Authorities in northern France have closed a third factory after discovering bacteria linked to a severe outbreak of Legionnaires' disease.
The bug had already been found at this petrochemical plant
Ten people have been killed and more than 70 infected in and around Lens since the outbreak started in November.
Health Minister Jean-Francois Mattei said it was "a vicious strain of Legionnaires' never before seen, neither in France nor elsewhere".
The illnes is a kind of pneumonia caused by bacteria in water droplets.
It can be easily spread through contaminated air condititoners and ventilators. It can be treated with antibiotics.
The latest discovery of the bacteria was in the cooling system of a potato chips factory at Harnes, which is owned by the food group McCain.
The bug had previously been traced to the cooling tower at the Noroxo petrochemical plant in the same town, and another factory further east.
All three plants have now been closed.
Mattei, who visited the region on Sunday, said the authorities were exercising "utmost caution".
The most recent victim was an 80-year-old man who died on Friday.
Legionnaires' disease takes its name from the first known outbreak in 1976 when it killed 29 people at an American Legion Convention in Philadelphia.
Its symptoms include high fever, dry cough, lung congestion and subsequent pneumonia.