CRYPTOSPORIDIOSIS (Cryptosporidium spp. ) • Cryptosporidium are apicomplexan gastrointestinal parasites that infect a range of animals. Numerous species are recognised, some with relatively restricted host ranges, while others are capable of infecting a broad range of hosts. • Cryptosporidium canis and C. felis are host-adapted canine and feline species respectively, and are rarely found in humans or other animals. Cryptosporidium hominis is a human adapted species and is the most common cause of cryptosporidiosis in people. • Most cases of cryptosporidiosis in humans are due to human-to-human transmission of C. hominis , and to a lesser extent C. parvum (typically livestock associated), however zoonotic infections with C. canis and C. felis have been reported, albeit rarely.
ACAZAP RECOMMENDATIONS
• Prevention of cryptosporidiosis is dependent on good hygiene. Alcohol-based hand sanitisers do not effectively inactivate Cryptosporidium oocysts, therefore thorough hand washing is essential. • Prompt removal of animal faecal matter (at least daily) and thorough cleaning of litter trays and toileting areas is recommended. • Cryptosporidium spp. are environmentally resilient and resistant to many common disinfectants when used at standard concentrations and contact times. High level disinfection (e.g. 50% ammonia, 3% hydrogen peroxide or 10% formalin) is necessary. 1 Steam and heat sterilisation may be required to inactivate oocysts.
• Infected animals should be isolated, particularly in group housed animal facilities. High density kennel situations should be avoided. • Special recommendations for immunosuppressed individuals, children or those populations at risk: - Consider careful pet selection, choosing age-appropriate pets and avoiding adoption of young or stray animals. - Minimise exposure to potentially contaminated faeces, with other household occupants cleaning litter boxes/ disposing of faeces where possible. If required to dispose of faecal material, disposable gloves should be worn.
IN ANIMALS
AETIOLOGY AND EPIDEMIOLOGY • Dogs and cats become infected through direct contact with infected hosts or indirectly through ingestion of oocysts from contaminated food, water, soil or through coprophagia. • The primary species infecting dogs and cats are C. canis and C. feli s respectively. Cryptosporidium parvum has also been detected in naturally infected dogs together with rare reports of C. muris .
• Cryptosporidium spp. complete their life cycle in a single host, alternating between asexual and sexual reproduction. After ingestion of sporulated oocysts, excystation occurs in the gastrointestinal tract followed by the release of sporozoites which infect the epithelial cells and undergo repeated merogony (asexual replication). The ability of Cryptosporidium to produce and release oocysts within the same host can lead to autoinfection. There are two types of oocyst: thin- walled and thick-walled. Thin-walled oocysts are responsible for autoinfection and thick-walled oocysts are shed into the environment.
CONTENTS
32 Companion Animal Zoonoses Guidelines
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