Parasitism | Part 1

We know all about the horrific tapeworms (parasitic worms that can grow up to 30 metres inside your body) and roundworms (parasitic worms that will sometimes exit your body through your nose and mouth – eek!). If these are enough to make you cringe, you may not want to read about these next examples. These are definitely *not* parasite pals.

Filarial worms 

Wuchereria bancrofti 

As if mosquitos aren’t annoying enough, their level of annoying is greatly increased if they are infected by Filarial worms.

Filarial worms are parasitic nematodes of the tropics, and one particular type – Wuchereria bancrofti – are tiny. Microscopic, even. They can’t be seen with the naked eye, but they pack a hell of a punch and make their presence known in the most horrific of ways. Mosquitos infected by these worms unwittingly inject hundreds of their larvae into us every time they feed.


© Vibhuti Patel

Once in the human body, the worms start to mature, and grow in size as well as malcontent. They move to the lymphatic system – which is the part of the body that expels excess fluids – and clog the lymph nodes. Fluids start backing up, tissues inflate, and then this happens.


Image credit: Maggie Steber/For The Washington Post (source: 10/03/haiti-women-takes-on-dreaded-disease-elephantiasis-one-mouth-at-a-time/)

It’s called Elephantiasis, and it gives the victim grossly enlarged limbs and/or genitalia. Despite what they say about bigger is better, please do not actively seek out this parasite. You will regret it.

Loa loa 

Eyes. Perhaps one of the most sensitive and (arguably valuable) parts of our bodies, so much so that they come equipped with little protective covers and their own inbuilt cleaning system. Tears, eyelashes and eyelids all act to protect our eyes from hostile, external forces.


© Vibhuti Patel

But what if our eyes came under attack from the inside? What then?!

In Africa, there exists another type of Filarial worm, known as the Loa loa. This one doesn’t attack the lymphatic system, though. Here’s what happens.

  1. Humans are bitten by an infected mango fly. This is incredibly painful in itself, since the flies literally rip the skin open to get to the blood (does this make the precise, painless methods of a mosquito seem almost civil? Forgivable? …no).
  2. The Loa loa grows to be quite a bit larger than the W. bancrofti, reaching up to 20cm long. It causes what I would imagine to be a very strange sensation as well as extreme pain, by crawling around beneath the skin (a certain Linkin Park song comes to mind…).

However, the only reason I included it in this post was because you can actually see them when they move through the white part of the eye. This looks completely terrifying.



…I’m sorry. But just imagine actually feeling that.

Apart from this, the worms also cause intense itching, fatigue, retina damage and are associated with kidney disease.

Candiru (Vandellia cirrhosa)

There’s something that lurks in the Amazon that is worse than even the dreaded piranha. Whatever you do, don’t wet yourself in fear. Because, if you’re swimming in the Amazon as you read this, you’re going to be in a lot of trouble.

This is the fearsome candiru.


© Vibhuti Patel

Looks pretty harmless, right? Cute? Well, it would be, if it didn’t swim up your urinary tract and drink your blood from the inside. 

The candiru is part of the catfish family, and it is found mostly in the Amazon river. It grows to be about six inches long (which is pretty big for something that swims up such a narrow tube, cringe) and is sometimes known as the vampire fish. This is because its diet consists of blood. Of other fish, mainly, but humans too.

The candiru is attracted to ammonia, and follows trails of ammonia to larger fish. When it finds them, it climbs into their gills, lodges itself in there with the use of a sharp spine, and gorges itself on blood.

Unfortunately, when humans go swimming, they also excrete ammonia (a compound that occurs naturally in human urine). This, I’m sure you can imagine, is very bad news. There have been multiple confirmed cases of the candiru swimming up a human penis or vagina, and attaching itself using its razor-sharp spine. Once there, it can only be removed using complex surgery.

Could there be anything more embarrassing than to tell someone that you have a fish lodged up your nethers?

Take some solace in knowing that this is generally rare, and the fish is more likely to find other entry points to get inside you. We’ve got that going for us, I guess.

So, if you want to keep safe from these parasites:

  1. don’t go to the tropics,
  2. wear copious amounts of insect repellent,
  3. don’t swim,
  4. don’t drink,
  5. just sit in your room and cry.

Next time! More cases of parasitism in humans and animals!

Coming soon: Deep sea terrors | Horrific historical science experiments | Weird human illnesses | Unsolved mysteries | Astrobiology | and more – stay tuned!

Featured image is sourced from


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