Toxoplasma able to pass from the gut into the central nervous system, says report

A food-borne parasite that infects domestic cats can get inside the human brain by commandeering special cells of the immune system which it uses as a Trojan horse to enter the central nervous system, a study has found.

Scientists believe they have finally discovered the mechanism that allows Toxoplasma gondii – a single-celled parasite – to pass from the human gut to the brain where it may cause behavioural changes.

Researchers have shown that the parasite can infect the dendritic white blood cells of the immune system causing them to secrete a chemical neurotransmitter that allows the infected cells, and the parasite, to cross the natural barrier protecting the brain.

Toxoplasma gondii can live in many different species but it can only complete its life cycle in cats, which secrete the parasite in their faeces. Studies have shown that toxoplasma affects the behaviour of rats and mice, making them more likely to be eaten by cats, thereby completing parasite’s complex life-cycle.

Latest figures released in September by the Food Standards Agency show about 1,000 people a day in Britain – 350,000 a year – are being infected with toxoplasma, probably from either direct contact with cats or by eating poorly-cooked meat or vegetables.
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