On the presence of a Filaria in “craw-craw”.

In 1874, while examining skin snips from craw-craw patients in Ghana, during his service on the H. M. S. Decoy, the Irish surgeon O’Neill discovered the subcutaneous microfilaria. This was the earliest known visual identification of the O. volvulus parasite, fifty years before the worm was linked with blindness (onchocerciasis). In May 2015 O'Neill's paper could be read at this link.