Nerve cells in the gut have a leading role in preventing a misery that afflicts millions of people every year: diarrhoea and vomiting caused by infection with Salmonella bacteria.

Nerve cells called nociceptors monitor the gut and, if they notice problems, trigger a defence response, such as stomach pain. To investigate these cells’ defensive powers, Isaac Chiu at Harvard Medical School in Boston, Massachusetts, and his colleagues bred mice missing one class of nociceptors. The team then infected the mice with the bacterium Salmonella enterica, a common cause of intestinal distress. One day later, the mice without nociceptors had nearly 100 times more bacteria in one portion of the gut than normal mice did.

The researchers also found that when nociceptors are active, the density of gut cells that provide entry points for Salmonella bacteria is lower. The nerve cells also maintain the presence of beneficial gut microbes called segmented filamentous bacteria, which ward off Salmonella infection.

Targeting nociceptors might yield effective treatments for infectious and inflammatory diseases, the authors say.