title: Interruption of transmission of Onchocerca volvulus in the Southern Chiapas Focus, México.
abstract: BACKGROUND
  The Southern Chiapas focus of onchocerciasis in Southern Mexico represents one of the major onchocerciasis foci in Latin America. All 559 endemic communities of this focus have undergone semi-annual mass treatment with ivermectin since 1998. In 50 communities of this focus, ivermectin frequency shifted from twice to four times a year in 2003; an additional 113 communities were added to the quarterly treatment regimen in 2009 to achieve a rapid suppression of transmission.
  
  
  RESULTS
  In-depth epidemiologic and entomologic assessments were performed in six sentinel communities (which had undergone 2 rounds of ivermectin treatment per year) and three extra-sentinel communities (which had undergone 4 rounds of ivermectin treatment per year). None of the 67,924 Simulium ochraceum s.l. collected from this focus during the dry season of 2011 were found to contain parasite DNA when tested by polymerase chain reaction-enzyme-linked immunosorbent assay (PCR-ELISA), resulting in an upper bound of the 95% confidence interval (95%-ULCI) of the infective rate in the vectors of 0.06/2,000 flies examined. Serological assays testing for Onchocerca volvulus exposure conducted on 4,230 children 5 years of age and under (of a total population of 10,280 in this age group) revealed that 2/4,230 individuals were exposed to O. volvulus (0.05%; one sided 95% confidence interval = 0.08%).
  
  
  CONCLUSIONS
  The in-depth epidemiological and entomological findings from the Southern Chiapas focus meet the criteria for interruption of transmission developed by the international community.
authors.affiliation: Centro de Biotecnología Genómica, Instituto Politécnico Nacional, Reynosa, Tamaulipas, México. drmarodriguez@hotmail.com
authors.forename: Mario A
authors.initials: MA
authors.lastname: Rodríguez-Pérez
authors.forename: Alfredo
authors.initials: A
authors.lastname: Domínguez-Vázquez
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Unnasch
authors.forename: Hassan K
authors.initials: HK
authors.lastname: Hassan
authors.forename: Juan I
authors.initials: JI
authors.lastname: Arredondo-Jiménez
authors.forename: María Eugenia
authors.initials: ME
authors.lastname: Orozco-Algarra
authors.forename: Kristel B
authors.initials: KB
authors.lastname: Rodríguez-Morales
authors.forename: Isabel C
authors.initials: IC
authors.lastname: Rodríguez-Luna
authors.forename: Francisco Gibert
authors.initials: FG
authors.lastname: Prado-Velasco
mesh_terms: D000818:Animals; D000871:Anthelmintics / Q000008:administration & dosage*; D002648:Child; D002675:Child, Preschool; D018509:DNA, Helminth / Q000302:isolation & purification; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007223:Infant; D007559:Ivermectin / Q000008:administration & dosage*; D008297:Male; D008800:Mexico / Q000453:epidemiology; D017181:Onchocerca volvulus / Q000235:genetics / Q000302:isolation & purification*; D009855:Onchocerciasis / Q000188:drug therapy / Q000453:epidemiology* / Q000469:parasitology / Q000517:prevention & control*; D016133:Polymerase Chain Reaction; D012843:Simuliidae / Q000469:parasitology
chemical_list: D000871:Anthelmintics; D018509:DNA, Helminth; D007559:Ivermectin
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