File picture: Damaris Helwig/Independent Media

London - A young father was left fighting for his life after being bitten by a 91 cm adder that slithered under his little boy’s buggy.

Josh Rose, 27, was taking his children for a picnic in a west London park when he spotted the snake – the only poisonous wild variety in Britain.

But when he tried to flick it away from the pram’s undercarriage it darted out and bit his finger.

Almost instantly Mr Rose went into anaphylactic shock and was temporarily paralysed while he helplessly watched the snake crawl closer to his young sons – Sebastian, two, and Lincoln, three.

Luckily, a passing walker on Hounslow Heath rushed over and forced the snake away with a stick before calling an ambulance.

Mr Rose told The Sun: "I was paralysed, my blood started to clot and I couldn’t speak.

"I was foaming at the mouth. I could hear everyone talking, but couldn’t open my eyes or speak. It was horrible."

The builder from Twickenham, south-west London, was taken by ambulance to West Middlesex Hospital as his pulse dropped to just four beats per minute.

Doctors gave him an antidote and he spent 24 hours in intensive care.

He said: "I feel like I’ve been hit by a truck."

The adder normally spends its time hiding between rocks.

The last death in the UK from an adder was in 1975, when a five-year-old boy was bitten on the ankle in the Trossachs in Scotland.

Research published after this incident showed there had been only 14 deaths from adders in the previous 100 years.

The researchers found one death from an adder bite between 1950 and 1972, but 61 deaths from bee or wasp stings in the same period.

Adder bite symptoms include swelling, vomiting, nausea and dizziness. In most cases, the only treatment required is observation in hospital. More severe bites are treated with anti-venom medication.

Children bitten by an adder will usually make a full recovery in about one to three weeks, but some adults can take up to nine months.

About 100 adder bites are reported in the UK each year, with most between February and October.