NEW drugs which it is hoped will offer an alternative treatment to antibiotics could increase the spread of disease, according to researchers.

Scientists have given a cautious welcome to treatments currently being developed by pharmaceutical companies, which work by limiting the symptoms caused by a bug or virus in the body, rather than killing it.

However, they also warn the medicines might mean that patients feel well when they are highly infectious. As a result they may continue their daily lives, mixing with others and passing on the illness.

Dr Pedro Vale, from Edinburgh University School of Biological Sciences, worked on the research, which has been published in the journal PLoS Biology. He said it was important to develop new ways of tackling infection because of the way bugs had become resistant to antibiotics.

He said: "Fifty, sixty years ago, no one could have guessed that all this antibiotic resistance would have emerged. We can plan from history, so if we are planning new drugs we have to understand what the long-term consequences are."

The new "damage limitation" therapies are intended to help patients tolerate disease and buy the immune system time to get rid of the infection naturally.

Mathematical models were used by the research teams to predict the likely impact of these treatments.

Dr Vale said: "Damage limitation therapies may be a useful alternative to antibiotics, but we should be cautious, and investigate their consequences."