1 Oct 2020
New RVC research has highlighted the considerable behavioural and psychiatric effects of Toxoplasm gondii parasite around the world.
James Westgate
Job TitleA study by the RVC has shown that the human infection burden of Toxoplasma gondii around the world has been greatly underestimated.
In fact, researchers on the study, published in Trends in Parasitology, estimate that globally each year T gondii infection potentially causes between 150,000 and 335,000 cases of schizophrenia, between 2.1 million and 10.2 million non-fatal traffic accidents, and between 0.5 million and 2.9 million non-fatal suicide attempts.
The zoonotic parasite is found in every continent and is estimated to infect up to a third of the world’s human population, via its two main post-natally acquired transmission routes of eating infected undercooked or raw meat, or of ingesting parasites shed in the faeces of infected cats via contaminated soil, food or water.
Infection results in the formation of parasite cysts in the brain, eyes and other tissues, which potentially last for life.
If the parasite is acquired during pregnancy, transmission to the fetus may cause either abortion or stillbirth, or if the baby is brought to term, a range of abnormalities and development problems (termed congenital toxoplasmosis).
T gondii shares a family tree with other commonly known Apicomplexan parasites, including malaria parasites, and is more commonly known for its danger to pregnant women and those with weakened immune systems.
However, the study, which involved collecting and analysing published data that examined links between T gondii infection and human disorders, highlighted that otherwise healthy T gondii–infected people have a higher risk of developing a range of autoimmune, psychiatric and behavioural conditions, including an increased risk of addiction, suicide attempts and even traffic accidents.
These findings highlight the considerable global health impact that T gondii may cause and suggest the burden of toxoplasmosis has been considerably underestimated.
Gregory Milne, lead author and PhD student under the supervision of Martin Walker and Joanne Webster, at the RVC, said: “While it has been suspected since as early as the 1950s that T gondii infection might cause neurological diseases like schizophrenia, the scale of the problem has often not been truly appreciated.
“I am excited to share our study, which confirms that T gondii poses a significant burden on human health worldwide and demonstrates the sheer diversity of conditions that can result from T gondii infection. My hope is that our paper stimulates future research in this field.”
