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Parasites
Outdoors
By Dr. Mark Wise
Barefoot
Walking || Fresh Water Swimming
BAREFOOT WALKING
There’s nothing
like kicking off your shoes and going for a walk on the beach. Just
keep in the back of your mind that there are sometimes microscopic worms,
fleas, men (and women) -of-war waiting to puncture your skin.
Cutaneous larva migrans, or "Creeping Eruption", is an interesting
infection caused by dog and cat hookworms. These larva which might have
been left on the beach by the local pet can penetrate your unbroken
skin. This usually occurs on your foot, though it can happen anywhere,
depending upon how you choose to sunbathe. It will cause an itchy, blistered,
serpiginous rash, which seems to be advancing a few centimetres a day.
It does not creep anywhere else, such as your brain, liver or wife!
It can usually be recognized by a doctor who has seen it before. It
is treatable with a drug called Albendazole. Try to avoid doctors who
are anxious to freeze the worm, or worse still, cauterize it. I would
not go as far as telling people not to walk barefoot, but try to avoid
places where the local dogs, cats, and sometimes people, have left their
droppings! Staying close to the water’s edge is a bit safer, as the
tide can wash away anything harmful.
In addition to animal hookworms, there are also human hookworms that
might be lurking in the soil where proper sanitary facilities are lacking.
These can also penetrate your bare feet. Hookworm is a major cause of
iron deficiency anemia in those who are constantly exposed to such conditions.
So beware of where you tread , and wear your sandals.
FRESHWATER
SWIMMING
Schistosomiasis. It might not roll off the tip of your tongue, but it
is an infection that affects more than 200 million people worldwide
in the tropics. It is caused by a tiny worm, whose eggs are passed by
humans in their urine or feces, depending upon the species(of worm,
that is). Assuming our human has no access to toilets or latrines, then
the local freshwater river or lake is the next best spot. These eggs
will then inhabit certain types of snails, and after a month there,
are released into the water.
Local people with freshwater exposure become infected when these immature
worms penetrate the unbroken skin. After a complicated migration in
the human body, they develop into adult worms, and go about producing
more eggs. The eggs can cause damage to various organs, including our
liver, bowel or bladder.
And that is why we suggest to people that they avoid swimming in fresh
water, particularly in rural areas of Southeast Asia. If you have no
choice, i.e. the lake looked too inviting, then try to swim in the deeper
water where there are no snails (assuming you know how to swim). Fast
moving streams, which is where whitewater rafters get exposed, are probably
less of a risk. If you do think you have been exposed, rubbing your
skin down vigourously with a towel will lessen the risk of larval penetration.
© Copyright 2000 Dr. Mark Wise
Dr. Mark Wise is the director
of The Travel
Clinic (TM)) in Thornhill, Ontario, Canada and the Medical Director
of The Travel Wise (TM) Clinic in Scarborough, Ontario, Canada. He is a
family physician with training from the London School of Tropical Medicine
in Tropical Diseases. He is a parent himself and often see potential adoptive
parents in his clinic. Dr. Wise gives lectures and writes articles on the
subject of travel medicine, for both medical and non-medical groups. |
