Lack of active Onchocerca volvulus transmission in the northern Chiapas focus of Mexico.
The northern Chiapas onchocerciasis focus has undergone 11 years of ivermectin mass treatment. No evidence of microfilariae in the cornea and/or anterior chamber of the eye or in skin snips was seen in residents examined in 2006 in two sentinel communities (upper limit of the 95% confidence interval [UL 95% CI] = 0.5% and 0.3%, respectively). In children 10 and under, 0 of 305 were found to harbor antibodies to Ov16, a marker of parasite exposure; 0 of 4,400 Simulium ochraceum s.l. collected in 2005 contained parasite DNA, giving an UL 95% CI for the infective rate of 0.9/2,000, and an UL 95% CI of the seasonal transmission potential of 1.2 L3/person. These data, assumed to be representative of the focus as a whole, suggest that there is no ongoing transmission of Onchocerca volvulus in the northern Chiapas focus. Community-wide treatments with ivermectin were halted in 2008, and a post-treatment surveillance phase was initiated.
Rodríguez-Pérez
Mario A
MA
Centro de Biotecnología Genómica, Instituto Politécnico Nacional, Reynosa, Tamaulipas, México. drmarodriguez@hotmail.com
Unnasch
Thomas R
TR
Domínguez-Vázquez
Alfredo
A
Morales-Castro
Alba L
AL
Richards
Frank
F
Peña-Flores
Graciela P
GP
Orozco-Algarra
María Eugenia
ME
Prado-Velasco
Gibert
G
D000818:Animals; D000871:Anthelmintics / Q000627:therapeutic use; D002648:Child; D002675:Child, Preschool; D018562:Disease Transmission, Infectious / Q000517:prevention & control*; D006801:Humans; D007559:Ivermectin / Q000627:therapeutic use; D008800:Mexico / Q000453:epidemiology; D017181:Onchocerca volvulus / Q000187:drug effects* / Q000276:immunology; D009855:Onchocerciasis / Q000276:immunology / Q000469:parasitology / Q000635:transmission*
D000871:Anthelmintics; D007559:Ivermectin