The annual number of reports of a deadly disease resulting from foodborne bacteria have more than doubled from 2011 to last year as people eat more pre-packaged food, doctors at the Centre for Food Safety said on Wednesday. 

A total of 26 cases of listeriosis, a serious bacterial infection that has a mortality rate of about 20 per cent, were reported last year and in 2012. In the previous three years, the annual average number of reported cases was 11.

The disease is caused by Listeria monocytogenes, a type of bacteria which thrives on pre-prepared food that is refrigerated for more than a week. 

Sixteen cases have already been reported in the first seven months of this year. The disease can lead to miscarriage, stillbirth, blood and brain infections among high-risk people such as pregnant women, newborns and elderly people.

Some of the cases reported this year had resulted in miscarriages, the centre said.