Fig 10 - uploaded by Maria Grillet
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Dibujo representando el cibario de especies de simúlidos con armadura cibarial presente (a y b), y ausente (c y d); vistas frontales (a y c) y laterales (b y d) (Omar & Garms, 1975)
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En este artículo se describe la oncocercosis humana, la cual afecta al pueblo Yanomami en el foco amazónico del sur de Venezuela y se revisa el conocimiento actualizado de la enfermedad y su control. La epidemiología de esta infección parasitaria (causada por Onchocerca volvulus), y transmitida por insectos simúlidos, es altamente dependiente de la...
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Citations
... The gold standard for the onchocerciasis diagnosis historically has been microscopic examination of skin biopsies from the iliac crests (African patients) and/or from the shoulders (Guatemalan-Mexican patients) and/or from the lower part of the body in individuals of the Amazonian focus (Vivas-Martínez et al. 2007) for microfilariae (WHO 1987). This method depends on the intensity and prevalence of the infection in the communities. ...
... In some areas of LA, successful vector control campaigns using the larvicide Temephos have been realized, including the San Vicente Pacaya area in Guatemala (Ochoa et al. 1997). In general, however, in LA vector control campaigns have been difficult to implement due to the limited access imposed by the geographical localization of the foci and elevated operational costs (Shelley 1991;Vivas-Martínez et al. 2007). ...
Onchocerciasis, a chronic, debilitating, poverty-promoting parasitic disease, is one of the five most common of the officially designated neglected tropical diseases. It has been found in 13 discrete foci distributed among six countries (Brazil, Colombia, Ecuador, Guatemala, Mexico, and Venezuela) in Latin America (LA). Onchocerciasis was brought to the Americas through the slave trade in the sixteenth century, was transmitted to the indigenous American population once introduced, and was then spread through migration. Since its discovery in LA, numerous efforts have been put forth to understand the epidemiology of the disease to control and eventually eliminate the disease. The establishment of public–private partnerships and the development of community wide mass distribution programs of Mectizan® (ivermectin, donated by Merck, Sharpe, and Dohme) have resulted in dramatic progress against onchocerciasis in all of the endemic foci of LA. Transmission has been interrupted in 11 of 13 foci in LA, including all foci in Colombia, Ecuador, Guatemala, and Mexico as well as in two of the three foci in Venezuela. Transmission remains active only in the two foci straddling the border between Brazil and Venezuela. This area is inhabited by the Yanomami tribe indigenous to the Amazonian forest, and evidence suggests that transmission has been suppressed in some Yanomami communities. Interruption of transmission in these Amazonian foci, the last active foci in LA, will require intensified efforts and cross-border collaboration, but once successful, will culminate in the complete elimination of this scourge from the Americas.
... In Mexico, vector control has not been accepted as part of the integral onchocerciasis control, and there have been few scientific research activities towards the search of new options for vector control. In onchocerciasis areas in South America, the use of vector control has been extremely difficult to implement as a strategy for the control and elimination of onchocerciasis given the elevated operational costs in areas where communities are dispersed on mountain ranges and with high numbers of large and small rivers serving as breeding sites (Shelley, 1991;Vivas-Martínez et al., 2007). ...
... However, the nomadic Yanomami populations from the Amazon rainforest are one of the most severely affected groups given that they are at continuous risk of exposure to infected black flies. They represent only 2.6% of the total population at risk in the Americas, but they all reside in a vast single focus (the Amazonas-Roraima focus), bordering between Venezuela and Brazil (Moraes, 1991;Vivas-Martínez et al., 2007). Given this situation, active transmission is believed to continue in the two cross-border foci of the Yanomami area (South Venezuela and Amazonas). ...
... The development of different methods of diagnosis of onchocerciasis has proved to be useful for the The gold standard diagnosis method for onchocerciasis is the bloodless skin snip (WHO, 1987). Typically, 2-6 skin snips or biopsies are taken from both iliac crests (African patients) and/or from shoulders (Guatemalan-Mexican patients) and/or from lower part of the body in individuals of the Amazonian focus (Vivas-Martínez et al., 2007) using either a corneoscleral biopsy instrument (an obsolete ophthalmological surgical instrument) or a scalpel blade. These biopsy punches enable snips to be taken easily and rapidly, but are expensive, need regular setting and sharpening and should be sterilized between patients. ...
Onchocerciasis has historically been one of the leading causes of infectious blindness worldwide. It is endemic to tropical regions both in Africa and Latin America and in the Yemen. In Latin America, it is found in 13 foci located in 6 different countries. The epidemiologically most important focus of onchocerciasis in the Americas is located in a region spanning the border between Guatemala and Mexico. However, the Amazonian focus straddling the border of Venezuela and Brazil is larger in overall area because the Yanomami populations are scattered over a very large geographical region.
Human onchocerciasis is a chronic parasitic disease caused by Onchocerca volvulus and transmitted by Simulium black flies. Clinical manifestations include skin and eye disease, leading to loss of vision and blindness. The interaction between parasite, transmitting fly (vector), and human host highlights the relationship between environmental variables and infection risk. Environmental, cultural, entomological, and parasitological features influencing the heterogeneous geographical distribution of onchocerciasis in the Amazonian onchocerciasis focus of southern Venezuela are described and discussed. Unique features of the region where this focus is located include its ancient geological origin, highly structured and varied landscapes, large extensions of rainforest and mountainous areas crisscrossed by rivers where transmission occurs, seminomadic and rainforest-dwelling characteristics of the at-risk Yanomami population inhabiting the area, and multiplicity of Simulium vectors. Use of a landscape epidemiology approach and application of remote sensing and geographical information system technologies have permitted identification and mapping of environmental variables and landscape elements that collectively provide the niche in which the dynamics of parasite, human, and vector populations take place, both locally and connectedly. A thorough, yet holistic understanding of this host–parasite–vector system in intimate relationship with its special environment is essential for successful onchocerciasis control in the Amazonian focus.
