title: Evidence of suppression of onchocerciasis transmission in the Venezuelan Amazonian focus.
abstract: BACKGROUND
  The World Health Organization (WHO) has set goals for onchocerciasis elimination in Latin America by 2015. Most of the six previously endemic countries are attaining this goal by implementing twice a year (and in some foci, quarterly) mass ivermectin (Mectizan®) distribution. Elimination of transmission has been verified in Colombia, Ecuador and Mexico. Challenges remain in the Amazonian focus straddling Venezuela and Brazil, where the disease affects the hard-to-reach Yanomami indigenous population. We provide evidence of suppression of Onchocerca volvulus transmission by Simulium guianense s.l. in 16 previously hyperendemic Yanomami communities in southern Venezuela after 15 years of 6-monthly and 5 years of 3-monthly mass ivermectin treatment.
  
  
  METHODS
  Baseline and monitoring and evaluation parasitological, ophthalmological, entomological and serological surveys were conducted in selected sentinel and extra-sentinel communities of the focus throughout the implementation of the programme.
  
  
  RESULTS
  From 2010 to 2012-2015, clinico-parasitological surveys indicate a substantial decrease in skin microfilarial prevalence and intensity of infection; accompanied by no evidence (or very low prevalence and intensity) of ocular microfilariae in the examined population. Of a total of 51,341 S. guianense flies tested by PCR none had L3 infection (heads only). Prevalence of infective flies and seasonal transmission potentials in 2012-2013 were, respectively, under 1% and 20 L3/person/transmission season. Serology in children aged 1-10 years demonstrated that although 26 out of 396 (7%) individuals still had Ov-16 antibodies, only 4/218 (2%) seropositives were aged 1-5 years.
  
