The Blood Service begins testing blood donors for hepatitis E

In mid-February, the National Institute for Health and Welfare (THL) announced that an elevated number of hepatitis E infection were observed in Finland in the beginning of the year. According to THL, most infections are likely from certain mettwurst products.

Due to the infections, the Blood Service has obtained a highly sensitive genetic amplification test in its laboratory to test for hepatitis E in blood donors. The prevalence of hepatitis E was retroactively examined from donated sample batches. According to current information, the prevalence of the hepatitis E virus in these donor samples is 1:1500, or 0.07%. In March, blood was collected from around 14,000 blood donors.

The Blood Service routinely tests donor blood for hepatitis A, B, and C, as well as for HIV, parvovirus, and syphilis. The test programme is based on regulatory requirements and on a risk assessment by the Blood Service that deemed that the aforementioned pathogens may pose a risk to the patient’s health if transmitted through blood. Hepatitis E was not previously part of the testing programme due to its low prevalence and the low risk of infection.

The transmission of hepatitis E through blood products is rare because it is mainly spread through food and it is not very infectious. Patients may not notice that they are infected with hepatitis E because they are asymptomatic or their symptoms may also be due to other causes, because hepatitis E most often resolves itself and is less likely to become chronic than hepatitis B or C.

Hepatitis E is often asymptomatic

The hepatitis E virus causes inflammation of the liver. There are different forms of the virus. In the past, hepatitis E mainly affected low-hygiene countries, where transmission occurs, for example, through contaminated water, similar to hepatitis A. In the 21st century, a subtype of the virus that occurs in humans, pigs, game animals, and others, was identified in Western countries. In Europe, the primary source of a hepatitis E virus infection is undercooked pork.

In healthy individuals, hepatitis E most often causes minor symptoms or is even asymptomatic, 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, for example patients undergoing stem cell and other transplants, and people with liver disease. Chronic hepatitis E infections are rare.

Donors infected with hepatitis E will be contacted

The Blood Service will contact all donors whose blood samples have been found to contain the hepatitis E virus. In healthy individuals, the infection is transient and requires no special intervention. Blood donors who are found to have hepatitis E will face a year’s donation deferral.
These blood products, which may potentially contain the hepatitis E virus, will be traced in accordance with the normal procedure with the hospital that used the blood product. Tracing will examine whether the hepatitis E virus was transmitted to the patient and whether it has had any effect on the patient’s treatment.

The Blood Service has informed the supervisory authority Fimea of the results of the report and that testing has begun, and it has collaborated with THL in the matter. Beginning in early April, the Blood Service will examine blood donations for the hepatitis E virus, at least until the epidemic is found to have returned to normal levels. Blood from donors infected with hepatitis E will not be further processed or forwarded.