Parvovirus B19 increasing in U.S., CDC warns. How to prevent it, recognize symptoms.

**U.S. health officials reported on Tuesday that infections from Parvovirus B19, a highly transmissible seasonal respiratory virus, have been increasing. The virus can be particularly dangerous for pregnant women and individuals with blood disorders.**

Parvovirus B19 spreads through respiratory droplets from both symptomatic and asymptomatic carriers. This summer, evidence including blood plasma samples and anecdotal reports suggests a rise in cases, prompting the U.S. Centers for Disease Control and Prevention (CDC) to issue a broad warning to healthcare providers, health agencies, and the public.

According to the CDC's alert, the proportion of individuals testing positive for antibodies—indicative of recent infection—has risen across all age groups. The rate of immunity increased from under 3% in 2022 to 10% by June 2024. The most significant rise has been observed in children aged 5 to 9. Plasma samples from donors revealed an increase in virus DNA prevalence, jumping from 1.5% in December to 19.9% in June. Additionally, there have been growing reports of complications among pregnant women and those with sickle cell disease. Europe also experienced "unusually high numbers of cases" in the first quarter of 2024.

Parvovirus B19 is highly contagious, with about 50% of those exposed in a household contracting the virus, a trend also seen in schools during outbreaks. Most infections are mild, with symptoms such as fever, headache, cough, and sore throat. Children may develop a characteristic "slapped cheek" rash after initial flu-like symptoms, while adults might experience painful and swollen joints lasting one to three weeks.

For individuals with blood disorders or weakened immune systems, Parvovirus B19 can lead to severe anemia. High-risk groups include people with leukemia, other cancers, organ transplant recipients, those with HIV, and individuals with sickle cell disease or thalassemia. Severe outcomes are rare but can include myocarditis (inflammation of the heart muscle), encephalitis (brain inflammation), and hepatitis.

Pregnant women who contract the virus can potentially pass it to their babies, which in rare cases may result in miscarriage.

The U.S. lacks routine surveillance for Parvovirus B19, and it is not a reportable condition. There is no vaccine or specific treatment available. Previous infection is believed to provide lifelong immunity, according to the Mayo Clinic. Preventive measures include regular hand-washing, avoiding touching the face, and not sharing food. Masks can also help reduce transmission, similar to other respiratory illnesses.