Elimination of onchocerciasis in Ecuador: Findings of post-treatment surveillance

Ángel Guevara, Raquel Lovato, Roberto Proaño, Mario A. Rodriguez-Perez, Thomas Unnasch, Philip J. Cooper, Ronald H. Guderian

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

© 2018 The Author(s). Background: The Esmeraldas focus of onchocerciasis in Ecuador expanded geographically during the 1980s and was associated with severe ocular and skin disease. Mass drug administration (MDA) with ivermectin started in 1991, initially once but later twice a year, in the principle endemic focus followed by all satellite foci. Treatment was stopped in 2009 when entomological assessments determined that transmission of Onchocerca volvulus had been interrupted. Methods: Three years after the cessation of ivermectin treatment in 2012, as defined by the WHO guidelines for onchocerciasis elimination, blackfly collections were done in four sentinel sites in former hyperendemic areas. The presence of infective larvae in local vectors, Simulium exiguum and Simulum quadrivittatum, was assessed by detection of O. volvulus DNA by PCR. Additional flies captured in four extra-sentinel sites located in former hyper- and mesoendemic dispersed isolated areas were also assessed. Results: The results from 68,310 captured blackflies, 40,114 from four sentinel villages in the previously hyperendemic areas (Corriente Grande, El Tigre, San Miguel on Río Cayapas and Naranjal on Río Canandé) and 28,197 from extra-sentinel locations, were all negative for the presence of O. volvulus. These extra-sentinel sites (Hualpí on Río Hoja Blanca, Capulí on Río Onzole, La Ceiba on Río Tululví and Medianía on Río Verde) were included to provide additional evidence of the impact of MDA on the transmission of O. volvulus in isolated endemic areas. Conclusions: Our data indicate that transmission of O. volvulus has been stopped in all endemic areas in Ecuador, including all satellite foci outside the main focus. These findings indicate that a strategy of ivermectin distribution twice a year to over 85% of the treatment-eligible population was effective in eliminating the infection from Ecuador in a focus with a highly competent primary vector, S. exiguum, and where the infection rates were equal to or greater than observed in many onchocerciasis foci in Africa.
Original languageAmerican English
JournalParasites and Vectors
DOIs
StatePublished - 24 Apr 2018

Fingerprint

Onchocerca volvulus
Ecuador
Onchocerciasis
Simuliidae
Ivermectin
Ceiba
Therapeutics
Withholding Treatment
Eye Diseases
Infection
Skin Diseases
Diptera
Pharmaceutical Preparations
Larva
cyhalothrin
Guidelines
Polymerase Chain Reaction
DNA
Population

Cite this

Guevara, Ángel ; Lovato, Raquel ; Proaño, Roberto ; Rodriguez-Perez, Mario A. ; Unnasch, Thomas ; Cooper, Philip J. ; Guderian, Ronald H. / Elimination of onchocerciasis in Ecuador: Findings of post-treatment surveillance. In: Parasites and Vectors. 2018.
@article{893aaa02a925425b8576981b2dca4efb,
title = "Elimination of onchocerciasis in Ecuador: Findings of post-treatment surveillance",
abstract = "{\circledC} 2018 The Author(s). Background: The Esmeraldas focus of onchocerciasis in Ecuador expanded geographically during the 1980s and was associated with severe ocular and skin disease. Mass drug administration (MDA) with ivermectin started in 1991, initially once but later twice a year, in the principle endemic focus followed by all satellite foci. Treatment was stopped in 2009 when entomological assessments determined that transmission of Onchocerca volvulus had been interrupted. Methods: Three years after the cessation of ivermectin treatment in 2012, as defined by the WHO guidelines for onchocerciasis elimination, blackfly collections were done in four sentinel sites in former hyperendemic areas. The presence of infective larvae in local vectors, Simulium exiguum and Simulum quadrivittatum, was assessed by detection of O. volvulus DNA by PCR. Additional flies captured in four extra-sentinel sites located in former hyper- and mesoendemic dispersed isolated areas were also assessed. Results: The results from 68,310 captured blackflies, 40,114 from four sentinel villages in the previously hyperendemic areas (Corriente Grande, El Tigre, San Miguel on R{\'i}o Cayapas and Naranjal on R{\'i}o Canand{\'e}) and 28,197 from extra-sentinel locations, were all negative for the presence of O. volvulus. These extra-sentinel sites (Hualp{\'i} on R{\'i}o Hoja Blanca, Capul{\'i} on R{\'i}o Onzole, La Ceiba on R{\'i}o Tululv{\'i} and Median{\'i}a on R{\'i}o Verde) were included to provide additional evidence of the impact of MDA on the transmission of O. volvulus in isolated endemic areas. Conclusions: Our data indicate that transmission of O. volvulus has been stopped in all endemic areas in Ecuador, including all satellite foci outside the main focus. These findings indicate that a strategy of ivermectin distribution twice a year to over 85{\%} of the treatment-eligible population was effective in eliminating the infection from Ecuador in a focus with a highly competent primary vector, S. exiguum, and where the infection rates were equal to or greater than observed in many onchocerciasis foci in Africa.",
author = "{\'A}ngel Guevara and Raquel Lovato and Roberto Proa{\~n}o and Rodriguez-Perez, {Mario A.} and Thomas Unnasch and Cooper, {Philip J.} and Guderian, {Ronald H.}",
year = "2018",
month = "4",
day = "24",
doi = "10.1186/s13071-018-2851-3",
language = "American English",
journal = "Parasites and Vectors",
issn = "1756-3305",
publisher = "BioMed Central Ltd.",

}

Elimination of onchocerciasis in Ecuador: Findings of post-treatment surveillance. / Guevara, Ángel; Lovato, Raquel; Proaño, Roberto; Rodriguez-Perez, Mario A.; Unnasch, Thomas; Cooper, Philip J.; Guderian, Ronald H.