  
  CONCLUSIONS
  We report evidence of recent transmission and morbidity suppression in some communities of the focus representing 75% of the Yanomami population and 70% of all known communities. We conclude that onchocerciasis transmission could be feasibly interrupted in the Venezuelan Amazonian focus.
authors.affiliation: Centro Amazónico de Investigación y Control de Enfermedades Tropicales Servicio Autónomo CAICET, Ministerio del Poder Popular para la Salud, Puerto Ayacucho, Estado Amazonas, Venezuela. okotoima@gmail.com.
authors.forename: Carlos
authors.initials: C
authors.lastname: Botto
authors.affiliation: London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, Faculty of Medicine (St Mary's campus), Imperial College London, London, UK. m.basanez@imperial.ac.uk.
authors.forename: María-Gloria
authors.initials: MG
authors.lastname: Basañez
authors.affiliation: Centro Amazónico de Investigación y Control de Enfermedades Tropicales Servicio Autónomo CAICET, Ministerio del Poder Popular para la Salud, Puerto Ayacucho, Estado Amazonas, Venezuela. marisela.escalona@gmail.com.
authors.forename: Marisela
authors.initials: M
authors.lastname: Escalona
authors.affiliation: Centro Amazónico de Investigación y Control de Enfermedades Tropicales Servicio Autónomo CAICET, Ministerio del Poder Popular para la Salud, Puerto Ayacucho, Estado Amazonas, Venezuela. yaro62@yahoo.com.
authors.forename: Néstor J
authors.initials: NJ
authors.lastname: Villamizar
authors.affiliation: Centro Amazónico de Investigación y Control de Enfermedades Tropicales Servicio Autónomo CAICET, Ministerio del Poder Popular para la Salud, Puerto Ayacucho, Estado Amazonas, Venezuela. ozonoya6@yahoo.com.|Instituto de Medicina Tropical, Facultad de Medicina, Universidad Central de Venezuela, Caracas, Venezuela. ozonoya6@yahoo.com.
authors.forename: Oscar
authors.initials: O
authors.lastname: Noya-Alarcón
authors.affiliation: Centro Amazónico de Investigación y Control de Enfermedades Tropicales Servicio Autónomo CAICET, Ministerio del Poder Popular para la Salud, Puerto Ayacucho, Estado Amazonas, Venezuela. simulidos03@yahoo.com.
authors.forename: José
authors.initials: J
authors.lastname: Cortez
authors.affiliation: Cátedra de Salud Pública. Facultad de Medicina (Escuela Luis Razetti), Universidad Central de Venezuela, Caracas, Venezuela. svivasm@hotmail.com.
authors.forename: Sarai
authors.initials: S
authors.lastname: Vivas-Martínez
authors.affiliation: Centro Amazónico de Investigación y Control de Enfermedades Tropicales Servicio Autónomo CAICET, Ministerio del Poder Popular para la Salud, Puerto Ayacucho, Estado Amazonas, Venezuela. coronelpablo22@gmail.com.
authors.forename: Pablo
authors.initials: P
authors.lastname: Coronel
authors.affiliation: Instituto de Altos Estudios "Dr. Arnoldo Gabaldón", Ministerio del Poder Popular para la Salud, Maracay, Estado Aragua, Venezuela. mentomologico@gmail.com.
authors.forename: Hortencia
authors.initials: H
authors.lastname: Frontado
authors.affiliation: Instituto Geográfico de Venezuela "Simón Bolívar", Caracas, Venezuela. jflores2916@gmail.com.
authors.forename: Jorge
authors.initials: J
authors.lastname: Flores
authors.affiliation: Instituto Nacional de Investigaciones Agrícolas, Puerto Ayacucho, Estado Amazonas, Venezuela. bgraterol@gmail.com.
authors.forename: Beatriz
authors.initials: B
authors.lastname: Graterol
authors.affiliation: Centro Amazónico de Investigación y Control de Enfermedades Tropicales Servicio Autónomo CAICET, Ministerio del Poder Popular para la Salud, Puerto Ayacucho, Estado Amazonas, Venezuela. oneida.camacho@gmail.com.
authors.forename: Oneida
authors.initials: O
authors.lastname: Camacho
authors.affiliation: Centro Amazónico de Investigación y Control de Enfermedades Tropicales Servicio Autónomo CAICET, Ministerio del Poder Popular para la Salud, Puerto Ayacucho, Estado Amazonas, Venezuela. jugenyse@gmail.com.
authors.forename: Yseliam
authors.initials: Y
authors.lastname: Tovar
authors.affiliation: Centro Amazónico de Investigación y Control de Enfermedades Tropicales Servicio Autónomo CAICET, Ministerio del Poder Popular para la Salud, Puerto Ayacucho, Estado Amazonas, Venezuela. danielwatoiparima@gmail.com.
authors.forename: Daniel
authors.initials: D
authors.lastname: Borges
authors.affiliation: Onchocerciasis Elimination Program for the Americas (OEPA), Guatemala City, Guatemala. almorales@oepa.net.
authors.forename: Alba Lucia
authors.initials: AL
authors.lastname: Morales
authors.affiliation: Onchocerciasis Elimination Program for the Americas (OEPA), Guatemala City, Guatemala. drios@oepa.net.
authors.forename: Dalila
authors.initials: D
authors.lastname: Ríos
authors.affiliation: Instituto Geográfico de Venezuela "Simón Bolívar", Caracas, Venezuela. guerrafl@gmail.com.
authors.forename: Francisco
authors.initials: F
authors.lastname: Guerra
authors.affiliation: Onchocerciasis Elimination Program for the Americas (OEPA), Guatemala City, Guatemala. sofia.mag309@gmail.com.
authors.forename: Héctor
authors.initials: H
authors.lastname: Margeli
authors.affiliation: Centro de Biotecnología Genómica, Instituto Politécnico Nacional, Reynosa, Mexico. drmarodriguez@hotmail.com.
authors.forename: Mario Alberto
authors.initials: MA
authors.lastname: Rodriguez
authors.affiliation: Department of Global Health, University of South Florida, Tampa, FL, USA. tunnasch@health.usf.edu.
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Unnasch
authors.affiliation: Laboratorio de Biología de Vectores y Parásitos, Instituto de Zoología y Ecología Tropical, Facultad de Ciencias, Universidad Central de Venezuela, Apartado Postal 47072, Caracas, 1041-A, Venezuela. mariaeugenia.grillet@gmail.com.
authors.forename: María Eugenia
authors.initials: ME
authors.lastname: Grillet
mesh_terms: D000818:Animals; D002675:Child, Preschool; D005260:Female; D005843:Geography; D006801:Humans; D007223:Infant; D007303:Insect Vectors / Q000469:parasitology*; D007306:Insecticides / Q000627:therapeutic use*; D007559:Ivermectin / Q000627:therapeutic use*; D008297:Male; D008842:Microfilariae; D017181:Onchocerca volvulus / Q000235:genetics / Q000502:physiology*; D009855:Onchocerciasis / Q000453:epidemiology / Q000469:parasitology / Q000517:prevention & control / Q000635:transmission*; D015995:Prevalence; D012621:Seasons; D012843:Simuliidae / Q000469:parasitology*; D014687:Venezuela / Q000453:epidemiology
chemical_list: D007306:Insecticides; D007559:Ivermectin
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