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Epidemiological impact

The most significant results in the interruption of transmission have been achieved in the Southern Cone and the Central American countries. The national programs of Argentina, Brazil, Chile, and Uruguay had shown important results even before the launching of the Initiative. Fig. 4.1 shows the current trends of the incidence of infections in the Southern Cone countries as a consequence of elimination of vectorial transmission in Uruguay, Chile, and Brazil.60,61

In Central America, after the creation of the IPCA, the response of the governments was very effective and complemented by the participation of international cooperation agencies in the financing and execution of control activities. In the Andean countries the difficulties encountered by the IPA were twofold: on the one hand the variety of epidemiological and entomological situations and on the other side the different degrees of political commitment of the governments. The concept of risk stratification was developed in the context of this Initiative and was an important contribution to the other ones.62—64 In addition it was felt the need to define better the objectives such as the elimination of T. dimidiata in Ecuador, of R. ecuadoriensis in Peru, and of R. prolixus in Colombia.

With respect of the Amazon Initiative (AMCHA) it is recognized that it is still in an initial phase of generation of knowledge on the magnitude of the problem and development of control methodologies, in particular in Brazil and to a lesser extent in Ecuador.

The impact of vector control programs and the possible influence of other variables, such as the general socioeconomic development of the populations at risk, can be better evaluated by the trends of the number of infected cases in different moments. Table 4.1 shows those data in three different moments: 1975—85, 1995, and 2005 to estimate the prevalence and 1990, 1995, and 2005 to estimate the incidence.

As the information compiled in this table has different sources (WHO/OPS, 200665), the interpretation should be cautious and should be considered as the best estimation of the real epidemiological situation.

The impact on the decrease of the burden of disease measured in DALYs lost due to Chagas disease has been the most important in the period 1990—2001 for Latin America and the Caribbean. The number of DALYS dropped from 2.8 million in 1990 to 0.8 in 2001, a reduction of 78%, the highest among the top eight communicable diseases in the region.65,66

The impact on mortality due to Chagas disease is evidenced by the reduction in mortality from 45,000 annual deaths in 1980 (Moncayo, 1993) to 14,000 in 2001 (World Bank, 2006) a net decrease of 70%. Table 4.3 summarizes the reduction in incidence, prevalence, mortality, and distribution of Chagas disease on the

continent.37

In Table 4.5 the data on coverage of blood Banks screening and the percentage of positive samples for 2005 are shown. The sources of this information are the official reports of the governments to the meetings of the Intergovernmental Commissions of the Subregional Initiatives. The high coverage and low percentage of seroreactivity in the different countries can be observed.

 
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