A person can become infected more than once with the type of virus that causes gastroenteritis, commonly referred to as stomach flu, according to the United States Centers for Disease Control and Prevention (CDC). This type of virus is known in medical jargon as a norovirus.
In the U.S., norovirus infections account for an annual estimate of 19 to 21 million illnesses, as reported by the CDC. It is the most predominant cause of gastroenteritis in the country.
Individuals infected with the norovirus commonly experience vomiting, queasiness, abdominal cramps and loose bowel movements due to irritation and swelling of the gastrointestinal tract. On average, people are exposed to the norovirus around five times within the span of their lives.