a slithering viper, rifle-wielding tribesmen and a fuel leak are just some of the challenges Steve Fabes has beaten on his round-the-world challenge.

But as well as testing his skills of bravery and adventure, the trip is also putting his medical knowledge to good use.

The Oxford doctor has now reached Kenya, where he is helping people affected by tropical diseases.

Dr Fabes, who grew up in North Oxford, battled punctures, searing heat and crocodile-infested rivers to reach the remote clinic in the north of the African country.

Since leaving Britain early last year, the former Abingdon School pupil has cycled 13,000km across 19 countries.

Now he plans to spend a few weeks helping people affected by diseases which occur in areas of poverty.

Writing on his blog, Dr Fabes, 29, said the approach to the Merlin clinic – a charity he hopes to raise £50,000 for – was one of the hardest parts of his journey so far.

He said: “I was covering only 50km per day, with gale-force winds slowing my progress to walking pace.

“In the distance a haze hung over the hills the way smog hangs over a city. I guessed that it was a sandstorm and I was heading right into its maw.

“Soon I was engulfed, my senses obliterated, eyes, nose, mouth and ears full of sand. I was completely disorientated in the murk.

“I pushed my bike on through the storm and finally reached yet another catholic mission and then some beautiful, glorious Tarmac.

“For two more days I pedalled, each turn was a huge effort in my weary and underfed state.

“At last I arrived into Merlin’s base at Lodwar to a warm welcome from the staff at the compound.”

Dr Fabes is helping fellow doctors treat people with conditions thought to affect as many as one billion people worldwide.

Despite having to fly home for knee surgery last year, he still aims to cycle the 50,000 miles in five years.

Dr Fabes said he had a close encounter with a deadly assailant just days after arriving in Kenya.

He said: “I pitched my tent and discovered a small carpet viper slithering inconspicuously nearby. It made a retreat when I pelted it with stones, but I slept restlessly knowing that the zip to my tent was broken.”

The following day Dr Fabes suffered two punctures, a fuel leak in his bag and was forced to hand over a bottle of water to a tribesman with a rifle.

But he said he was still in good spirits and described the journey as “amazing”.

After covering two of the six continents on his route, the medic has raised more than £17,000.

To follow Dr Fabes’s progress, or to donate, see cyclingthe6.blogspot.com dhearn@oxfordmail.co.uk