The next time you go to see a doctor, check if he’s wearing a necktie. If he is? RUN FOR YOUR LIFE. That’s the conclusion of a clever study conducted by Steven Nurkin, who, while an intern doing surgical studies at the New York Hospital Medical Center of Queens, noticed something interesting: Men almost never dry-clean their ties.

The thing is, cloth is well-known to harbor zillions of infectious viruses and bacteria. That’s why doctors regularly clean their medical coats and clothes, and change them between each shift: They don’t want to cross-contaminate sick people within the hospital. They even clean their pagers and PDAs, actually, because studies have shown that those devices can play host to bugs also.

But neckties fall into an interesting cultural blank spot, because, almost alone amongst clothing items, they are rarely cleaned. As the Toronto Star reports, Nurkin decided to check them out:

So he and some colleagues from the hospital’s infectious disease lab swabbed the ties of 42 doctors, physician assistants and medical students, and cultured the swabs to see what, if anything, would grow. They compared the results to swabs taken of the ties of 10 hospital security guards, who were used as a control because though they work in a similar environment, they rarely come in contact with patients.

Nearly half of the doctors’ ties were positive for bugs like Staphylococcus aureus, which can cause wound infections, pneumonia, meningitis and food poisoning, among other things. Only one of the security guards’ ties tested positive.