The CDC currently counts 30 cases of E. coli O145 infection (23 confirmed and 7 probable) in the romaine lettuce outbreak linked to Freshway Foods lettuce.  The 30 cases are residents of four states: Ohio, Michigan, New York, and Tennessee.  The recognized exposure period–i.e. the time period during which the contaminated lettuce was in the market and being consumed–was from early to late April (see image below).  The contaminated, recalled lettuce is no longer in the market.

"lettuce outbreak" "e. coli O145" "e. coli outbreak" "Freshway outbreak"

Does this mean that the risk of exposure to E. coli O145 in this outbreak is over?  Unfortunately, the answer is "not necessarily."  We have received calls from a number of Ohio, Michigan, and New York residents who have recently suffered a severe gastrointestinal illness–some with bloody diarrhea, which is a hallmark symptom of E. coli infection–and are undoubtedly beyond the exposure period for this outbreak.  Several characteristics of this outbreak in particular require that these illnesses be further investigated to determine their relationship to the lettuce E. coli O145 outbreak.

"Secondary infection," a well-recognized epidemiological phenomenon that is a significant public health risk in many outbreaks, occurs when an outbreak victim (someone who became infected from the implicated product) unknowingly passes the outbreak strain of bacteria to other people, who then become ill despite not having consumed the implicated product.  In the lettuce E. coli O145 outbreak, the risk of secondary infection may well be heightened due to the fact that the implicated romaine lettuce was sold to and served in schools, where there are lots of people and lots of contact.  As a result, there are many more vectors for transmission of disease from one person to another, even after the outbreak exposure period is over. 

Further complicating the problem, and heightening the risk, is the fact that, in contrast to its more prevelant relative E. coli O157:H7, E. coli O145 is not regularly tested for by the government or medical providers.  This means that a person infected by E. coli O145 is far less likely to have his or her infection confirmed.  As a result, the prophylactic measures typically instituted for a person infected with a communicable disease will not be put in place.  For instance, a person confirmed for infection by E. coli O157:H7 will be prohibited, by the local health department, from working in foodservice, childcare, or medical care settings due to the risk of secondarily infecting other people.  But because E. coli O145 is not typically tested for, health departments may never have an opportunity to prevent an infected person from working in one of these settings.

In the romaine lettuce outbreak, however, the problem reaches even further.  It has been well-publicized that most of the victims in this outbreak are college students, at Ohio State, the University of Michigan, and Daemen College in New York.  Some college kids work, and many work in foodservice establishments.  Often, the restaurants they work at have rather flimsy sick-leave policies that don’t pay the kids for days missed from work, meaning that the kids who need money have an incentive to get back to work as soon as possible, sometimes while they are still shedding E. coli O145 bacteria and, as a result, are still contagious. 

It is also a well-recognized phenomenon that people infected by E. coli bacteria–or, for that matter, salmonella, campylobacter, hepatitis, or any other infectious disease–may remain infected long past the end of their symptomatic illness.  The bottom line is that college kids, or anybody else working in foodservice or healthcare, who were infected in the E. coli O145 romaine lettuce outbreak, may yet be a continuing vector for the transmission of disease.  Add to this the problem that E. coli O145 is not regularly tested for by medical providers, thus thwarting the ability of health departments to institute appropriate prophylactic measures against the further spread of disease, and the result may well be ongoing infection in this outbreak . . . and many more people ill