Killer Cold Virus Appears in U.S.

Nov. 15, 2007 -- A virulent new form of an old cold virus is spreading in the U.S., causing severe pneumonia and death even in healthy adults.

The virus is adenovirus type 14 or Ad14. Since May 2006, when it killed a 12-day-old girl in New York City, there have been 10 deaths among 141 confirmed cases. Except for the infant girl, the cases came in outbreaks in Oregon, Washington, and Texas.

Different adenovirus strains have caused outbreaks in the past. But this seems to be a particularly "challenging" virus, says CDC epidemic intelligence officer John Su, MD, PhD.

"This particular [adenovirus] is unusual in that it can cause very severe illness in healthy young adults with no other medical condition. That is why this adenovirus stands out from the crowd," Su tells WebMD.

Adenovirus expert Gregory C. Gray, MD, MPH, director of the Center for Emerging Infectious Diseases at the University of Iowa, says particularly virulent strains of adenovirus pop up from time to time.

"I think this Ad14 strain is a matter of concern," Gray tells WebMD. "Something makes this unique. The question is what makes it cause outbreaks of severe disease. It's a bit of a mystery."

U.S. Ad14 Outbreaks

The CDC, in the Nov. 16 issue of Morbidity and Mortality Weekly Report, chronicles the four known Ad14 outbreaks.

New York City, May 2006: An infant girl born after normal pregnancy and delivery had some weight loss three days after birth, but seemed healthy. Over the next week, her physical activity and feeding dropped off. At age 12 days, she was found dead in her bed. A postmortem exam showed she'd had a deep lung infection with Ad14, resulting in acute respiratory distress syndrome.

Oregon, April 2007: A doctor reported that an unusually large number of patients had been showing up at the same hospital with severe pneumonia. A state health department investigation found that Ad14 was responsible for the majority of cases involving adenovirus infections.

Investigators found 30 people infected with Ad14. Five of the cases were in children under age 5; the rest were in people over 18. Twenty-two of the patients had to be hospitalized, 16 of them in the intensive care unit. Seven of these people -- 23% -- died of severe pneumonia.

In contrast, there were no deaths or ICU admissions among people infected with other adenovirus strains.

Washington State, May 2007: Four residents aged 40-62 of the same unit of a residential-care facility were hospitalized for pneumonia. One of these patients had AIDS; the other three had chronic pulmonary obstructive disease ( COPD). Three of the patients required mechanical ventilation. After eight days in the hospital, the patient with AIDS died. The others recovered. All four patients tested positive for adenovirus. Three of the isolates were further tested; all three were Ad14.