Toxoplasmosis
Cats, toxoplasmosis and people.
Toxoplasmosis is a disease caused by the parasite, Toxoplasma gondii (T. gondii) which can infect many animals, including cats, humans, sheep and dolphins. Poultry, deer, pigs, rabbits, marsupials, and birds can also suffer outbreaks of disease.
Cats are key for the parasite's survival because it can only reproduce and produce eggs (oocysts) in the gut of cats. Once in their lifetime, typically when they're young, cats shed these eggs via their faeces.
Living with a cat does not increase your risk of being exposed to the parasite. The most common route of infection for people is from eating or handling raw meat that contain Toxoplasma cysts, but exposure to contaminated soil, eating unwashed vegetables and dealing with contaminated litter trays are also possible sources of infection.
Toxoplasmosis and
cats.
While cats plays an important part in the life cycle of toxoplasmosis, it's important to note that shedding of oocysts in cats' faeces happens only once in their life time, and only for a limited time - mostly when they are kittens or young.
Living with a cat does not increase the risk of human infection with the parasite - it does not live on a cat’s fur, meaning stroking a cat will not spread infection.
Most cats infected with the parasite don't have clinical signs. When signs are observed, they can include high temperatures, muscle pain, breathing difficulties and diseases of the nervous system.
Toxoplasmosis and
people.
About one quarter of people worldwide have been exposed to toxoplasmosis, but exposure rates vary by region.
Most people show no symptoms but those with weakened immune systems, (unborn babies, the young & the elderly, pregnant people, chemotherapy patients) may experience minor to serious illness.
Most human infection comes from eating and handling contaminated meat. However, people can be infected following exposure in gardens and uncovered sandpits, on unwashed vegetables or when dealing with cat litter trays.
Toxoplasmosis and marine mammals.
Oocysts can survive in the environment for months and are carried by rainwater into waterways.
Disposal of cat faeces into household toilets contributes to wastewater burden.
Standard water treatment methods are not effective against the Toxoplasma parasite. That means contaminated water acts as a source of infection for marine mammals such as Hector’s and Māui dolphins who either ingest infected water or become infected through eating infected fish.
Toxoplasmosis and other animals.
Many warm blooded animals - both domestic and wild animals - can carry T. gondii. Rats and mice are a common source of infection for cats.
Similar to other species, infected farm animals usually don't show clinical signs, but serious disease may occur in various species at certain times.
Infected pregnant sheep and goats are at high risk of abortion and death of their young, which is both disastrous for them and has a serious impact on farm productivity.
Research
Toxoplasmosis in wild birds in New Zealand
Hunter, S. A., & Alley, M. R. (2014). Toxoplasmosis in wild birds in New Zealand. Kokako, 21(2), 58-59. https://www.sciquest.org.nz/browse/publications/article/112757
Impact of feral cat control on toxoplasmosis levels in sheep as part of the Cape to City Programme
Niebuhr, C. N., & Norbury, G. (2020). Impact of feral cat control on toxoplasmosis levels in sheep as part of the Cape to City Programme. Contract Report: LC3836. Maanaki Whenua Landcare Research. https://www.pfhb.nz/assets/Document-Library/LC3836-Niebuhr-and-Norbury-2020-Impact-of-feral-cat-control-on-toxoplasmosis-in-sheep-MWLR-report-2020.pdf
Four cases of fatal toxoplasmosis in three species of endemic New Zealand birds
Howe, L., Hunter, S., Burrows, E., & Roe, W. (2014). Four cases of fatal toxoplasmosis in three species of endemic New Zealand birds. Avian Diseases, 58, 171-5. https://doi.org/10.1637/10625-080413-Case.1
The effects of Toxoplasma gondii on New Zealand wildlife: Implications for conservation and management
Roberts, J. O., Jones, H. F. E., & Roe, W. D. (2021). The effects of Toxoplasma gondii on New Zealand wildlife: Implications for conservation and management. Pacific Conservation Biology, 27, 208-220. https://doi.org/10.1071/PC20051