LINDSEY TANNER, AP Medical Writer

CHICAGO (AP) — Hundreds of children in more than 10 states have been sickened by a severe respiratory illness that public health officials say may be caused by an uncommon virus similar to the germ that causes the common cold.

Nearly 500 children have been treated at one hospital alone — Children’s Mercy in Kansas City, Missouri — and some required intensive care, according to authorities.

The suspected germ, enterovirus 68, is an uncommon strain of a very common family of viruses that typically hit from summertime through autumn.

The virus can cause mild coldlike symptoms but this summer’s cases are unusually severe, said Mark Pallansch, director of the viral diseases division at the federal Centers for Disease Control and Prevention.

“It’s not highly unusual but we’re trying to understand what happened this year in terms of these noticeable and much larger clusters of severe respiratory disease,” Pallansch said Monday.

The virus typically causes illness lasting about a week and most children recover with no lasting problems.

Cases have been confirmed in Missouri and Illinois. A CDC spokesman said the agency also is testing to see if the virus caused respiratory illnesses reported in children in Alabama, Colorado, Georgia, Iowa, Kansas, Kentucky, Ohio, Oklahoma and Utah.

Children with asthma and other health problems are especially at risk for the enterovirus, but reported cases include children without asthma who have developed asthmalike breathing problems, Pallansch said. He said no deaths have been reported in the outbreak.

Dr. Mary Anne Jackson, director of infectious diseases at Children’s Mercy, said local cases began appearing in mid-August and they appear to have peaked in her area.

Schuchat, said the strain involved also appeared in the United States last year and in specimens from other countries. She said the CDC learned it had reappeared in this country last month when authorities in Chicago and Kansas City notified the agency about severe illnesses in children who had to be hospitalized. She said the virus was found in 11 of 14 specimens from Chicago and in 19 of 22 specimens from Missouri.

In the Denver area, more than 900 children were treated for severe respiratory illnesses at Children’s Hospital Colorado and its urgent care locations and 86 were hospitalized in recent weeks. The hospital said samples were sent to the CDC to confirm any link to the virus.

The University of Chicago’s Comer Children’s Hospital has treated several cases, including extremely sick children requiring life-support machines, said Dr. Rachel Wolfson, an intensive care unit physician.

Affected children are “as small as infants all the way up to teenagers,” Wolfson said.

The virus can spread through sneezing and experts say good hand-washing practices are important to curb transmission.

“The take-home point is wash your hands and keep your hands away from your face,” Wolfson said.