Friday, 12 December 2014

Creature 73: Dracunculus medinensis

Enormous African parasite

I had written another creature up for today but I decided to change it to a more topical creature in the last minute as I saw one of the species on my list in the newspaper.

Dracunculus medinensis is a nematode parasite commonly known as Guinea worm which is specialized for infecting humans. Infections of these parasite are called dracuncunliasis. The males grow up to 4 cm long, but if you think that's a pretty big parasite, you should see the females which can grow up to 80 cm long.

They enter the human body by infecting Copepods or Cladocerans, much like Daphnia which we looked at in an earlier post. When you drink the water with these microscopic crustaceans the Guinea worms will make their way to your intestines. They will soon burrow out of your intestines into your gat and muscle where they will mature into adults. Once they are mature they will breed and the males will die off. The females then make their way down to your feet where they blister the foot. They then excrete a chemical which creates a burning sensation in your foot, enticing you to submerge your foot in water for relief. Once you do that they puncture a hole in the blister and release their fertilized eggs into the water so that their juveniles can infect the planctonic crustaceans and so they cycle continues.

The big news was that a man in Melbourne, Victoria (Australia) was found to have been infected by these worms and had them removed. It is almost certain that he picked them up from the Sudan where he was living up until four years ago.  It is remotely possible that they have found their way into bodies of water in the Melbourne area.....

The Guinea worm used to exist among human populations throughout the tropical regions of Africa and Asia, however fairly successful eradication programs have restricted their distribution to the horn of Africa and some areas of the Sahel. It was always most common around these areas, probably because they have been co evolving with humans for a very long time and those areas are most likely the original distribution of our species. But there I go speculating again.

Kingdom: Animalia
Phylum: Nematoda
Class: Secernentea
Order: Camallanida
Family: Dracunculidae
Genus: Dracunculus
Species: Dracunculus medinensis

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