Safety of blood supply for infectious diseases in Latin American countries, 1994-1997.

The potential risk of acquiring a transfusion-transmitted infection by the human immunodeficiency virus (HIV), hepatitis B (HBV) virus, hepatitis C (HCV) virus, or Trypanosoma cruzi was estimated for seven South American and five Central American countries during the period 1994-1997. The estimates were based on official national reports of the number of donors, blood screening coverage, and prevalence of serologic markers for infectious diseases. Coverage of screening in 1997 was 100% in 12 and 11 countries for HIV and HBV respectively. Complete screening for HCV was reported by only one country in 1994 and by six in 1997. For T. cruzi, the number of countries with 100% screening coverage increased from two in 1994 to four in 1997. In 1994, three countries showed risk of transfusion-transmitted infections for HIV, seven for HBV, eight for HCV, and seven for T. cruzi. The risk of receiving an infected blood unit and acquiring a transfusion-transmitted infection has been reduced with time in 10 of the 12 countries due to improvements in screening coverage. In Uruguay, the risk was theoretically nil from 1994-1997 because at the beginning of the study period they already had 100% blood donor screening for all infectious diseases transmitted by blood. In 1994, Colombia and Venezuela had the highest health risk associated with blood transfusion (spreading index of 101 and 62, respectively); during the period 1996-1997, Costa Rica presented the highest figures (spreading index of 53 and 83, respectively). The analysis of the potential risk associated with transfusion of tainted blood highlights the need for continuous monitoring of the safety of blood supply.

[Health care reform, decentralization, prevention and control of vector-borne diseases]. / La reforma del sector salud, descentralización, prevención y control de enfermedades transmitidas por vectores.

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.

Transfusion-transmitted infectious diseases in Argentina, 1995 through 1997.

BACKGROUND: Assessment of the safety of the blood supply, the quality of screening procedures, and the risk of transfusion transmission of infectious diseases in any country can be estimated by reviewing the records of blood donations and screening procedures and the prevalence of serologic markers of infectious diseases. STUDY DESIGN AND METHODS: Information on blood donors, particularly the number of screened donors, and on the prevalence of serologic markers of infectious diseases was available from Argentina for 1995 through 1997. This information permitted the estimation of the risks and costs of preventing transfusion transmission of infectious diseases within the country during this period. RESULTS: Screening coverage was higher in the private sector. The proportion of donors screened for HIV increased from 84.52 percent in 1995 to 97.97 percent in 1997; in the same period, serologic screening for HbsAg increased from 83.71 percent to 98.48 percent; that for HCV from 69. 92 percent to 97.83 percent; and that for syphilis from 87.94 percent to 98.71 percent. One hundred percent of donors were screened for Trypanosoma cruzi throughout the period. The overall prevalence of HIV per year varied from 2.42 to 3.36 per 1,000 donors; that of HBV, from 5.80 to 9.76 per 1,000; of HCV, from 7.39 to 16.61 per 1,000; and of syphilis, from 5.25 to 7.65 per 1,000. The overall prevalence of antibodies to T. cruzi ranged from 36.53 to 49.20 per 1,000 donors. The overall index of the spread of infectious viral disease through blood transfusion decreased from 47. 74 per 10,000 donations in 1995 to 4.75 per 10,000 in 1997. The ratio of acquired infections to donations improved from 1:209 to 1:2, 102 during the same period. The risk of T. cruzi infection from 1995 through 1997 was, in theory, nil, given the 100-percent screening. The greatest threat to the quality of the blood supply throughout the period studied was HCV. CONCLUSION: The status of the blood supply in Argentina improved steadily from 1995 to 1997, as shown by the increase in screening coverage.

[Risk of Chagas disease through transfusions in the Americans]. / Riesgo de la enfermedad de Chagas a través de las transfusiones en las Américas.

