Traveller’s Diarrhoea (TD)

• Diarrhoea is the most common health issue experienced by travellers to lower income countries. This applies more to travellers who have grown up in a high-income countries like Australia, New Zealand, Western Europe and North America.
• TD is very dependent on the destination (some countries more than others). High risk locations include Egypt, Morocco, Zanzibar, South Asia and Mexico.
• Most cases of TD occur in the first week of travel.
• Most episodes of TD last between 3 and 5 days (not good if you are away for a week or travelling for business)
• 10% have symptoms lasting more than a week and 1-2% more than a month.
• There is no gender bias. All seem equally at risk. There is possibly a genetic predisposition.
• TD is more common in the warmer months.
• There is no vaccine against TD  although there is a vaccine for cholera called (Dukoral). It has some cross protective effect against one of the common causes, enterotoxigenic E Coli (ETEC). It is expected that newer ETEC vaccines will become available in the future.
• More than 80% cases are due to bacterial contamination of food and water. Whereas community acquired diarrhoea in developed countries is usually caused by viruses spread person to person.
• There is increasing bacterial resistance to the medications we are using to treat TD.
• Parasites such as giardia occasionally cause traveller’s diarrhoea (especially in certain parts of the world).

Consider some of the colourful names we give Traveller’s Diarrhoea: …. “Bali Belly”, “Montezuma’s Revenge”, “Mexican Two Step”, “Rangoon Runs”, “Cleopatra’s curse” etc.

Time lost through a diarrhoeal illness can be considerable. Up to 20% of people will lose at least 1 day and 5% more than 3 days. Many studies show that between 20% and 50% of travellers will be affected in a 2 week stay. Of these 12% become ill after returning home.

In some places, (Mexico, Central America and North Africa) up to 80% of visitors can be affected. Travel to developed countries is not without risk. Think about it: if you eat out every meal, you are relying on the personal hygiene and food hygiene practices of a lot of strangers!

The incidence of traveller’s diarrhoea has remained unchanged over the last 20 years despite good knowledge about its causes. Many areas of the world simply do not have the capability to ensure that water supplies and public food handling are safe, whether it be for their own people or visitors.

The old adage of “boil it, peel it, cook it or forget it” should be known by all travellers visiting income poor countries.  So, why don’t travellers comply?   Does it spoil the fun of diving into the local culture and cuisine?

BOIL IT, PEEL IT, COOK IT OR LEAVE IT
but we know…
Within 48 hours of leaving home, 98% of travellers will disobey the rules of eating and drinking safely in low income countries.

The vast majority of travellers will rely on bottled water during travel.  It is readily available in most places.  The seal should always be checked before use. In low-income countries an extra level of safety might be added by using your own water bottle with a filter. In lower risk destinations it is always possible to fill up your water bottle. Many countries in Europe provide taps in public places. Carrying your own water bottle also reduces waste. More than a million plastic water bottles are added to the rubbish every day in Australia alone!

WATER DISINFECTION ……where safe water isn’t readily available.

Boiling is very effective but not always practical. It can kill amoebic cysts which are resistant to chlorine. To be safe, water should be vigorously boiled for at least 1 minute and then allowed to cool. Most gut germs are killed within seconds of boiling and letting it stand improves the taste. The boiling point is reduced at altitude but the temperature achieved at all but extreme altitude should still be adequate for sterilisation.

Disinfection depends on the concentration of halogen and the time in contact with the pathogen.

Chlorine is an effective disinfectant against bacteria and some viruses but is less effective against amoebic cysts.

Iodine: The water must be clear (free of dirt and large particles) or the tablets will not work. Add one tablet to one litre of water and allow it to stand – the length of time depends on the water temperature … 30 mins at 15deg C and 60 mins at 5deg C.  A concentration of 8 mg/ litre of free iodine will kill Giardia within 20 minutes provided the temperature is above 5deg C.

The taste of water after chemical disinfection can be improved by adding Vitamin C tablets.

Filters are simple to use and do not cause an unpleasant taste.  They work by removing organisms according to size.  Bacteria and parasites are much bigger than viruses and filtration works well for them. Portable filters cannot be relied on to remove viruses.  Filters are rated in microns (Um).