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During the last 25 years the safety of blood products has improved dramatically with regard to infectious risk, notably to the threat represented by retroviruses (HIV and human T‑cell lymphotropic virus) and hepatitis B and C viruses. However, both residual and emergent viral infections are still responsible for contaminations in recipients of blood products. Along with other viruses (human herpesvirus‑8, human parvovirus B19, hepatitis A and E viruses, etc.), special attention has recently been paid to emerging arboviruses, such as West Nile virus in North America, and Dengue and Chikungunya viruses in Europe. Another blood‑linked risk, notably in the United Kingdom and France, is the prion agent responsible for the variant form of the Creutzfeldt‑Jakob disease. Hemophilia care has been the model for improvements in the safety and availability of safe blood components free of infectious agents. In this regard, several measures aimed to halt transmission of viruses have been implemented in blood banks, including the exclusion of at‑risk donors, specific sensitive diagnostic tests, leukocyte reduction of labile blood products, and the physical or chemical treatments aiming at nonspecific inactivation of infectious agents potentially present in blood without impairing significantly its physiological properties.

The use of blood donor history and state-of-the-art FDA-licensed serological and nucleic acid testing (NAT) assays have greatly reduced the "infectious window" for several transfusion-transmitted pathogens. Currently transmission of human immunodeficiency virus (HIV), Human T-cell Lymphotropic Virus (HTLV), hepatitis viruses and West Nile Virus are rare events. The seroprevalence of cytomegalovirus in the donor population is high and cytomegalovirus infection can cause significant complications for immunocompromised recipients of blood transfusion. Careful use of CMV seronegative blood resources and leukoreduction of blood products are able to prevent most CMV infections in these patients. Currently, bacterial contamination of platelet concentrates is the greatest remaining infectious disease risk in blood transfusion. Specialized donor collection procedures reduce the risk of bacterial contamination of blood products; blood culture and surrogate testing procedures are used to detect potential bacterially contaminated platelet products prior to transfusion. A rapid quantitative immunoassay is now available to test for the presence of lipotechoic acid and lipopolysaccharide bacterial products prior to platelet transfusion. Attention has now turned to emerging infectious diseases including variant Creutzfeldt-Jakob disease, dengue, babesiosis, Chagas' disease and malaria. Challenges are presented to identify and prevent transmission of these agents. Several methods are being used or in development to reduce infectivity of blood products, including solvent-detergent processing of plasma and nucleic acid cross-linking via photochemical reactions with methylene blue, riboflavin, psoralen and alkylating agents. Several opportunities exist to further improve blood safety through advances in infectious disease screening and pathogen inactivation methods.

Background: Plasma fractionators have implemented many improvements over the past decade directed toward reducing the likelihood of pathogen transmission by purified blood products, yet little has been published attempting to assess the overall impact of these improvements on the probability of safety of the final product., Study Design and Methods: Safety margins for human immunodeficiency virus (HIV), hepatitis C virus (HCV), hepatitis B virus (HBV), hepatitis A virus (HAV), parvovirus B19, and variant form of Creutzfeldt-Jakob disease (vCJD) were calculated for the two fibrin sealants licensed in the United States and for thrombin. These products were selected because their use in a clinical setting is, in most cases, optional, and both were relatively recently approved for marketing by the US Food and Drug Administration (FDA). Moreover, thrombin and fibrinogen both undergo two dedicated virus inactivation steps and/or removal steps in accord with the recommendations of regulatory agencies worldwide. Safety margins were determined by comparing the potential maximum viral loads in contaminated units to viral clearance factors, ultimately leading to the calculation of the residual risk per vial., Results: The residual risk of pathogen transmission per vial was calculated to be less than 1 in 10(-15) for HIV, HCV, HBV, and HAV for both fibrinogen and thrombin. Owing to the greater quantities that can be present and its greater thermal stability, the calculated risk for parvovirus transmission was 1 in 500,000 vials for fibrinogen and less than 1 in 10(7) per vial for thrombin. Assuming that vCJD is found to be present in plasma donations, its risk of transmission by these purified and processed plasma derivatives would appear to be very low., Conclusions: The pathogen safety initiatives implemented by plasma fractionators over the past 10 to 20 years have resulted in products with excellent pathogen safety profiles. Of the agents examined, parvovirus continues to have the lowest calculated margin of safety. Despite this, parvovirus transmissions should be rare. Manufacturers are encouraged to continue exploring processes to further enlarge parvovirus safety margins and to continue exploring ways of eliminating prions.

Background: The risk compensation theory is a widely used concept in transport economics to analyze driver risk behaviour. This article explores the feasibility of applying the theory in blood transfusion to raise important questions regarding the increased blood safety measures and their possible effects on blood usage (e.g., the appropriateness in transfusion). Further, it presents the findings of a pilot survey of physicians in Canada., Discussion: While studies have attempted to define transfusion appropriateness, this article argues that if the risk compensation theory holds true for transfusion practice, physicians may actually be transfusing more. This may increase the possibility of contracting other unknown risks, such as the variant Creutzfeldt-Jakob Disease (vCJD), as well as increasing the risk of non-infectious transfusion risks, such as transfusion reactions., Summary: A much larger study involving psychosocial assessment of physician decision making process to fully assess physician behaviour within the context of risk compensation theory and transfusion practice in Canada is needed to further explore this area.

