My role as a public health physician is to help individuals reduce the risk of preventable disease.
Advice on vaccine preventable disease is easy and I can draw on my many experiences as a paediatrician in the 1980’s. If vaccinations are the only aspect of your travel consultation then you are being short changed.
Eating and drinking safely, insect protection, security, altitude –related issues and travelling with pre-existing conditions are just some of the topics that might be discussed in a travel consultation. The destination and type of travel determines the focus of the consultation. In recent years I have added another topic I discuss with patients – responsible tourism! One aspect of responsible tourism relates to preventable disease namely traveller’s diarrhoea (TD). This common problem is largely preventable. A good bout of TD can wipe out an entire trip and leave you wondering why you bothered to spend the money on travel in the first place!
So where does “responsible tourism” come into a discussion on tummy problems during travel. It’s about the plastic bottle used to deliver safe drinking water. Why don’t you do a calculation next time you travel in a group. Let’s consider a 14 day tour in Vietnam, starting in Hanoi, travelling out to Halong Bay then back to Hanoi and down the coast to Hoi Án, Ho Chi Minh and the delta. The travel company is very much aware about the risks of the “Ho Chi Minhs” and immediately makes sure that everyone has access to bottled water during the trip. A standard group of 24 people on a bus could consume 70 to 80 litres of water a day or close to a 1000 litres for the trip! Consider the number of bottles for just one tour group. Are they being recycled? Probably not! Travellers have provided me with images of ravines full of plastic bottles on walking trips. Will they end up as an island of plastic in the Pacific?
Water is essential for life and the body can’t store it. Most adults require about 2.5 litres per day with female requirements (2.2 litres) slightly less than males (2.6 litres). Daily replenishment is to replace fluids lost through the lungs, kidneys, skin and gastrointestinal tract. Many factors can influence the rate of loss including daily activities, weather and diet. A 3 hour flight can deplete bodily fluids by as much as 1.5 litres and a diarrhoeal illness can be devastating. Consideration of fluid replacement is essential for all travellers whether you are undertaking a cruise down the Rhine or walking Kokoda. Water must be accessible and safe.
There are a number of ways to address this in your travel preparation.
DISINFECTION OF WATER
Water heated above 65C (149F) will kill most germs in a few seconds. The protozoans, Giardia and Cryptosporidium, are resistant to chlorine disinfection but will be destroyed at temperatures above 55-60C. Worm eggs and larvae are also destroyed by boiling. It is recommended to boil water for 1 minute for complete sterilisation. At altitudes above 2000m it is recommended to continue boiling for at least 3 minutes.
Boiling water may be the desired method but it isn’t always practical and in some circumstances harmful to the environment when travellers use scarce firewood.
2. Chemical Disinfection.
This is the most common way to disinfect water. The agents include chlorine, iodine and silver. Bacteria and viruses are the most sensitive while amoebae and parasites are the least. Iodine and Silver are more effective than chlorine but contact time is very important. Other factors include turbidity (cloudiness) and temperature. Cold water may need a longer period of disinfection. Taste can be affected by iodine but improved by the addition of vitamin C. Chemical disinfection provides a way to carry your own personal container from home and make available water safe as you go. It might be important to consider quantity and also take an empty 1 litre bottle which can be kept in your accommodation for topping up the water bottle. This allows for a longer disinfection time. Top up fluids during the day include tea, coffee and internationally labelled soft drinks or alcohol. These are considered safe.
Chlorine: Chlorine has been the mainstay of water disinfection for many years. Together with filtration it is the main source of protection for urban water supplies in industrialised countries. It does have limitations for the traveller when used on its own in a contaminated environment. Its effectiveness against protozoans is reduced by organic matter that coats and hides the organism. Chlorine can be used at higher doses and for longer periods but with better products available it will have limited use. Chlorine is available as tablets and drops.
Iodine: Iodine is an excellent disinfectant but the water must be clear (free of dirt and large particulate matter) or the tablets won’t work. The temperature of the water will determine the length of time taken for disinfection. Allow 30 minutes at 15C (59F) and 60 minutes at 5C (41F). A contact time of only 20 minutes may be satisfactory at a temperature above 50C provided the concentration of free iodine is above 8mg/ litre. Longer times improve the level of disinfection, particularly if you are considering protozoan cysts. Iodine is also available as drops or tablets.
Silver: This disinfectant is very popular in Europe, less so in the USA. It is available in Australia as Micropur and Aquatabs. It has been shown to be bactericidal in low doses and tastes much better than both chlorine and iodine. One concern is the possibility of it being adsorbed onto the surface of the container rendering it less effective. There are limited studies on its effectiveness against protozoan cysts, for which higher concentrations and 2-4 hour exposure times may be necessary.
Filtration provides an excellent way for travellers to manage their water needs while protecting the environment. A pore size of less than 2 microns will filter out many enteric pathogens including protozoans and their cysts (5-8 microns). Viruses are much smaller than bacteria and protozoans so an additional means of protection is still required. Filtration bottles with some form of extra disinfection are excellent for this purpose. We have received good feedback on the Fill2Pure water bottle and filters. The filter pore is small enough to remove all protozoans and most bacteria and with disinfection through an iodine resin and adsorption/ chelation process, it is being promoted as able to remove greater than 99.9% of pathogens. Contact time in the filter is still very important. Some travellers prefer the plastic bottle over the metal one as water can be easily dispensed onto a toothbrush in situations where tap water cannot be used.
Some level of filtration is strongly recommended for those intending adventurous remote travel. Single use plastic bottles should never be considered for hikers.
4. UV light
Studies suggest that UV light is effective against all waterborne pathogens but CDC notes that pre-filtration is also required. Portable devices such as the Steripen Quantum are available at a reasonable price. Most work on easily available AA batteries. They should not be used where water is turbid. The water bottle needs to have a decent size cap to allow good access.
Enjoy your travels but consider the environment. Don’t buy bottled water in destinations like Australia, New Zealand, Japan, Europe, North America and other developed regions. The tap is fine! Just fill up your own water bottle.