The Centers for Disease Control and Prevention (CDC) issued a health alert advising parents to watch out for a common childhood virus called parechovirus, as it spreads across the U.S. in multiple states, and one baby has died.

Especially severe in children under 3 months old, it can cause severe symptoms and even death. The agency issued an alert over cases of the virus in newborns and infants, as the virus causes the most severe illness in children under 3 months old. They've been receiving reports from clinicians across the country about newborns and young infants being infected with the virus since May of this year. In June, at just 34 days old, a baby boy died after uncontrollable seizures with no explanation. He was diagnosed with the virus when he was just eight days old.

The virus tends to make the rounds in summer and fall, and the CDC is urging clinicians to consider parechovirus as a possible diagnosis when infants present with seizures, sepsis-like symptoms and/or meningitis with no other cause apparent.

In humans, the parechovirus can cause a host of symptoms, from asymptomatic to mild to severe and even death. In children between 6 months and 5 years, the virus usually presents as an upper respiratory tract infection, rash and fever. In babies under 3 months, and particularly under a month, it can cause seizures and brain swelling, as well as a sepsis-like illness that often requires hospitalization. It can also lead to neurodevelopmental issues, though that's rare.

The virus spreads through fecal particles that end up in the mouth, respiratory droplets and saliva. Shedding from respiratory infections can last up to three months and in gastrointestinal tracts, up to six months. Asymptomatic but infected individuals can spread the virus.

Nationally, there's no surveillance of parechovirus so it's not known if this is a higher incidence than in years past, but while it's a common virus, it's a virtually unknown word to many parents and even underthought of by clinicians.