Chinese scientists discover why flu can deliver a kick in the guts

SCIENTISTS have worked out why flu wreaks havoc in the gut — it’s not the virus, but an immunity mix-up.

Influenza, flu, cold - generic image of a brunette woman sneezing and blowing her nose.

SCIENTISTS have worked out why flu wreaks havoc in the gut — not because of a direct attack by the virus, but a mix-up in the immune system.

Researchers from the University of Science and Technology of China have found that flu changes the “homing receptors” on immune cells, sending re­inforcements to the small intestine rather than the lungs. Once there, they upset the natural balance of bacteria in the gut.

The study, reported in the Journal of Experimental Medicine, explains why flu viruses — which infect only the nose, throat, bronchial tubes and lungs — can cause gastro­intestinal symptoms. Experiments found infection with the PR8 influenza virus strain caused white blood cells to flood the gut. This triggered a release of “interferon” proteins, whose role is to prevent the replication of the virus. But with no virus in the intestine, the proteins instead interfered with the “microbiota” which helps keep the gut in balance.