Outbreak of giardiasis: effect of a new antiflagellate drug, tinidazole.

We describe here an intensive outbreak of mostly symptomatic (90%) Giardia lamblia infestation in a Swedish student group visiting the U.S.S.R. A new antiflagellate drug, ethyl (2-(2-methyl-5-nitro-1-imidazolyl)ethyl) sulphone, tinidazole, Pfizer, was given in a dosage of 150 mg twice daily for seven days to 10 healthy volunteers and to 24 students infested with G. lamblia. The drug was found to be effective in curing giardiasis and in eradicating G. lamblia from the intestinal tract. All the students with symptomatic giardia infestation became free from gastrointestinal disturbance, usually soon after treatment was started. None of the 24 students had G. lamblia in their stools after tinidazole treatment was discontinued or at follow-up. No side effects of the drug were seen and all of the subjects tolerated it very well.