The new variant form of Creutzfeldt-Jakob Disease (vCJD), which has been diagnosed in about 100 patients--mostly in the United Kingdom (UK)--is considered to be associated with the consumption of beef contaminated with the agent bovine spongi-form encephalopathy (BSE). Although no cases of vCJD have been reported until now in the Netherlands, large quantities of beef have been imported from the UK in previous years; furthermore about 17 cattle with BSE have been detected in the Netherlands. Concern about the possible transmission of vCJD via blood and blood-products has led to a number of countries taking precautionary measures. Following questions raised by the Minister of Health, Welfare and Sport, the Health Council of the Netherlands issued a report to address the need for certain precautionary measures such as the leukodepletion of blood and the exclusion of donors at risk for vCJD. The Health Council recommends the routine leukodepletion of cellular blood components. The exclusion of donors who have resided in the UK for six or more months during the period 1980-1996, was considered to be insufficient to contribute to risk reduction. The Minister has recently decided to follow these two recommendations. However, she is of the opinion that the Health Council's recommendation to exclude all donors who have previously been transfused with cellular blood components is unnecessary. A common European position regarding such precautionary measures is deemed to be necessary. This would allow the exchange of blood components between countries and would also prevent donors, patients and the public at large from being confused or uncertain about the safety of blood components.

The impact of improved safety on maintaining a sufficient blood supply is becoming an increasingly real issue facing the National Blood Service in England and North Wales. This paper shows the extent of the impact that safety measures can have on reducing collection levels, without making any value judgement on the safety critera themselves. It demonstrates that underlying trends in collection are making it increasingly difficult to meet demand. Further potential restrictions, perhaps associated with variant Creutzfeldt-Jacob disease (vCJD), will require a reassessment of the safety-sufficiency trade-off. The analysis strongly suggests that continual enhancement of safety criteria, for both individual donor and patient benefit, will lead to insufficient supply to meet current levels of hospital demand. New approaches are needed to effectively manage blood throughout the supply chain, thereby ensuring sufficient supply.

Blood is defined as a 'drug' under the Drugs and Cosmetics Act. The Standard of drugs is laid down in the Indian Pharmacopoeia. The first step towards blood safety is to encourage blood donations, which are voluntary, non-remunerated and obtained from low-risk and regular donors. A regular donor is one who donates blood two to three times a year and continues to donate at least once a year. Over the last 8 years, the Drug Control Authority has been taken up many steps to improve the quality of blood in circulation. As a result, blood centres are now equipped with minimum modern tests for making blood safer. The inspectors are also emphasising the need to employ uniform procedures for donor selection, donor deferral, validation of equipment, and so on. Over the last 5 years, quality control of diagnostic kits prior to their registration and marketing have been streamlined to ensure that blood centres use highly sensitive kits while testing for blood transmissible diseases. Therefore, current methods of donor screening and testing of donated blood have led to a remarkable decrease in the incidence of transfusion-transmitted infection and a blood supply that is very safe. The greatest threat to blood safety is donation by seronegative individuals during the infectious window period when they are undergoing seroconversion and infection cannot be detected by available laboratory tests. Look-backs is the process whereby blood collection facilities attempt to indentify prior recipients of blood donated by individuals who subsequently test positive TTD. This alone can assure safety.

Bio Products Laboratory (BPL), the main fractionator of plasma-derived medicines, are undergoing a change from UK plasma to plasma from the USA. BPL aim to maintain continuity of supply and a seamless changeover, despite meticulous cleaning of its production plant and months of auditing by both the organization and regulatory authorities.

Selection of donors is an important means to improve the overall safety of the blood supply. Since the AIDS epidemic emerged and after the introduction of sensitive screening tests for HIV, it became clear that blood donations given in the infectious 'window' period, formed the most important risk for recipients of blood products. Therefore, selection criteria became more and more stringent to exclude these high risk donors. Means to exclude high risk donors are non-remuneration, including a clear policy to provide no incentives which can be readily converted to cash, the avoidance of replacement donations, the discouragement of 'HIV test seeking' donors, education and information of donors about HIV and other blood-borne infectious diseases and the in depth questioning about risk behaviour, orally as well as by questionnaires. Although this policy of donor selection is recognized by most blood centers in the world, the efficacy of this selection has not been well documented. Therefore in future, studies should be performed to base these selection criteria on evidence.

The Food and Drug Administration (FDA) is announcing the availability of a guidance document entitled "Revised Precautionary Measures to Reduce the Possible Transmission of Creutzfeldt-Jakob Disease (CJD) by Blood and Blood Products," dated December 11, 1996. The guidance document is intended to provide recommendations to the blood industry and may include information useful to other interested persons.

Considers the legal and ethical obligations of blood suppliers to warn recipients of blood products about possible contamination of the blood supply with Creutzfeldt-Jakob disease, a rare but fatal neurological disease.