Raw meat parasite linked to common eye disease

Toxoplasma gondiia parasite closely associated with cats, is the cause of retinal scarring in one in 150 Australians, according to a new analysis from Flinders University.

Many animals around the world are infected with the parasite, usually contracting the disease from environments soiled by infected cats or by consuming other infected animals. For humans, while domestic cat feces can be carriers, the most common route of infection is through consumption of undercooked or raw meat from infected livestock.

“Given Australia’s large population of feral cats known to be infected, as well as high levels of animal husbandry and meat-rich diets, it is imperative that we understand the prevalence of the disease across the country,” said said the study’s lead author, Professor Justine Smith, Professor of Strategy. in eye and visual health at Flinders University.

Smith and his team analyzed retinal photographs of more than 5,000 people living in the Busselton area of ​​Western Australia, previously collected to assess the prevalence of glaucoma and age-related macular degeneration for a long-term study. term on healthy aging.

Three specialist ophthalmologists, including Professor Smith, assessed the scans for toxoplasma retinochoroiditis, with positive cases confirmed by antibody blood tests.

“Among the 5,000 people, we found eight participants with toxoplasma retinal scarring confirmed by blood tests. Add to that about three-quarters of the retinal lesions would be in a position not visible in these particular photographs, we were able to estimate the prevalence of ocular toxoplasmosis at 1 in 149 people,” he said.

“Although there is no cure or vaccine, the symptoms of toxoplasmosis vary depending on the age, health and genetics of the infected individual. Many people are asymptomatic, but the disease most common that we see in the clinic is retinal inflammation and scarring called ocular toxoplasmosis.

“Studies from around the world show that 30-50% of the world’s population is infected with Toxoplasma, but despite this, we didn’t know how common the associated eye disease was,” Smith said.

The work claims to represent the first effort to quantify the rate of ocular toxoplasmosis in Australia, with the results indicating that the disease can be considered common. With previous research showing the infection can lead to reduced vision in more than 50% of eyes and even blindness, the authors say it’s important for people to understand the risk factors for toxoplasmosis and ways to prevent it. ‘avoid.

“While people often know of pregnant women who should avoid cat litter boxes, we also need everyone to know that meat preparation is a significant risk factor,” Smith said.

Research by Smith in 2019 found a high prevalence of Toxoplasma in Australian lamb sold in supermarkets.

“Add to this that it is now increasingly common to prepare meat in and out of restaurants to be deliberately undercooked or raw, then the likelihood of people becoming infected with Toxoplasma increases.

“We need people to know this disease exists, so they can make informed decisions about how they prepare and eat their meet. The parasite can be killed easily by cooking the meat to an internal temperature of 66°C (or average) or by freezing it before cooking.

The research follows a series of papers recently published by Smith and his team on the disease, including one that uses new retinal imaging technology to show the changes that occur in ocular toxoplasmosis at the tissue level, and another which highlights the best clinical practice for managing the disease.

Image caption: Ocular scan showing ocular toxoplasmosis. Image credit: Associate Professor João M Furtado.

Leave a Comment