Elimination of Onchocercia volvulus Transmission in the Santa Rosa Focus of Guatemala

Lindblade, Kim A.; Arana, Byron; Zea-Flores, Guillermo; Rizzo, Nidia; Porter, Charles H.; Domínguez, Alfredo; Cruz-Ortiz, Nancy; Unnasch, Thomas R.; Punkosdy, George A.; Richards, Jane; Sauerbrey, Mauricio; Castro, Jarbas C.; Catú, Eduard; Oliva, Orlando; Richards, Frank O.

doi:10.4269/ajtmh.2007.77.334

Cited by 72 publications

(112 citation statements)

References 21 publications

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“…The bodies were analyzed first, using the standard O-150 PCR assay to detect O. volvulus deoxyribonucleic acid (DNA). 19,20 Pools that were PCR positive were confirmed by a second PCR. If a positive body pool was confirmed, then all the head pools from that community for that transmission season were tested.…”

Section: Methodsmentioning

confidence: 99%

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One Hundred Years After Its Discovery in Guatemala by Rodolfo Robles, Onchocerca volvulus Transmission Has Been Eliminated from the Central Endemic Zone

Richards¹,

Rizzo²,

Espinoza³

et al. 2015

The American Journal of Tropical Medicine and Hygiene

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Abstract. We report the elimination of Onchocerca volvulus transmission from the Central Endemic Zone (CEZ) of onchocerciasis in Guatemala, the largest focus of this disease in the Americas and the first to be discovered in this hemisphere by Rodolfo Robles Valverde in 1915. Mass drug administration (MDA) with ivermectin was launched in 1988, with semiannual MDA coverage reaching at least 85% of the eligible population in > 95% of treatment rounds during the 12-year period, 2000-2011. Serial parasitological testing to monitor MDA impact in sentinel villages showed a decrease in microfilaria skin prevalence from 70% to 0%, and polymerase chain reaction (PCR)-based entomological assessments of the principal vector Simulium ochraceum s.l. showed transmission interruption by 2007. These assessments, together with a 2010 serological survey in children 9-69 months of age that showed Ov16 IgG4 antibody prevalence to be < 0.1%, meeting World Health Organization (WHO) guidelines for stopping MDA, and treatment was halted after 2011. After 3 years an entomological assessment showed no evidence of vector infection or recrudescence of transmission. In 2015, 100 years after the discovery of its presence, the Ministry of Health of Guatemala declared onchocerciasis transmission as having been eliminated from the CEZ. INTRODUCTION Human onchocerciasis (river blindness) is caused byOnchocerca volvulus, a tissue-dwelling filarial nematode transmitted by certain species of the genus Simulium.1 Adult male and female worms form fibrous, often palpable, subcutaneous onchocercomas ("nodules"), in which fertilized female worms produce microfilariae (mf). The mf leave the nodule and reside in the dermis. They may also enter the eyes. Human disease results largely from death of the mf, which results in inflammation, itching, visual impairment, and blindness. The Simulium ("black fly") vectors breed in rapidly flowing rivers and streams and become infected when they ingest mf during a blood meal; in competent black fly species, mf develop into third stage larvae that can infect humans when the vector takes a subsequent blood meal. There are no important animal reservoirs of O. volvulus to maintain the transmission cycle independent of the human population itself. Human onchocerciasis is thought to have originated in Africa when Onchocerca species in ungulates adapted to man; the parasite is believed to have been brought to the Americas through the Atlantic slave trade.3 Transmission was only focally established in the Americas, in contrast to the extensive transmission zones that exist in Africa. In the Americas, due to a limited distribution of competent vectors, transmission zones ("foci") are small and sharply delimited geographically, and are generally maintained by high vector biting rates. Before control measures were implemented, there were 13 foci in six countries in Latin America (Brazil, Colombia, Ecuador, Guatemala, Mexico, and Venezuela), with an overall human population at risk in 2013 of just over 500,000 persons. 4Guatemala...

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Section: Methodsmentioning

confidence: 99%

“…The indicator used was the presence of mf in the anterior chamber (MfAC). 18,19 Examinations were conducted in a darkened area after the patients were asked Simulium ochraceum s.l. seeking a blood meal were collected in the SV being studied on at least 2 days/month.…”

Section: Methodsmentioning

confidence: 99%

One Hundred Years After Its Discovery in Guatemala by Rodolfo Robles, Onchocerca volvulus Transmission Has Been Eliminated from the Central Endemic Zone

Richards¹,

Rizzo²,

Espinoza³

et al. 2015

The American Journal of Tropical Medicine and Hygiene

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“…Sera were eluted from the dried spots and examined for the presence of Ov-16 IgG4 antibodies by enzyme-linked immunosorbent assay (ELISA) as previously described. 25 Entomological activities. Mapping of vector breeding sites and their upper elevation breeding limits began in March of 2007.…”

Section: Methodsmentioning

confidence: 99%

“…22 The prevalence of immunoglobulin G4 (IgG4) antibodies to Ov-16, a recombinant antigen of Onchocerca volvulus, was used as a measure of infection/exposure in children. [25][26][27] A sample size of 3,000 children is needed to exclude 0.1% antibody prevalence with 95% confidence.…”

Section: Methodsmentioning

confidence: 99%

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Transmission of Onchocerca volvulus by Simulium neavei in Mount Elgon Focus of Eastern Uganda Has Been Interrupted

Katabarwa¹,

Lakwo²,

Habomugisha³

et al. 2014

The American Journal of Tropical Medicine and Hygiene

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Abstract. The study determined that Simulium neavei-transmitted onchocerciasis in Mount Elgon onchocerciasis focus had been interrupted. Annual mass treatment with ivermectin changed to two times per year along with vector elimination in 2007. Then, baseline microfilaria (mf) prevalence data of 1994 in five sentinel communities were compared with follow-up data in 2005 and 2011. Blood spots from 3,051 children obtained in 2009 were analyzed for Onchocerca volvulus immunoglobulin G4 antibodies. Fresh water crab host captures and blackflies collected indicated their infestation with larval stages of S. neavei and presence or absence of the vector, respectively. Mf rates dropped from 62.2% to 0.5%, and 1 (0.03%) of 3,051 children was positive for O. volvulus antibodies. Crab infestation dropped from 41.9% in 2007 to 0%, and S. neavei biting reduced to zero. Both remained zero for the next 3 years, confirming interruption of onchocerciasis transmission, and interventions were halted.

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Progress Toward the Development of Rapid Diagnostic Tests for Lymphatic Filariasis and Onchocerciasis

Peck¹,

Faulx²,

Santos³

2019

Revolutionizing Tropical Medicine

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Elimination of Onchocercia volvulus Transmission in the Santa Rosa Focus of Guatemala

Cited by 72 publications

References 21 publications

One Hundred Years After Its Discovery in Guatemala by Rodolfo Robles, Onchocerca volvulus Transmission Has Been Eliminated from the Central Endemic Zone

One Hundred Years After Its Discovery in Guatemala by Rodolfo Robles, Onchocerca volvulus Transmission Has Been Eliminated from the Central Endemic Zone

Transmission of Onchocerca volvulus by Simulium neavei in Mount Elgon Focus of Eastern Uganda Has Been Interrupted

Progress Toward the Development of Rapid Diagnostic Tests for Lymphatic Filariasis and Onchocerciasis

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