This initial phase takes one to four days. “The more you inhale, the shorter the incubation period,” said Dr. William Schaffner, an infectious disease specialist at Vanderbilt University School of Medicine in Nashville. “In the beginning, you don’t feel sick. You don’t even know it’s there.”
As the virus colonizes your respiratory tract, your body starts to figure out something is amiss and rallies its immunologic troops in an inflammatory response, releasing proteins called interferons — because they interfere with alien invaders. Interferons flood your bloodstream and set up camp in your mucous, prompting more proteins called cytokines to join the battle. These protein soldiers circulate throughout your body, ready to rumble.
“Paradoxically, our own soldiers created for the fight are what cause us to have symptoms,” said Dr. Schaffner.
“War creates damage and so you get fever and a headache and muscular aches and pains,” which you experience as the abrupt and intense opening salvos of the flu. These early symptoms are usually what distinguishes the flu from just a normal cold.
The achiness and fever also signal that you need to start drinking a lot of fluids. The battle royal being waged inside you will dehydrate you more than you think. You may notice that your urine will get darker and you’ll have to go less often. Experts say to make sure you drink a cup or so of water or other liquid every hour, avoiding alcoholic and caffeinated beverages.
Drinking fluids will diminish your headache and also bolster your immune response because your protein soldiers are conveyed via bodily fluids. Dehydration hampers their movement. It’s one reason people tend to want soup when they’re sick and may crave watery fruits like citrus and melon.
While you may feel rotten all over, the real battle is going on in your respiratory tract where the virus is localized. When the war is winding down, you stop feeling achy and feverish but you have…