Simuliidae and the transmission and control of human Onchocerciasis in Latin America

Shelley, A. J.

doi:10.1590/s0102-311x1991000300003

Cited by 18 publications

(16 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The results show that simuliids with armed foreguts require higher average parasite intakes than those by unarmed species in order to acquire equivalent levels of effective infection, measured as mean larval burdens per fly and as percentage of flies with larvae. Nevertheless, these same indicators suggest an increased vectorial efficiency of the armed species over the species without armature at heavier microfilarial intakes, in agreement with the remarks made by Shelley (1988Shelley ( , 1991. These differences will be further explored in the light of parasite-induced vector mortalities elsewhere.…”

Section: ( • ) S Damnosum Sl; ( • ) S Guianense (C)supporting

confidence: 80%

Density-dependent processes in the transmission of human onchocerciasis: relationship between the numbers of microfilariae ingested and successful larval development in the simuliid vector

et al. 1995

Self Cite

View full text Add to dashboard Cite

SUMMARYA previous paper reported that the intake of Onchocerca volvulus microfilariae (mff) by different species of Simulium is essentially proportional to the parasite load in the skin of infected carriers. This paper examines the fate of the ingested mff in susceptible vectors to assess the relationship between parasite intake and infective larval output in blackfly species with and without well-developed cibarial armatures. Analysis is based on data from 3 onchocerciasis endemic areas: /S. sirbanum) and the Amazonian focus between South Venezuela and Northern Brazil (S. guianense and S. oyapockense s.L).The data, which include published and unedited information collected in the field, record experimental studies of parasite uptake by wild flies maintained in captivity until the completion of the extrinsic incubation period. The relationship between L3 output (measured as the mean number of successful larvae/fly or, as the proportion of flies with infective larvae) and average microfilarial intake, was strongly non-linear. This non-linearity was best represented by a sigmoid function in case of armed simuliids (S. ochraceum s.L, S. oyapockense s.L), or by a hyperbolic expression in that of unarmed flies (S. damnosum s.L, S. guianense). These results are compatible, respectively, with the patterns of 'initial facilitation' and 'limitation' described in culicid vectors of lymphatic filariases. A maximum mean number of 1-3 L3/fly was observed in all 4 vectors. It is concluded that O. volvulus larval development to the infective stage is regulated by density-dependent mechanisms acting at the early phase of microfilarial migration out of the blackfly's bloodmeal. Damage by the bucco-pharyngeal armature may also be density dependent. A hypothesis, based on this density dependence is forwarded to explain initial facilitation, so far only recorded in vectors with well-developed cibarial teeth. Our results provide quantitative support for the conjecture that chemotherapy alone is likely to have a greater impact on reducing onchocerciasis transmission in endemic areas where the main vector has a toothed fore-gut than in foci where the vectors have unarmed cibaria.

show abstract

Section: ( • ) S Damnosum Sl; ( • ) S Guianense (C)supporting

confidence: 80%

Density-dependent processes in the transmission of human onchocerciasis: relationship between the numbers of microfilariae ingested and successful larval development in the simuliid vector

et al. 1995

Self Cite

View full text Add to dashboard Cite

show abstract

“…Genotypic and phenotypic variation plays an important role in the ecology of transmission of onchocerciasis in LA (Shelley 1991). Most importantly, O. volvulus is transmitted by several different species of black fly in LA (Fig.…”

Section: The Parasite and The Vectormentioning

confidence: 99%

Neglected Tropical Diseases - Latin America and the Caribbean

Franco‐Paredes¹,

Santos-Preciado²

2015

Neglected Tropical Diseases

View full text Add to dashboard Cite

“…Such information, in conjunction with cytogenetical studies, is needed for elucidating the differential status and importance of Amazonian onchocerciasis vectors such as S. exiguum s.l. , which appear to vary between localities ( Shelley, 1991).…”

Section: Introductionmentioning

confidence: 99%

Phosphoglucomutase and trehalase isoenzymes of Venezuelan Simulium vectors of Onchocerca volvulus

Davies

Basáñez

Frontado³

et al. 2000

Medical Vet Entomology

View full text Add to dashboard Cite

Phosphoglucomutase (PGM) and trehalase (Tre) isoenzymes of five species of Simulium blackflies (Diptera: Simuliidae), vectors of onchocerciasis in Venezuela, were investigated by means of a portable electrophoresis field kit. Tre differed between S. incrustatum and S. oyapockense s.l. Electrophoretic variation of Tre in other members of the S. amazonicum and S. incrustatum groups merit further investigation. PGM appears to be more useful for separating populations within species complexes. Multiple populations and/or seasonal changes in population structure of S. guianense s.l., S. exiguum s.l. and S. metallicum s.l. were inferred from elecrophoretic variation of PGM.

show abstract

Simuliidae and the transmission and control of human Onchocerciasis in Latin America

Cited by 18 publications

References 17 publications

Density-dependent processes in the transmission of human onchocerciasis: relationship between the numbers of microfilariae ingested and successful larval development in the simuliid vector

Density-dependent processes in the transmission of human onchocerciasis: relationship between the numbers of microfilariae ingested and successful larval development in the simuliid vector

Neglected Tropical Diseases - Latin America and the Caribbean

Phosphoglucomutase and trehalase isoenzymes of Venezuelan Simulium vectors of Onchocerca volvulus

Contact Info

Product

Resources

About