Rapid Suppression of Onchocerca volvulus Transmission in Two Communities of the Southern Chiapas Focus, Mexico, Achieved by Quarterly Treatments with Mectizan

Rodríguez‐Pérez, Mario A.; Unnasch, Thomas R.; Domínguez-Vázquez, Alfredo; Sauerbrey, Mauricio; Segura‐Cabrera, Aldo; Hassan, Hassan K.; Richards, Frank O.; Hernández-Hernández, Raymundo; Lizarazo-Ortega, Cristian; Lutzow-Steiner, Miguel A.

doi:10.4269/ajtmh.2008.79.239

Cited by 33 publications

(30 citation statements)

References 22 publications

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“…Statistical testing applied to the entomological and serological survey data excluded the UL transmission thresholds of 0.05% flies carrying infective larvae, for the ATP and 0.1% exposure in children. Mathematical modeling and field studies estimated threshold ATP for interruption of the disease transmission between 5 and 54, 24 24,35,36 The reported 95% CI UL ATP of 1.99 L3/person per year in Abu Hamed is well below all of these reported limits. Although the number of communities tested for mf was small, the data also satisfied the parasitological requirements of mf prevalence 1% in 90% of sample villages and a prevalence 5% in 100% of sample villages.…”

Section: Discussionmentioning

confidence: 99%

Interruption of Onchocerca volvulus Transmission in the Abu Hamed Focus, Sudan

Higazi

Zarroug

Mohamed

et al. 2013

The American Society of Tropical Medicine and Hygiene

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Abstract. Abu Hamed, Sudan, the northernmost location of onchocerciasis in the world, began community-directed treatment with ivermectin (CDTI) in 1998, with annual treatments enhanced to semiannual in 2007. We assessed the status of the parasite transmission in 2011 entomologically, parasitologically, and serologically. O-150 pool screening showed no parasite DNA in 17,537 black flies collected in 2011 (95% confidence interval upper limit [95% CI UL] = 0.023). Skin microfilariae, nodules, and signs of skin disease were absent in 536 individuals in seven local communities. Similarly, no evidence of Onchocerca volvulus Ov16 antibodies was found in 6,756 school children 10 years (95% CI UL = 0.03%). Because this assessment of the focus meets the 2001 World Health Organization (WHO) criteria for interrupted transmission, treatment was halted in 2012, and a post-treatment surveillance period was initiated in anticipation of declaration of disease elimination in this area. We provide the first evidence in East Africa that long-term CDTI alone can interrupt transmission of onchocerciasis.

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Section: Discussionmentioning

confidence: 99%

Interruption of Onchocerca volvulus Transmission in the Abu Hamed Focus, Sudan

Higazi

Zarroug

Mohamed

et al. 2013

The American Society of Tropical Medicine and Hygiene

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“…The daily biting rate and the seasonal biting rate were estimated as previously described. 13 Because S. ochraceum s.l. females were not collected throughout the year, it was not possible to precisely calculate the annual transmission potential (ATP).…”

Section: Study Areamentioning

confidence: 99%

Interruption of Transmission of Onchocerca volvulus in the Oaxaca Focus, Mexico

Rodríguez‐Pérez

Unnasch²,

Domínguez-Vázquez³

et al. 2010

The American Society of Tropical Medicine and Hygiene

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Abstract. All endemic communities of the Oaxaca focus of onchocerciasis in southern Mexico have been treated annually or semi-annually with ivermectin since 1994. In-depth epidemiologic assessments were performed in communities during 2007 and 2008. None of the 52,632 Simulium ochraceum s.l. collected in four sentinel communities was found to contain parasite DNA when tested by polymerase chain reaction-enzyme-linked immunosorbent assay (PCR-ELISA), resulting in an upper bound of the infection rate in the vectors of 0.07/2,000. The prevalence of microfilariae (mf) in the cornea and/or anterior chamber of the eye was also zero (0 of 1,039 residents examined; 95%-UL = 0.35%). Similarly, all 1,164 individuals examined by skin biopsy were mf negative (95%-UL = 0.31%), and sera collected from 3,569 children from 25 communities did not harbor Ov16 IgG4-antibodies (95%-UL = 0.09%). These meet the criteria for absence of morbidity and parasite transmission in the Oaxaca focus. As a result mass treatments with ivermectin were halted in 2009.

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“…9,15 Phase I includes ivermectin treatment until transmission is suppressed. In Phase II, suppression is maintained through treatment of the mean reproductive lifespan of the adult female.…”

Section: Discussionmentioning

confidence: 99%

“…15 Because S. ochraceum s.l. females were not collected throughout the year, it was not possible to precisely calculate the annual transmission potential (ATP).…”

Section: 11mentioning

confidence: 99%

Lack of Active Onchocerca volvulus Transmission in the Northern Chiapas Focus of Mexico

Rodríguez‐Pérez¹,

Unnasch²,

Domínguez-Vázquez³

et al. 2010

The American Society of Tropical Medicine and Hygiene

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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.

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Rapid Suppression of Onchocerca volvulus Transmission in Two Communities of the Southern Chiapas Focus, Mexico, Achieved by Quarterly Treatments with Mectizan

Cited by 33 publications

References 22 publications

Interruption of Onchocerca volvulus Transmission in the Abu Hamed Focus, Sudan

Interruption of Onchocerca volvulus Transmission in the Abu Hamed Focus, Sudan

Interruption of Transmission of Onchocerca volvulus in the Oaxaca Focus, Mexico

Lack of Active Onchocerca volvulus Transmission in the Northern Chiapas Focus of Mexico

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