Liz Szabo

USA TODAY

Hundreds of children across the Midwest have been hospitalized with severe respiratory illness in recent weeks, health officials report. USA TODAY medical reporter Liz Szabo asked leading health experts to answer questions about the illness.

Q: What's causing this illness?

A: It's a virus, called EV-D68, which causes coughing and wheezing, according to the Centers for Disease Control and Prevention. It belongs to a family of viruses called enteroviruses that generally peak at this time of year, says Roya Samuels, a pediatrician at Cohen Children's Medical Center in New Hyde Park, N.Y. Many people with an enterovirus never even realize they're infected, because they have no symptoms. Others have mild symptoms similar to those of a cold.

Q: How serious is it?

A:This virus, which is relatively rare, is far more serious than most. In Denver, Children's Hospital Colorado treated more than 900 children, both in the emergency room and urgent care centers throughout the metro area, with 86 admitted to the hospital, health system spokeswoman Natalie Goldstein says.

About 12% of the more than 500 children seen at Children's Mercy Hospital & Clinics in Kansas City, Mo., have needed intensive care, says Mary Anne Jackson, director of the hospital's division of infectious diseases. The size of the outbreak is also unusual, Jackson says. Most earlier outbreaks were small clusters, she says.

"We've never had an outbreak as comprehensive and as widespread due to this virus," says William Schaffner, a professor and infectious disease expert at the Vanderbilt University School of Medicine in Nashville. No deaths have been reported, however, and Schaffner says children should make full recoveries. "The good news is that they get better, and they get better promptly," he says, adding that most children will be back to school in a week.

Q: Who is at greatest risk?

A: Enteroviruses usually affect school-age children. In Kansas City, about two-thirds of children who have gone to the emergency room for care also have asthma, Jackson says. Doctors haven't seen any adult cases, says Anne Schuchat, with the CDC's National Center for Immunization and Respiratory Diseases.

But Schuchat says parents shouldn't panic. "Most of the running noses out there aren't going to be turning into this," she says.

Q: Where is the outbreak centered?

A: Hospital officials first reported a spike in cases in Kansas City and Chicago last month. Doctors are now reporting cases in a total of about a dozen states, according to the CDC.

The CDC is working closely with other states to learn how many states are affected, Schuchat says. "The situation is evolving rapidly," she say. "We don't know as much as we'd like about this virus."

Q: What are enteroviruses?

A: There are more than 100 kinds of enteroviruses. They include hepatitis A, which can cause food-borne illness outbreaks, as well as polio, says Gail Shust, an assistant professor of pediatrics and infectious disease at Mount Sinai Hospital in New York. Enteroviruses cause more than 10 million illnesses in Americans each year, according to the CDC.

Q: How does it spread?

A: The virus infects the gastrointestinal tract. It often spreads when children get fecal matter on their hands and then touch their mouths, says Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota. Kids can spread the virus by coughing, Shust says. The virus can live on surfaces such as doorknobs.

Q: Is there a vaccine or other way to prevent the virus?

A: No, there's no vaccine, Samuels says. However, people can reduce their risk of this virus — and most infectious diseases — by washing their hands frequently with warm water and soap, and wiping surfaces to reduce the risk of spreading the virus, Shust says. But if someone in your household is infected, it's hard to avoid. Schuchat recommends that people get flu shots to protect themselves from respiratory infections in general.

Q: How is the virus treated?

A: The most common treatment is simply to make patients comfortable until the immune system fights the virus off, Osterholm says. Children who are breathing rapidly or wheezing should see a doctor, Samuels says. Pediatricians should consider that kids with severe respiratory illness might have this virus, the CDC says.

Q: Where can people learn more?

A: The CDC is posting information on its website: cdc.gov/non-polio-enterovirus