Gongylonema pulchrum

Gongylonema pulchrum is the only parasite of the genus Gongylonema capable of infecting humans. Gongylonema pulchrum infections are due to humans acting as accidental hosts for the parasite. There are seven genera of spirudia nematodes that infect human hosts accidentally: Gnathostoma, Thelazia, Gongylonema, Physaloptera, Spirocerca, Rictularia. The G. pulchrum parasite is a nematode worm of the order Spirurida. It is a relatively thin nematode, and like other worms within its class, it has no circulatory or respiratory system. Most other Gongylonema species infect birds and mammals: there are 25 species found in mammals and 10 species found in birds. This parasite is multi-cellular, and capable of movement. They have numerous rear mucosal projections, which assumedly assist propulsion through the thin layer of skin on the inside of the human host's mouth. They also have an excretory system possessing lateral canals. This parasite eats epithelial cells. Also, very often the canals are a place of inflammation, with accumulation of exudates in them. Gongylonema also swallows these exudates. Gongylonema pulchrum was first named and presented with its own species by Molin in 1857. The first reported case was in 1850 by Dr. Joseph Leidy, when he identified a worm 'obtained from the mouth of a child' from the Philadelphia Academy. He originally described it as Filariae hominis oris, and initially considered the worm was a guinea worm (Dracunculus medinensis), but because of the unique location of the worm (buccal cavity), and the relatively short size compared to the guinea worm, the hypothesis was disregarded. There have only been around 50 reported human cases of G. pulchrum worldwide since 1864, and these infections have been widespread and globally ubiquitous. G. pulchrum infections have been notoriously and historically hard to diagnose due to symptom complaints by patients (see 'Symptoms' and 'Diagnosis' below). Also, morphological diagnosis of the parasite is also somewhat complicated because of the variable size of adult worms, and the tendency of the worm to be different lengths depending on what host the worm is recovered from (see 'Morphology' below).