The European Centre for Disease Prevention and Control (ECDC) recently warned that 14 countries in the European Union and the European Economic Area (EU/EEE) have seen a significant increase in parvovirus B19 (B19V) cases since March 2024.
In Denmark, parvovirus B19 infection is endemic throughout the year, with epidemics occurring approximately every 3-4 years (the most recent epidemic occurred in 2017), usually in the spring. In March 2024, parvovirus B19 in Denmark had a positive IgM rate of 5.4% and a PCR test positivity rate of 1.5%, which was 2 and 4.5 times higher than in March 2017. At present, the number of parvovirus B19 infections in Denmark in 2024 has exceeded that in 2017.
1. Parvovirus B19
Parvovirus B19 (human parvovirus B19, HPV-B19 or B19) is an unenveloped, single-stranded filamentous DNA virus. B19 virus infection is widespread in the human population, can be transmitted through the respiratory tract, blood, placenta, etc., and can occur in all ages, especially in pregnant women and children, and susceptible groups also include immunodeficiency or insufficiency patients and anemia patients.
2. Parvovirus B19 infection-related diseases and diagnosis
1) Eugenics
B19 infection in pregnant women can lead to mother-to-fetal transmission, and the probability of acute infection being transmitted to the fetus through the placenta is 17% to 33%, resulting in adverse pregnancy outcomes. About 33% of primary infections before 20 weeks of gestation are transmitted vertically through the placenta, resulting in serious fetal complications, such as fetal anemia, edema, pleural and abdominal effusion, etc., 8%-20% of non-immune edema fetuses are caused by infection with B19, and spontaneous abortion, preterm birth and stillbirth can occur in severe cases.
At present, the common methods for the detection of B19 virus infection include serological antibody detection, nucleic acid detection and antigen detection, among which B19 virus serological antibody detection is the main method for clinical auxiliary diagnosis and epidemiological investigation and research of B19 virus infection. For example, the Expert Consensus on Standardized Testing and Clinical Application of TORCH Laboratory (2020) recommends B19 infection detection, and the detection process during pregnancy is as follows.
2) Blood system
B19 infection is most commonly seen in clinical practice. In immunocompetent people, B19 infection may cause transient arrest of erythroid hematopoiesis. B19 infection in patients with hemolytic anemia (eg, hereditary spherocytosis, sickle cell anemia) may cause aggravation of anemia and even aplastic crisis. Pure red cell aplasia (PRCA) occurs in about 9% of immunocompromised patients infected with B19, and leukopenia and thrombocytopenia may also occur in 38% and 21% of patients, respectively.
For example, in the clinical diagnosis of B19 infection in kidney transplant recipients, the initial investigation for suspected B19 infection includes serology, nucleic acid testing, and viral genomic testing.
3) Erythema infectiosum (disease No. 5)
Erythema infectiosum, also known as the fifth disease, is a contagious disease caused by human parvovirus B19, which is mainly transmitted through respiratory droplets. The disease is more common in children, with the highest prevalence in children under 5 years of age, especially in winter and spring. The characteristic manifestation is that the child's cheeks are red, as if someone has been slapped, but other symptoms are not serious, including rash in other parts of the body, fever, runny nose, myalgia, and headache.
The onset is similar to that of many other viruses, so it can be difficult to diagnose early. In addition to observing the typical rash, tests such as serological B19-IgM/IgG antibody testing are required to assist in diagnosis.
4) Autoimmune diseases (e.g. arthropathy)
Symmetrical, peripheral polyarthropathy, or arthritis occurs in 40% to 80% of infected adults, particularly in women. Similar to erythema infectiosum in children, the onset of arthralgia after B19 infection in adults coincides with the timing of B19-specific IgM and IgG antibodies detected in peripheral blood.
5) Myocardial damage
Viral myocarditis caused by B19 infection may rely on the α5β1 integrin coreceptor located on the surface of coronary artery endothelial cells, resulting in abnormal coronary artery endothelial cell function, myocardial ischemia, and finally myocardial dysfunction. B19-infected myocarditis is characterized by isolated left ventricular diastolic dysfunction, often with increased coronary vascular responsiveness, myocardial ischemia, or infarction.
6) Neurological disorders
Patients with acute meningitis of unknown etiology may have peripheral and central nervous system complications, including neuralgic amyotrophy, Guillain-Barré syndrome, encephalitis, encephalopathy, meningoencephalitis, etc.
7) Liver damage
Patients with hepatitis of unknown etiology, such as isolated aminotransferase elevation without obvious symptoms, acute hepatitis, acute fulminant hepatitis, etc., are more common in children.
8) Kidney damage
B19 virus infection can lead to acute glomerular lesions, and variable focal segmental glomerulonephritis and hemolytic ureatoxin syndrome can occur.
9) Respiratory infections
The main manifestations are flu-like symptoms such as runny nose, sore throat, and muscle pain, and respiratory failure may occur in severely infected patients.
10) Other clinical manifestations
Necrotizing vasculitis, Kawasaki disease, Henoch-Schonlein purpura, giant cell motor artiitis, hock-sleeve syndrome, chronic fatigue syndrome.
Source: Weirun Sairun Information