Beware of these Dreadful Critters

The health sections of guidebooks for anywhere faintly exotic can be absolutely terrifying.

Once you’ve dealt with the usual suspects – malaria, dengue fever, rabies, tetanus – you’re treated to an increasingly harrowing host of parasitic possibilities. It’s a small wonder that unseasoned travellers don’t show up in tropical environs wearing astronaut suits fastened with padlocks.

It should be noted that the chances of you falling victim to one these gruesome invaders are incredibly slim. The people most at risk are those for whom poor sanitation and a lack of medical resources is a fact of daily life, and for whom we should definitely spare a thought.

Naegleria fowleri

This microscopic horror, which lives in warm freshwater, is the only parasite in our list that has been known to strike the world over, including the UK. It begins its journey of destruction in your nose and soon makes its way deep into your head. At this point it unveils a sucking apparatus which it uses to devour your brain, piece by piece. Once infected, less than 5% of victims survive.

Where? Everywhere

Just to be safe... Get good at backstroke.

The candiru fish

Gents, prepare yourselves: this is just awful. The candiru is a tiny, translucent creature, also known as the ‘toothpick’ or ‘vampire’ fish. It can usually be found gorging deep within the gills of other, larger fish, but on occasion it’s been known to swim into the male urethra. Once inside, it locks itself in place with sharp spines and proceeds to feast on the soft tissue. And to think you were worried about piranhas.

Where? The Amazon Basin

Just to be safe... Don't pee in the Amazon River

The candiru fish

The giant roundworm

It’s about as pleasant as it sounds. Once ingested, the larvae of these hideous things begin a full bodily exploration. They usually make their way to the lungs (via the heart canals) in the initial stages, and when they reach a certain size are coughed up and promptly swallowed again, growing to full size – about 30cm – in the small intestine. They often exit the body through the nose and mouth.

Where? Tropical and sub-tropical areas worldwide

Just to be safe... Don't eat mud.

The guinea worm

You won’t know you even have the guinea worm until it decides to leave. It enters the body in larvae form through the ingestion of contaminated water, and then quietly spends the next year roaming your insides, growing to an appalling length of about 4ft. It usually exits through a blister on a lower limb, causing intense pain – both physical and psychological. The process of extraction can take months.

Where? Tropical areas of Africa, Asia and South America

Just to be safe... Don't drink from puddles.

Removing a guinea worm

The botfly

This one will literally make your skin crawl. It begins with a botfly attaching its eggs to a mosquito, which then injects the eggs into the next thing it bites. The eggs hatch into larvae, which eat their way into the victim’s skin. Soon you’ll be able to see the larvae wriggling beneath your skin, sometimes poking their heads out for air. Eventually the inch-long beasts will hatch into big, hairy botflies. Godspeed.

Where? Tropical areas in South America and Africa

Just to be safe... Complete three lengths each morning in a swimming pool of DEET.

Warning: this is harrowing