Michael Mosley: Infested! Living With Parasites

Confirmed for BBC Four on Wednesday 19 February from 9pm to 10pm

Ep 1/1

Wednesday 19 February



Continuing BBC Four’s Natural History Season, Dr Michael Mosley turns his body into a living laboratory by deliberately infecting himself with some of the most extraordinary, powerful and surprising parasites of them all.

Almost every animal on Earth has its own parasites – and humans are no exception. These strange creatures will feed on him and even make his body their home.

Michael infects himself with the infamous tapeworm by swallowing live cysts sourced from infected meat in Kenya. Tapeworms have evolved over millions of years to the particular environment of the human gut. By swallowing a tiny camera – the pill-cam - the tapeworms’ stomach churning growth inside Michael’s body can be seen close up.

For his next itchy encounter, Michael is joined by entomologist Dr James Logan as he gets to grips with one of the most widespread childhood nuisances in the UK – the head louse. These little blood suckers are so dependent on humans that Michael has to keep them alive on his own skin. Using a video microscope Michael and James observe the lice exploring Michael’s body and digesting their latest blood meal. They see how perfectly the head louse is adapted to climbing and gripping onto human hair. Through comparing the body shapes of head, pubic and body lice James reveals that they tell us something about our own history.

Another common parasite, which is not visible to the human eye, is thought to alter behaviour by infecting the brain. Surprisingly, around a quarter of the population is infected by toxoplasma gondii which is contracted from cat faeces. Some scientists believe it makes the carrier more likely to adopt riskier behaviour. Michael takes a test to find out if he’s infected.

The life-threatening malaria parasite is carried by mosquitos, and infects human blood. It’s something Michael is not prepared to risk, so a new imaging technique is used to show his blood cells being taken over in a test tube.

But other parasites can cure as well as kill. The leech, once sold by medieval quacks, is now used in cutting edge microsurgery. Michael adds to his parasitic load by being bitten by a leech – and sees how it can consume more than five times its own body weight in blood.