Real-Time Polymerase Chain Reaction Method for the Detection of Onchocerca volvulus in Post-Elimination Surveillance of Onchocerciasis in Ecuador

Esteban Salazar Instituto de Biomedicina, Carrera de Medicina, Universidad Central, Quito, Ecuador;
Distrito 17D03 Ministerio de Salud Pública del Ecuador, Quito, Ecuador;
Infectious and Tropical Diseases Research Group, Biomedical Research Institute of Salamanca Research Centre for Tropical Diseases at the University of Salamanca, Faculty of Pharmacy, University of Salamanca, Salamanca, Spain;

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Diego Morales Instituto Nacional de Investigación en Salud Pública Dr. Leopoldo Izquieta Pérez, Quito, Ecuador

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Begoña Febrer-Sendra Infectious and Tropical Diseases Research Group, Biomedical Research Institute of Salamanca Research Centre for Tropical Diseases at the University of Salamanca, Faculty of Pharmacy, University of Salamanca, Salamanca, Spain;

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Pedro Fernández-Soto Infectious and Tropical Diseases Research Group, Biomedical Research Institute of Salamanca Research Centre for Tropical Diseases at the University of Salamanca, Faculty of Pharmacy, University of Salamanca, Salamanca, Spain;

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Julio López-Abán Infectious and Tropical Diseases Research Group, Biomedical Research Institute of Salamanca Research Centre for Tropical Diseases at the University of Salamanca, Faculty of Pharmacy, University of Salamanca, Salamanca, Spain;

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Paul Quinatoa Instituto Nacional de Investigación en Salud Pública Dr. Leopoldo Izquieta Pérez, Quito, Ecuador

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Ángel Guevara Instituto de Biomedicina, Carrera de Medicina, Universidad Central, Quito, Ecuador;

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Antonio Muro Infectious and Tropical Diseases Research Group, Biomedical Research Institute of Salamanca Research Centre for Tropical Diseases at the University of Salamanca, Faculty of Pharmacy, University of Salamanca, Salamanca, Spain;

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ABSTRACT.

Onchocerciasis has been declared eliminated in Ecuador and surveillance measures are of great interest. In this study, we examined the infectivity rates of Simulium exiguum by Onchocerca volvulus in previously hyperendemic areas in Esmeraldas province of Ecuador. These areas had previously undergone mass administration of ivermectin, which led to the interruption of transmission in 2009 and the certification of elimination in 2014. The study included three communities in Río Cayapas and one in Río Canandé, and a total of 2,950 adult S. exiguum were collected in 2018. We used quantitative polymerase chain reaction with O. volvulus O-150 plasmid control DNA to analyze 59 pools. Our findings revealed that the infectivity rates were zero, indicating that the transmission of O. volvulus remained suspended in the area.

Author Notes

Financial support: A. Muro, P. Fernández-Soto, and J. López-Abán received funds from Institute of Health Carlos III, ISCIII, Spain (www.iscii.es), grant PI22/01721. J. López-Abán was funded by MCIN/AEI/doi 10.13039/501100011033, cofounded by the European Union, grant PID2021-127471OB-I00. A. Muro was funded by MCIN/AEI/doi 10.13039/501100011033, cofounded by the European Union, grant PID2022-136462NB-I00. B. Febrer-Sendra was funded by the Predoctoral Fellowship Program of Junta de Castilla y León, cofunded by Fondo Social Europeo (BDNS; 422058).

Authors’ addresses: Esteban Salazar, Instituto de Biomedicina, Carrera de Medicina, Universidad Central, Quito, Ecuador, Distrito 17D03 Ministerio de Salud Pública del Ecuador, Quito, Ecuador, and Infectious and Tropical Diseases Research Group, Biomedical Research Institute of Salamanca Research Centre for Tropical Diseases at the University of Salamanca, Faculty of Pharmacy, University of Salamanca, Salamanca, Spain, E-mail: essalazar15@gmail.com. Diego Morales and Paul Quinatoa, Instituto Nacional de Investigación en Salud Pública Dr. Leopoldo Izquieta Pérez, Quito, Ecuador, E-mails: diegomoralesviteri@gmail.com and pquinatoa@inspi.gob.ec. Begoña Febrer-Sendra, Pedro Fernández-Soto, Julio López-Abán, and Antonio Muro, Infectious and Tropical Diseases Research Group, Biomedical Research Institute of Salamanca Research Centre for Tropical Diseases at the University of Salamanca, Faculty of Pharmacy, University of Salamanca, Salamanca, Spain, E-mails: begofebrer@usal.es, pfsoto@usal.es, jlaban@usal.es, and ama@usal.es. Ángel Guevara, Instituto de Biomedicina, Carrera de Medicina, Universidad Central, Quito, Ecuador, E-mail: agguevara@uce.edu.ec.

Address correspondence to Antonio Muro or Julio López-Abán, Institute of Biomedical Research of Salamanca–Center for Research on Tropical Diseases of the University of Salamanca, Faculty of Pharmacy, University of Salamanca, 37007 Salamanca, Spain. E-mails: ama@usal.es or jlaban@usal.es
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