Causes
The causes may be viral, bacterial, or parasitic, although viral gastroenteritis is by far the most common variety. Children usually contract the condition through the rotavirus, whereas adults are most likely to be affected by the norovirus or Campylobacter (a strain of bacteria). Because it’s so contagious, the rotavirus vaccine is recommended for all children.
In the United States, most adults develop gastroenteritis as a result of norovirus. Outbreaks generally occur when people are in close proximity to one another and in the presence of an infected person, as sometimes happens on cruise ships, in hospitals, or at restaurants. Bacterial infections, although they only account for a small percentage of cases, are usually caused by exposure to raw or undercooked poultry, meat, and seafood; unpasteurized dairy products; and fruit and vegetable juices.
Cases caused by parasites are extremely rare in the United States. Other causes may include Crohn’s disease, lactose intolerance, celiac disease, and certain medications. These causes are not contagious.