Researchers believe appetite loss accompanying infection part of the problem, not the solution

Researchers now believe the loss of appetite which often happens with an infection was part of the problem, not the solution.

A study on mice infected with salmonella revealed those who ate more survived longer, which was due to the fact that the bacteria did not have to spread outside the intestine to feed.

Containing an infection made it easier to treat, according to experts.

Doctors now are looking to explore whether appetite-boosting drugs could be used to treat other ­illnesses which triggered appetite loss.

Professor Janelle Ayres, of the Salk Institute in San Diego, California, told journal Cell: ''It's long been known that infections cause loss of appetite but the function of that, if any, is only beginning to be understood.

''What we found was that appetite loss makes the salmonella more virulent, perhaps because it needs to go beyond the intestines to find itself nutrients.''

Researchers at Yale, last year found that mice with a fever due to infection by the food poisoning bacterium listeria died when fed sugar.

However, the ones that were not given food eventually recovered.

When the study was repeated with a flu virus they found the opposite effect. Mice that had been force-fed sugar survived while those that were denied food died.

The  Salk Institute researchers found that the mice, survived the disease better than mice that restricted their caloric intake. Also in the well-fed mice, the salmonella strains actually got on board and began working to inhibit the body's appetite loss.

"What we found was that appetite loss makes the Salmonella more virulent, perhaps because it needs to go beyond the intestines to find nutrients for itself," said Sheila Rao, a Salk research associate and the first author on the study.

"This increased virulence kills its host too fast, which compromises the bacteria's ability to spread to new hosts. The tradeoff between transmission and virulence has not been appreciated before – it was previously thought that virulence and transmission were coupled."