The Centers for Disease Control and Prevention (CDC) recently issued a Health Alert Network (HAN) advisory for the human parvovirus B19 across the United States. Although this virus is not new, the sudden surge in cases has raised concerns among healthcare providers, public health authorities, and the general public.

Fifth Disease

Parvovirus B19 is the only virus in its family that affects humans and is most common in children. It causes a disease commonly known as “slapped cheek disease” or “fifth disease,” which presents as a rash.

The virus spreads primarily through respiratory droplets expelled when an infected person coughs or sneezes. Around 8 in 10 infected people don’t show any visible symptoms.

However, this mode of transmission means that even those who are asymptomatic can unknowingly spread the virus to others. Given that the symptoms of parvovirus B19 infection are often mild or even absent in healthy individuals, it is easy for the virus to circulate unnoticed, making widespread outbreaks a real possibility.

According to the CDC, when parvovirus B19 hits strongly, it hits in two phases.

“Although many people with parvovirus B19 infection are asymptomatic, immunocompetent children and adults with symptomatic disease typically develop a biphasic illness.

“The first phase of illness is characterized by symptoms of fever, myalgia, and malaise and develops approximately 7 days after infection. This phase lasts approximately 5 days. People with parvovirus B19 infection are most contagious during the first phase when viral loads in respiratory secretions and saliva are highest.”

“During the second phase of illness (approximately 7–10 days after the first phase), children often present with a characteristic facial rash (erythema infectiosum, or “slapped cheek” appearance), which may be followed by reticulated body rash or joint pain (arthralgia) 1–4 days later. In immunocompetent adults, the most common symptoms of parvovirus B19 disease typically occur during the second phase and include a reticular rash on the trunk and joint pain (arthralgia).”

A seasonal disease not usually tracked

One of the problems in addressing the current surge in parvovirus B19 cases is the lack of routine surveillance. This makes it difficult to track the true prevalence of the virus and respond effectively to outbreaks. We know we have a surge of it, but we don’t know how much.

However, the CDC has issued an advisory, saying it’s received numerous reports of parvovirus B19 from parents whose children have the condition, particularly in children aged 5-9. The positivity rate in tests has jumped from around 15% in 2022 to 40% in 2024.

Adults in contact with infected children (typically parents and school workers) also have a high risk of infection. Many adults will experience joint pain that lasts a few weeks and goes away without major problems.

Currently, there is no vaccine or specific antiviral treatment available for parvovirus B19. Management of the infection primarily focuses on supportive care, which may include hydration, pain relief, and treatment of any complications that arise. For those at high risk of severe outcomes, early diagnosis, and monitoring are crucial.

Per the CDC, you should seek medical help if you:

1. are pregnant and have been exposed to a person with suspected or confirmed parvovirus B19 or you have signs and symptoms of parvovirus B19.
2. have a weakened immune system or a chronic hemolytic blood disorder including sickle cell disease, thalassemia, and hereditary spherocytosis, and you have signs and symptoms of parvovirus B19.

Even if you are not in one of these two categories, however, the CDC advises staying on alert and being aware of the symptoms and the risk.