In: Parasites and Vectors, 24.04.2018.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Elimination of onchocerciasis in Ecuador: Findings of post-treatment surveillance

AU - Guevara, Ángel

AU - Lovato, Raquel

AU - Proaño, Roberto

AU - Rodriguez-Perez, Mario A.

AU - Unnasch, Thomas

AU - Cooper, Philip J.

AU - Guderian, Ronald H.

PY - 2018/4/24

Y1 - 2018/4/24

N2 - © 2018 The Author(s). Background: The Esmeraldas focus of onchocerciasis in Ecuador expanded geographically during the 1980s and was associated with severe ocular and skin disease. Mass drug administration (MDA) with ivermectin started in 1991, initially once but later twice a year, in the principle endemic focus followed by all satellite foci. Treatment was stopped in 2009 when entomological assessments determined that transmission of Onchocerca volvulus had been interrupted. Methods: Three years after the cessation of ivermectin treatment in 2012, as defined by the WHO guidelines for onchocerciasis elimination, blackfly collections were done in four sentinel sites in former hyperendemic areas. The presence of infective larvae in local vectors, Simulium exiguum and Simulum quadrivittatum, was assessed by detection of O. volvulus DNA by PCR. Additional flies captured in four extra-sentinel sites located in former hyper- and mesoendemic dispersed isolated areas were also assessed. Results: The results from 68,310 captured blackflies, 40,114 from four sentinel villages in the previously hyperendemic areas (Corriente Grande, El Tigre, San Miguel on Río Cayapas and Naranjal on Río Canandé) and 28,197 from extra-sentinel locations, were all negative for the presence of O. volvulus. These extra-sentinel sites (Hualpí on Río Hoja Blanca, Capulí on Río Onzole, La Ceiba on Río Tululví and Medianía on Río Verde) were included to provide additional evidence of the impact of MDA on the transmission of O. volvulus in isolated endemic areas. Conclusions: Our data indicate that transmission of O. volvulus has been stopped in all endemic areas in Ecuador, including all satellite foci outside the main focus. These findings indicate that a strategy of ivermectin distribution twice a year to over 85% of the treatment-eligible population was effective in eliminating the infection from Ecuador in a focus with a highly competent primary vector, S. exiguum, and where the infection rates were equal to or greater than observed in many onchocerciasis foci in Africa.

AB - © 2018 The Author(s). Background: The Esmeraldas focus of onchocerciasis in Ecuador expanded geographically during the 1980s and was associated with severe ocular and skin disease. Mass drug administration (MDA) with ivermectin started in 1991, initially once but later twice a year, in the principle endemic focus followed by all satellite foci. Treatment was stopped in 2009 when entomological assessments determined that transmission of Onchocerca volvulus had been interrupted. Methods: Three years after the cessation of ivermectin treatment in 2012, as defined by the WHO guidelines for onchocerciasis elimination, blackfly collections were done in four sentinel sites in former hyperendemic areas. The presence of infective larvae in local vectors, Simulium exiguum and Simulum quadrivittatum, was assessed by detection of O. volvulus DNA by PCR. Additional flies captured in four extra-sentinel sites located in former hyper- and mesoendemic dispersed isolated areas were also assessed. Results: The results from 68,310 captured blackflies, 40,114 from four sentinel villages in the previously hyperendemic areas (Corriente Grande, El Tigre, San Miguel on Río Cayapas and Naranjal on Río Canandé) and 28,197 from extra-sentinel locations, were all negative for the presence of O. volvulus. These extra-sentinel sites (Hualpí on Río Hoja Blanca, Capulí on Río Onzole, La Ceiba on Río Tululví and Medianía on Río Verde) were included to provide additional evidence of the impact of MDA on the transmission of O. volvulus in isolated endemic areas. Conclusions: Our data indicate that transmission of O. volvulus has been stopped in all endemic areas in Ecuador, including all satellite foci outside the main focus. These findings indicate that a strategy of ivermectin distribution twice a year to over 85% of the treatment-eligible population was effective in eliminating the infection from Ecuador in a focus with a highly competent primary vector, S. exiguum, and where the infection rates were equal to or greater than observed in many onchocerciasis foci in Africa.

U2 - 10.1186/s13071-018-2851-3

DO - 10.1186/s13071-018-2851-3

M3 - Article

C2 - 29690907

JO - Parasites and Vectors

JF - Parasites and Vectors

SN - 1756-3305

ER -