PEMBINA, N.D. – If anthrax comes to Canada, it will likely get here the same way everything else the U.S. ships here does: On the back of a trucker.

Cross-border truckers are among the only Canadians facing the bio-terror threat face-to-face, almost on a daily basis. Not only are they moving in and out of areas were spores have infected and killed Americans, but they are often in close contact with loading dock and mailroom employees – who stand on the front lines of this newest front opened by Osama bin Laden’s terrorist network.

If, as you make your way through this story, you suddenly notice a slight (or not so slight) fever, body aches, cough, congestion, joint pain and stiffness – wouldn’t you like to know what it is? With flu season in full swing, how can you tell whether you’ve got a run-of-the-mill infection or the more potentially deadly inhalation form of anthrax disease?

Medical experts are calling for extra vigilance this year and for good reason.

So far, one misdiagnosed case of anthrax has cost a Washington, D.C., postal worker his life. Although both the flu and inhalation anthrax can inflict catastrophic damage to the body, they are vastly different germs.

The flu, or influenza, is a respiratory infection caused by a variety of contagious viruses and is spread through coughing and sneezing. Symptoms include headache, chills, a dry cough, fever and body aches as well as upper respiratory symptoms such as nasal congestion and sore throat.

Anthrax, by contrast, is caused by the bacterium Bacillus Anthracis, which can lead to infection when spores of the bacterium are inhaled. (While there are other ways to catch the disease, this method has proven to be the most common.)

Initial symptoms of inhalation anthrax may resemble a common cold. These may then decline for a short period before returning in the form of breathing problems and shock.

“We’re having to learn about the disease as we go along; there have been so few cases in the world,” Dr. Adrian Long, medical director of Kaiser Permanent Mid Atlantic, tells media. “We’re in uncharted territory.”

Kaiser’s physicians are currently treating the two D.C.-based postal workers who came down with inhalation anthrax infection in October.

Medical professionals are being forced to profile each patient they see complaining of the nondescript symptoms. Where does the individual work? Where have they been? How at risk are they of being exposed to anthrax?

It’s this index of suspicion that is critical. A trucker hauling mail out of New Jersey complaining of a cough, for example, is much more likely to be held in the hospital than his co-worker on a similar run to Edmonton.

The daunting task of sorting out symptoms is also aided by the use of chest X-rays. There are often tell-tale swollen lymph nodes in the chests of inhalation anthrax patients. X-rays are quick and convenient, but they are only going to work if the patient is demonstrating the symptom.

“It’s a lot like taking a pregnancy test right after your honeymoon, you have to wait for symptoms,” complains one U.S. doctor.

“From the cases we’ve seen, the symptoms are not following the textbook definition (of anthrax),” adds Long.

Health professionals are calling on everyone, especially those frequently traveling to the U.S. to get a flu shot this year. They hope the vaccine can help calm people’s hysterical fears over the spread of the man-made plague, as well as make their job of diagnosis easier.

Doctors urge everyone – truckers or otherwise – to remember, the possibility of contracting the infection is very remote.

Initial symptoms of anthrax are much like a common cold, and may mimic flu-like symptoms: Headache Dry cough Chills General aches and pain Fever of up to 104 F Nasal congestion and sore throat Fatigue and weakness However, several hours to several days later, anthrax will generally progress to severe breathing problems and shock. If symptoms persist, become severe or localized in the throat, stomach or lungs, or if other symptoms such as vomiting and behavioral changes occur, consult your physician.