Epidemiology of Chagas disease in non endemic countries: the role of international migration

Human infection with the protozoa Trypanosoma cruzi extends through North, Central, and South America, affecting 21 countries. Most human infections in the Western Hemisphere occur through contact with infected bloodsucking insects of the triatomine species. As T. cruzi can be detected in the blood of untreated infected individuals, decades after infection took place; the infection can be also transmitted through blood transfusion and organ transplant, which is considered the second most common mode of transmission for T. cruzi. The third mode of transmission is congenital infection. Economic hardship, political problems, or both, have spurred migration from Chagas endemic countries to developed countries. The main destination of this immigration is Australia, Canada, Spain, and the United States. In fact, human infection through blood or organ transplantation, as well as confirmed or potential cases of congenital infections has been described in Spain and in the United States. Estimates reported here indicates that in Australia in 2005-2006, 1067 of the 65,255 Latin American immigrants (16 per 1000) may be infected with T. cruzi, and in Canada, in 2001, 1218 of the 131,135 immigrants (9 per 1000) whose country of origin was identified may have been also infected. In Spain, a magnet for Latin American immigrants since the 2000, 5125 of 241,866 legal immigrants in 2003 (25 per 1000), could be infected. In the United States, 56,028 to 357,205 of the 7,20 million, legal immigrants (8 to 50 per 1000), depending on the scenario, from the period 1981-2005 may be infected with T. cruzi. On the other hand, 33,193 to 336,097 of the estimated 5,6 million undocumented immigrants in 2000 (6 to 59 per 1000) could be infected. Non endemic countries receiving immigrants from the endemic ones should develop policies to protect organ recipients from T. cruzi infection, prevent tainting the blood supply with T. cruzi, and implement secondary prevention of congenital Chagas disease

Prevention of Transfusional Trypanosoma cruzi Infection in Latin America

Trypanosoma cruzi is a protozoan infection widely spread in Latin America, from Mexico in the north to Argentina and Chile in the south. The second most important way of acquiring the infection is by blood transfusion. Even if most countries of Latin America have law/decree/norms, that make mandatory the screening of blood donors for infectious diseases, including T. cruzi (El Salvador and Nicaragua do not have laws on the subject), there is usually no enforcement or it is very lax. Analysis of published serologic surveys of T. cruzi antibodies in blood donors done in 1993, indicating the number of donors and screening coverage for T. cruzi in ten countries of Central and South America indicated that the probability of receiving a potentially infected transfusion unit in each country varied from 1,096 per 10,000 transfusions in Bolivia, the highest, to 13.02 or 13.86 per 10,000 transfusions in Honduras and Venezuela respectively, where screening coverage was 100%. On the other hand the probability of transmitting a T. cruzi infected unit was 219/10,000 in Bolivia, 24/10,000 in Colombia, 17/10,000 in El Salvador, and around 2-12/10,000 for the seven other countries. Infectivity risks defined as the likelihood of being infected when receiving an infected transfusion unit were assumed to be 20% for T. cruzi. Based on this, estimates of the absolute number of infections induced by transfusion indicated that they were 832, 236, and 875 in Bolivia, Chile and Colombia respectively. In all the other countries varied from seven in Honduras to 85 in El Salvador. Since 1993, the situation has improved. At that time only Honduras and Venezuela screened 100% of donors, while seven countries, Argentina, Colombia, El Salvador, Honduras, Paraguay, Uruguay and Venezuela, did the same in 1996. In Central America, without information from Guatemala, the screening of donors for T. cruzi prevented the transfusion of 1,481 infected units and the potential infection of 300 individuals in 1996. In the same year, in seven countries of South America, the screening prevented the transfusion of 36,017 infected units and 7, 201 potential cases of transfusional infection

