Germ Cloud Wraps Some Hospital Workers
March 12, 2000 (Atlanta) -- They look like other people, and they feel healthy -- until they get a common cold. Then these "cloud health care workers" emit invisible billows of airborne germs, according to a report at a CDC-sponsored conference on hospital infections.
As many as 90% of health care workers have low-level nasal infections with Staphylococcus aureus, or staph, which can cause dangerous infections. Most do not spread the germ through the air, but exactly how many can, and under what conditions, remain a mystery.
"We don't know what it's about yet," Robert J. Sherertz, MD, tells WebMD. "Available data suggest that cloud health care workers exist, but [how many] is unknown. As many as 4% of health care workers have the potential [based on] staph and upper respiratory infections."
The original "cloud baby," which spread infection throughout a nursery, was described in 1960. The first possible "cloud adult" may have been a surgical health care worker who in 1968 somehow transmitted his or her anal staph infection to patients.
Sherertz, a Wake Forest University researcher in Winston-Salem, N.C., has studied two such cloud health care workers. He found the first one 12 years ago after tracing an outbreak of skin infections among infants in two nurseries to occasions when a nurse who worked in both hospitals had a cold. A more recent staph outbreak among eight patients in a surgical intensive care unit led to the discovery of the second worker: a physician who had a mild, drug-resistant staph infection in his nose. At first, the doctor's staph infection did not seem unusual. Then Sherertz remembered the nurse who turned into a cloud health care worker when she got a cold.
"We tested him, and then he was given an experimental rhinovirus infection and tested again," Sherertz says. "There was no air dispersal [of staph] until he got the virus infection." The physician agreed to participate in further experiments, for which Sherertz designed an air-flow chamber to measure the number of staph germs a person gives off into the air. Only when he had a cold did the doctor emit clouds of germs. Five other health care workers with nasal staph infections participated in the experiment. Some gave off measurable amounts of staph when infected with rhinovirus, but none of them became cloud health care workers.
"In certain settings, the cloud carrier may be asymptomatic," Sherertz says. "The real question is how prevalent this is." He has received an NIH grant to study it further.