The safety of blood transfusion depends on a country's laws, decrees and/or regulations concerning the collection, production and use of blood and blood derivatives. It also needs governmental enforcement of those instruments, as well as trained health professionals to obtain blood and produce blood derivatives, following total quality control procedures both at collection and production, and use. By 1998, all Latin American countries had laws, decrees and/or regulations that governed the production and use of blood, with the exception of El Salvador and Nicaragua. During the past six decades, economic need in Latin America has promoted migration to urban areas. Consequently, at present time, more than 60% of the population live in cities, which increases the probability of finding blood infected by Trypanosoma cruzi among donors. Unless all the blood from infected donors is discarded, the possibility of transmitting infection by transfusion remains. Moreover, infection by T. cruzi through transfusion is a potential problem in developed countries, now that tens of thousands of individuals from Latin America have migrated to the United States, Canada, western Europe, Australia and Japan. When donors are not screened for T. cruzi, the risk of transfusing infected blood is greater at higher prevalence rates of infection in the donor population; it also increases with the number of transfusions received by the recipient. In 1993, Bolivia presented the highest risk of receiving infected blood and becoming infected with T. cruzi; this country was followed by Colombia, El Salvador and Paraguay. As the coverage of HIV screening became almost universal, the probability of receiving blood infected by HIV and becoming infected was low in all countries. In the case of hepatitis B (HVB), the highest probability of infection was in Bolivia, Nicaragua and Guatemala. This probability was even greater for Hepatitis C (HVC), given the low coverage of donor screening in all countries. In absolute numbers, the highest potential for occurrence of cases of T. cruzi infection were present in Bolivia, the greatest number of HVC cases in Colombia, and the most cases of HVB in Nicaragua. Only in two countries, Bolivia and Colombia, HIV could be potentially transmitted by blood transfusion. Although the situation has improved since 1993, and 100% of donors are being screened for T. cruzi in Argentina, Colombia, Ecuador, El Salvador, Honduras, Paraguay, Uruguay and Venezuela, success will only be assured by: total enforcement of the law by governments; implementation of altruistic and volunteer blood donations, exclusively; 100% of donors are screened for communicable diseases; the collection, processing and use of blood strictly follow quality control norms; reagents used in diagnosis are adequate, and the use of blood and blood derivatives is limited to cases where it is only absolutely necessary.

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.

Risk for transfusion-transmitted infectious diseases in Central and South America.

We report the potential risk for an infectious disease through tainted transfusion in 10 countries of South and Central America in 1993 and in two countries of South America in 1994, as well as the cost of reagents as partial estimation of screening costs. Of the 12 countries included in the study, nine screened all donors for HIV; three screened all donors for hepatitis B virus (HBV); two screened all donors for Trypanosoma cruzi; none screened all donors for hepatitis C virus (HCV); and six screened some donors for syphilis. Estimates of the risk of acquiring HIV through blood transfusion were much lower than for acquiring HBV, HCV, or T. cruzi because of significantly higher screening and lower prevalence.rates for HIV. An index of infectious disease spread through blood transfusion was calculated for each country. The highest value was obtained for Bolivia (233 infections per 10,000 transfusions); in five other countries, it was 68 to 103 infections per 10,000. The risks were lower in Honduras (nine per 10,000), Ecuador (16 per 10,000), and Paraguay (19 per 10,000). While the real number of potentially infected units or infected persons is probably lower than our estimates because of false positives and already infected recipients, the data reinforce the need for an information system to assess the level of screening for infectious diseases in the blood supply. Since this information was collected, Chile, Colombia, Costa Rica, and Venezuela have made HCV screening mandatory; serologic testing for HCV has increased in those countries, as well as in El Salvador and Honduras. T. cruzi screening is now mandatory in Colombia, and the percentage of screened donors increased not only in Colombia, but also in Ecuador, El Salvador, and Paraguay. Laws to regulate blood transfusion practices have been enacted in Bolivia, Guatemala, and Peru. However, donor screening still needs to improve for one or more diseases in most countries.

