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

BACKGROUND: Blood donors are, in principle, healthy individuals who may be revealed as infectious for blood-borne agents by the laboratory screening process, depicting the asymptomatic burden of the disease. Therefore, monitoring hepatitis C virus (HCV)-infected donor and human immunodeficiency virus (HIV)-infected donor and associating to their demographical and behavioural characteristics may shed light on the dynamics and contemporary changes in these viruses' epidemiology. METHODS: Donors presenting repeatedly reactive HCV or HIV serology/nucleic acid testing (NAT) screening results were submitted to confirmatory testing. Confirmed positive donors were invited to return to the blood bank for notification and counselling when a follow-up sample was obtained and an interview performed to eventually disclose potential risks. HCV- or HIV-infected donors identified over 11 years of screening (2004-2015) were evaluated for demographic and behavioural parameters. RESULTS: In the period, 139 160 donations were screened, and 36 (0.025%) were found positive for HIV, stemming from 29 male and 7 female donors. Among those, eight subjects were repeat donors. A total of 95 donations were found repeatedly reactive for HCV (0.068%), obtained from 60 men and 35 women. Noticeably, in despite of a higher HCV prevalence in the donor population, the incidence of HIV among repeat donors was 10 times that of HCV (18 × 1.6/100 000 persons-year, respectively). On average, HIV-seroreactive men were found to be younger (mean = 34 years old) than women (mean = 40 years old). A total of 10 donors acknowledged sexual behaviours not previously informed, including 2 who were aware of their HIV-positive status and another 2 who admitted to be seeking HIV testing. No window period donation was verified. DISCUSSION: The majority of the HIV-infected donors are young males who deny risk factors in the interview and also ignore the confidence self-exclusion opportunity. As they may reiterate this behaviour in serial donations, use of the most sensitive laboratory testing is justified in this setting.

Absence of nonprimate hepacivirus-related genomes in blood donors seroreactive for hepatitis C virus displaying indeterminate blot patterns.

Despite intensive search, no primate homologue to the Hepatitis C Virus (HCV) has ever been found. The search for a zoonotic origin for HCV has been renewed recently when a virus, now known as non-primate hepacivirus (NPHV), with a high homology to HCV was found in dogs. A variable proportion of anti-HCV reactive blood donors submitted to the immunoblot (IB) to confirm their HCV status, present indeterminate results. The degree of homology between HCV and NPHV suggests that humans may be infected by NPHV or NPHV-like viruses. Maximum similarity between NHPV and HCV is observed in the nonstructural regions 3 and 5. Peptides representing both domains are present in IB assays, so it is reasonable to suppose that blood donors harboring such viruses may display cross-reactivity to the HCV antigenic fractions. Fifty-nine plasma samples from blood donors found reactive for anti-HCV and presenting IB indeterminate results were submitted to five distinct PCR reactions under low-stringency conditions, employing primers targeting GBV-C 5'UTR and NS3, Flavivirus-genus NS5 and NPHV 5'UTR and NS3. No amplification was obtained with all primer pairs tested except for five samples that amplified both 5'UTR and NS3 fragments from GBV-C. Unbiased next-generation sequencing may prove or rule out the existence of HCV-related viruses in IB indeterminate samples.