Look What Just Flu In

The Los Angeles-to-New York flight is nonstop, and so is the cough of the traveler in the next seat.

Within the close quarters of an airplane, cruise ship, bus, train or conference room, there’s often no place to run and, thus, no easy way to minimize germ exposure. Healthy travelers worry about catching a cold or flu or even more serious ailments such as tuberculosis or, recently, the Ebola virus.

While the risk of contracting diseases in close quarters en route is real, travel medicine specialists say we should learn to put risks in perspective and take reasonable precautions to reduce them.

In the midst of the Ebola outbreak in Zaire earlier this year, a patient canceled a trip to Zimbabwe, said Dr. John A. Horton, a Westlake Village family practice physician with expertise in travel medicine. Zimbabwe was well outside what experts deemed the danger zone.

Tuberculosis is another disease high on travelers’ fear scales, according to travel medicine experts. But the danger is limited. Since 1992, a crew member and a passenger traveling on commercial airplanes have infected others, according to the Centers for Disease Control and Prevention, which published results of an investigation of crew members or passengers traveling while infectious with TB. The crew member infected several other associates; the passenger infected four other passengers during an 8 1/2-hour flight, according to a CDC spokeswoman.

Yet risk of TB transmission on an aircraft “does not appear to be greater than in other confined spaces,” according to the report. Further, it seems to be connected with the length of the flight, with trips of longer than eight hours posing more risk, according to the CDC. People who got TB were probably seated near the ailing traveler.

Legionnaires’ disease, a form of pneumonia named after an outbreak that occurred among members of the American Legion at a Philadelphia meeting in 1976, tends to affect people in hospitals, hotels and other buildings, although the bacterium responsible is found in lakes, creeks and rivers. The sources of outbreaks have been pinned down to organisms from the evaporative condensers of air-conditioning systems or contaminated shower heads. No person-to-person transmission has been shown, according to experts. Thus, there is little a traveler can do to minimize risk, said Dr. Shirley Fannin of the Los Angeles County Department of Health Services, short of going to the cruise ship or hotel operators and inquiring whether the air-conditioning system is cleaned regularly to prevent recirculation of bacteria.

Catching a cold is also a real possibility while traveling, but probably less likely the shorter the flight or other exposure time, said Elliot Dick, professor of preventive medicine at the University of Wisconsin, Madison, and a leading researcher on common cold viruses.

Dick has conducted numerous studies to determine how easily cold viruses are transmitted. In one study, he assembled people in close quarters--half the group was infected with a cold virus, the other half was not--and found no transmission after two or three hours.

However, the risk of catching another person’s cold would rise, Dick said, if one of the people has a severe cold or if the exposure time increases. The brief flight time from Los Angeles to Phoenix, for example, might not result in transmission even if one were seated next to a passenger with a cold. But during a longer flight, from New York to Los Angeles, “you are going to get some transmission,” Dick said.

To his knowledge, no one has looked at transmission of colds specifically within planes. But his group has studied transmission among married couples. In one study, Dick followed 24 couples in which one partner was infected with a cold virus and the other not. After a week, only a third of the healthy spouses had come down with a cold.

Cold viruses are transmitted most easily through the air, Dick said. Cold virus transmission is also possible via the hands, according to Dick, but he doesn’t believe this is the normal transmission route, although other virologists disagree.

Whether cold viruses in a plane continue to circulate, Dick said, “depends on the filters and how good they are.”

The closer the contact with infected people, the higher the risk of catching that cold. “If your seat mate is a mother with a small child with a runny nose, and you offer to walk the child,” it is possible that you will catch that cold, Dick said.

Catching influenza from a fellow traveler is also a real possibility. “If it’s the type of flu you are susceptible to, forget it,” Fannin said. “With the influenza virus, every cough fills the air,” with virus particles that are so small, they can hang suspended in the air for hours, Fannin said.

“Respiratory viruses are more efficiently spread in close quarters than respiratory bacteria,” she said.

But intestinal infections caused by bacteria, such as shigella, can be highly contagious, Horton said, particularly in closed spaces such as cruise ships. “If you’re a smart traveler, you’ll take along antibiotics,” he said, and use them at the first sign of the condition. Among initial symptoms are abdominal cramping, watery stools and stomach gurgling, he said.

While there is no way to eliminate contracting diseases on the road, some simple precautions might help, experts agreed. Try to boost the immune system before traveling in close quarters, Horton said. He recommends taking extra supplements of Vitamin C, beta carotene, Vitamin E, zinc and selenium, although not if a traveler is known to be sensitive to higher than usual amounts. Checking with one’s own physician before boosting vitamin and mineral intake is advised.

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The Healthy Traveler appears the second and fourth week of every month.