Between 2022 and 2024, only around 3 percent of the U.S. population had immunoglobulin M (IgM) antibodies to parvoviruses, indicating that only that amount of the population had been infected with parvovirus. But in June 2024, the number grew to 10 percent.
IgM antibodies are immune proteins the body produces after a recent encounter with a virus or bacteria.
Children aged 5 to 9 had the most significant increase in infections, rising from 15 percent to 40 percent.
Parvovirus B19 is a seasonal respiratory virus; infections usually occur in late winter, spring, and early summer. The virus is highly contagious and transmitted through respiratory droplets, nasal mucus, and saliva.
Around half of American adults are expected to have antibodies to the virus by age 20.
There is no routine surveillance for parvovirus B19 in the United States. The CDC detected the rise in cases after receiving reports from commercial laboratories noting an increase in parvovirus B19 test positivity. The surge has also been detected in samples from plasma donations.
Doctors have also reported anecdotally to the CDC more than the expected number of cases of parvovirus B19 infection in pregnant women. Some cases have resulted in pregnancy loss or severe fetal anemia requiring blood transfusions. There has also been a related increase in anemia in people with sickle cell disease.
2 Phases of Disease
Parvovirus B19 is a common and generally mild infection in people who are otherwise healthy.Most people infected will be asymptomatic or have mild symptoms. In people showing symptoms, there are usually two phases of the disease.
The first phase mimics a regular fever. A person enters this phase, characterized by fever, body pains, and malaise, about seven days after infection. The phase generally lasts about five days, during which people are the most contagious.
A rash appears about seven to ten days after the first phase. Children often present with a facial rash with a “slapped cheek” appearance and may develop joint pain one to four days later.
Facial rashes typically do not appear until the viral load has decreased. Therefore, people with rashes tend to be less contagious.
Most healthy adults tend to display symptoms in the second phase and may experience a rash on their trunks and joint pain.
In rare cases, parvovirus infections can cause serious health complications that affect the nerves, joints, or blood system.
Rare neurological complications include encephalitis, meningitis, and Parsonage-Turner syndrome. Some patients may develop arthritis.
Parvovirus infections can cause a sudden drop in blood count, also known as anemia, in people with certain blood disorders and those immunocompromised. People with blood disorders like sickle cell disease and thalassemia are particularly at risk.
Parvovirus can also cause myocarditis, though rare.
Treatment and Prevention
There is currently no treatment or vaccination recommended for parvovirus. Symptoms will generally resolve within a few days.The CDC recommends practicing good hand hygiene and improving ventilation to reduce the spread of parvovirus.
People at higher risk of severe outcomes or complications who work in environments with a high risk of parvovirus B19 exposure should also consider avoiding sharing food or drinks and wearing a respirator or mask while at work, the CDC wrote in the alert.
Copy
