Control of CD began to be institutionalized in the 1960s in the form of national campaigns implemented in Venezuela and several countries in the Southern Cone. In 1991 the Southern Cone Initiative, initiated by the Health Ministers from Argentina, Bolivia, Brazil, Chile, Paraguay, and Uruguay, allowed national control activities to be maintained, expanded, or instituted on a regular basis. The goal was to eliminate transmission by T. infestans and prevent transmission by transfusion of blood products throughout the region. The PAHO/WHO, which played a key role as technical secretariat of the Initiative, clearly defined the objectives, monitored the quality of work, and oversaw shared activities in border areas. After 15 years, the progress achieved is undeniable. Transmission by T. infestans has been shown to be interrupted in Chile, Uruguay, Brazil, and parts of Argentina and Paraguay. In many areas, it appears that the vector itself has been eliminated, although this has not been demonstrated with absolute certainty so far.
Other initiatives followed that of the Southern Cone, including the Central American countries in 1997, the Andean countries in 1999, Mexico in 2003, and the Amazonian region in 2004. The WHO reports have demonstrated the impact of the programs: decrease in the case incidence, lower prevalence of infections as measured by serological screening of populations, and a decrease in mortality.
Domiciliated species of bugs such as T. infestans and R. prolixus, especially in areas in which the last one was introduced, are susceptible to elimination by spraying of houses and buildings in the peri-domestic areas. Other species live mainly in natural environments, but have the capacity to sporadically invade and colonize human dwellings. Thus, T. brasiliensis, T. pseudomaculata, T. sordida, T. dimidiata, and P. megistus tend to persist following application of insecticide to dwellings, and control of these species requires constant monitoring and periodic spraying (D´ıas, 2002).
Currently, in the Southern Cone countries, the major concerns regarding control are sustainability of the accomplished results and implementation of strong antitriatomine actions in countries still infested by T. infestans, mainly Bolivia, southern Peru, and areas of Argentina. There is also an urgent need for research on appropriate techniques of epidemiological surveillance and promoting community involvement in control activities in coordination with the health system.
Control Of The Other Transmission Routes
Control of blood for transfusion through serological testing of blood donors has not been completely implemented in endemic countries. Considering the high risk of infection through this route, it is mandatory that a screening strategy be uniformly adopted and sustained. Some countries are increasing efforts to screen pregnant women to facilitate detection of congenital infections. In the future, when complete control of vectorial and transfusion-associated transmission is achieved, congenital transmission will be the only source of new cases. In some nonendemic countries such as the United States, which have large numbers of immigrants from endemic areas, programs to screen blood donors are being implemented. An additional challenge for these countries is to identify and provide proper medical care for infected persons, including congenitally infected infants.
Needs For The Future
To improve CD control perspectives, we are faced with numerous challenges: in the short term, to continue entomologic surveillance, to complete activities to prevent new acute cases, to do research to improve existing interventions, and to facilitate better diagnosis and follow-up of clinical cases. Midand long-term challenges include development of a vaccine that prevents the disease from developing in persons already infected or lessens the risk of infection, and improvement of the economic, social, and educational conditions of populations at risk.
Bibliography:
- Blanco SB, Segura EL, Cura EN, et al. (2000) Congenital transmission of Trypanosoma cruzi, an operational outline for detecting and treating infected infants in northwestern Argentina. Tropical Medicine and Internal Health 5(4): 293–301.
- Cecere MC, Vasquez-Prokopec GM, Gurtler RE, and Kitron U (2006) Reinfestation sources for Chagas disease vector, Triatoma infestans, Argentina. Emerging Infectious Diseases 12(7): 1096–1102.