Home Economics American Trypanosomiasis Chagas Disease, Second Edition: One Hundred Years of Research
Transmission through vectors
Data on the prevalence and distribution of Chagas disease improved in quality during the 1980s as a result of the demographically representative cross-sectional studies carried out in countries where accurate information was not available. A group of experts met in Brasilia in 1979 and devised standard protocols to carry out countrywide prevalence studies on human T. cruzi infection and triatomine house infestation.
These studies were carried out during the 1980s in collaboration with the Ministries of Health of Argentina, Bolivia, Brazil, Chile, Colombia, Costa Rica, Ecuador, El Salvador, Guatemala, Honduras, Panama, Paraguay, Peru, Uruguay, and Venezuela. The accurate information obtained has made it easier for individual countries to plan and to evaluate the effectiveness of national control programs5-20 (Table 4.1).
On the basis of these individual countrywide cross-sectional surveys, it was estimated that the overall prevalence of human T. cruzi infection in the 18 endemic countries reaches 17 million cases. Some 100 million people (25% of all the inhabitants of Latin America) were at risk of contracting T. cruzi infection (Table 4.1).
The incidence was estimated at 700—800,000 new cases per year and the annual deaths due to the cardiac form of Chagas disease at 45,000.21
The originally endemic area with vectorial transmission in the human domicile comprised 18 countries with higher Trypanosoma cruzi infection rates in the regions infested by Triatoma infestans (Southern Cone countries) and Rhodnius prolixus (Andean countries and Central America) which were the triatomine species best adapted to the human domicile.
The epidemiological quantification was one of the reasons to prioritize the control of the disease but the final political decision came from the demonstration of the high cost—benefit ratio of the control programs versus the costs of the medical care and the social security of the infected patients (Akhavan, 1998).
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