Advances in molecular epidemiology of cryptosporidiosis in dogs and cats

• Cryptosporidium infections in dogs and cats and the associated risk factors have been studied extensively. • Zoonotic Cryptosporidium canis , C. felis , and C. parvum are the dominant species in canine and feline cryptosporidiosis. • The use of gp60 subtyping tools has confirmed the occurrence of transmission between dogs or cats and humans. • Potentially host-adapted C. canis and C. felis subtype families have been identified. • More epidemiological studies using the new subtyping tools are needed to assess the importance of zoonotic transmission. The use of molecular tools has led to the identification of several zoonotic Cryptosporidium spp. in dogs and cats. Among them, Cryptosporidium canis and Cryptosporidium felis are dominant species causing canine and feline cryptosporidiosis, respectively. Some Cryptosporidium parvum infections have also been identified in both groups of animals. The identification of C. canis, C. felis and C. parvum in both pets and owners suggests the possible occurrence of zoonotic transmission of Cryptosporidium spp. between humans and pets. However, few cases of such concurrent infections have been reported. Thus, the cross-species transmission of Cryptosporidium spp. between dogs or cats and humans has long been a controversial issue. Recently developed subtyping tools for C. canis and C. felis should be very useful in identification of zoonotic transmission of both Cryptosporidium spp. Data generated using these tools have confirmed the occurrence of zoonotic transmission of these two Cryptosporidium spp. between owners and their pets, but have also shown the potential presence of host-adapted subtypes. Extensive usage of these subtyping tools in epidemiological studies of human cryptosporidiosis is needed for improved understanding of the importance of zoonotic transmission of Cryptosporidium spp. from pets.