An apparent outbreak of listeria in Colorado grew to 13 cases over the weekend, including two deaths since Aug. 1.

The Denver Post reports in an earlier outbreak, in June, two people diagnosed with the infection died.

Has DNA fingerprinting linked the June cases with the ost recent outbreak?

The cause of the most recent outbreak is still under investigation and there is no clear link between the cases, said Mark Salley, spokesman for the Colorado Department of Public Health and Safety.

Colorado averages about 10 cases of listeria per year.