Professor Smith and her team screened more than 5,000 eye photographs and estimated that one in 150 Australians has a Toxoplasma scar in their retina, making it surprisingly common for a disease of which few would consider themselves to be at risk.
The Professor’s other findings, though, suggest why.
“Separately, we did a project where we went down to the local supermarket looking for Toxoplasma in meat,” she says “We sampled lamb mince and found that, conservatively, 40% was positive and less conservatively, maybe two-thirds.
“So, you have to cook your meat.”
Alternatively, if you want to eat meat rare, Professor Smith advises to freeze it before you cook it, which is another way of killing Toxoplasma.
That’s the easy part as, once infected, there is no drug or vaccine that can eradicate the parasite.
“There are a lot of anti-microbials that will act against the parasite, but none of them are curative. Once you've been infected with Toxoplasma, you carry it for life like the herpes virus.”
However, Professor Smith says treatment can minimise damage.
“Part of the damage is the caused by the reactive inflammation inside the eye against the parasite, and so we treat patients with anti-inflammatories, usually corticosteroid-based drugs, drugs, along with the anti-microbials.
“We can inject them into the eye or give them to the patient by mouth.”
In the search for a better solution, Professor Smith used her myriad international connections to form a worldwide study group of almost 200 uveitis specialists to describe their approach to tackling ocular toxoplasmosis.
They published a paper this year, effectively providing a blueprint for how to manage the disease.
Back home, Professor Smith is working on the only study in the world using human eye tissue to study the mechanisms of Toxoplasma infection.
“At Flinders University, we have unique access to human eye tissue and we isolate different cells from that eye tissue,” she says. "That's really important because humans have a different response and recognition system for the parasite than animals.”
Thanks to that work, we now have a good understanding of how the parasite gets into the eye, moves across the blood vessel walls, and infects retinal cells.
Meanwhile, she continues to research the human cost of the disease around the world, which may be more devastating than we thought. A collaboration with the University of São Paulo, Brazil, is leveraging the country’s big population to study a large cohort of patients.
“If you take all the patients that come to the clinic with ocular toxoplasmosis, a quarter of them are blind in one of their eyes,” Professor Smith adds, underscoring the importance of her mission.
