Medical name: gastroenteritis, colitis, or gastritis

Major symptoms: fever, vomiting, and frequent, watery (usually nonbloody) diarrhea

Caused by: most commonly caused by norovirus in adults and rotavirus in kids under 2; it can also be caused by food poisoning (Another shameless vaccine plug: all kids should get the full series of the rotavirus vaccine before 6 months of age!  This has reduced infant deaths dramatically since its introduction).  It can be caused by bacteria as well (think cholera, C. difficile, E. coli, Salmonella, Shigella, among others) — these tend to be far more severe, involve significant stomach pain, high fever, and stool with blood, pus, and/or mucous.

How you catch it: in the case of bacteria and viruses, exposure to contaminated environments (i.e. caring for a sick person and/or touching contaminated surfaces); with food poisoning, exposure to preformed toxins in the food in question.

How long am I contagious? And how to treat it? For infectious processes, you are generally infectious as long as you have symptoms; this makes it very, very important to try to keep areas around sick people clean and to wash your hands religiously if you’re caring for a sick person.  Those with foodborne illness aren’t contagious.  Treatment for viral processes is to make sure you’re rehydrating well (Gatorade or Pedialyte both work well); the illness must run its course.  If you have more severe symptoms (described above), reach out to a medical professional for guidance, testing, and possible treatment with medicines or even hospitalization!

It can turn into: dehydration and electrolyte disturbances!  This is particularly true in older and younger people.  What’s coming out needs to be matched with liquids going in, so if your loved one isn’t able to drink enough to keep up, urgent evaluation is needed!