Researchers may never know exactly how salmonella tainted 13 million pounds of California almonds this year, but they are learning more about the organism that can cause serious, and sometimes fatal, infections.

The fact that salmonella enteritidis was recently found in almonds, while rare, may not be altogether surprising since almonds are shaken to the ground, and inevitably mix with dust during the harvesting process.

Ali Bay California reports that to date, 29 patients in 12 states and Canada have reported cases of the food-borne illness that has been traced back to raw almonds shipped from Los Angeles-based Paramount Farms Inc. Millions of packages of natural, raw almonds have been recalled internationally as state and federal regulatory agencies continue to investigate how the almonds became contaminated.