Listeria monocytogenes contamination of crops grown on soil treated with sewage sludge cake.

Listeria monocytogenes was found in the sewage sludge cake which is commonly used as an agricultural fertilizer in Iraq. Soils treated with this material were contaminated with the organism. Pot and field experiment showed that crops grown on treated soil became contaminated with L. monocytogenes and when alfalfa plant was grown on farmland soil treated with sewage sludge cake, listerias were found on 10% of 50 plants sampled at harvest, but the organism was detected only in low numbers on these crops (less than or equal to 5 cells/g). This could add to the risk to animals and man.