Brain Bug

Toxoplasma gondii parasites (pictured) can infect most warm-blooded animals, including humans, but their main hosts are cats. The bugs sexually reproduce in felines and their offspring (oocysts) are dispersed via the animals’ faeces. Humans can become infected if they accidentally ingest the parasite, for example by consuming contaminated water or plants, or not washing their hands thoroughly after cleaning a litter box. In most cases, infected people don't show symptoms and live unaffected by the dormant parasite. But when symptoms are present they tend to be neurological in nature. Indeed toxoplasmosis can cause confusion, seizures, headaches and inflammation in the brain. Because these symptoms are observed in other neurological disorders, such as Alzheimer’s disease researchers hope that studying the effects of T. gondii on the brain will provide insights into a variety of neurological pathologies, not just toxoplasmosis, and may offer clues on how to treat them.

Written by Ruth Williams

Ruth Williams

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Ruth is a freelance science journalist based in the US. She's a regular correspondent for The Scientist, and her work has appeared in The Lancet, Nature, Scientific American Mind, BBC Focus and elsewhere. Twitter @rooph

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• Image from work by Ke Hu and John M. Murray, associated with a publication in PLOS Pathogens 2006
• Current research from School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds, UK and Centre de Physiopathologie Toulouse Purpan (CPTP), Inserm, CNRS, Université de Toulouse, Toulouse, France
• Image published with a Creative Commons Attribution 4.0 International (CC BY 4.0)
• Current research published in Trends in Immunology, December 2020