One Cell to Rule Them All

First seen through a microscope in 1681 by Antony van Leeuwenhoek, the eukaryotic parasite Giardia lambila now infects animals and humans on a global level. The parasite is in a category of eukaryotes with flagella, which are tail-like projections used to propel the organism forward. Giardia infections were commonly known as “Beaver Fever”. This is because of its prevalence in streams and lakes that were inhabited by beavers. We now know that Giardia not only infects beavers, but has the ability to infect all animals.
Giardia is a single-celled organism that will infect its host if ingested, and is found in contaminated waters. For this reason, hikers and campers drinking unfiltered water often pick it up, as well as animals such as dogs or cats that drink from ponds. The organism is very simple, and has only two life stages: the cyst and the trophozoite (active swimmer). The cyst exists in a latent stage in which Giardia acts as a bacterial endospore in the sense that it can survive in quite hostile environments. This is the reason for its ability to efficiently thrive in water, which is always variable in temperature and pH.

Drinking from a pond
If ingested, Giardia enters and lives in the small intestines of mammals. Some may have no symptoms of the disease, but most have prominent signs such as diarrhea, nausea, and eventual malnourishment that stem from a compromised immune system. The disease is not generally life-threatening in healthy organisms. However, its prevalence in contaminated water means that it is very common in third world countries.
Though observed by Leeuwenhoek first, Giardia lambila was described by Vilem Dusan Lambl in 1859, then again by Alfred Giard in 1895. The organism was thought to be harmless in communities at first observations. However, outbreaks in the 1970s led to different species of Giardia being recognized as pathogenic. It was observed in stools of travelers returning from third world areas where the organism is endemic to the region.
Currently, there are multiple social issues involved with Giardiasis, the disease caused by Giardia. Each year, public swimming waters are infested with the disease and must be kept closed until the issue can be resolved. Impoverished communities are especially prominent in social issues, and often call to first world countries for assistance. Whether it is social, economical, or physical, Giardia has the ability to affect every human or animal on the planet.

– Jenna Rindy

http://web.clark.edu/tkibota/240/Disease/Giardiasis.pdf

http://web.stanford.edu/group/parasites/ParaSites2006/Giardiasis/history.htm

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