Human parvovirus B19 cases in the U.S. are increasing, especially among children, according to a new advisory from the Centers for Disease Control and Prevention (CDC).
Parvovirus B19 is a highly contagious respiratory virus also known as fifth disease. While many people have mild or no symptoms, certain high-risk groups can become seriously ill.
The U.S. does not have routine surveillance for parvovirus B19, but commercial laboratory data indicate the proportion of people with antibodies increased from less than 3% in 2022-’24 to 10% in June 2024, according to the CDC advisory. Children ages 5-9 years with antibodies increased from 15% to 40% during that time. The rate of parvovirus B19 in pooled samples from plasma donors increased from 1.5% in December 2023 to 19.9% in June 2024. In addition, the CDC has been receiving reports from clinicians of increasing infections among pregnant people. Earlier this year, public health officials in 14 European countries also observed unusually high case counts.
Typically, the first phase of illness lasts about five days and consists of fever, myalgia and malaise. People who are infected are most contagious during this time, according to the CDC. In the second phase of illness, children may present with the characteristic facial rash known as “slapped cheek” rash, which may be followed by body rash or joint pain. In immunocompetent adults, the most common symptoms in the second phase include a reticular rash on the trunk and joint pain.
By age 20, about half of adults have detectable antibodies that are thought to protect against reinfection. People without this immunity who are pregnant, immunocompromised or have chronic hemolytic disorders can experience more serious health consequences, and pregnant people can transmit the infection to their fetus.
There are no vaccines or specific treatments for parvovirus B19. The CDC made the following recommendations for clinicians.
- Have increased suspicion for parvovirus B19 among people with compatible symptoms.
- Provide preventive counseling and have a low threshold to test people who present with signs and symptoms if they are at higher risk of severe disease, including pregnant people, people with severely immunocompromising conditions, people who are receiving chemotherapy and people with chronic hemolytic blood disorders.
- Inform people with suspected or confirmed parvovirus B19 or their caregivers about the need for exposed high-risk contacts to consult their health care provider.
- Follow standard of care for testing pregnant people who have been exposed or have symptoms of maternal or fetal parvovirus B19 disease.
- Promote CDC recommendations to prevent respiratory illness.
- Follow recommended infection control precautions for people with parvovirus B19 in health care settings.
The public should learn about parvovirus symptoms and risk factors for severe disease. Those at higher risk of severe disease should seek medical care if they have been exposed or have symptoms. Everyone should follow general respiratory precautions, which may include wearing a mask for people at higher risk of severe disease.
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