Donor selection and microbial screening

Chagas disease

Chagas disease is the clinical condition triggered by infection with the protozoan Trypanosoma cruzi. The infection is transmitted by triatomine insects while blood feeding on a human host. Field studies predict that one third of an estimated 18 million T cruzi-infected humans in Latin America will die of Chagas disease. Acute infections are usually asymptomatic, but the ensuing chronic T cruzi infections have been associated with high ratios of morbidity and mortality: Chagas heart disease leads to unexpected death in 37.5% of patients, 58% develop heart failure and die and megacolon or megaoesophagus has been associated with death in 4.5%. The pathogenesis of Chagas disease appears to be related to a parasite-induced mutation of the vertebrate genome. Currently, treatment is unsatisfactory.

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.

Epidemiology of blood collection in France

The objectives of the cross-sectional study (EpiCoS) were to describe, at different stages, volunteers offering their blood, and to characterize various ways of collecting blood. From 15 September 1996 to 31 December 1996, individuals presenting at fixed or mobile sessions in one of 11 randomly selected blood banks were included after they had a medical examination. Variables studied were relative to type of collection, individuals, medical examination, patterns of blood letting, use of collected donations and if unused, reasons for discarding. Sixty four thousand and ninety two volunteers, aged 17-66 years old were included. The proportion of exclusion during medical examination was 10.8% (95% confidence interval (CI): 10.6-11.0%). Exclusions were more frequent among new volunteers and were mostly related to the safety of recipients. Most of the 57,003 donations were whole blood (94.0%) and collected in mobile sessions (89.9%). Five percent of collected donations were discarded; 3.5% (95% CI: 3.4-3.7%) of donations discarded for biological abnormalities, including 1.5% only for initial screen reactions to infectious disease markers (HBs antigen, anti-HBc antibodies, anti-HCV antibodies, anti-HIV antibodies, anti-HTLV antibodies, malaria antibodies and anti-syphilitic antibodies). The most frequent biological abnormality was a high alanine aminotransferase level. A follow-up of these indicators, within the French haemovigilance system, should allow further identification of risk factors and high-risk contexts, and planning means of optimizing blood collection in France.

Blood transfusion in developing countries: problems, priorities and practicalities

The acute medical services could not exist without blood transfusions--life-savers in many situations. But transfusions can also be a quick and easy route for the transmission of infectious agents such as HIV, HBV, HCV and malaria. Infection through blood supply is a major issue in all countries but particularly in those with economic constraints which limit safety. This study was carried out in India (March-May 1997) and involved centres in Delhi, Calcutta and Vellore. It examined many aspects of blood transfusion including donor screening, use of professional donors, blood testing and criteria for blood use. The many problems in Indian blood transfusion services are mirrored in other countries. Here we examine the problems, priorities and practicalities of blood transfusion particularly in developing countries.