Homeless people are suffering from a disease thought to have disappeared after the first world war because of their appalling living conditions, medical experts say.

At least three people, including two rough sleepers, contracted trench fever in London last year and one died.

Researchers fear that the disease may be far more widespread than it appears after a French study, published in the Lancet, found that 30% of the homeless population in Marseilles had been exposed to the bacterium.

Trench fever was discovered in 1915 and reached epidemic proportions in the cramped and filthy trenches of the Western Front. It is caused by bacteria spread through body lice. Weakened immune systems and a lack of washing facilities are now making rough sleepers on city streets as vulnerable as their forefathers were on the battlefield.

While there are no figures for its prevalence in Britain, Dr Tim Harrison of the public health laboratory service told the Big Issue magazine: "I suspect the situation here is very similar to Marseilles."

Trench fever is curable with antibiotics but recurs up to 10 years after initial infection if not treated properly and can lead to depression, weight loss and heart valve infections in those with weak immune systems.

Infection with the disease occurs when people scratch louse bites, rubbing infected faeces into the tiny wound. They develop a fever which lasts for five to six days before dropping for several days and then recurring.

They also experience dizziness, shivering, headaches, a mild skin rash and severe muscle and bone pain, noticeably in the shins.

Health workers fear that the disease may be going undiagnosed because it is easily mistaken for influenza.