Contrasting HCV and HIV seroepidemiology in 11 years of blood donors screening in Brazil

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Historically, blood banks have been an important source of data on the epidemiology of infectious agents for which screening is performed routinely. A drawback in the use of such data is the difference between donors and the general population. As donors exclusively comprise persons between 16–18 years old and 60–65 years old, they provide a partial portrait. More importantly, donors undergo a pre‐donation screening interview where those with clinical and/or epidemiological risk of blood‐borne agents are refrained from donating. Clearly, several rounds and years of donors' selection lead to a marked reduction of infectious markers on the donor population when compared to the general public. This is well illustrated by the situation in South Africa where the human immunodeficiency virus (HIV) prevalence is one of the highest in the world, approximately 15%, whereas among repeat blood donors, it is at least 100 times lower (Vermeulen et al., 2009). Another issue is the low positive predictive value of screening tests in a healthy population, meaning that blood bank seroprevalence data are always overestimates and shall represent true prevalence exclusively when reactive donations are confirmed by supplementary tests of higher specificity, for instance, the Western blot for HIV.
Antibody detection was essential in reducing the transfusion transmission (TT) risk of both the hepatitis C virus (HCV) and HIV Perkins & Busch, 2010). Interestingly, mandatory screening of HCV in blood banks is thought to have played a role in reducing HCV burden in the US population (Klevens et al., 2012) by virtually eliminating TT while disclosing infected subjects (donors) whom, under counselling, may avoid transmitting HCV to householders and partners and seek treatment. In contrast, reducing HIV TT has had little effect on the overall prevalence of this agent due to the weight of sexual transmission on general epidemics (Custer et al., 2015).
As the target of a 100% safe blood supply is pursued, although not realistically achievable, nucleic acid testing (NAT) was added to the screening menu in order to prevent the few TT cases caused by window‐period donors (Roth et al., 2012). Different from most countries, where NAT for HCV and HIV were introduced at the beginning of the millennium, in Brazil, NAT became mandatory only in 2014. However, a few centres voluntarily introduced NAT much earlier, including our service at the Hospital Israelita Albert Einstein (HIAE) in São Paulo, which started molecular screening in 2002.
HIAE is a private, non‐profit, organisation of approximately 650 beds. It is a general hospital offering a broad range of health services for clinical and surgical specialties, including high complexity services and maternity, performing specialised procedures, such as liver and bone marrow transplantations. The blood bank service collects circa 1000 donations per month and transfuses approximately the same number of units. A total of 11 years of serological and molecular screening for HCV and HIV allowed gathering a significant piece of data described and discussed as follows.

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