Cruise ships, with hundreds, even thousands of people in close quarters, can also be a hotbed of germs Sign up to Simon Calder’s free travel email for expert advice and money-saving discounts Get Simon Calder’s Travel email Get Simon Calder’s Travel email Email * SIGN UP I would like to be emailed about offers, events and updates from The Independent. Read our Privacy notice A cruise can be the perfect summer holiday. But cruise ships , with hundreds, even thousands of people in close quarters,