noun, plural: schistosomula
The invasive larval stage of schistosome
Schistosomulum is a schistosome larva and is considered as the invasive larval stage leading to schistosomiasis. Schistosomes are flatworms belonging to the phylum Platyhelmintes. They are also called as blood flukes. One of their distinctive morphological features is their being dioecious. The species has separate male and female sex organs. The male and female schistosomes may also be differentiated morphologically. The male is larger than the female and the former has a gynaecophore where the smaller female fits and resides throughout the adulthood. The gynaecophore allows the male to have a direct contact with the female always thus ensuring reproduction. The adult schistosomes infest the blood vessels of the definitive host (many vertebrates, including humans). The female passes the eggs together with the faeces (or urine, depending on the schistosome species infecting the host). When the conditions outside (external environment) are optimal, the eggs hatch and the miracidia are released. The miracidia are the infective stage of the intermediate host, i.e. snails. Within the snails, the miracidia develop and give rise to sporocysts and ultimately to the production of cercariae. The cercariae swim to reach their definitive host, e.g. humans. They penetrate the skin of the definitive host and shed their forked tail to become schistosomula. The schistosomula migrate to tissues and then into the veins.1
1 Centers for Disease Control and Prevention. (2011). “Schistosomiasis: Life Cycle.” Retrieved from ://www.cdc.gov/parasites/schistosomiasis/biology.html.