#19. This will make your skin crawl....

I am both repelled and fascinated by parasites, particularly those that effect and can be seen on and in the skin. So this post is dedicated to a discussion I had about parasites and sharing some of the ones that really creep me out.


The Bot Fly, or warble or gadfly, are flies that lay their eggs in the skin of the host (or some grow in the stomach). These larvae then eat the flesh and poke out holes to the surface for gas exchange. Eventually, they will climb out. While they are truly skin crawling they do not cause permanent damage or death to the host. One of the most ick inducing infestation, IMHO, is the botfly incubating in the human eyelid.
How botfly maggots are extracted.


Scabies, from the Latin word "to scratch or itch". This is a small mite that infests the skin. Scabies mites burrow into the skin and then live there in burrows. There are several times of scabies, each with their own infestation and spreading rates. Norwegian or Crusted Scabies is the worst causing crusts of skin under which the scabies colony lives. This is also one of the most contagious forms as it causes the most intense scratching. Scabies is not deadly, in most cases, and can be treated with medication. From the CDC.

A delightful illustration of the scabies mite in the skin.

 Screwworm. The larvae of another fly, this of the Screwfly. This fly lays its eggs on open wounds. The maggots then emerge and burrow into the wound to feast on the host's flesh. These do not kill the host as they do not remain in the host for long before dropping off/chewing out to pupate in the ground. 

More on the screw worm 

Video of a Nasal Myiasis (I am not very squeamish and this was quite possibly one of the ickiest things I have ever seen.)

Gnathostomiasis or larva migrans profundus is introduced by eating poorly cooked fish, frogs, crustaceans and other meats. After incubation these larvae begin to eat their way from the digestive tract to the skin. Due to humans not being the usual vector for these parasites they do not complete their life cycle, are hard to detect and can cause many complications. This larvae migrates around beneath the surface of the skin. An in depth discussion here.

Life cycle of larva migrans profundus

Guinea worm is contracted through contaminated drinking water. This is a roundworm that starts in the intestinal tract and the female migrates the body. This female usually leaves the body through the feet and can be as large as a 3 foot long spaghetti noodle. One method of extracting these worms is to roll them around a stick and gently pull them out.
On the NY Times (A short documentary about the eradication efforts.
The Carter Center which is trying to eradicate the Guinea worm
On the CDC

Chigoe flea is a type of flea which burrows into the skin. Once inside it develops causing a painful, reddened swelling. Eventually a black dot appears on the swelling which is the hind legs, breathing organs and reproductive organs poking from the skin. While the flea is not directly harmful, secondary infections and large scale infestations can be very dangerous for the host. These fleas infect most warm-blooded hosts.
Video of the parasite from National Geographic