Essentially, this is about how much risk you're willing to take in life. There's a risk associated with everything, so you have to decide what you're comfortable with.
How risk averse are you for your health?
When you think about the ways you can get these infections, the best way to reduce the risk is to reduce your exposure to these organisms. The longer you stay in a place and a country, the greater the risk.
Avoid ice, use bottled water and try a water filter, which removes bacteria and viruses and practice from water. That’s the first line offence of preventing these organisms from getting into your body.
There are also interesting studies on using prebiotics and probiotics to bolster your resistance to gut infections. Using the right strain is important: the probiotic ‘Culturelle’ has been shown to have some effect.
Using probiotics to avoid travel-related gut issues
Most of the studies on probiotics and prebiotics use them for a week before travelling, then for the duration of the time away.
They’ve been shown to reduce infection rates or instances of traveller's diarrhoea by about 40 percent, and the yeast saccharomyces boulardii reduced rates by about 25 percent. They seem to work by preventing the adhesion of unfriendly microbes to the gut wall.
When a parasite or a pathogenic microbe clings on to the gut wall, they cause inflammation that can result in symptoms like cramping and diarrhoea. You can think about it like keeping the parking spaces full along your digestive tract. You’re making sure that there’s no room for opportunistic organisms to take hold.
So try starting to take probiotics such as Culturelle or saccharomyces boulardii a week before travelling. In the studies, the people who did get gut symptoms despite taking these probiotics had less serious symptoms, and for less time than expected.