The strain of influenza believed to be the source of the 1918-19 pandemic, disappeared in the 1950s, when the next flu pandemic hit, but returned in the 1970s. One theory holds that it had been kept alive in a lab -- and managed to "escape."
"From historical evidence, we know that those people that have more direct contact, and people in the service industry, have a greater chance of getting the flu and cold," said Palen.
And while that can include people who need to greet others, it can include public safety officers we would hope meet fewer people on a day-to-day basis.
In addition to dealing with people who may not have the officer's personal health in mind, police officers often have to enter environments that don't have microbe safety in mind.
"There's been a lot of training with police officers putting on latex or non-latex gloves," said Palen.
And that extends to other public safety officers, such as firefighters and paramedics.
While public safety officers work their jobs with the safety of others in mind, they often need to watch out for hypodermic needles and other potentially problematic objects while in the line of duty.
"Now these people should be wearing surgical gloves while they deal with it," said Palen.
Farmers, agricultural workers and anyone with enough exposure to live animals can pick up diseases from them.
But animal control officers have the distinct disadvantage of having to deal with the unruly animals.
In addition to rabies, animal control officers can be exposed to other diseases, even when an animal is not present, such as when they are called in to clean up dead animals or animal waste.
But cleaning that waste is essential, as a variety of parasites can be contracted by children who are exposed to feces.
Of course, like germs in general, exposure to animals may not be all bad. Studies in Europe have shown that children who grow up on farms are less likely to develop allergies, perhaps because of the greater number of bacteria to which they are exposed.
Janitors and plumbers encounter many other people's germs -- and can sometimes be responsible for getting rid of them.
"When you talk about a plumber or a janitor, or someone who is cleaning an appliance in a bathroom ... they're at greater risk," said Palen.
Surfaces are responsible for a lot of the germs we pick up, and janitors and plumbers face no shortage of germy surfaces.
But if they work in a nursing home or a hospital, they may need to take extra precautions, as they can pick up the same kinds of germs that other health care workers are exposed to, noted Palen.
Because of that increased awareness, he said, janitors will take extra precautions now when they clean a health care facility. They are often compelled to wear disposable gloves whenever they clean a patient care area.
In some professions, workers are literally surrounded by germs at all times.
"I would say those are professions where you need to keep aspirate clothing for work," said Scott.
Few would question the germiness of a job where workers have to deal with solid waste all day. In a profession like this, the problem may be in bringing germs home with them.
"Their clothing should be laundered separately and washed at high temperature, with probably a bleach additive," said Scott.