Human parvovirus on the rise in the U.S. Should you worry?

Human parvovirus B19 cases are increasing in the U.S., according to the Centers for Disease Control and Prevention, which warns that the seasonal respiratory virus can have dangerous complications for those with blood disorders, weak immune systems or who are pregnant.

The CDC issued a health advisory Tuesday that noted Europe is seeing unusually high numbers of parvovirus B19 and there’s also considerably more activity in the U.S. The notice highlighted clusters of complications in people with sickle cell disease and among pregnant women. Signs of recent infection were also seen to increase in samples from plasma donors.

Parvovirus B19 is highly transmissible in respiratory droplets — and people with symptoms and those without symptoms can spread it. The CDC said studies show that when someone in a household gets parvovirus, it passes to about half of the people who live there. In school outbreaks, 20% to 50% of those exposed get parvovirus. The report noted that by age 20, about half of adults have detectable antibodies showing they’ve been infected by the virus; that rises to 70% by age 40.

It’s believed antibodies from an infection protect against any future infection.

The recent outbreaks have been largest among children between ages 5 and 9. And the prevalence in the plasma samples jumped from 1.5% in December to nearly 20% in June.

Parvovirus symptoms

Most people handle the virus without severe symptoms. Flulike symptoms are common, including runny nose, headache, stomach issues and fever. Adults often experience joint pain, while children develop a “slapped cheek” rash on their face. The rash shows up in a second phase, after the flulike symptoms have passed. People are far less apt to spread the illness after the first phase. The rash sometimes leaves and comes back for a couple of weeks.

“Parvovirus infection has also been known as fifth disease because, historically, it was fifth in a list of common childhood illnesses characterized by a rash,” according to the Mayo Clinic .

As USA Today reported , “Parvovirus B19 can cause severe drops in blood count, or anemia, for people with blood disorders or weakened immune systems. Those at greater risk include people with leukemia or other cancers, organ transplant recipients, people with HIV, and blood disorders such as sickle cell and thalassemia. Severe outcomes are rare. They include myocarditis, or inflammation of the heart muscle, encephalitis, or swelling of the brain, and hepatitis.”

A rare outcome in women who are pregnant is miscarriage.

There is no vaccine or specific treatment. Pregnant women who believe they’ve been exposed to parvovirus B19 or have symptoms and those with weakened immune systems or known blood disorders should seek medical care. The CDC adds that people in high-risk groups might want to wear a mask around other people while the infection rate is high.

The U.S. does not require that parvovirus be reported to a health authority and there is no routine surveillance for it.

Avoiding parvovirus

While there’s no particular treatment, prevention relies on the old standbys of good hygiene and being considerate of others. According to the Mayo Clinic:

• Wash your hands and your child’s hands often.
• Do not touch your face.
• Don’t share food or drinks.
• Avoid people who are ill.