While visiting a house of a friend whom had recently acquired a very cute little puppy, I lost all manly control and started playing with the dog. During the tussle, the puppy vehemently licked my face. Obviously consumed with jealousy, my girlfriend quipped that I should not let the dog lick my face lest I become infected with hydatids and my face explodes. Having no idea what hydatids were and being interested in the face-explosion aspect of it, I looked into it further.
Officially called Echinococcosis, face explosion disease (or FED, as it will now be referred to) is caused by tapeworms of the Echinococcus family.
In the tapeworm’s daily routine, carnivorous hosts (e.g. foxes, dogs, cats) eat the offal of infected herbivorous/omnivorous hosts (e.g. sheep, goats, swine) and ingest tapeworm larvae. The larvae mature into adults, have sexy times in the fox/dog/cat’s gut and shoot eggs out into the gastrointestinal tract. They make their way out the backdoor and end up in the environment.
Sheep (or other animals) end up ingesting these eggs, which latch onto the intestinal wall and release their hatchlings into the bloodstream. These hatchlings embed themselves into organs where the blood is moving very slowly, usually the liver or lungs, but occasionally the brain, eyes, kidneys, muscles or spleen. The host’s immune reaction to this foreign matter is to wall it off, forming a cyst (you’ve heard about this in James’ tuberculosis article). That’s exactly what the tapeworm wants: the hatchlings mature into larvae and reproduce in the cyst. The balloon of tapeworm larvae grows, eventually killing its host, and sits there just waiting to be eaten by a fox or dog to continue its lifecycle.
Where it becomes a big problem for us is when we take the place of the sheep. This can happen many ways: through flies that feed off faeces, ingesting tainted soil or indeed having an infected dog eat its own poop then lick your face. Whatever the way, it’s estimated that 50 people in Australia are infected each year.
The majority of people with FED will not know about it right away. Microscopic cysts don’t usually manifest symptoms. As the cyst grows, you start to experience non-specific symptoms first: a cough and a slight fever. As it gets bigger, more organ-specific symptoms start showing: if the cyst is in the lungs, you’d see a chronic cough, blood in the sputum, and chest pain; if the cyst is in the liver, you’d see jaundice and abdominal pains.
The really bad news comes if the cyst breaks open. A spill of all this foreign material into the bloodstream causes anaphylactic shock. Anaphylactic shock is when the body’s reaction to foreign material goes into overdrive. When your body experiences a foreign invader, it opens up blood vessels to let more blood into that area. Then all the white blood cells can get there and battle them off. We see that as inflammation.
But if this foreign invader is everywhere (such as the case when you’ve had a cyst burst into your blood), your body opens up the blood vessels everywhere. This causes swelling everywhere, including in the muscles surrounding your throat and lung passages. This makes it difficult to breathe. On top of this, your blood pressure is dropping. This is because your body is flushing all the toilets in the house while you’re in the shower; there’s not enough pressure to go around. Your internal organs suffer as a result: because they aren’t getting enough blood, they start to shut down. If you haven’t lost consciousness, you’ll be feeling very light-headed and thoughts of impending doom as your brain runs out of fuel. Severe anaphylaxis like this is fatal if not treated immediately.
Then there’s the rare case of ocular cysts, when the hatchling settles in the eye. A 52 year old woman had this happen and only experienced her eyes bulging out of her head. It didn’t hurt, so she didn’t complain for about 6 months. That’s when the cyst popped and she went to the hospital with “sudden vision loss accompanied with severe orbital pain”. The doctors ended up cutting the cyst out, but the woman remained blind in that eye.
In conclusion, while there is a risk of my eye exploding or death from anaphylaxis secondary to liver cyst rupture, the dog is really cute and I think I’ll let it lick my face.
Eye cyst-popping fun at –