‘VERY SERIOUS DISEASE’

The E. coli O157:H7 strain that led to the McDonald’s outbreak is the same as a strain linked to a 1993 incident at Jack in the Box that killed four children. It can cause “very serious disease,” especially for the elderly, children and people who are immunocompromised, said Shari Shea, director of food safety at the Association of Public Health Laboratories.

McDonald’s suppliers test their products frequently and did so in the date range the CDC gave for the outbreak, and none of them identified this E. coli strain, company spokespeople said.

U.S. food safety attorney Bill Marler, who represented a victim in the Jack in the Box outbreak, said this is a relatively large and serious outbreak for which McDonald’s will face “a lot” of liability for the contamination.

Analysts flagged the outbreak as a potential black eye for McDonald’s ahead of earnings.

Analysts said McDonald’s fourth-quarter sales could experience some pressure from the outbreak, but it was too early to say whether it would be worse than the previous two E. coli cases.