Gendreau studies germiness while traveling, and he knows just how infectious travel can be.
"The risk of contracting a contagious illness is heightened when we travel within any enclosed space, especially during the winter months, when most of the respiratory viruses thrive," Gendreau said.
Studies show that germs can travel easily on an airplane, where people are packed together like sardines.
For example, a woman on a 1994 flight from Chicago to Honolulu transmitted drug-resistant tuberculosis to at least six of her fellow passengers, according to a New England Journal of Medicine study.
In 2003, 22 people came down with severe acute respiratory syndrome from a single fellow passenger who had SARS but didn't have any symptoms, according to another New England journal study.
But the airplane isn't the only place along your travel route where germs thrive. Here are five ways to avoid germs while traveling.
1. Sit toward the front of the airplane.
"Pick a seat near the front, since ventilation systems on most commercial aircraft provide better air flow in the front of the aircraft," Gendreau advised. If you can afford it, sit in first class, where people aren't so squished together.
2. Don't drink coffee or tea on an airplane.
Monitoring by the Environmental Protection Agency shows that water in airplanes' water tanks isn't always clean -- and coffee and tea are usually made from that water, not from bottled water, according to Victoria Day, a spokeswoman for the Air Transport Association.
The EPA advises anyone with a suppressed immune system or anyone who's "concerned" about bacteria to refrain from drinking coffee or tea on an airplane.
"While boiling water for one minute will remove pathogens from drinking water, the