People who harbour ulcer-causing bacteria in their stomachs may be protected against some diarrheal diseases, according to an Israeli study.

Some previous studies had suggested that being infected with the bacterium, Helicobacter pylori, increases the risk of diarrhoea, while others have reported finding the opposite, said researchers from Tel Aviv University.

“Our findings suggest an active role of H. pylori in the protection against diarrhoeal diseases,” wrote lead author Dani Cohen in the journal Clinical Infectious Diseases.

The bacterium is especially common throughout the developing world, but only causes symptoms in a minority of those it infects. People with chronic H. pylori infections are known to have an increased risk of stomach cancer and related diseases.

Cohen’s team studied 595 male Israeli soldiers, close to one-third of whom visited a base clinic for diarrhoea during their field training.

All of the soldiers had their blood taken before the start of training, which researchers used to determine which men were chronically infected with H. pylori.

It turned out that between 32 and 36 percent of soldiers who had diarrhoea  due to different types of bacteria than H. pylori, or from unknown causes, had been infected with H. pylori before training. By contrast, up to 56 percent of soldiers who had been infected with H. pylori before training reported no diarrhoea.  The researchers calculated that being infected with H. pylori meant solders were about 60 percent less likely to get diarrhoea  from Shigella bacteria.

They also had a lower chance of having diarrhoea  caused by Escherichia coli bacteria — although statistically, that particular finding could be due to chance.                   –Reuters