The Centers for Disease Control and Prevention (CDC) issued a health advisory this week to health care providers and the public following a rise in parvovirus B19 cases.
“In the first quarter of 2024, public health authorities in 14 European countries observed unusually high numbers of cases of parvovirus B19,” the CDC said in its alert. “Recently, CDC has received reports indicating increased parvovirus B19 activity in the US.”
Here’s what you need to know about the contagious virus, how it is spread and treated and who is at high risk.
What is parvovirus B19?
Parvovirus B19 is a seasonal virus spread through respiratory droplets, i.e. coughing and sneezing by people who are symptomatic or asymptomatic.
It’s called “fifth disease” because it’s part of a group of childhood illnesses that cause a rash, like measles and scarlet fever.
A blood test can check for antibodies to parvovirus B19, indicating current or past infection, susceptibility or immunity.
How does parvovirus B19 spread?
The virus is highly transmittable. According to the CDC, 50% of people are infected after household exposure, while 20% to 50% of students and staff are infected during school outbreaks.
Antibodies from previous infections are thought to prevent and protect against future infection. According to the CDC, by age 20, 50% of adults have these antibodies, and by age 40, that number jumps to 70%.
Parvovirus B19 infection can also be transmitted during pregnancy from the mother to the fetus and via blood and plasma transfusions, though transfusion-associated parvovirus B19 infection is extremely rare.
What are the symptoms of parvovirus B19?
Symptoms of parvovirus B19 are usually mild and may include:
- Fever
- Headache
- Cough
- Sore throat
- Rashes
- Joint pain
Many people who contract parvovirus B19 exhibit no symptoms.
Those with symptoms experience them in two phases. Phase one develops about a week after infection — it’s characterized by fever, muscle pain, sore throat and fatigue. During this phase, which lasts approximately five days, people are most contagious as viral loads (the measure of infectiousness) in spit and respiratory secretions peak.
During phase two, roughly seven to 10 days after phase one, children with parvovirus B19 often display a telltale facial rash, sometimes followed by joint pain and/or a mottled body rash. In healthy adults, the most common symptoms occur during the second phase, including joint pain and a mottled rash on the torso.
Typically, when a facial or body rash is present, the person is no longer contagious.
How is parvovirus B19 treated?
There is no vaccine or specific treatment for parvovirus B19.
Most people who contract parvovirus B19 do not require medical treatment and will recover completely. Severe outcomes, such as myocarditis, hepatitis or encephalitis, are rare.
Most cases of fetal parvovirus B19 infection during pregnancy resolve without negative outcomes. However, there is a 5% to 10% risk of fetal anemia or miscarriage when infection occurs in the mother between weeks 9 and 20 of pregnancy.
Treatment for infection in the pregnant woman includes monitoring for and addressing severe fetal anemia.
What to do if you think you have parvovirus b19
In healthy individuals, parvovirus B19 typically resolves itself without medical assistance. However, the CDC urges people to seek medical care if they are pregnant and are experiencing symptoms or have been exposed to a person with suspected or confirmed parvovirus B19.
People with compromised immune systems, including those with chronic hemolytic blood disorders, such as sickle cell disease, thalassemia and hereditary spherocytosis, are also urged to seek medical care if signs and symptoms of parvovirus B19 present themselves.
