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The prevalence of onchocerciasis in Africa and Yemen, 2000–2018: a geospatial analysis

Abstract

Background: Onchocerciasis is a disease caused by infection with Onchocerca volvulus, which is transmitted to humans via the bite of several species of black fly, and is responsible for permanent blindness or vision loss, as well as severe skin disease. Predominantly endemic in parts of Africa and Yemen, preventive chemotherapy with mass drug administration of ivermectin is the primary intervention recommended for the elimination of its transmission.

Methods: A dataset of 18,116 geo-referenced prevalence survey datapoints was used to model annual 2000–2018 infection prevalence in Africa and Yemen. Using Bayesian model-based geostatistics, we generated spatially continuous estimates of all-age 2000–2018 onchocerciasis infection prevalence at the 5 × 5-km resolution as well as aggregations to the national level, along with corresponding estimates of the uncertainty in these predictions.

Results: As of 2018, the prevalence of onchocerciasis infection continues to be concentrated across central and western Africa, with the highest mean estimates at the national level in Ghana (12.2%, 95% uncertainty interval [UI] 5.0–22.7). Mean estimates exceed 5% infection prevalence at the national level for Cameroon, Central African Republic, Democratic Republic of the Congo (DRC), Guinea-Bissau, Sierra Leone, and South Sudan.

Conclusions: Our analysis suggests that onchocerciasis infection has declined over the last two decades throughout western and central Africa. Focal areas of Angola, Cameroon, the Democratic Republic of the Congo, Ethiopia, Ghana, Guinea, Mali, Nigeria, South Sudan, and Uganda continue to have mean microfiladermia prevalence estimates exceeding 25%. At and above this level, the continuation or initiation of mass drug administration with ivermectin is supported. If national programs aim to eliminate onchocerciasis infection, additional surveillance or supervision of areas of predicted high prevalence would be warranted to ensure sufficiently high coverage of program interventions.

More information

Type
Journal Article
Author
Schmidt CA
Cromwell EA
Hill E
Donkers KM
Schipp MF
Johnson KB
Pigott DM
Schmidt CA
Cromwell EA
Hill E
Pigott DM
Abbas J
Adekanmbi V
Adetokunboh OO
Ahmed MB
Alanezi FM
Alanzi TM
Alipour V
Andrei CL
Andrei T
Anvari D
Appiah SCY
Aqeel M
Arabloo J
Jafarabadi MA
Ausloos M
Baig AA
Banach M
Bärnighausen TW
Bhattacharyya K
Bhutta ZA
Bijani A
Brady OJ
Bragazzi NL
Butt ZA
Carvalho F
Chattu VK
Dahlawi SMA
Damiani G
Demeke FM
Deribe K
Dharmaratne SD
Diaz D
Didarloo A
Earl L
Zaki MES
El Tantawi M
Fattahi N
Fernandes E
Foigt NA
Foroutan M
Franklin RC
Guo Y
Haj-Mirzaian A
Hamidi S
Hassankhani H
Herteliu C
Higazi TB
Hosseini M
Hosseinzadeh M
Househ M
Ilesanmi OS
Ilic IM
Ilic MD
Irvani SSN
Jha RP
Ji JS
Jonas JB
Jozwiak JJ
Kalankesh LR
Kamyari N
Matin BK
Karimi SE
Kayode GA
Karyani AK
Khan EA
Khan MN
Khatab K
Khater MM
Kianipour N
Kim YJ
Kosen S
Kusuma D
La Vecchia C
Lansingh VC
Lee PH
Li S
Maleki S
Mansournia MA
Martins-Melo FR
McAlinden C
Mendoza W
Mestrovic T
Moghadaszadeh M
Mohammadian-Hafshejani A
Mohammadi SM
Mohammed S
Moradzadeh R
Moraga P
Naderi M
Nagarajan AJ
Negoi I
Nguyen CT
Nguyen HLT
Oancea B
Olagunju AT
Bali AO
Onwujekwe OE
Pana A
Rahimi-Movaghar V
Ramezanzadeh K
Rawaf DL
Rawaf S
Rawassizadeh R
Rezapour A
Ribeiro AI
Samy AM
Shaikh MA
Sharafi K
Sheikh A
Singh JA
Skiadaresi E
Soltani S
Stolk WA
Sufiyan MB
Thomson AJ
Tran BX
Tran KB
Unnikrishnan B
Violante FS
Vu GT
Yamada T
Yaya S
Yip P
Yonemoto N
Yu C
Yu Y
Zamanian M
Zhang Y
Zhang Z
Ziapour A
Hay SI
Hay SI