Dehydration can occur anywhere in the world. On of the main causes of dehydration is diarrhoea. The other main cause is through not planning ahead this can be caused by misjudging the amount you need to get you from a to b or by over rationing your supplies.
The human body is made up of about 71% water losing 5% of this will cause you to start feeling unwell. If you wait till you feel thirsty before drinking then you are already feeling the effects of dehydration. Water is lost by sweating, urinating, vomiting and diarrhoea.
5% dehydration will lead to thirst, lack of appetite,nausea,headache, irritability and drowsiness. 10% can cause dizziness, lack of salvia, clumsiness, slurring and difficulty breathing, 20% will cause a dulling of senses, delirium and swelling of the tongue and throat.
The prevention is obvious make sure you drink plenty. This means planning ahead if you are in extreme heat and walking you may find that you need at least 1 litre per hour to stop dehydration. Obviously some times you may get caught out, to avoid this at the minimum when travelling in the third world or walking away from populated areas anywhere in the world take some puritabs for water purification. Find the cleanest stream or well you can and use the puritabs to give you some level of protection. Dehydration is more serious than anything you are likely to get if the puritabs fail to kill everything, they take up so little room there is no excuse.
To prevent dehydration keep covered wear a hat and light long trousers and long sleeved tops. Remember all the desert people of the world keep themselves well covered in lose fitting clothes.
If you are travelling with others keep an eye on them and make sure they are not getting dehydrated. Its usually easy to keep an eye on the number of times they are urinating rather than what they are drinking. Its better to be spend the day finding bushes than collapsing in the middle of nowhere.
Knowing what dehydration feels like in advance helps you understand it more and if you expect to be pushing your body to the limit letting yourself become slightly dehydrated in the controlled conditions of home before you leave will better prepare you for its effects. Obviously if you do this be careful....
The cure is to get liquids inside you and find shade to sit in usually helps.
If you are drinking a lot of water then there is the danger that the salt balance in your body may become upset. It is therefore important to take on salt either with food or on its own. The symptoms are similar to the first stage of dehydration, muscle craps, headaches etc. The difference is that salt imbalance occurs over several days. There are ready made sachets which have the correct salts to replace any loss, these are usually sold for re-hydration after diarrhoea (Dioralyte, Rehidrat) and are worth having a couple of sachets of. Alternatively a solution of six teaspoons of sugar and a half-teaspoon of salt to a litre of water. Coca Cola also has a lot of the required salts and sugars to help with rehydration.