The brown-banded broodsac, scientific name Leucochloridium variae, is a species of a trematode whose life cycle involves the alternate parasitic invasion of certain species of snail and bird. While there is no external evidence of the worm's existence within the bird host, the invasion of the snail host involves the grotesque swelling of one or both of the snail's eye stalks as well as the takeover of the snail's brain. This invasion does not cause the snail's death, and snails who are thus invaded sometimes live longer than those which are not.
The swollen, pulsating eye stalk resembles a maggot, and this is what attracts birds: the bird rips off the eye stalk and eats it and later on the parasite's egg is dropped with the bird's feces. Similar life-histories are found in most species in the genus Leucochloridium including Leucochloridium paradoxum.
The snail regenerates a replacement eye stalk, which also becomes infected by the parasite.
North America: Iowa, Nebraska, Ohio and others. Worm eggs unknowingly ingested by the amber snail hatch in the snail's digestive tract. The larva then change into sporocysts, causing drastic mutations in the snail's neural ganglia and physiology. Healthy snails seek darkness to hide from predators, but the infected amber snail moves itself into dangerous open space and light. It is also helpless to retract its newly swollen, pulsating tentacles.
Intermediate host of Leucochloridium variae include:
There was no finding of difference in length of shells in parasited and in non-parasited snails.
Hosts of Leucochloridium variae include:
- Bernard Fried, Paul D. Lewis, Jr. and Kelly Beers 1995. Thin-Layer Chromatographic and Histochemical Analyses of Neutral Lipids in the Intramolluscan Stages of Leucochloridium variae (Digenea, Leucochloridiidae) and the Snail Host, Succinea ovalis. Journal of Parasitology, volume 81(1): 112-114.
- Michael A. Barger & John A. Hnida. 2008. Survey of Trematodes from Terrestrial Gastropods and Small Mammals in Southeastern Nebraska, U.S.A. Comparative Parasitology 75(2):308-314. doi:10.1654/4357.1
- Bakke, Tor A. 1982. The Morphology and Taxonomy of Leucochloridium (L.) variae Mclntosh (Digenea, Leucochloridiidae) from the Nearctic as Revealed by Light and Scanning Electron Microscopy. Zoologica Scripta 11(2):87–100 doi:10.1111/j.1463-6409.1982.tb00521.x
- A Burky & Daniel J. Hornbach. 1979 Comparison of carbon and nitrogen content of infected and uninfected snails, Succinea ovalis, and the trematode Leucochloridium variae. Journal of Parasitology 65(3): 371-374
- Staff, ZRS. "ZOMBIE SNAILS SPREAD INFECTION".
- Fried B., Beers K., Lewis PD Jr. 1993 (February). Lipids in the broodsac of Leucochloridium variae (Digenea, Leucochloridiidae) and its snail host Succinea ovalis. Int. J. Parasitol. 23(1):129-131.
- Parasites of the Robin Archived July 4, 2010, at the Wayback Machine.. Accessed 12 February 2009.
- Paul D. Lewis, Jr. - Helminths of Terrestrial Molluscs in Nebraska. II. Life Cycle of Leucochloridium variae McIntosh, 1932 (Digenea: Leucochloridiidae). - The Journal of Parasitology, Vol. 60, No. 2 (Apr., 1974), pp. 251–255
- A parasite for sore eyes - Article in the Daily Mirror
- Video on YouTube from National Geographic
- Video on YouTube
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