Viral blood donor testing for hepatitis E to stop as epidemic subsides

29.11.2024

In March, the Finnish Red Cross Blood Service began to test blood donor samples for the hepatitis E virus after a higher rate of hepatitis E infections were observed in Finland. After discussions with the Advisory Board on Communicable Diseases and the Finnish Medicines Agency Fimea, the Blood Service will stop testing for hepatitis E as the epidemic has subsided. In the event of new outbreaks of hepatitis E, the Blood Service will have the ability to quickly resume testing.

Sample tubes in Blood Service laboratory

In mid-February, the National Institute for Health and Welfare (THL) announced an outbreak of hepatitis E in Finland. Similar hepatitis E viruses to those detected in patient samples were found in the mettwurst sausages of a domestic manufacturer. A donor who contracted the virus from food could transmit the virus onwards through donated blood to recipients, which raised concerns in the Blood Service.

Due to the epidemic, the Blood Service began testing blood donors for hepatitis E in the spring to ensure the safety of blood products and to do its part to ascertain the extent of the epidemic. Blood donors are not required to be tested for hepatitis E in Finland, and no testing requirements were presented to the Blood Service as a result of the epidemic. Nevertheless, the Blood Service obtained tests and initiated testing on its own initiative.

Hepatitis E virus was found in blood donors during the epidemic

Testing blood donors for the Hepatitis E virus proved necessary, as samples from blood donors tested during the epidemic from February to April revealed the virus in a total of 31 cases. The donors were asymptomatic or had mild symptoms and were informed about the virus only after the Blood Service contacted them.

Tests implemented in late March ensured that any hepatitis E infection in the donor could not be passed to patients through blood products. In general, people infected with hepatitis E will recover completely and not be carriers of the virus. However, in immunocompromised patients, hepatitis E contracted via blood transfusion can cause severe symptoms.

Additionally, the Blood Service investigated the prevalence of the Hepatitis E virus in blood samples donated between mid-February and the end of March. The blood products made from these donations had mostly already been transferred to patients. The investigation showed that Hepatitis E can be transmitted through blood, as the Blood Service received seven reports of suspected transfusion-transmitted Hepatitis E virus infections. In five of these cases, the blood product was considered a likely or possible source of infection.

The prevalence of Hepatitis E clearly decreased in the summer, with only one positive sample per month. From September to November, there has been only one Hepatitis E-positive donor sample in total, which corresponds to the prevalence level of Hepatitis E in Finland before the epidemic.

Testing programme to resume if necessary

The Blood Service has requested the opinions of the Advisory Board on Communicable Diseases, the authority supervising the Blood Service, i.e. Fimea, and specialist doctors at hospitals on the need for testing for hepatitis E. The general view is that ongoing testing for hepatitis E is not necessary in a situation where the incidence of the virus is very low in the population.

The Advisory Board on Communicable Diseases found that the ongoing hepatitis E testing of blood donated in the current epidemic situation is not an effective use of national resources when taking the cost of the testing into account. However, the Advisory Board emphasised that the hepatitis E epidemic should be closely monitored, and if signs of a new epidemic are found, the testing of donated blood should be resumed without delay.

As a result, the Blood Service will stop testing blood donors for hepatitis E as of 2 December 2024. The same applies to stem cell donors, who were also tested for the presence of the Hepatitis E virus during the epidemic, without any findings. At the same time, the Blood Service will prepare to quickly resume testing if the incidence of the virus increases and new epidemics occur.

What is the hepatitis E virus?

The hepatitis E virus causes inflammation of the liver. There are different forms of the virus. Hepatitis E is common in countries with low hygiene standards, where infection occurs, for example, through contaminated water. In the 21st century, a viral genotype has been identified in Europe that occurs in humans as well as in pigs and wild animals. In Europe, the primary source of hepatitis E virus infection is undercooked pork.

In healthy individuals, hepatitis E most often causes minor symptoms or even occurs asymptomatically, and resolves spontaneously. A carrier of the virus may not even know that they are infected. However, the European form of hepatitis E can cause severe liver inflammation in people with impaired immunity, such as patients undergoing stem cell or organ transplants, and people with liver disease. Chronic hepatitis E infections are rare.