A cruise can be the perfect summer holiday. But cruise ships , with hundreds, even thousands of people in close quarters, can also be a hotbed of germs. In particular, cruises are somewhat notorious for outbreaks of gastro. One study, which looked at close to 2,000 cruises docking in Sydney, found 5% of ships reported they’d had a gastro outbreak on board. If you’re about to head off on a cruise, there’s no need to panic. There are some precautions you can take to give yourself the best chance of a happy, gastro-free holiday. What causes gastro? Viruses are the leading cause of acute gastroenteritis in Australia. Norovirus is the main culprit, causing an estimated 2.2 million cases of gastro each year. Norovirus is usually transmitted from person to person via the faecal-oral route, where virus particles found in the stool of one person end up being swallowed by another person.…