The Effects of Repetitive Community-Wide Ivermectin Treatment on Transmission of Ochocerca Volvulus in Guatemala

Cupp, E. W.; Ochoa, J. O.; Collins, Richard C.; Cupp, Mary S.; Gonzales-Peralta, C; Castro, Jarbas C.; Zea-Flores, Guillermo

doi:10.4269/ajtmh.1992.47.170

Cited by 58 publications

(40 citation statements)

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“…1B, Table 1). Transmission intensity was concomitantly measured only in the Guatemalan study (18), so it is difficult to ascertain whether this is due to a reduction in the force of infection or a cumulative impact of ivermectin on female worm fertility (13,14). No significant difference in the rate of skin repopulation was seen between rounds 1, 2, and 4 if hosts with no detectable microfilariae at the time of treatment were excluded from the analysis (Table 1).…”

Section: Resultsmentioning

confidence: 99%

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Identifying sub-optimal responses to ivermectin in the treatment of River Blindness

Churcher

Pion

Osei-Atweneboana

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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Identification of drug resistance before it becomes a public health concern requires a clear distinction between what constitutes a normal and a suboptimal treatment response. A novel method of analyzing drug efficacy studies in human helminthiases is proposed and used to investigate recent claims of atypical responses to ivermectin in the treatment of River Blindness. The variability in the rate at which Onchocerca volvulus microfilariae repopulate host's skin following ivermectin treatment is quantified using an individual-based onchocerciasis mathematical model. The model estimates a single skin repopulation rate for every host sampled, allowing reports of suboptimal responses to be statistically compared with responses from populations with no prior exposure to ivermectin. Statistically faster rates of skin repopulation were observed in 3 Ghanaian villages (treated 12-17 times), despite the wide variability in repopulation rates observed in ivermectin-naïve populations. Another village previously thought to have high rates of skin repopulation was shown to be indistinguishable from the normal treatment response. The model is used to generate testable hypotheses to identify whether atypical rates of skin repopulation by microfilariae could result from low treatment coverage alone or provide evidence of decreased ivermectin efficacy. Further work linking phenotypic poor responses to treatment with parasite molecular genetics markers will be required to confirm drug resistance. Limitations of the skin-snipping method for estimating parasite load indicates that changes in the distribution of microfilarial repopulation rates, rather than their absolute values, maybe a more sensitive indicator of emerging ivermectin resistance. drug resistance ͉ helminth parasites ͉ Onchocerca volvulus ͉ overdispersion

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Section: Resultsmentioning

confidence: 99%

“…The possible causes of the lower microfilarial load after round 3 have been discussed elsewhere (hosts contributing data from 4 consecutive rounds of chemotherapy largely come from a single study in Guatemala, see refs. 14,18,19).…”

Section: Resultsmentioning

confidence: 99%

Identifying sub-optimal responses to ivermectin in the treatment of River Blindness

Churcher

Pion

Osei-Atweneboana

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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“…[96][97] Consequently single treatments with ivermectin do not change the infection status of treated subjects, and the effect of ivermectin mass treatment on infection prevalence is primarily due to reduction in transmission. [98][99][100][101][102][103] Between 1987 and 2011, the Mectizan Donation programme approved 139,265,010 ivermectin treatments for Africa. 104 Adverse reactions to ivermectin treatment of O. volvulus infection constitute the body's reaction to the microfilaria killed and include primarily itching, rash, gland pain and tenderness, joint and muscle pain, fever and headache, pulse and blood pressure changes, all of which disappear within a few days.…”

Section: Parasitesmentioning

confidence: 99%

Nodding syndrome in Mundri county, South Sudan: Environmental, nutritional and infectious factors

Spencer¹,

Vandemaele

Richer³

et al. 2013

Afr H. Sci.

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Background: Nodding Syndrome is a seizure disorder of children in Mundri County, Western Equatoria, South Sudan. The disorder is reported to be spreading in South Sudan and northern Uganda. Results: Nodding Syndrome was associated with Onchocerca volvulus and Mansonella perstans infections, with food use of a variety of sorghum (serena) introduced as part of an emergency relief program, and was inversely associated with a history of measles infection. There was no evidence to suggest exposure to a manmade neurotoxic pollutant or chemical agent, other than chemically dressed seed intended for planting but used for food. Food use of cyanogenic plants was documented, and exposure to fungal contaminants could not be excluded. Conclusion: Nodding Syndrome in South Sudan has an unknown etiology. Further research is recommended on the association of Nodding Syndrome with onchocerciasis/mansonelliasis and neurotoxins in plant materials used for food.

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“…Phase III trials had shown that the drug was effective in preventing ocular lesions, but information was urgently required on how safe the drug was in large-scale treatment and of the effect that mass treatment would have on onchocerciasis transmission. The OCP and the UNDP/ World Bank/WHO Special Programme for Research and Training in Tropical Diseases (TDR) therefore launched a number of community trials to answer those questions (De Sole et al 1989;Taylor et al 1990;Cupp et al 1992;Abiose et al 1993;Boussinesq et al 1995). The largest trial, undertaken in the hyper-endemic focus of Asubende on the river Pru in Ghana, provided the most detailed information on the effect on transmission, showing a major reduction in vector infectivity but still significant residual transmission after treatment (Remme et al 1989a) and a subsequent increase in infectivity levels to near pretreatment levels 12 months later.…”

Section: Ivermectin: a New Tool For Onchocerciasis Controlmentioning

confidence: 99%

Research for control: the onchocerciasis experience*

Remme

2004

Tropical Med Int Health

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SummaryOnchocerciasis control has been very successful in Africa and research has played a critical role. An overview of the main epidemiological and implementation research activities undertaken over the last 20 years in collaboration with the African onchocerciasis control programmes and of the impact this research had on control is given. The research included the development of epidemiological modelling and its application in programme evaluation and operational planning, research on disease patterns and disease burden in different bioclimatic zones to justify and guide control operations, community trials of ivermectin to determine its safety for large-scale use and its impact on transmission, rapid assessment methods to identify target communities for treatment and community-directed treatment for sustained drug delivery. Lessons learned during this unique collaboration between research and control are discussed.

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The Effects of Repetitive Community-Wide Ivermectin Treatment on Transmission of Ochocerca Volvulus in Guatemala

Cited by 58 publications

References 0 publications

Identifying sub-optimal responses to ivermectin in the treatment of River Blindness

Identifying sub-optimal responses to ivermectin in the treatment of River Blindness

Nodding syndrome in Mundri county, South Sudan: Environmental, nutritional and infectious factors

Research for control: the onchocerciasis experience*

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