Diarrhoea is the most common illness in travellers.
Diarrhoea is caused by food and drink contaminated with bacteria, virus or parasites.
boiling destroys all microorganisms.
Diarrhoea is prevented by
making sure that the food is thoroughly cooked or fried;
boil the water before use;
drink bottled water, juice or beer;
do not drink tap water;
do not use ice cubes in drinks and food unless you know where the water comes from;
do not eat home made ice-cream;
avoid mayonnaise, raw egg yolk, raw vegetables and shellfish.
Mild diarrhoea is treated with rest and fluid for instance water or tea with sugar.
If the diarrhoea is bloody, you should contact a doctor.
If you can't get medical advice, self-treatment with a quinolone antibiotics for instance Ciproxin should be tried. Quinolones work on bacteria but not on parasites and virus. Resistance against quinolones has been reported especially in southeast Asia.
Frequent diarrhoea (more than 6 times a day), the diarrhoea may be stopped with Loperamid.
Immunization against cholera and travellers diarrhoea can be tried with the oral vaccine Dukoral.
Drinking water The traveller does seldom have any knowledge of the quality of the drinking water in any specific place. The traveller must therefore make sure that the water is safe before it is used (drinking, cooking brushing teeth). Rainwater may also be contaminated and water from streams and lakes are absolutely not suitable.
Water purification Start with water, which is as pure as possible like tap water, spring water, or rain water.
I. FilteringIf the water is dirty it can be filtered through a towel or a filter for brewing coffee.
II. Purification i. Boiling. Boiling is the most efficient method for water purification and clears bacteria, virus and parasites even if the water is very dirty. The water has been boiled sufficiently if it has been "bubbling" for a few minutes. The boiling time is prolonged with one minute for every 1000 meters increase in altitude.It is practical to boil the water for next days consumption in the evening and let it cool in a clear container overnight. ii. Ceramic filtering. Ceramic filters in stainless steel containers are efficient for remov-ing bacteria and parasites, but do not clear virus. The pore size is between 0.2 and 2 microns. The filters need regular cleaning and must be discarded if cracks appear. It takes time to pump water through the filter. Filters with "active carbon" will clear chemical impurities but have no effect on microorganisms. Chemical purification Iodine solution. 0.5 cc of a 2.5% solution of iodine alcohol can be used for purification of 1 litre. The water need to be left for at least 10 minutes after the iodine has been added to be effective. Iodine works on bacteria, virus and parasites. Iodine tablets like Cochlans potable. 1 tablet per 1 litre water.All iodine preparations give the water a brownish colour and can also be tasted. Chlorine for instance 5% can be used, 2 drops per litre. Let the water stand for at least 30 minutes before use. Silver. Different silver salts (Micropur) can be used to prevent growth of bacteria. but do not kill the microorganisms. The dosages given are at 20C. If the water is dirty use double dose and if the water in colder, double the treatment time. iv. Combination of filtering and iodine treatmentSome water purification products first add iodine to kill all microor-ganisms and then pass the water through a carbon filter to remove the colour and taste from the iodine.This is an effective but expensive system and the carbon filters need replacement from time to time. v. Osmotic purification. The system has a semi permeable membrane with a concentrated solution of an inert sugar on one side of the membrane. On the other side the dirty water is added and the osmotic pressure from the sugar solution draw the water over the membrane and leave microorganisms behind. The system works on bacteria, virus and parasites. The system is slow but effective, but as a backup procedure it may be useful.