The hepatitis E virus (HEV) causes acute hepatitis, which can progress to chronicity in immunosuppressed patients. Although it is transmitted mainly by the fecal-oral or zoonotic routes, there is current evidence that it can be transmitted by blood transfusions. An increasing number of cases of transfusion-transmitted HEV had been reported in Europe and Asia. The majority of HEV viraemic blood donors have been reported to be asymptomatic and seronegative for anti-HEV antibodies (IgM and IgG) at the time of donation. Besides, it is postulated that asymptomatic HEV carriers could play a potential role as human reservoirs, and the virus can be transmitted by asymptomatic carriers or before the onset of the acute phase of hepatitis E in cases with symptomatic outcome. In response to a threat posed by HEV for transfusion safety and related public, political and reputational concerns, some countries from Europe have implemented universal or selective screening of blood donations for the presence of HEV RNA, and others are considering so.
In South America, where the circulation of HEV-3 is well known (detected in humans, pigs, wild boars and environmental matrices), and some detections of HEV-1 have been performed, most of studies about HEV in blood banks have been carried out detecting HEV antibodies and with the aim of describing the prevalence in healthy adult population. Two recent investigations have reported the presence of viral RNA in blood donors from Brazil and Uruguay, positioning blood-borne transmission as a possible threat for acquiring HEV in South America.
A recent study led by Dr. María Belén Pisano investigated HEV infections in blood donors in Argentina, within the framework of a hemovigilance program. They studied the presence of IgG anti-HEV and HEV RNA in serum samples from a blood bank from Cordoba, central area of the country. The team found an IgG prevalence of 3.47% and HEV RNA was found to be present in the 0.18% of the studied donors, without serological evidence of infection.
In Argentina, as well as in all South America, no post-transfusion HEV cases have yet been reported, although very few investigations have been carried out in this regard, and, as a consequence, the epidemiological scenario of HEV circulation and infection is not entirely clear. The finding of HEV RNA in the absence of HEV antibodies, together with previous detections in the continent, highlights the possibility of transfusing blood with HEV and the consequent transfusion-transmitted hepatitis E to the recipient.
The results of this study suggest that HEV could represent a threat for transfusion safety in the region and show the importance of consider HEV screening in blood banks. Since transmission of HEV through blood transfusion could only occur when donors are viraemic, the implementation of molecular assays to screen blood samples should be the best option, although it would mean a high cost. Grouping by pools would probably be an appropriate option for HEV screening in places where cost-effectiveness should be evaluated, together with the screening in populations at high risk of developing chronic hepatitis E. Performing larger studies in blood banks, including surveillance of HEV, the follow up of positive blood donors, as well as recipients of positive HEV blood, would provide relevant information to clarify the importance of transfusion-transmitted HEV in Argentina and the entire region, and will help answer the initial question about the threat that HEV could pose to transfusion safety in the region.
Read the full article (Travel Med Infect Dis. 2022 May 10;48:102355.) DOI: 10.1016/j.tmaid.2022.102355
