title: Evidence for Suppression of Onchocerciasis Transmission in Bioko Island, Equatorial Guinea.
abstract: Onchocerciasis or "river blindness" is a chronic parasitic neglected tropical disease which is endemic both in mainland and insular Equatorial Guinea. We aim to estimate the current epidemiological situation of onchocerciasis in Bioko Island after vector elimination in 2005 and more than sixteen years of Community Directed Treatment with Ivermectin (CDTI) by using molecular and serological approaches for onchocerciasis diagnosis. A community-based cross-sectional study was carried out in Bioko Island from mid-January to mid-February 2014. A total of 544 study participants were recruited. A complete dermatological examination was performed and three skin snips were performed in every participant for parasitological and molecular assessments. Blood spots were also taken for determination of Ov16 IgG4 antibodies trough an "in-house" ELISA assay. Overall, we found 15 out of 522 individuals suffering any onchocerciasis specific cutaneous lesions and 16 out of 528 (3.0%) with onchocercal nodules in the skin. Nodules were significantly associated with age, being more common in subjects older than 10 years than in younger people (3.9% vs. 0%, p = 0.029). Regarding the onchocerciasis laboratory assessment, no positive parasitological test for microfilaria detection was found in the skin snips. The calculated seroprevalence through IgG4 serology was 7.9%. No children less than 10 years old were found to be positive for this test. Only one case was positive for Onchocerca volvulus (O. volvulus) after skin PCR. The present study points out that the on-going mass ivermectin treatment has been effective in reducing the prevalence of onchocerciasis and corroborates the interruption of transmission in Bioko Island. To our knowledge, this is the first time that accurate information through molecular and serological techniques is generated to estimate the onchocerciasis prevalence in this zone. Sustained support from the national program and appropriate communication and health education strategies to reinforce participation in CDTI activities are essential to ensure progress towards onchocerciasis elimination in the country.
authors.affiliation: Jimenez Diaz Foundation, Madrid, Spain.|National Center for Tropical Medicine, Institute of Health Carlos III, Madrid, Spain.
authors.forename: Laura
authors.identifier: 0000-0003-2753-3352
authors.initials: L
authors.lastname: Moya
authors.affiliation: National Center for Tropical Medicine, Institute of Health Carlos III, Madrid, Spain.|Network Biomedical Research on Tropical Diseases (RICET in Spanish), Madrid, Spain.
authors.forename: Zaida
authors.initials: Z
authors.lastname: Herrador
authors.affiliation: Malaria & Other Emerging Parasitic Diseases Laboratory, National Microbiology Center, Institute of Health Carlos III, Madrid, Spain.
authors.forename: Thuy Huong
authors.initials: TH
authors.lastname: Ta-Tang
authors.affiliation: Network Biomedical Research on Tropical Diseases (RICET in Spanish), Madrid, Spain.|Malaria & Other Emerging Parasitic Diseases Laboratory, National Microbiology Center, Institute of Health Carlos III, Madrid, Spain.
authors.forename: Jose Miguel
authors.initials: JM
authors.lastname: Rubio
authors.affiliation: Network Biomedical Research on Tropical Diseases (RICET in Spanish), Madrid, Spain.|Malaria & Other Emerging Parasitic Diseases Laboratory, National Microbiology Center, Institute of Health Carlos III, Madrid, Spain.
authors.forename: Maria Jesús
authors.initials: MJ
authors.lastname: Perteguer
authors.affiliation: Malaria & Other Emerging Parasitic Diseases Laboratory, National Microbiology Center, Institute of Health Carlos III, Madrid, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Hernandez-González
authors.affiliation: National Center for Tropical Medicine, Institute of Health Carlos III, Madrid, Spain.
authors.forename: Belén
authors.initials: B
authors.lastname: García
authors.affiliation: National Program for Onchocerciasis and other Filariasis Control, Ministry of Health, Malabo, Equatorial Guinea.
authors.forename: Rufino
authors.initials: R
authors.lastname: Nguema
authors.affiliation: National Program for Onchocerciasis and other Filariasis Control, Ministry of Health, Malabo, Equatorial Guinea.
authors.forename: Justino
authors.initials: J
authors.lastname: Nguema
authors.affiliation: National Center for Tropical Medicine, Institute of Health Carlos III, Madrid, Spain.
authors.forename: Policarpo
authors.initials: P
authors.lastname: Ncogo
authors.affiliation: Network Biomedical Research on Tropical Diseases (RICET in Spanish), Madrid, Spain.|Malaria & Other Emerging Parasitic Diseases Laboratory, National Microbiology Center, Institute of Health Carlos III, Madrid, Spain.
authors.forename: Teresa
authors.initials: T
authors.lastname: Garate
authors.affiliation: National Center for Tropical Medicine, Institute of Health Carlos III, Madrid, Spain.|Network Biomedical Research on Tropical Diseases (RICET in Spanish), Madrid, Spain.
authors.forename: Agustín
authors.initials: A
authors.lastname: Benito
authors.affiliation: National Program for Onchocerciasis and other Filariasis Control, Ministry of Health, Malabo, Equatorial Guinea.
authors.forename: Anacleto
authors.initials: A
authors.lastname: Sima
authors.affiliation: National Center for Tropical Medicine, Institute of Health Carlos III, Madrid, Spain.|Network Biomedical Research on Tropical Diseases (RICET in Spanish), Madrid, Spain.
authors.forename: Pilar
authors.initials: P
authors.lastname: Aparicio
mesh_terms: D000818:Animals; D000977:Antiparasitic Agents / Q000008:administration & dosage*; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D016703:Equatorial Guinea / Q000453:epidemiology; D005260:Female; D006801:Humans; D007559:Ivermectin / Q000008:administration & dosage*; D008297:Male; D017181:Onchocerca volvulus / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology; D015827:Onchocerciasis, Ocular / Q000188:drug therapy* / Q000453:epidemiology / Q000469:parasitology; D016896:Treatment Outcome
chemical_list: D000977:Antiparasitic Agents; D007559:Ivermectin