Serious cases of parvovirus B19 infection in children and cases of death, mainly in newborns due to maternal infection during pregnancy, are recorded by the European Center for Disease Control (ECDC) from the end of 2023 to the first quarter of 2024, in several European countries. Recently in our country, a 3.5-year-old child died after being infected with parvovirus B19.

Stylianos Asimakopoulos, Professor of Pathology – Infectious Diseases, Department of Medicine, University of Patras, head of the Special Infectious Diseases Unit of the University Hospital of Patras, member of the Hellenic Society of Infectious Diseases, answers all questions about parvovirus B19.

What is parvovirus (Parvovirus B 19) and what is the geographical, age and seasonal distribution of the infections it causes?

Parvovirus B19 (Parvovirus B19) is the best-known member (genotype) of the erythroparvovirus genus, which take their name from the special “love” they have for attacking the precursor cells of red blood cells. Parvovirus B19 affects only humans and not animals (e.g. dogs and cats) as is the case with other parvoviruses. Parvovirus B19 infection usually occurs in the spring and early summer and can occur in any area of ​​the world with cases of infection, either sporadically, or in the form of sporadic outbreaks or even small local outbreaks, such as in school units , where 25-50% of students can be affected. Local epidemics or sporadic outbreaks may follow cycles of recurrence every 4-10 years. The virus infects the population mainly at school age, so that by the age of 15 half of the teenagers have been infected by the virus. In later adulthood, this percentage reaches 60-70% and in advanced age 80-90% of people have been infected by the virus.

Is there an increase in cases of parvovirus infection?

The European Center for Disease Control (ECDC) in its recent report (April 2024) indicates a significant increase in cases of parvovirus B19 infection from the end of 2023 to the first quarter of 2024 in several European countries (France, the Netherlands, Ireland, Denmark , Norway). Although in many European countries parvovirus B19 infection is not a disease under systematic surveillance, the available data show an increase in infections in all age groups. Consequently, there has been an increase in serious cases of parvovirus infection in children and cases of death, mainly in newborns due to infection of the mother during pregnancy, which led to infection of the fetus (congenital infection). The observed increased circulation of the virus in the community puts at risk certain population groups such as pregnant women (for adverse pregnancy outcome, especially if the infection occurs in the first 20 weeks), patients with hemoglobinopathies and the immunosuppressed.

How is the virus spread?

Parvovirus B19 is mainly transmitted through respiratory secretions (with large droplets that reach a radius of 2 meters), so it requires close contact with a person who has an infection, or contact with infected surfaces and then transferring the virus with hands to the nose, eyes and mouth and causing infection. A sick person is most contagious in the early stages of the disease, when they have a fever and symptoms of a respiratory infection, while in the later stages, such as when the rash of the disease appears, they are much less or not at all contagious. Parvovirus B19 can also be transmitted through blood (increased risk in people with frequent transfusions and intravenous drug users) and from the pregnant mother to the fetus with a risk of fetal complications when transmission occurs in the first 20 weeks of pregnancy .

What are the symptoms of parvovirus B19 infection?

Parvovirus B19 causes erythema infectiosum (also known as fifth disease) in children and adolescents because it is classified among the five classic childhood diseases that manifest with a rash (measles, rubella, mumps, scarlet fever). There is a fever and symptoms of a viral infection (headache, sore throat, cough, nasal congestion, conjunctivitis) and a characteristic rash that starts on the face and resembles “slapped” cheeks, while there is relative pallor around the mouth. It then extends to the extremities (with a glove-sock type peripheral distribution), the trunk and the buttocks. The rash has a maculopapular or purpuric morphology, while after a few days some areas clear and a reticular (or lacy) pattern remains. The rash may persist for several weeks with flare-ups. The virus can also cause joint pain (mainly in adults, rarely in children). About 20% of those infected with parvovirus B19 will have no symptoms at all, while the vast majority will become mildly ill, as in an uncomplicated virus.

What are the complications of parvovirus B19? Parvovirus B19 infection can cause severe anemia, since, as mentioned, this particular virus likes to attack the stem cells of our red blood cells, so their production stops in the early stages (red cell aplasia). Anemia is usually severe and requires blood transfusions until the body can deal with the infection. Prone to this complication are people suffering from hereditary hemoglobinopathies (sickle cell anemia, spherocytosis, β Mediterranean anemia). Chronic infection and anemia may develop in severely immunosuppressed individuals (transplant recipients). Another serious complication concerns pregnant women and causing damage to the fetus, especially in the first 20 weeks of pregnancy. The percentage of pregnant women who are not immune to the virus and may become ill during pregnancy is estimated at 30%-40%. Affecting the fetus can cause severe anemia in the developing fetus (hydrops fetalis), heart damage, and spontaneous abortion in about 5-10% of cases.

How is the disease diagnosed and what is the treatment?

The suspicion of parvovirus B19 disease is raised by the doctor based on the clinical picture and the characteristic rash, while the diagnosis is confirmed with a special serological blood test to detect antibodies against the virus, or with a molecular blood test to detect its genetic material virus (PCR). There is currently no antiviral treatment or vaccine available. Mild forms are treated symptomatically with painkillers-antipyretics, good hydration and rest. In case of arthritis, anti-inflammatory drugs are administered. The severe forms of the disease and the complications are treated by hospitalization of the patient and support with transfusions, if severe anemia (aplastic crisis) has developed, while in some cases immunological treatments are also administered.

What are the preventive measures?

In the absence of a vaccine, prevention measures focus on avoiding close contact with sick people and following strict hygiene rules, such as regular hand washing with soap and water, especially after contact with shared surfaces, and avoiding sharing food or of drinks. Those who are sick should stay home while they have a fever (contagious stage) and cover their mouth and nose when they cough or sneeze to avoid spreading and transmitting the virus. Pregnant women with high-risk occupations (e.g. workers in the health sector, daycare centers, schools, etc.) must be particularly diligent in observing the above. Because the risk of contracting the virus is similar in the community, it is not recommended to abstain from work. Exclusion from work as a measure to prevent parvovirus B19 infection in seronegative pregnant women and up to the 21st week of pregnancy can be applied in cases where a confluence of cases occurs in the workplace (2 or more cases in patients or hospital staff within three weeks, or 2 cases in the same class or three in the same school unit in a period of three weeks). In hospitals, hospitalized patients with severe disease (aplastic crisis) should preferably be hospitalized in a single room (isolation) for one week and immunosuppressed patients with chronic infection for their entire hospitalization period, while the medical and nursing staff treating them will must take contact precautions (hand wash, apron, mask, goggles, gloves). For the rest of the non-immunosuppressed patients, there is no need for isolation, but precautions are taken by the staff for contact with droplets.