Princess Cruises spokeswoman Karen Candy says about 37 passengers on the Crown Princess reported being sick while the ship was in San Francisco on Monday. But after two days, on Wednesday, 66 passengers and 17 crew members were sick having flu-like symptoms and had to be isolated to their cabins. They reported a gastrointestinal illness with nausea, abdominal cramps, diarrhea and vomiting. It’s supposed that the cause is the infection with Norwalk Virus. The ship has implemented sanitation procedures. This virus is passed from one person to another very quickly through person to person contact, consuming food or water contaminated with the virus, or by contact with contaminated surfaces (door handles, elevator buttons, hand rails, and food utensils are the big offenders). Cooked foods may also be contaminated though handling by an infected crew member. The Norwalk Virus is common in situations where there are a lot of people in a group. There’s no real treatment for Norwalk Virus, only treatment for the symptoms. The objective of treatment is to replace fluids and electrolytes (salt and minerals) lost by diarrhea and/or vomiting. It isn’t deadly but causes some uncomfortable symptoms that will pass in 24 to 48 hours. It takes a few days for a person to completely cure from the illness. This is not the first time when Norwalk Virus appeared on a cruise ship. In January six hundreds people were infected on such a vessel. The CDC (Center for Disease Control) already estimates that each year 23 million people in the United States alone become ill from the Norwalk virus.