A "mind-bending" disease found in cat faeces and spread to human brains has been enlisted in Gareth Morgan's war on moggies.
About 40 per cent of people in New Zealand are infected at some time in their lives with toxoplasmosis - an incurable disease caused by a parasite that lives only in cat faeces and has been linked to a raft of psychological disorders.
They include schizophrenia, impaired memory, suicidal thoughts, risky behaviour, poor concentration, headaches, extreme fatigue and a higher risk of post-natal depression and self-harm in new mothers.
Although usually dormant in healthy people, the disease could flare up at any time, in ways that were only just being understood, Morgan said.
"Forty per cent of New Zealanders getting toxoplasmosis is an indictment of our nonchalance toward wandering cats. This mind-bending parasite is yet another reason why we need to manage cats like dogs," said the Cats To Go campaigner, who once said any free-ranging cat should be "a dead cat".
Morgan wants cats kept indoors to protect native wildlife, and wants councils to register and microchip them, as with dogs.
Until people had the right to keep cats off their property, they would not be free to garden or let their children play outside without the risk of catching toxoplasmosis, he said.
About two-thirds of cats carry the pathogen but Mark Thomas, associate professor of clinical molecular medicine and pathology at Auckland University's School of Medical Sciences, said that although links to human health had been established, the parasite was not a threat to most people.
In 2012 Thomas released research showing toxoplasmosis could be much more severe and disabling than previously thought.
While chronic toxoplasmosis had been shown to have a strong association with brain conditions such as schizophrenia, and with suicide and self-harming behaviour, the disease in its acute phase was usually benign, trivial and self-healing, he said.
Thomas has since called for further research on the effects of brain infection as tests on lab rats have shown the parasite can lift the production of dopamine - the brain's reward hormone - making the rats less risk-averse and becoming more vulnerable to being eaten.
Infected rats then passed the disease to cats - where the parasite can reproduce. "Given the impact on rats, and that dopamine is our reward chemical, toxoplasmosis seems to be altering the way our brain weighs up risks and rewards," Morgan said.
One European study found latently infected people were also likely to be more involved in car crashes.
The disease is a well-known risk for pregnant women and can cause miscarriage, stillbirth, newborn deaths and a range of serious health problems for children later in life. In New Zealand, around 164 pregnant mothers contract the disease every year, passing it on to 66 babies, which is about one in 1000 births.
"It doesn't matter if you are worried about becoming a crazy cat lady, or the growing evidence of links between toxoplasmosis and schizophrenia or even traffic accidents. The fact is that this is a scary, mind-altering parasite that scientists are just starting to understand," Morgan said.
"Cats should be kept on their owners' property. When you think about toxoplasmosis, it's a no-brainer - literally."
HOW TO STOP SPREAD OF TOXOPLASMOSIS?
Toxoplasmosis can be picked up from cat litter, garden soil, unwashed vegetables and contaminated water so keep your cat indoors but well away from kitchen surfaces.
If you don't live with a cat, either keep them out of your garden, or wear gloves when gardening and be wary of allowing children to scratch around, burrow and dig in soil. The parasite can be transmitted through soil so thoroughly cook or wash potentially tainted food.
Pregnant women and those with compromised immunity are particularly susceptible and should avoid cat faeces and eating undercooked meat and eggs, and unpasteurised milk.
- Sunday Star Times