Tissue-reacting immunoglobulins in patients with different clinical forms of Chagas' disease.

Antibodies against endocardium, blood vessels, interstitium, and plasma membrane of skeletal and heart muscle cells (EVI), as well as antibodies against structures from peripheral nerve (PN), were studied in serum samples from 27 individuals with negative Trypanosoma cruzi serology and 102 seropositive individuals with or without Chagas' disease from the State of Goiás, Brazil. Although significantly higher titers of EVI and PN antibodies were found in some of the seropositive individuals their presence was not correlated with the clinical symptoms and signs which characterize the chronic stage of the disease, nor with the severity of the disease.

Acetate oxidation by bloodstream forms of Trypanosoma cruzi.

Bloodstream forms of Trypanosoma cruzi had a substantial increase in respiration in the presence of acetate. Oxidation of acetate took place via the tricarboxylic acid cycle and involved an antimycin A-sensitive respiratory pathway. Oxygen uptake in the presence of acetate was a sensitive to antimycin A inhibition as was CO2 production. There was a 6--7% residual O2 uptake which was not inhibited by high antimycin concentrations. Human anti-T. cruzi sera had no effect on oxygen uptake.

Tissue-reacting antibodies (EVI antibodies) in nifurtimox-treated patients with Chagas's disease.

Antibodies reacting against endothelial cells, vascular structures, and heart and skeletal muscle cells (EVI antibodies) were studied in 10 patients (one to 14 years of age) treated with Nifurtimox. The patients were observed for several months to two years after the onset of symptoms of acute infection with Trypanosoma cruzi. Although these 10 patients were selected because after treatment their sera became negative for antibodies to T. cruzi as detected by the immunofluorescence test, sera from six patients remained positive for EVI antibodies. It is suggested that EVI antibodies may be self-perpetuated in the absence of infection. Further studies are needed to determine the pathogenic significance of EVI antibodies.

Tissue reacting antibodies in a rhesus monkey with long-term Trypanosoma cruzi infection.

Immunoglobulins (Igs) reacting against endothelial and vascular structures and striated muscle cells as well as against cells from a peripheral nerve were detected by indirect immunofluorescent test (IIF) in a rhesus monkey infected for 29 yr with Trypanosoma cruzi. Anti-T. cruzi antibodies in this monkey showed a titer of 1:128 in the IIF test and the direct agglutination test. Tissue-reacting Igs were bound in vivo to the tissues, as was established by direct treatment of a biopsy of the deltoid muscle with Ig-labeled antisera. Electron microscopy of this tissue showed that Igs reacted with the plasma membrane of the muscle cells. Neither tissue-reacting Igs nor specific antibodies were detected in three uninfected adult monkeys.

Induction of capping in blood-stage trypomastigotes of Trypanosoma cruzi by human anti-Trypanosoma cruzi antibodies.

The effect of human-specific antibody on surface membrane antigens of trypomastigotes of Trypanosoma cruzi was studied in vitro by using immunofluorescence methods. Immune sera induced aggregation of surface antigens in trypomastigotes to form polar cell caps.

Immunoglobulin concentration in treated human acute Chagas disease. A follow-up study.

Immunoglobulin M, G, and A concentrations were studied by radial immunodiffusion technique in 16 individuals (two were 16 and 14 yr of age, respectively, while the remaining 14 uere 15 yr of age or less) with acute Trypanosoma cruzi infection. Serum samples were obtained from these patients beginning with the onset of symptoms and continuing until several months after treatment with nifurtimox was completed. Soon after infection the concentration of IgM was higher than the average found in healthy children. Some of the samples also had higher values than those found in children with other acute infections. At this time isolated increases in IgG and/or IgA concentrations were also found in T. cruzi-infected patients. Immunoglobulin concentrations had usually returned to normal when treatment with nifurtimox was completed, both in the patients with negative serology and in those who remained positive. However, some of the sera showed isolated higher IgM, IgG, and/or IgA values than those found in healthy controls.