TOXOPLASMOSIS (Toxoplasma gondii)
• Toxoplasmosis is a zoonotic disease caused by the obligate intracellular protozoan parasite Toxoplasma gondii. • Toxoplasma gondii can infect multiple warm-blooded animal species including companion animals, livestock, birds and wildlife, with cats being the definitive host. • Most cases of toxoplasmosis in humans are thought to occur indirectly through ingestion of uncooked or undercooked meat or contaminated food, however direct contact with cat faeces is a potential risk.
ACAZAP RECOMMENDATIONS
• Preventing infection in cats requires minimising opportunities for exposure. It is therefore recommended to keep cats indoors to prevent hunting and scavenging, and to avoid feeding raw meat and poultry. • Gloves should be worn when handling cat litter trays. Daily emptying of litter trays and prompt removal of faeces from the environment is recommended to prevent oocysts from sporulating. After being passed in faeces, oocysts can sporulate (become infective) in one to five days and can survive in the environment up to 1.5 years in optimal cool and humid conditions. • Children’s sandpits should be protected or covered when not in use and gloves worn when gardening to prevent exposure. • Good hand hygiene is essential after contact with raw meat, soil and sand. This is especially true when handling raw meat and poultry. Prevent these foods and their juices from contacting already cooked or ready-to-eat foods and fresh produce.
• To reduce the risk of humans acquiring T. gondii , proper food preparation is essential. Meat should be cooked to an internal temperature of 67°C or higher to inactivate tissue cysts. 1 Freezing meat at -10°C for 3 days or -20°C for 2 days is considered sufficient to inactivate tissue cysts or bradyzoites. 2 Thorough washing of fruit and raw vegetables prior to consumption is also of benefit. • Due to the increased risk associated with infection in pregnant women and immunosuppressed individuals, additional
precautions for these higher risk groups include: - Avoid direct contact with soil, cat litter or areas contaminated with cat faeces.
- When considering adopting a new cat, consider healthy adult cats rather than young kittens, as recently weaned kittens and feral/stray cats are potentially a greater source of infection.
IN ANIMALS
AETIOLOGY AND EPIDEMIOLOGY • Felidae , inclusive of domestic cats, are the definitive hosts of T. gondii , while most other mammalian and avian species can be intermediate hosts. • Toxoplasma gondii has a complex life cycle with three infectious stages: - Sporozoites – contained in oocysts shed in the faeces of the definitive host. The enteroepithelial life cycle results in the shedding of oocysts and occurs only in cats. - Tachyzoites – actively multiplying stage of the parasite in extra-intestinal tissues. Occurs in definitive and intermediate hosts.
- Bradyzoites – latent or slowly multiplying stages, encapsulated within extra-intestinal tissue (central nervous system, muscle and viscera), also referred to as 'tissue cysts', are responsible for life-long chronic infection. Occurs in definitive and intermediate hosts. • Cats and dogs can become infected by ingesting intermediate hosts (e.g. rodents and birds) or raw meat and poultry harbouring tissue cysts, or by consuming sporulated oocysts in soil or contaminated food and water. Sporulated oocysts are resistant to environmental conditions and many routine disinfectants. Less commonly, transplacental or transmammary transfer of tachyzoites from mother to offspring can occur in pets. 3
CONTENTS
88 Companion Animal Zoonoses Guidelines
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