Safety of the Blood Supply in Latin America

Appropriate selection of donors, use of sensitive screening tests, and the application of a mandatory quality assurance system are essential to maintain the safety of the blood supply. Laws, decrees, norms, and/or regulations covering most of these aspects of blood transfusion exist in 16 of the 17 countries in Latin America that are the subject of this review. In 17 countries, there is an information system that, although still incomplete (there are no official reports on adverse events and incidents), allows us to establish progress made on the status of the blood supply since 1993. Most advances originated in increased screening coverage for infectious diseases and better quality assurance. However, in 2001 to 2002, tainted blood may have caused infections in 12 of the 17 countries; no country reached the number of donors considered adequate, i.e., 5% of the population, to avoid blood shortages, or decreased significantly the number of blood banks, although larger blood banks are more efficient and take advantage of economies of scale. In those years, paid donors still existed in four countries and replacement donors made up >75% of the blood donors in another eight countries. In addition, countries did not report the number of voluntary donors who were repeat donors, i.e., the healthiest category. In spite of progress made, more improvements are needed

La reforma del sector salud, descentralización, prevención y control de enfermedades transmitidas por vectores Health system, decentralization, and the control of vector-borne diseases

Con las nuevas macropolíticas mundiales, la salud en América Latina ha sufrido importante transición en direción a la decentralización, sin compatibilizar la salud pública con la lógica de las economías de mercado. Con esto, el control decentralizado de las enfermedades endémicas presenta dificultades políticas y operativas. Aunque la decentralización se justifica por los presupuestos teóricos, no hay tradición de este control en los niveles municipales, lo que dificulta la simple o burocrática transferencia de encargos para estos niveles. La falta de expertise, el turn-over político y la corrupción son dificultades adicionales, conllevando a una extinción de varias instituiciones y programas. La falta de efectividad en el enfrentamiento del dengue, de la malaria y de la enfermedad de Chagas son algunos ejemplos. Requierese una modernización con responsabilidad, con una transición compartida entre los niveles y garantizada por acciones continuadas. Sugierese mantener estructuras regionales para referencia, consolidación epidemiológica, normatización, capacitación y supervisión, incluso con reserva técnica para acciones finalísticas supletivas.Economic policies are changing Latin American health programs, particularly promoting decentralization. Numerous difficulties thus arise for the control of endemic diseases, since such activities traditionally depend on vertical, and centralized structures. Theoretical arguments in favor of decentralization notwithstanding, no such tradition exists at the county level. The lack of program expertise at peripheral levels, intensive staff turnover, and even corruption are additional difficulties. Hence, the simple bureaucratic transfer of activities from the Federal to county level is often irresponsible. The loss of priority for control of endemic diseases in Latin America may mean the inexorable extinction of traditional control services. Malaria, dengue fever, and Chagas disease programs are examples of the loss of expertise and effectiveness in Latin America. A better strategy for responsible decentralization is required. In particular, a shared transition involving all governmental levels is desirable to effectively modernize programs. Maintenance of regional reference centers to ensure supervision, surveillance, and training is suggested

La reforma del sector salud, descentralización, prevención y control de enfermedades transmitidas por vectores

Con las nuevas macropolíticas mundiales, la salud en América Latina ha sufrido importante transición en direción a la decentralización, sin compatibilizar la salud pública con la lógica de las economías de mercado. Con esto, el control decentralizado de las enfermedades endémicas presenta dificultades políticas y operativas. Aunque la decentralización se justifica por los presupuestos teóricos, no hay tradición de este control en los niveles municipales, lo que dificulta la simple o burocrática transferencia de encargos para estos niveles. La falta de expertise, el turn-over político y la corrupción son dificultades adicionales, conllevando a una extinción de varias instituiciones y programas. La falta de efectividad en el enfrentamiento del dengue, de la malaria y de la enfermedad de Chagas son algunos ejemplos. Requierese una modernización con responsabilidad, con una transición compartida entre los niveles y garantizada por acciones continuadas. Sugierese mantener estructuras regionales para referencia, consolidación epidemiológica, normatización, capacitación y supervisión, incluso con reserva técnica para acciones finalísticas supletivas