Gastric Flu = Inflammation of digestive tract, usually caused by
a virus transmitted by personal contact; can also be caused by
contaminated food or water, by specific food which produce an
extreme allergic reaction, by a sudden change in diet (abroad, for
example), or by any illness or drug which alters natural balance of
bacteria in gut.
Symptoms vary in severity, usually pass off within 48 hours; a bad
case will cause repeated Nausea and vomiting, Diarrhoea, cramping
Abdominal pain, Fever, and exhaustion; a mild case may be limited
to vague nausea and a loose stool or two. In infants and elderly
people, 'stomach upsets' can be serious as they easily lead to
dehydration and even Shock. Best treatment is rest and plenty of
fluids, though GP may prescribe drugs to control vomiting and
diarrhoea.
I think i got it from my 2 boys 
