Toxoplasma gondiia parasite closely associated with cats is behind retinal scars in one in 150 Australians, according to a new analysis from Flinders University.
Many animals around the world are infected with the parasite, which generally catches the disease in environments contaminated by infected cats or from eating other infected animals. While the feces of domestic cats can be a carrier for humans, the most common route of infection is the consumption of undercooked or raw meat from infected livestock.
“Given the significant population of feral cats in Australia that are known to be infected, in addition to the high levels of farming and diets rich in meat, it is imperative that we understand the prevalence of the disease across the country,” he said. The study’s lead author, Professor Justine Smith, a strategic professor of Eye & Vision Health at Flinders University.
Smith and her team analyzed retinal images of more than 5,000 people living in the Busselton area of Western Australia, previously collected to evaluate the prevalence of glaucoma and age-related macular degeneration for a long-term study of healthy aging.
Three specialist ophthalmologists, including Professor Smith, assessed the scans for toxoplasmic retinochoroiditis, with positive cases confirmed with blood tests for antibodies.
“Among the 5,000 people, we found eight participants with blood-tested toxoplasmic retinal scars. Add to that the fact that about three quarters of retinal lesions would be in a position not visible in these particular pictures, we were able to estimate the prevalence of ocular toxoplasmosis at 1 per 149 individuals,” he said.
While 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 most common disease we see in the clinic is retinal inflammation and scarring that are known as ocular toxoplasmosis.
“Studies around the world show that 30% to 50% of the world’s population is infected with Toxoplasma, but despite knowing that, we didn’t know how common the related eye disease was,” Smith said.
The work claims to be the first attempt to quantify the rate of ocular toxoplasmosis in Australia, with the findings indicating the condition can be considered common. With previous research showing that the infection can lead to impaired vision in more than 50% of the eyes and even blindness, the authors say it’s important for people to understand the risk factors of toxoplasmosis and ways to avoid it.
“While people are often familiar with pregnant women avoiding litter boxes, we also want everyone to know that preparing meat is a major risk factor,” Smith said.
Research by Smith in 2019 indicated a high prevalence of toxoplasma in Australian lamb sold in supermarkets.
“In addition, as it becomes more and more common to cook meat in and out of restaurants to be deliberately undercooked or raw, the chances of people becoming infected with Toxoplasma are increasing.
“We need people who know this disease exists so that they can make informed decisions about how to prepare and eat their meat. The parasite can be killed easily by cooking the meat to an internal temperature of 66ºC (or medium) or by freezing it before cooking.”
The research follows a series of papers recently published by Smith and her team on the condition, including one that uses new retinal imaging technology to show the changes that occur in ocular toxoplasmosis at the tissue level, and another. highlighting best clinical practice. for controlling the disease.
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