This chapter describes the notification of confirmed positive, indeterminate and false-positive microbiological test results to donors and the circumstances and objectives of the subsequent discussion. We have based our chapters on extensive experience and describe examples of arrangements in England.
The procedures described in this chapter have been developed over many years. Historically, notification of donors with significant test results began within the National Blood Service (NBS) in the early 1970s with the introduction of routine screening for hepatitis B virus (HBV).
The introduction of screening tests for antibody to human immunodeficiency virus (HIV) throughout the UK in October 1985 initiated a more formal approach to ‘donor counselling’, and the NBS, which covers England and North Wales, now has national formal standard procedures for donor notification. The role and value of HIV counselling consultation meetings, which began in 1985, and which have now been widened to include discussion of issues relating to other microbiological markers, has also been recognized (Miller et al., 1989).
In addition, as part of the National Health Service, the NBS has excellent links with hospital clinicians and general practitioners, which facilitates donor referral to specialist services. Within England there are 12 blood centres which deal in an average year with 200–300 confirmed infections out of approximately 2 to 2.25 million blood donations (see Table 23.1).
The majority of these infections will be detected in first-time blood donors.
This chapter is primarily concerned with the investigation of reports of infection in transfusion recipients, in order to determine whether the infection was transmitted to the patient by transfusion. In addition, the question of ‘look-back’ is briefly considered. We describe our experience in the National Blood Service (NBS), England.
The NBS provides a service to England and North Wales from 12 centres sited throughout the country. All staff involved in the investigation of post-transfusion infection work to national policies and procedures which have been developed as a result of experience over the last 25 years.
The NBS is part of the National Health Service and therefore has strong links and good communication with hospital clinicians, hospital transfusion laboratories and general practitioners. Since the late 1990s there have been NBS hospital liaison staff whose role is to work closely with the hospital transfusion laboratories and hospital transfusion committees. This initiative has strengthened the flow of information and communication between the NBS and the hospitals it serves.
Reports of possible infection associated with blood transfusion may arise from a number of sources, but within the NBS all reports reach one central office which has close links with the Serious Hazards of Transfusion scheme (SHOT). (Please refer to Chapter 21) Although the investigation of possible transfusion-transmitted infection involves liaison locally with hospitals and donors, the process is managed centrally within the transfusion microbiology clinical function of the NBS and each case is reviewed at the close of the investigation.
Prion diseases include a spectrum of disorders in animals and man (see Table 9.1). Scrapie, endemic in sheep and goat populations throughout most of the world, was first recognized over 250 years ago and was demonstrated to be experimentally transmissible in 1936. Chronic wasting disease (CWD) is endemic in Rocky Mountain elk, white-tailed deer and mule deer in several areas of the USA and is increasing in both incidence and geographic distribution. The routes by which these two endemic prion diseases are transmitted remain unclear. Transmissible mink encephalopathy was first recorded to have occurred in 1947 in farmed mink in Wisconsin and was probably transmitted through prion infected food.
Bovine spongiform encephalopathy (BSE) was first recognized in the UK in 1985/86 (Wells et al., 1987). Affected cattle become apprehensive, hypersensitive, ataxic and generally difficult to handle, giving rise to the common name of mad cow disease. It remains unclear whether BSE arose spontaneously in cattle or resulted from transmission of scrapie from sheep, but onward transmission is thought to have occurred through the practice of feeding cattle ruminant-derived meat and bone meal. Over 180,000 clinical cases of BSE have been reported in the UK since 1985, though the annual incidence has now fallen to just over 100 cases per annum. Over 4500 infected cattle have been detected elsewhere, mainly in Europe, the majority associated with the export of BSE infected cattle or meat and bone meal from the UK. It is estimated that between 1 and 2 million cattle may have become infected and entered the human food chain before developing evidence of clinical disease (Donnelly et al. 2002).
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