One third of visitors to poor countries from rich countries get
sick. Experts warn tourists to avoid uncooked food, street vendors, ice, and
tap water. By obeying, they lower the risk of getting sick to… one third. The
truth is that no one knows how to prevent traveler’s diarrhea. Poor sanitation
seems essential, but travel itself must play a role. The Swiss get sick when
they visit the US.
Tourists visiting the tropics worry unnecessarily
about parasites. Germs and protozoa like malaria remain a problem, but larger
creatures reproduce slowly. Victims must stay long enough and undergo repeated
exposure before they accumulate enough to realize something is wrong. If you
harbor a few dozen schistosomes, flukes, or hookworms, you won’t notice.
Having said this, I visited one horrified guest
who had seen what looked like an earthworm swimming in the toilet after a bowel
movement. Unfortunately for my education, he had flushed it down. This was
undoubtedly an ascarid, a parasite that affects a billion people worldwide and
an unknown number in the US. Unlike parasites such as hookworms which bite into
the intestine and eat your blood, ascarids swim freely and eat what you eat.
You can support a dozen without difficulty. Victims get into trouble when huge
numbers cause an obstruction or when a single worm crawls into a duct and gets
stuck. If you return from vacation with a small infestation, you have little to
worry about. The females will mate, but their eggs only hatch outside the body
in warm earth, so they disappear down the sewer, and the average ascarid dies
after a year or two.
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