More than 1,000 times a year, Panhandle Health District receives a secure fax or phone call. Someone living within the five northern counties has been diagnosed with giardia or salmonella or whooping cough or any one of Idaho's more than 70 reportable illnesses.

PHD's epidemiologist team snaps into action.

"We track down where the individual acquired the infection," says Dave Hylsky, one of PHD's three epidemiologists: disease detectives. "We educate, make sure people get adequate treatment and figure out how to prevent it from happening again."

Infectious disease is the epidemiologist's specialty, and Norovirus is a good example.

Norovirus is a nasty intestinal virus that's highly contagious and infects anyone. When norovirus gets in group settings - nursing homes, schools, cruise ships - dozens become sick with nausea, vomiting and diarrhea. PHD's epis collect stool samples from infected people to test and confirm that norovirus is the cause of the illness.

They interview the people who are sick to find similarities. Did they all eat the same dish in the cafeteria? When did the symptoms start? Were they around anyone who was sick?

Controlling the spread of norovirus is tough. The virus spreads in the air, on people, in food and water. You can pick it up on contaminated surfaces.

Epis advise people to clean and sanitize all commonly touched surfaces with a bleach solution, wash their hands frequently and use hand sanitizers, thoroughly wash and cook all foods and wear gloves when handling foods served to the public.

People sick with norovirus should isolate themselves and limit their activities. Epis discourage family style meals and buffet food service where norovirus is circulating.

"Just ask the cruise line industry how hard norovirus is to control," Hylsky said.

More than 70 illnesses are reportable in Idaho. That means that labs or doctors need to contact their local health district office after they've confirmed a patient has one of the reportable illnesses.

Last year, PHD received reports on 1,123 reportable diseases in the five northern counties. About 600 required a full follow-up with an investigation, interviews, site visits for some and final reports. All require attention to prevent spreading, but some are easier than others.

When hepatitis A is diagnosed in someone and reported, PHD's epis find out if the person handles food for the public. Anyone exposed to that person within a certain amount of time needs to be notified. People possibly exposed should get vaccinated if they're not already. The person with hepatitis A is isolated until the infection is gone and there's no threat of spread.

In any one year, PHD's epis protect community residents from the spread of whooping cough and gastrointestinal illnesses such as salmonella, giardia, norovirus, hepatitis A and cryptosporidiosis. They do their best to control the spread of sexually transmitted illnesses such as chlamydia and gonorrhea.

The epi response to a tuberculosis exposure at Coeur d'Alene High in 2005 was TB testing for all students and staff twice. There was no indication the infection spread.

The next time you're advised to wash hands thoroughly to prevent catching a contagious illness, don't ignore the wisdom. PHD's epis know what it takes to keep you well.

Cynthia Taggart is the public information officer for the Panhandle Health District. She can be reached at ctaggart@phd1.idaho.gov.