IN ANIMALS continued
PREVALENCE AND RISK FACTORS • The pooled global prevalence of Cryptosporidium in dogs in a recent meta-analysis was 8%. 2 In Australia, prevalence of faecal oocyst shedding has been reported in several studies and ranges from 0.6% to 2%. 3,4 Dogs residing in rural areas and less than one year of age have a higher infection rate. • Overall prevalence of Cryptosporidium in Australian cats has been reported as 2.2%, with infection rates higher in cats from shelters (3.5%) than owned pet cats (1.0%). 4 Prevalence was higher in cats under one year of age. CLINICAL DISEASE • A role for Cryptosporidium as a primary pathogen in dogs and cats is unclear, as clinical signs are rarely seen in healthy animals. Immunosuppression or concurrent
gastrointestinal infection or parasitism may lead to clinical signs. • If clinical signs are seen, animals typically present with self- limiting large-volume small-bowel diarrhoea, anorexia and weight loss. Systemic signs are rare. 5 • Chronic, asymptomatic infection with relatively low intensity oocyst shedding can occur. DIAGNOSIS • Specialised stains such as the Ziehl-Neelsen or modified acid-fast staining of direct faecal smears are useful for visualisation of oocysts but lack sensitivity if oocyst shedding is low. • Immunodiagnostic coproantigen ELISA assays and genus-based real-time PCR-based assays offered through commercial veterinary laboratories are the most reliable methods of diagnosis.
Life cycle of Cryptosporidium spp .
Life cycle of Cryptosporidium spp.
D.H. Dog and cat
Infective form (sporozoites)
Oocyst
Faeces
Oocyst containing four sporozoites
Faecal-oral transmission (contamination of food/water)
Other possible hosts (humans and small mammals)
D.H. = definitive host
Extracted from the Textbook of Clinical Parasitology in dogs and cats, Beugnet F., Halos L., Guillot J., Ed Servet, 2018. Life cycles adapted from Pet Owner Educational Atlas. Parasites, Carithers D. and Miro G., Ed Servet, 2012. Life cycle from Beugnet, F., et al (2018) Textbook of Clinical Parasitology in Dogs and Cat. Grupo Asis Biomedica, S.L.; Adapted from Carithers, D., et al (2012) Pet Owner Educational Atlas.
CONTENTS
Companion Animal Zoonoses Guidelines 33
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