By Dr Eddy Bajrovic*
You don’t need to go overseas to experience ‘traveller’s diarrhoea’. You can get TD by swimming in your council or backyard pool – even if it’s properly chlorinated.
Australia is currently experiencing one of its worst years in more than a decade for the parasitic disease Cryptosporidium, which is a leading cause of TD in developing and developed countries.
‘Crypto’ is a notifiable disease in Australia and there have been 3568 confirmed cases nationwide in 2015, with Queensland (1237 cases) and NSW (898) already registering more than double last year’s total. Because the disease is not severe in most healthy people, many more cases have gone undiagnosed.
Notifications of cryptosporidiosis, the disease caused by swallowing the parasites, increased by more than three times the usual average in NSW during October and November, NSW Health Director of Health Protection, Dr Jeremy McAnulty said in a statement last week.
He urged people who have, or recently had, diarrhoea to stay out of public swimming pools for two weeks in an effort to prevent widespread outbreaks this summer.
Chlorine kills nasties – but very slowly
The main source of intestinal diseases is faecal matter and in recreational water it often comes from kids – especially infants in nappies. However, even the hygiene practices of an adult with diarrhoea may fail to remove all faecal matter from their skin.
You’re probably wondering why chlorine doesn’t kill the parasites when they find their way into pool water.
Chlorine does kill most diarrhoea-causing germs that find their way into pools, but it can take up to an hour for the chlorine to work. That means that if a healthy child follows a child with diarrhoea into the pool it may not be enough time for the chlorine to kill germs and prevent infection.
Indeed, the crypto parasite can survive in water for more than 10 days – even when the water is treated to the recommended chlorine and pH levels.
And, it’s so small it can evade filtration systems, too.
Parasites can overwhelm victims
While most intestinal illnesses are due to swallowing water, they can also be transferred to the mouth after handling contaminated sand or soil, or by breathing in mist containing parasites like crypto.
Beside pools, just about any recreational water can be polluted with crypto, including hot tubs, fountains, water parks, lakes, rivers, and oceans.
Becoming ill depends on the number of parasites swallowed, but millions can be released in a bowel movement from an infected human or animal.
Parasite ‘shedding’ begins when the symptoms begin and can last for weeks after the diarrhoea ends.
Stomach acidity and immune mechanisms protect us to a degree, but the body can simply be overwhelmed by the sheer number of organisms.
Crypto one of many TD risks overseas
Inadequate water treatment and the lack of food sanitation found in many developing countries means that travellers are generally at greater risk for water-borne infections, of which Crypto is just one.
Others include shigella, norovirus, and another parasitic disease, giardiasis, which together are responsible for many of the cases of TD in visitors in developing countries.
Experts agree that the number of water-borne disease outbreaks is increasing worldwide.
Once infected, it is the elderly, infants and people with lower immunity who are most at risk for severe disease from crypto. Infants are especially susceptible in swimming pools because:
- They often swallow water when their heads are dunked. (Dunking babies to get them ‘used to the water’ is not a good idea: It can actually make them ill.)
- They have little or no immunity against the microorganisms.
- It takes fewer parasites to make them ill.
- They are often in the water with other babies, which increases their risk of exposure to crypto and other germs, and of having more severe symptoms.
Some people get severely ill
Most people who have healthy immune systems recover from crypto infection without treatment.
The drug, Nitazoxanide is not registered in Australia, but is available on the special access scheme to treat gastro intestinal infection caused by cryptosporidium in adults and children aged 12 months and older if treating the symptoms doesn’t prove effective.
The dehydration that often results from diarrhoea usually can be addressed with adequate fluid intake.
Young children and pregnant women may be more susceptible to the effects of dehydration and should drink plenty of fluids. But, rapid fluid loss may be especially life threatening to babies and parents should talk to their doctor about the options for fluid replacement.
See your doctor too if your child has other symptoms beside loose bowel movements. Of particular concern are fever, blood in the stool, listlessness, and not drinking.
Even in such cases fluids alone may suffice, but this is a decision for a medical professional.
How to avoid crypto infection
Prevention is always better than cure. Keep your child (and everyone else) healthy by:
- Encourage them not to swallow water in the pool or when playing in water.
- Keeping them out of the water when he or she has diarrhoea, conjunctivitis (‘pink eye’), or any other contagious disease.
- Don't let your child in the water if he has an open wound (it could become infected or cause infection in others).
- Don't share towels.
- Have your child take a shower before swimming in a pool.
* Dr Bajrovic is the Medical Director of Travelvax Australia.
Travelling overseas? Call 1300 360 164 during business hours for expert, no-obligation advice or to book a one-stop pre-departure consultation with an experienced team of travel medicine professionals.