GLASGOW scientists have made a major discovery in the study of how infection passes between animals and humans.

A study, involving academics from the University of Glasgow, shows that bacteria may be able to jump species easier than was previously thought.

Researchers, working alongside scientists from Edinburgh University, discovered that a single genetic mutation in a strain of bacteria infectious to humans enables it to also become infectious to rabbits.

They say the discovery has "major implications" on the way scientist assess the risk of bacterial diseases.

A spokesman for the University of Glasgow said: "It is well known that relatively few mutations are required to support the transmission of viruses - such as influenza - from one species to another.

"Until now it was thought that the process was likely to be far more complicated for bacteria."

Scientists studied a strain of bacteria called ST121 (Staphylococcus aureus), which is responsible for widespread epidemics of disease in the global rabbit farming industry.

The team looked at the genetic make-up of ST121 to work out where the strain originated and the changes that occurred that enabled it to infect rabbits.

They found that ST121 most likely evolved and jumped from humans to rabbits around 40 years ago with a single genetic mutation.

ST121 is found in the respiratory tract and on the skin of some people.

While it is usually harmless, the bacteria can cause a variety of conditions from minor skin infections to meningitis and sepsis.

In rabbits, the bacteria can cause serious skin infections.

Professor Jose Penades, of the Institute of Infection, Immunity and Inflammation at the University of Glasgow, who co-led the study, said: "Our results represent a shift in understanding of the minimal adaptations required for a bacterium to overcome species barriers and establish in new host populations."

Professor Ross Fitzgerald, from Edinburgh University's Roslin Institute, who co-led the study, said: "Domestication of animals, industrialisation of agriculture and globalisation have provided new opportunities for the transmission of bacteria between humans and animals.

"This latest research has important public and veterinary health implications which will require a re-examination of the future threat posed by bacterial host switching events."

The study was funded by the University of Glasgow, the Biotechnology and Biological Sciences Research Council and the Medical Research Council.