Think twice if Dr Mike Leahy invites you for a beer, because you could end up with a hideous parasite growing inside you.

The "mad" scientist - as his brother fondly describes him - talked regulars at the Shaven Crown pub, in Shipton-under-Wychwood, into taking part in a bizarre series of experiments, which involved introducing parasites into their bodies.

But at least Dr Leahy, who has an Oxford University PhD in virology, practised what he preached, by allowing 10 different parasites to feed off him at once.

The experiments were carried out at different locations around the county, including Didcot, Bladon and North Leigh, for a new television series called Invasion of the Bodyscratchers, which is being shown on Sky TV tonight.

For the three-part series, Dr Leahy, 40, who lives in Shipton-under-Wychwood, shared his body with headlice, leeches, bed bugs, dust mites, tics, malarial mosquitos, a two-metre-long tapeworm and a Bot fly.

His brother Aidy, 29, was persuaded to have a live Tunbu Fly inserted into his buttock and his drinking partner Duncan Lonsdale agreed to take part in an experiment to see whether tapeworms, which live in the gut, thrive better on healthy or less healthy food.

Two other customers at the pub were persuaded to become infested with tics and several more agreed to help with an experiment involving bed bugs.

Dr Leahy said: "I have always been interested in infectious diseases and parasites and the best way to see them is on a host.

"I have done experiments like this before, but thought it would be fun to get some other people involved as well.

"I just told them I would make them film stars and they decided to give it a go.

"The wife wasn't too happy at times though - she kicked me out on one occasion and I had to live in a shed at an airbase."

During filming, Dr Leahy met a hospital patient whose foot had become a temporary home to hundreds of maggots, placed on the wound by doctors to suck out an infection.

His brother Aidy said: "I think he's absolutely mad. I wouldn't go through with half the things he's put inside his body.

"I just did it out of interest really. I was apprehensive beforehand, especially when they wanted to put the Bot Fly on my genitals - there was no way I was going to do that - but they assured me it was not one of the nastier parasites, so I agreed to do it."

* Invasion of the Bodyscratchers is on Sky One tonight at 10pm.

Mini menaces

Tick - related to mites and spiders, not insects. Their serrated mouths cut into flesh,, then they apply a chemical cement which makes them difficult to get out. They can flesh out up to four times their size and spread Lyme Disease, which can cause rashes and arthritis and affect the nervous system.

Flea - still spreads bubonic plague - the Black Death - in some places. Extremely itchy and unpleasant.

Tapeworm - once used medically as a slimming aid. It does not work. Lives in the gut. Only really causes a problem if you are malnourished. Dr Leahy grew one in his body for 10 weeks.

Bot fly - often infects cows, lowering milk yield. Larvae form a tumour, called a warble, where they develop. Most injury to the host occurs when they force their way out through the warble.

Kissing Bugs -They are big, two inches long. They can sneak up on you in your sleep and feed on you. Their faeces carry chaga's disease, which is believed to have killed Charles Darwin. Around 20 million people around the world have Chaga's disease. It is very difficult to treat and particularly dangerous for young children.

Tunbu Fly - More of an irritant. Lays its eggs on all sorts of things including washing. Can get rid of it by ironing clothes. Drops out on own accord.

Kandari Fish - Nightmare parasite. Can kill you. Does not want to parasite you. Mistakes urine for fishes faeces and dies inside you, but blocks the system. Will enter women's uretha as well.