(NEXSTAR) — The Centers for Disease Control and Prevention issued a health alert Tuesday warning about a highly contagious respiratory illness detected especially among young children.

Over the past two years, there has been an uptick of the common seasonal illness, known as parvovirus B19, particularly among kids aged 5 to 9. The CDC said the percentage of positive cases in this age group rose from 15% between 2022 and early 2024 to 40% in June 2024.

The CDC has also received reports from doctors noting an unexpected rise in infections among pregnant people. Some of these cases have reportedly led to severe fetal anemia that required transfusions or resulted in pregnancy loss.

The virus, primarily transmitted through respiratory droplets, can spread rapidly in environments like schools and day cares, according the CDC. Cases typically occur in late winter, spring and early summer, with mini outbreaks happening roughly every three to four years.

People infected with the virus usually experience mild symptoms that can include fever, headache, sore throat, joint pain and a “slapped cheek” rash. However, the CDC said the virus can also pose serious risks for those with compromised immune systems or chronic blood disorders, like sickle cell disease.

“Most people require only supportive care during the acute phase of illness and will recover completely. Severe outcomes from parvovirus B19 disease, such as myocarditis, hepatitis, or encephalitis, are rare,” the CDC explained, while noting that there isn’t a vaccine for the virus.

The increase in cases has prompted the CDC to urge health care providers to be vigilant in diagnosing and managing the virus, especially in high-risk groups. The advisory also encourages preventive measures, including good hand hygiene, to reduce the spread of the virus.

The recent alert follows a similar spike in cases reported earlier this year in 14 European countries, including France, Spain and Germany.