I am not sure.... I wasn't sure if the SA article was saying that the worm only could exist in humans or that it had been eradicated everywhere else (perhaps because humans might be a preferred host).
It turns out the worm's lifecycle is fascinating. The embryos apparently are parasites of water fleas, and are consumed by humans when they drink water containing infected water fleas. The embryos then burrow into the intestines and from there into other tissues.
So I did some research. I started with Wikipedia which said the worm was known to infect some other animals, and then jumped off from there. Then I came across this site: http://medical-dictionary.thefreedictionary.com/Guinea+worm+...
It turns out the worm's lifecycle is fascinating. The embryos apparently are parasites of water fleas, and are consumed by humans when they drink water containing infected water fleas. The embryos then burrow into the intestines and from there into other tissues.
also according to http://medical-dictionary.thefreedictionary.com/Dracunculus at least some species of domestic animals can carry the worm. It doesn't say whether the worms can effectively reproduce in horses, cattle, or dogs though.