Efficacy of albendazole and two different doses of paromomycin for treatment of naturally occurring Giardia infection in lambs.

Giardia duodenalis is a protozoan that infects a variety of vertebrates. It is a major cause of diarrhea in agricultural animals. There have been reports of clinical signs in cattle and sheep, which include diarrhea, dehydration and weight loss, however; there are limited drugs available for the treatment of giardiasis in animals. In this study, we compared the therapeutic effect of 20 mg albendazole, 50 mg and 100 mg paromomycin (kg body weight orally) for 3 successive days in lambs naturally infected with giardiasis. The efficacy of these drugs was evaluated based on reduction in cyst excretion. In the group treated with albendazole, no cysts were seen in the feces after treatment on D5 (day 5) in 7 lambs and on D8 in all animals. In the group treated with 50mg/kg of paromomycin, no cysts were seen in the feces after treatment on D2 in 3 lambs and on D6 in all animals. In the group treated with 100 mg/kg of paromomycin, there were no cysts after treatment on D2 in 5 lambs and on D6 in all of lambs. White blood cell (WBC) levels were high in all groups before treatment; paromomycin decreased the total leukocyte count more than albendasole. In the present study, we found paromomycin to be more effective than albendozole for the treatment of lambs with giardiasis for both treatment regiments mentioned above.