An embalmer has been infected with tuberculosis (TB) transmitted from a corpse on which he was working.

The case, reported by researchers at Johns Hopkins School of Medicine in Baltimore, US, is believed to be the first of its kind.

Writing in the New England Journal of Medicine, Dr Timothy Sterling, assistant professor of infectious diseases, said: "Previous studies had shown that funeral home workers had unexpectedly high rates of TB infection and disease, but it was not known if this was due to exposure in the workplace."

TB is spread through the air by infectious aerosols, tiny particles that enter the body through the nose or mouth and lodge deep in the lungs.

In the new study, doctors identified an individual with active TB whose only known exposure to the bacterium was through the embalming of an infected cadaver.

During the embalming process, blood is removed and fluids are injected into the body to preserve it.

Dr Sterling said: "Aerosols can be generated by the injection of fluids, or by the frothing and gurgling of fluids through the mouth and nose.

"In addition, the cadaver can spasm during the embalming process, which can cause the release of respiratory secretions."

Embalming fluids are often dumped into a drain after the embalming process and this also could release infectious aerosols.

The discovery was uncovered during a major project to track TB infection in the Baltimore area.

As part of this initiative, every case of the disease in Baltimore reported to the Baltimore City Health Department undergoes DNA fingerprinting at Johns Hopkins.

Similar DNA fingerprints indicates recent transmission of the disease.

Dr Sterling said the research indicated that guidelines were needed to reduce the risk of possible TB infection in funeral parlours.

John Weir, media officer for the National Society for Independent Funeral Directors, said guidelines were already in place in the UK to protect embalmers from infectious disease.

Embalmers dealing with TB victims are told to wear breathing masks.

Mr Weir said: "When a body is being moved it can cause the airways to emit an aerosol type of spray and embalmers are very aware of the hygiene standards they need to employ."

TB is the second leading cause of death from an infectious disease.

World-wide, 2 million people die of TB annually, and 7-8 million new TB cases are diagnosed each year.

There has been an upsurge of cases in the UK, particularly in inner city London.

Therapy for tuberculosis requires a multidrug regimen of four drugs.