Updated

The latest E.coli outbreak at Chipotle Mexican Grill locations in Washington state and Oregon is making customers uneasy and has provided ammunition for an outspoken critic of the burrito chain.

Chubby Chipotle, an anti-Chipotle campaign backed by Washington, D.C.-based lobbyist Center for Consumer Freedom, ran a new advertisement in the New York Post on Wednesday, attacking the burrito chain for the outbreak of the food borne illnesses.

“You can’t spell ‘Chipotle’ without ‘E. coli,” reads the ad. It continues, “Chipotle specializes in deceptive, feel-good marketing: GMO-free, antibiotic-free, organic, etc. But what really matters is if your high-calorie burrito will make you feel sick to your stomach.”

For months, the group has been running an aggressive ad campaign against the fast-casual giant — warning diners that the food can pack on the pounds, like its overweight pitchman, or can make you sick.

No deaths have been reported in the current outbreak although it has sicken at least 39 people.  Some have begun questioning the chain's claims of serving healthy, fresh food and are not willing to run the risk.

A Chipotle customer from Washington state has already filed a lawsuit after getting sick and another victim of the E. coli strain has come forward to say he has sworn off the chain for good.

"The reality is there was waste in my food. Something I can never be able to tell unless I got sick," Oregon resident Chris Collins told the Associated Press. "For me, it doesn't seem to make sense to take that risk again."

In August, a norovirus outbreak in Simi Valley, Calif. shuttered several Chipotle locations and earlier this fall, at least 64 cases of salmonella in Minnesota were traced back to tomatoes served at the Mexican chain.

Health officials are still working to identify the cause the of the latest E.Coli outbreak but suspect they will be able to trace the bacteria back to fresh produce such as lettuce, tomatoes, cilantro or onions, or possibly even spices.

On Tuesday, Chipotle issued a statement reiterating that it was “aggressively” working to address all issues related to the outbreak including the immediate closure of 43 area outlets (including locations where E.Coli was not found), “conducting additional deep cleaning and full sanitization of its restaurants in the area,” replacing all possibly tainted food items, and performing batch tests before restocking kitchens.

Though Chipotle has yet to comment on how the most recent food poisoning debacle is affecting business, analysts are predicting the chain is likely to take a hit in the coming months.

"Even after the company sounds the 'all-clear,' we believe that it will take some time for traffic to return," Maxim Group restaurant analyst Stephen Anderson told Reuters. According to his estimates, same store sales could decrease by as much as 75 basis points (.75%) this quarter and 25 basis points in the first quarter of 2016.

In addition to the closures, analysts expect the wave of negative publicity will continue to depress sales.