Prevalence, molecular characterization, and risk factors of canine Giardiasis in Lebanon, Middle East and Sardinia, Italy

The present dissertation investigates the epidemiology, molecular characteristics, and risk factors of canine giardiasis in Sardinia (Italy) and Lebanon. Giardia duodenalis is a globally important intestinal protozoan with zoonotic potential, yet data from these regions are limited. This study combines copromicroscopy and molecular analysis to evaluate dogs as reservoirs within a One Health framework. Faecal samples were analyzed using zinc sulphate flotation and light microscopy (centrifugal in Sardinia, passive in Lebanon). In Sardinia, the prevalence was17.7%, while in Lebanon, it was 14.6%. Infection was higher in young dogs, confirming their key role in environmental contamination. Pasty faeces were significantly associated with infection, whereas sex, breed, and living conditions showed little effect. Polyparasitism was frequent in Sardinia, supporting integrated control approaches. In Lebanon, kennelled dogs had higher prevalence, while bottled water showed a non-significant protective trend. Many infections were asymptomatic in both regions. Molecular analysis (nested PCR targeting SSU-rRNA and Sanger sequencing) identified only canine-specific assemblages. In Sardinia, assemblages C and D were detected (mainly D), with minor variation; in Lebanon, all isolates were assemblage D, indicating limited zoonotic risk but ongoing environmental and dog-to-dog transmission. This thesis provides a comprehensive overview of canine giardiasis in both regions, highlighting young and kennelled dogs as main reservoirs. The predominance of host-adapted assemblages refines public health risk assessment and supports routine screening, improved hygiene, targeted control, and continued molecular surveillance