Every year some 1.7 million people in the U.S. who are admitted to hospitals hoping to get well instead end up getting sicker after picking up infections during their stays, according to the U.S. Centers for Disease Control and Prevention (CDC). About 100,000 of them die every year as a result of the hospital bugs—more deaths than all the U.S. casualties in the Vietnam War—and it costs an estimated $20 billion annually to treat these infections.

Hospitals are pooling places for sick people and all the germs they carry; just walking into one a puts everyone at a greater risk than normal of contracting an infection. But you're particularly vulnerable if you're immunosuppressed, elderly or an infant—or if you are there for surgery, because cutting the skin and sticking various tubes into the body provides germs new means of access. What's particularly scary is that an increasing number of hospital infections are now caused by superbugs—bacteria such as methicillin-resistant Staphylococcus aureus (MRSA) that are hard to kill because they have developed resistance to multiple antibiotics.

The good news is that there are precautions you can take to shield yourself from bugs—super and other. ScientificAmerican.com spoke with Stephen Streed, an epidemiologist who oversees infection control at the Lee Memorial Health System in Fort Myers, Fla., and a board member for the nonprofit Washington D.C.–based Association for Professionals in Infection Control and Epidemiology (APIC) to compile a list of the top 10 ways to do this. Following are his recommendations.

1. Insist on clean hands
When doctors and nurses walk into a room to examine you, ask them to clean their hands with soap and water or an alcohol-based sanitizer. (For hand washing, 15 seconds of lathering is enough, and for the hand sanitizer, 10 to 15 seconds should do the trick.) Insist even if they claim they already have, because they may have recontaminated their hands by touching, say, a germ-laden doorknob. (Studies show that superbugs can survive on inorganic objects for weeks.) Hand-washing is the single most important way to prevent infections, yet studies suggest that only about half of U.S. health care workers consistently clean their hands properly, Streed says. (Note to patients and visitors: hand hygiene applies to you, too. Be sure to wash your mitts after using the bathroom and touching surfaces or objects in the hospital room—and always before eating.)

2. Don't shave!
If you're getting surgery on a body part you regularly shave, allow the stubble to grow in for a few days before the procedure. Normally, the skin acts as a protective barrier against bugs, but a razor leaves a trail of nicks and micro-cuts in its wake, offering bacteria inviting entry points into the body. Ask your surgeons if they plan to remove hair around the incision site; if they say yes, tell them you'd prefer they use clippers instead of a razor. Despite 30 years of scientific evidence suggesting that shaving hikes the risk of infection, many surgeons still do it to clear incision areas, Streed says.

3. Kick the habit!
If you smoke, try to quit or cut down at least a few days before any surgical procedure. Smoking reduces the lungs' ability to scrub the blood of carbon dioxide and provide it with oxygen. When deprived of oxygen-rich blood, cells in the skin such as fibroblasts, responsible for healing wounds, become less efficient. And the longer it takes these cells to close off a wound, the more time bugs have to get inside.

4. Wash the bugs away
Scrub the incision site before surgery, because scalpels and other surgical instruments—no matter how sterile—can drag bacteria on the surrounding skin's surface into the incision. Many hospitals routinely send patients home with antiseptic cleansers and instructions on how to bathe in preparation for an operation. If your hospital is not one of them, buy an antiseptic cleanser containing the bacteria-killing ingredient chlorhexidine gluconate (found in a product marketed as HIBICLENS) at your local pharmacy and use it to clean the surgical site as well as other body parts that tend to harbor bacteria, such as the underarms, groin, and pubic area the night before and the morning of your operation. (The surgical team should also wash the incision site just before beginning the operation.)

5. Make sure you're kept warm
The air temperature in operating rooms typically hovers between 65 and 69 degrees Fahrenheit (18 and 20 degrees Celsius). That's great for the doctors and nurses bundled head to toe in scrubs, but not necessarily for the person on the table. Streed says that the body responds to chilly air by constricting vessels supplying blood to the skin and the tissues just below it; diverting blood away from the body's surface and toward its core is the body's strategy for conserving heat. With less blood supplying oxygen to the incision site, the immune cells there become oxygen-deprived and therefore less effective at battling invading germs. Ask the surgical team how they intend to keep you warm -- if they will crank up the room temperature by a few degrees, cover you in blankets, or warm you with IV fluids, for instance.

6. Ask about presurgery antibiotics
For many operations, including those involving the heart and bone, doctors routinely give patients preventive antibiotics to nip infections in the bud. One dose is typically given via IV an hour before the surgeons make the first cut, and sometimes two more doses are given over the next 24 hours, Streed says. If you think there is any possibility that you have an infection before going into surgery, tell your doctor so that he or she can treat you first. (Having an existing infection in, say, the bladder or skin ups the risk of developing a second, surgery-related infection, Streed warns.)

7. Minimize tubes
Every tube inserted into your body, from the IV supplying fluids to your arm vein to the catheter draining urine from your bladder, acts as "a superhighway for the bugs to enter [the body]," Streed says. And the longer the tubes are in place, the more time the bugs have to hitch rides. Be sure to ask your doctor or nurse to remove your IV or other tubes as soon as possible after your surgery.

8. Know the signs of infection
Even if the hospital takes every possible precaution, you could still get an infection. Some possible signs: a fever, dizziness, increasing pain, redness, warmth, swelling or pus around the incision as well as inside your body. If you experience any of these symptoms after surgery, alert your doctor immediately.

9. Investigate your hospital
Find out how well your hospital has done controlling infections. Twenty-six states have laws requiring hospitals to publicly disclose their infection rates; you can find out if your state is one of them by visiting APIC's online legislation map, says APIC spokesperson Liz Garman. Then contact your state's health department and ask where you can get hospital stats, she advises. Other good sources of info: Consumers Union's Stop Hospital Infections.org and the Committee to Reduce Infection Deaths' HospitalInfectionRates.org—both Web sites provide links to infection reports.

10. Get out of the hospital!
"Every day you're in the hospital increases your risk of developing an infection," Streed says. "Work with your caregivers to meet recovery goals on or before the scheduled date. Get well and out of the hospital ASAP."