Control of Chagas Disease
Introduction
Control of Chagas disease caused by the parasite Trypanosoma cruzi in Latin America over the last two decades has been a substantial public health achievement. The incidence of Chagas disease was reduced by over 65% between 1990 and 2000, from an estimated 700 000 cases per year to fewer than 200 000 (Schmunis et al., 1996; WHO, 2002). The Southern Cone Initiative (Iniciativa de Salud del Cono Sur, INCOSUR) was launched in 1991, aimed at elimination of the main vector, the reduviid bug Triatoma infestans, and elimination of transfusional transmission of T. cruzi in Argentina, Bolivia, Brazil, Chile, Paraguay, and Uruguay (PAHO, 1993). Since transmission by triatomine bugs accounts for over 80% of Chagas disease transmission, and the initiative successfully eliminated domestic Tri. infestans over large areas, this large-scale regional cooperation has significantly reduced disease transmission (Table 1) (WHO, 2002). The interruption of domiciliary transmission of T. cruzi by Tri. infestans has already been certified in Uruguay, Chile, four provinces in Argentina, 10 states in Brazil, and one state in Paraguay (PAHO, 1998, PAHO, 1999a, PAHO, 2000a, PAHO, (2002a), PAHO, 2003a). This success suggested that Chagas disease control is no longer a technical issue, but a political, economic, and organizational problem (Dias and Schofield, 1999; Schofield and Dias, 1999; Dias et al., 2002).
Based on the success of INCOSUR, the concept of region-wide control of Chagas disease has expanded to other regions such as Central America, where the endemic countries are facing new challenges in vector control. The World Health Organization (WHO) adopted the common goal of the elimination of Chagas disease in Latin America by the year 2010. In 1997, Belize, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, and Panama launched the Central American Initiative (Iniciativa de los países de Centroamérica, IPCA) and Colombia, Ecuador, Peru, and Venezuela launched the Andean Initiative (1997) to control vectorial and transfusional transmission of the disease. Mexico has begun a dialogue with IPCA, seeking to join in the control activities. In addition, the Amazon region has discussed launching a regional initiative for surveillance and control of sylvatic vector species. IPCA has made the most significant progress to date, especially in vector control. IPCA, however, must deal with an entomological, social, and political situation, which is different from that of the Southern Cone countries. The aims of this paper are to review the lessons of the Southern Cone Initiative and their application in Central America, and to discuss strategies to tackle the new challenges of sustainable triatomine control.
Section snippets
The Southern Cone Initiative
INCOSUR (the Southern Cone Initiative) provided valuable lessons for implementing Chagas disease control in the Americas. Recent reviews have evaluated the achievements of INCOSUR (e.g. Dias and Schofield, 1999; Morel, 1999; Schofield and Dias, 1999; Silveira and Vinhaes, 1999; Dias et al., 2002; WHO, 2002; Moncayo, 2003). These reviews summarize the following points:
- (i)
INCOSUR established the appropriate technology and strategy to interrupt the transmission of Chagas disease.
- (ii)
A control programme
The Central American Initiative
IPCA was created to duplicate the success of the Southern Cone countries. IPCA, however, differs from INCOSUR in the following ways: (i) its creation was concurrent with decentralization of the health system; (ii) a smaller number of scientists with limited influence on political decisions are present in the region; and (iii) a widely distributed species of vector with domestic, peridomestic, and sylvatic populations is the main vector (Tri. dimidiata). The initiative had limited success during
Challenges in Central America
The collaboration between IPCA and the decentralized health system has revealed new challenges. While the elimination of R. prolixus in Central America will be attainable in the near future, the control of Tri. dimidiata remains a difficult task. The key challenges lie in efficient geographic coverage and sustainability. Central American countries require control activity that will produce maximum results with minimum investment. In addition, attaining sustainability is important to permit
Chagas Disease Control Initiatives in Other Regions
Beside the Southern Cone and Central American regions, crucial areas in the control of Chagas disease are the Andean and Amazon regions and Mexico.
Conclusion
Interruption of Chagas disease transmission in Central America by 2010, as proposed by IPCA, seems achievable, although the process of maintenance, especially with Tri. dimidiata, needs to be accelerated. The vector control technologies and strategy developed by INCOSUR were largely applicable to Central American conditions. There are, however, some Central American situations that challenge this vector control strategy: the rapid decentralization of the health system and residual and
Acknowledgements
This review was written as part of the regional effort to combat Chagas disease in the Americas in collaboration with stakeholders in Central and South American countries as well as with international organizations such as PAHO, JICA, ECLAT, CIDA, MSF, and World Vision. We thank the vector control teams of the Ministry of Health of Guatemala, El Salvador, Honduras, and other Central and South American countries for their pursuit of Chagas disease vector control. We also thank C. Cordon-Rosales,
References (86)
- et al.
A cost-benefit analysis of Chagas disease control in north-western Argentina
Transactions of the Royal Society of Tropical Medicine and Hygiene
(1998) - et al.
Emerging Chagas disease in Amazonian Brazil
Trends in Parasitology
(2002) Control of Chagas disease in Brazil
Parasitology Today
(1987)- et al.
Chagas disease control in Venezuela: lessons for the Andean region and beyond
Trends in Parasitology
(2003) Epidemiology of Chagas disease in Mexico: an update
Trends in Parasitology
(2001)- et al.
Incidence of Trypanosoma cruzi infection in two Guatemalan communities
Transactions of the Royal Society of Tropical Medicine and Hygiene
(2002) - et al.
Interruption of Chagas’ disease transmission through vector elimination
Lancet
(1996) - et al.
The Southern Cone Initiative against Chagas disease
Advances in Parasitology
(1999) - et al.
Chagas disease vector control in Central America
Parasitology Today
(1997) - et al.
Comparison of intervention strategies for control of Triatoma dimidiata in Nicaragua
Memorias do Instituto Oswaldo Cruz
(2000)