Villagers in southern China are suffering a crippling disease causing their hands and feet to slowly deform, twist out of shape and erupt with blisters – leaving doctors baffled.

The bones in their limbs seem to be twisting, and in some cases, painful pustules are also appearing on their skin, The Daily Mail reports.

Some of villagers affected have been suffering from the disease for years and have been left unable to work because of their painful joints.

Medics sent to help the villagers have been left stumped, but the most popular theory is they could be suffering from rare condition called Kashin-Beck disease, also known as ‘Big Bone Disease’.

Occurring in China, Siberia and North Korea, it is caused mainly by lack of the element selenium in the water or food.

Although toxic in large amounts, a small amount of selenium is vital in humans for a healthy functioning body.

Health workers sent to help the villagers, in the Yalong township, on the outskirts of the city of Hechi in southern China's Guangxi Zhuang Autonomous Region, identified 20 people suffering from the bizarre disease.

In most cases it is the men in the village who are affected, although there are also some women with the condition.

Health care worker Doctor Li Wu, 41, said: 'In many cases this doesn't only just look bad, it also significantly affects the person's ability to work.

'For people in a rural community who have to carry out a lot of manual work it is a disaster.'

For example, Luo Guiyu, 38, can now only do light housework after first discovering she was suffering from the problem 12 years ago.

She said many of the villagers had sought medical help but nobody knew what was wrong with them.

She said: 'Many of my neighbours have been to different health centres and hospitals but nobody seems to know what the problem is, although it's great that the experts have now come here to try and get to the bottom of it.'

Doctor Wu and his team have been carrying out tests on the water and on the food that the villagers have been growing in the hope of confirming that it is Kashin-Beck disease the villagers are suffering from.

There is no cure for Kashin-Beck disease, but surgery or physical therapy can help with the symptoms.

However, tests are still being carried out and the experts say it is too early to say whether the rare condition, usually found in children, is definitely the cause.