I often recall a story told to me many moons ago by a colleague that still fascinates me today!

It is a phenomenon involving the parasite Toxoplasma gondii, which infects a wide range of warm-blooded animals, including humans. However, its primary host is the cat family (Felidae), particularly domestic cats.

Toxoplasma gondii is a single-celled parasite that reproduces in the intestines of cats. Cats become infected by ingesting the parasite through the consumption of infected prey, such as rodents or birds.

Once inside the cat’s digestive system, the parasite undergoes sexual reproduction and produces millions of eggs, known as oocysts, which are shed in the cat’s feces. These oocysts can survive in the environment for months to years.

Toxoplasma can infect a variety of intermediate hosts, including rodents like mice, rats, and birds. These animals can become infected by ingesting the oocysts from contaminated soil, water, or food.

Behavioural Manipulation

Here’s where the story gets interesting.

Under normal circumstances rodents avoid cats but toxoplasma infected rodents lose their instinctive fear of cats and are in fact drawn towards the cat’s scent.  It is believed that Toxoplasma manipulates the rodents’ brain chemistry, specifically targeting neurotransmitters such as dopamine, which are involved in reward and pleasure pathways.

The parasite may also affect the amygdala, a brain region associated with fear and anxiety responses, thereby reducing the rodent’s natural aversion to predators. In effect, the parasite has targeted the emotion system of the rodent’s brain responsible for fight or flight – what a marvellous hacking mechanism!

By altering the behaviour of the intermediate host, Toxoplasma increases the likelihood of its transmission back to its primary host, the cat. When the infected rodent is consumed by the cat, the cycle restarts as the parasite reproduces in the feline’s gut.

What is the relevance of this story?

The cat and mouse story involving Toxoplasma gondii showcases a remarkable example of how parasites can manipulate the behaviour of their hosts for their own survival and reproduction.

If our own gut gets infested with something untoward, it is imperative we take charge and not let that harmful organism sabotage our health and wellness as they pursue their primary goal of procreation.

This is the time we should be even more focussed on repopulating the gut with healthy microbes by eating a balanced and wholesome diet of nutrient-rich foods that helps promote a diverse and thriving microbiome.

Tips to feed a healthy microbome 

  • Fiber-rich Foods:. Fiber acts as a prebiotic, providing nourishment for beneficial bacteria in the gut. Sources include fruits (berries, apples, pears), vegetables (broccoli, Brussels sprouts, artichokes), whole grains (oats, quinoa, brown rice), legumes (lentils, chickpeas, black beans), and nuts and seeds.
  • Fermented Foods: Fermented foods are rich in beneficial bacteria (probiotics) Some examples include yoghurt (with live and active cultures), kefir, sauerkraut, kimchi, tempeh, and miso.
  • Polyphenol-Rich Foods: Polyphenols are plant compounds that act as antioxidants; eating the rainbow when it comes to colourful fruit and vegetables is important!
  • Omega-3 Fatty Acid Sources: Good sources include fatty fish (salmon, mackerel, sardines), flaxseeds, chia seeds, walnuts, and high quality fish oil supplements.
  • Probiotic-Rich Foods: In addition to fermented foods, specific probiotic-rich options can help promote a healthy microbiome. Look for products that contain strains like Lactobacillus and Bifidobacterium. Examples include certain yogurts, kefir, kombucha, and probiotic supplements.

Dr. Avani Karl, MBBS, FRNZCGP, DIP.Obs, currently practices in Auckland as a Functional Medicine Practitioner. Specialising in an individualised treatment approach, she works closely with her patients, empowering them to address the underlying cause of disease to achieve optimal wellness and health.

Dr Avani Karl - Women's Health