Virulence of Giardia lamblia isolates to laboratory mice.

Laboratory breed albino mice free of G. muris infection were inoculated with G. lamblia cysts isolated from the stools of patients with different clinical manifestations, symptomatic diarrhoeic, symptomatic non-diarrhoeic and asymptomatic cyst carriers. The virulence of various isolates was assessed by cyst excretion rate in the stools, trophozoite counts in the duodenum and histopathological lesions of jejunal mucosa. A marked variation in the virulence of cysts obtained from the 3 groups of patients was proved.