It is not uncommon to get some form of stomach infection while camping.
This is usually the result of diseases passed from other humans, but
also passed from livestock. Visitors from other countries will not have
been exposed to the range of even harmless bacteria in fresh mountain
water in Scotland and this will cause some, usually minor, upset.
prevent the more serious infections concentrate on stopping flies, birds
and other animals moving infection from human waste and food scraps
to fresh food and food containers; to plates or cooking pots.
Great care should be taken not to encourage rats, especially where these are living near livestock.
NB: camping in even the remotest parts of Scotland, you will attract mice to your tent. They will eat through a tent and rucksack to get to open food, so keep it securely hidden. However, mice do not carry the same infectious diseases as rats. Also, sheep are grazed over most Scottish land and wild deer are distributed over large parts of the Highlands. Cattle are grazed in more localised areas, so cross-infection through rats is always a possibility.