Francisco Rogerlândio FR Mazidi Mohsen M McAlinden Colm C Meharie Birhanu Geta BG Mendoza Walter W Mengesha Endalkachew Worku EW Mengistu Desalegn Tadese DT Mereta Seid Tiku ST Mestrovic Tomislav T Miller Ted R TR Miri Mohammad M Moghadaszadeh Masoud M Mohammadian-Hafshejani Abdollah A Mohammadpourhodki Reza R Mohammed Shafiu S Mohammed Salahuddin S Moradi Masoud M Moradzadeh Rahmatollah R Moraga Paula P Mosser Jonathan F JF Naderi Mehdi M Nagarajan Ahamarshan Jayaraman AJ Naik Gurudatta G Negoi Ionut I Nguyen Cuong Tat CT Nguyen Huong Lan Thi HLT Nguyen Trang Huyen TH Nikbakhsh Rajan R Oancea Bogdan B Olagunju Tinuke O TO Olagunju Andrew T AT Omar Bali Ahmed A Onwujekwe Obinna E OE Pana Adrian A Pourjafar Hadi H Rahim Fakher F Rahman Mohammad Hifz Ur MHU Rathi Priya P Rawaf Salman S Rawaf David Laith DL Rawassizadeh Reza R Resnikoff Serge S Reta Melese Abate MA Rezapour Aziz A Rubagotti Enrico E Rubino Salvatore S Sadeghi Ehsan E Saghafipour Abedin A Sajadi S Mohammad SM Samy Abdallah M AM Sarmiento-Suárez Rodrigo R Sawhney Monika M Schipp Megan F MF Shaheen Amira A AA Shaikh Masood Ali MA Shamsizadeh Morteza M Sharafi Kiomars K Sheikh Aziz A Shetty B Suresh Kumar BSK Shetty B Suresh Kumar BSK Shin Jae Il JI Shivakumar K M KM Simonetti Biagio B Singh Jasvinder A JA Skiadaresi Eirini E Soheili Amin A Soltani Shahin S Spurlock Emma Elizabeth EE Sufiyan Mu'awiyyah Babale MB Tabuchi Takahiro T Tapak Leili L Thompson Robert L RL Thomson Alan J AJ Traini Eugenio E Tran Bach Xuan BX Ullah Irfan I Ullah Saif S Uneke Chigozie Jesse CJ Unnikrishnan Bhaskaran B Uthman Olalekan A OA Vinkeles Melchers Natalie V S NVS Violante Francesco S FS Wolde Haileab Fekadu HF Wonde Tewodros Eshete TE Yamada Tomohide T Yaya Sanni S Yazdi-Feyzabadi Vahid V Yip Paul P Yonemoto Naohiro N Yousof Hebat-Allah Salah A HSA Yu Chuanhua C Yu Yong Y Yusefzadeh Hasan H Zaki Leila L Zaman Sojib Bin SB Zamanian Maryam M Zhang Zhi-Jiang ZJ Zhang Yunquan Y Ziapour Arash A Hay Simon I SI Pigott David M DM

PLoS neglected tropical diseases 20210728 7

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 a ...[more]

PMID: 34319976

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Project description:BackgroundOnchocerciasis (river blindness) is a parasitic disease transmitted by blackflies. Symptoms include severe itching, skin lesions, and vision impairment including blindness. More than 99% of all cases are concentrated in sub-Saharan Africa. Fortunately, vector control and community-directed treatment with ivermectin have significantly decreased morbidity, and the treatment goal is shifting from control to elimination in Africa.MethodsWe estimated financial resources and societal opportunity costs associated with scaling up community-directed treatment with ivermectin and implementing surveillance and response systems in endemic African regions for alternative treatment goals--control, elimination, and eradication. We used a micro-costing approach that allows adjustment for time-variant resource utilization and for the heterogeneity in the demographic, epidemiological, and political situation.ResultsThe elimination and eradication scenarios, which include scaling up treatments to hypo-endemic and operationally challenging areas at the latest by 2021 and implementing intensive surveillance, would allow savings of $1.5 billion and $1.6 billion over 2013-2045 as compared to the control scenario. Although the elimination and eradication scenarios would require higher surveillance costs ($215 million and $242 million) than the control scenario ($47 million), intensive surveillance would enable treatments to be safely stopped earlier, thereby saving unnecessary costs for prolonged treatments as in the control scenario lacking such surveillance and response systems.ConclusionsThe elimination and eradication of onchocerciasis are predicted to allow substantial cost-savings in the long run. To realize cost-savings, policymakers should keep empowering community volunteers, and pharmaceutical companies would need to continue drug donation. To sustain high surveillance costs required for elimination and eradication, endemic countries would need to enhance their domestic funding capacity. Societal and political will would be critical to sustaining all of these efforts in the long term.

Project description:BackgroundOnchocerciasis is a neglected tropical filarial disease transmitted by the bites of blackflies, causing blindness and severe skin lesions. The change in focus for onchocerciasis management from control to elimination requires thorough mapping of pre-control endemicity to identify areas requiring interventions and to monitor progress. Onchocerca volvulus nodule prevalence in sub-Saharan Africa is spatially continuous and heterogeneous, and highly endemic areas may contribute to transmission in areas of low endemicity or vice-versa. Ethiopia is one such onchocerciasis-endemic country with heterogeneous O. volvulus nodule prevalence, and many districts are still unmapped despite their potential for onchocerciasis transmission.Methodology/principle findingsA Bayesian geostatistical model was fitted for retrospective pre-intervention nodule prevalence data collected from 916 unique sites and 35,077 people across Ethiopia. We used multiple environmental, socio-demographic, and climate variables to estimate the pre-intervention prevalence of O. volvulus nodules across Ethiopia and to explore their relationship with prevalence. Prevalence was high in southern and northwestern Ethiopia and low in Ethiopia's central and eastern parts. Distance to the nearest river (RR: 0.9850, 95% BCI: 0.9751-0.995), precipitation seasonality (RR: 0.9837, 95% BCI: 0.9681-0.9995), and flow accumulation (RR: 0.9586, 95% BCI: 0.9321-0.9816) were negatively associated with O. volvulus nodule prevalence, while soil moisture (RR: 1.0218, 95% BCI: 1.0135-1.0302) was positively associated. The model estimated the number of pre-intervention cases of O. volvulus nodules in Ethiopia to be around 6.48 million (95% BCI: 3.53-13.04 million).Conclusions/significanceNodule prevalence distribution was correlated with habitat suitability for vector breeding and associated biting behavior. The modeled pre-intervention prevalence can be used as a guide for determining priorities for elimination mapping in regions of Ethiopia that are currently unmapped, most of which have comparatively low infection prevalence.

Dataset Information

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

Publications

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

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