|The Southern Cone Initiative against Chagas’ disease has been one of the most successful wide-scale public health interventions ever undertaken for a parasitic disease. In 1991 the governments of Argentina, Bolivia, Brazil, Chile, Paraguay, and Uruguay launched this ambitious strategy, aiming to interrupt the transmission of Chagas’ disease through vector elimination and blood product screening by the year 2005. Soon after the embarkation of the Southern Cone Initiative, other regional groups in the Americas adopted similar programs. The Andean Initiative, The Central American Initiative, and the Amazon Initiative employ the same public health strategies of vector and transfusional control to combat Chagas’ disease in their respective areas. This page will focus on the Southern Cone Initiative as it is the oldest and most well-documented of the programs.|
Various Initiatives for Chagas' elimination in Central and South America. Map courtesy of WHO-TDR. http://www.who.int/tdr/research/progress/chag_afr/map.htm.
The main mechanisms of controlling the reduviid bug are by fumigation, housing improvements, and education. The Southern Cone initiative mass produced and distributed fumigant canisters and insecticidal paints for use in homes and community buildings in endemic areas. Individual Ministries of Health all over South and Central America have played indispensable roles in the field work for fumigation campaigns. While fumigation interrupts the current infestation, it is not a sustainable vector-control technique because the bugs can easily re-colonize in cracked mud walls and thatched roofs. Housing improvements are therefore another key component to vector control. Replacement of mud walls and floors with cement, and thatched roofs with corrugated metal, reduces the number of suitable places for reduviid bugs to nest. Surveillance programs have been established to map out and monitor communities according to their social circumstances and needs for vector control. Population-directed education about the vector’s habitat and behavior is also important for reducing its contact with humans.
There has been an enormous increase in the screening of blood and blood product donors throughout South and Central America. The Southern Cone Initiative has supplied many blood banks with the proper serologic testing equipment and trained personnel to perform routine detection activities. Some blood banks treat blood products with gentian violet to kill trypanosomes. Although it effectively prevents new transfusional infections, this approach is rare because it causes an undesirable, temporary discoloration of blood in recipients.
The Southern Cone Initiative has met with great success. Millions of rural homes have been fumigated. Ten South and Central American countries screen 100% of their blood donors. Transmission of Chagas’ disease has been interrupted in Uruguay, Chile, and most of Brazil, with a 70% reduction in new infections across South America since the start of the program.
It is important, however, to keep in mind that while the incidence of the disease is decreasing, the prevalence of asymptomatic and chronic infections remains high. Because these people are capable of transmitting T. cruzi (either to the vector or through blood products), they are an important aspect of disease perpetuation in the human population. It is also for this reason that reducing the total impact of Chagas’ disease in the near future will require a combination of prevention and treatment strategies.
Construction effort in Honduras to prevent vector infestation. Photo courtesy of Sam Rice-Townsend.
New, vector-resistant housing in Honduras. Photo courtesy of Sam Rice-Townsend.
References: 9, 10, 11, 14, 15, 16