The Fifth Disease: Parvovirus B19

What’s up with the recent CDC advisory on Parvovirus?

“A close-up of a child’s face showing a red rash on the cheek, which is indicative of erythema infectiosum, commonly known as ‘slapped cheek syndrome’ or fifth disease.”

The Centers for Disease Control and Prevention (CDC) recently issued a health alert for increased parvovirus B19 activity. Those who own dogs might think this is the parvovirus that severely affects dogs, also known as “parvo.” The two viruses are related, but B19 is exclusively human.

According to the CDC:

“Recently, CDC has received reports indicating increased parvovirus B19 activity in the United States. These reports include data from commercial laboratories of increasing parvovirus B19 test positivity by nucleic acid amplification tests and serology in the general population and increased serological evidence of infection in plasma donors. The proportion of people with IgM antibodies increased among all ages from <3% during 2022–2024 to 10% in June 2024; the greatest increase was observed among children aged 5–9 years, from 15% during 2022–2024 to 40% in June 2024. Among plasma donors, the prevalence of pooled samples with parvovirus B19 DNA >104 IU/mL increased from 1.5% in December 2023 to 19.9% in June 2024. CDC has also received anecdotal reports from clinicians who have observed more than the expected number of cases of parvovirus B19 infections among pregnant people, including cases resulting in severe fetal anemia requiring fetal…