I've said it once before, but I'll say it again..
"The flu" is short for TWO illnesses
InFLUenza
AND
FLUx (aka the stomach flu). Flux is shorthand for ANY kind of gastrointestinal upset, but is traditionally reserved for dysentery, diahrrea without blood, vomitting, or any combination of the above.
Which is why people use both in common vernacular. Our grandparents used both, our parents used both.
But sister, I WILL JOIN YOU on the soapbox of bringing sick kids (and sick selves) out in public!!! The sheer and utter selfishness (and ignorance) of dragging germs around spreading them to immunocompromised people (babies, pregnant women, the elderly, anyone from child to elderly undergoing chemo, any transplant patient, anyone else on immunosuppressing drugs, hiv+ people... I JUST LOVE the self righteous argument I've heard about THAT one, let me tell you... the SMALLEST population of immunocompromised people are those with hiv).
We DO get Influenza every summer (except last summer... Childrens had the vax flown in for us, and one would assume others). Influenza is TYPICALLY a birdflu or swineflu that starts in China and heads west. As SOON as it's ID'd vaxes start being produced. Not quick enough for Eastern China, but they can usually get western china, and definitely have it for Eastern Europe and Africa... BUT... (remember h1n1 that started locally) it takes TIME to get those vaccines up and running. So they're not on the market HERE when the middle east and eastern europe is getting vax'd.
Guess who has friends and family who come visit every summer from Eastern Europe and the Middle East right at the beginning/middle of THEIR flu season? Yup. Us. So every summer we're housebound for 10-15 days (depending on how fast we incubate). Total pain in the keister. But we really DO self quarantine with influenza every year... and that IS something you'll hear come out of our mouths. "Sorry, we had the flu last week." And durn straight mean that influenza is why you didn't see us for the past week or two.
Thing is... there are HUNDREDS of strains of influenza (china creates several dozen every year in their poultry farms and pig farms, and the most virulent head west)... but they vary TREMENDOUSLY in virulence, strength, effects, etc. Most are *fairly* mild. As in you'll be miserable but IF you have a healthy immune system (not an infant, elderly, transplant recipient, etc.) you're in no risk of dying. Some others one WOULD havebeen at risk of death pre-tylenol and sports drinks (the salts in sports drinks- and pedialyte is JUST gatorade minus color and sugar)... but replacing lost salts keeps us from having seizures and strokes. A VERY SMALL percentage of influenza strains are lethal with modern medicine. ((Sounds like your friends' daughter had one of the nasty strains, or a particularly robust mutation of a regular strain going around)). Thing is... it doesn't matter (as far as going out in public) how mild the strain is. If you're immunocompromised... it's deadly.
You know how 30 deaths makes the news with some "pop-illnesses" and everyone freaks out? Do you KNOW how many people die IN THIS COUNTRY ALONE from the common cold and flu?
apx 50,000
Per year.
And we don't even blink.