A total of 195 faecal samples comprising (100 from buffalo calves and 95 from household persons) were parasitologically examined for the presence of Giardia lamblia using direct smear method and concentration techniques. The overall prevalence among household persons was 17.9% with a higher infection rate 24.4% in children compared to 12% in adults. Moreover, 28% of diarrhoeic versus 20% of non- diarrhoeic children and 15.4% of diarrhoeic versus 8.3% of non- diarrhoeic adults were shedding Giardia cysts. The overall infection rate in calves was 25% with a significant higher rate 30% (P < 0.05) among diarrhoeic versus 17.5% in non-diarrhoeic ones. Multivariate logistic regression analysis retained not washing hands after contact with calves and their manure as a potential significant risk factor strongly associated with the infection (OR= 40.67; CI: 3.89-424.85; P=0.002). Based on nested-PCR results, 292-bp fragment of SSUrRNA gene of G. lamblia was amplified in faecal samples from household persons and calves. Our results emphasize the role of buffalo calves in zoonotic transmission of G. lamblia to persons living in the same households.