The U.S. Centers for Disease Control and Prevention (CDC) has issued a health advisory concerning a significant rise in cases of parvovirus B19, commonly known as the Fifth Disease or “slapped cheek” illness due to the characteristic reddening of the cheeks it causes. This illness can be especially hazardous for pregnant women, according to the agency.

The CDC examined individuals with IgM antibodies, which indicate a recent infection, and found that the greatest increase occurred among children aged 5-9, with cases rising from “15% during 2022-2024 to 40% in June 2024.” Across all age groups, the prevalence of these antibodies increased from 3% during 2022-2024 to 10% in June 2024, the People reported.

The CDC states that parvovirus B19 is “highly transmissible in respiratory droplets.” Symptoms such as fever and malaise typically develop about a week after exposure. During the second week, the distinctive facial rash appears, often accompanied by body pain.

While most people only need supportive care, pregnant women face a risk of “adverse fetal outcomes,” including fetal anaemia, non-immune hydrops (which can strain the heart), or fetal loss. The risk is greatest if a pregnant woman contracts parvovirus between weeks 9 and 20 of pregnancy.

One case highlighted by NBC News involves Abby Parks, a teacher from Springfield, Illinois, who contracted parvovirus B19 at 18 weeks pregnant, resulting in fetal anaemia. She was hospitalized and received blood transfusions, which she believes were “lifesaving” for her fetus. “If that anaemia had persisted, with that low blood count, the baby could have died,” Parks said.

The CDC has received reports from clinicians observing “more than the expected number” of pregnant individuals with parvovirus B19, including cases of severe fetal anaemia requiring transfusions or resulting in pregnancy loss.

The agency advises that pregnant individuals seek medical care if exposed to parvovirus B19. However, the patient is no longer contagious once the characteristic facial rash appears.

Now at 30 weeks, Parks says she and her fetus are under close monitoring, describing the illness as “truly the most difficult experience to go through.” She adds, “He wasn’t guaranteed to come through the fetal anaemia.”