Probiotics
Probiotics are "good" bacteria in the intestines. They are small living organisms. Probiotics help prevent disease, facilitate digestion and help stimulate the production of antibodies that, by inhibiting "bad" bacteria, are a pillar of the immune system.
Stomach flu
A person with gastroenteritis is contagious as soon as they develop symptoms (diarrhea, fever, intestinal cramps, fatigue) and could contaminate their environment leaving other members of their family, or their colleagues at work at risk of contracting the disease.