Wildlife Damage Management, Internet Center for


Date of this Version

December 1985


The Giardia lamblia (Lambl) protozoan is not a recently discovered parasite. It was. in fact, one of the first organisms viewed and described by Antony van Leeuwenhoek (1681) as he designed the first usable microscope. Leeuwenhoek found this organism in a sample of his own diarrhetic stool and thus he constitutes the first confirmed case of human giardiasis. His finding represents proof of glardiasis’ close association with man for many years. Leeuwenhoek’s discovery of the giardial trophozoite was not elaborated on for some 178 years, however, as it was not until 1859 that Wilhelm D. Lambl systematically described the organism as being a distinct genus of protozoan parasite (Kudo 1966). Unfortunately Lambl made little mention of guardias' medical significance and the giardial protozoan was not accurately recognized as a major health concern until late in the twentieth century.