Elimination of Onchocerciasis from Mexico

Autor: Kristel B. Rodríguez-Morales, María E. Orozco-Algarra, Mario A. Rodríguez-Pérez, Pablo Kuri-Morales, Eddie W. Cupp, Alfredo Domínguez-Vázquez, Nadia A. Fernández-Santos, Jesús Felipe González-Roldán, Hassan K. Hassan, Thomas R. Unnasch, José A. Rodríguez-Atanacio, Francisco Gibert Prado-Velasco, Olga Real-Najarro, Frank O. Richards
Rok vydání: 2015
Předmět:
Zdroj: PLoS Neglected Tropical Diseases, Vol 9, Iss 7, p e0003922 (2015)
PLoS Neglected Tropical Diseases
ISSN: 1935-2735
DOI: 10.1371/journal.pntd.0003922
Popis: Background Mexico is one of the six countries formerly endemic for onchocerciasis in Latin America. Transmission has been interrupted in the three endemic foci of that country and mass drug distribution has ceased. Three years after mass drug distribution ended, post-treatment surveillance (PTS) surveys were undertaken which employed entomological indicators to check for transmission recrudescence. Methodology/Principal findings In-depth entomologic assessments were performed in 18 communities in the three endemic foci of Mexico. None of the 108,212 Simulium ochraceum s.l. collected from the three foci were found to contain parasite DNA when tested by polymerase chain reaction-enzyme-linked immunosorbent assay (PCR-ELISA), resulting in a maximum upper bound of the 95% confidence interval (95%-ULCI) of the infective rate in the vectors of 0.035/2,000 flies examined. This is an order of magnitude below the threshold of a 95%-ULCI of less than one infective fly per 2,000 flies tested, the current entomological criterion for interruption of transmission developed by the international community. The point estimate of seasonal transmission potential (STP) was zero, and the upper bound of the 95% confidence interval for the STP ranged from 1.2 to 1.7 L3/person/season in the different foci. This value is below all previous estimates for the minimum transmission potential required to maintain the parasite population. Conclusions/Significance The results from the in-depth entomological post treatment surveillance surveys strongly suggest that transmission has not resumed in the three foci of Mexico during the three years since the last distribution of ivermectin occurred; it was concluded that transmission remains undetectable without intervention, and Onchocerca volvulus has been eliminated from Mexico.
Author Summary Onchocerciasis, or river blindness, is one of the neglected tropical diseases targeted by the international community for elimination. In Mexico, onchocerciasis was historically endemic in three foci, which included Northern Chiapias, Southern Chiapas and Oaxaca. Both the criteria for verification of elimination and for post-treatment surveillance developed by the international community rely heavily on the use of entomological metrics. The absence of evidence of ongoing transmission of the parasite three years after mass drug distribution has been halted is considered to be evidence that elimination efforts have been successful. In the present study, we report entomological assessments carried out in the three endemic foci in Mexico that were performed three years following the end of mass drug distribution in each focus. None of the over 100,000 Simulium ochraceum s.l. vector black flies collected from sentinel and extra-sentinel communities in these foci were found to contain parasite DNA, suggesting vector parasite contact was non-existent. This data suggest that elimination of onchocerciasis from Mexico has been achieved.
Databáze: OpenAIRE
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