I spent time on Tuesday visiting the family of an 8-year-old who spent over a week at Children’s Hospital with an E. coli O26 infection that has been linked to a vegetarian meal at Chipotle.  The now weeks-old E. coli O26 episode has brought Chipotle into negative buzz territory and its lowest scores since YouGov BrandIndex initiated tracking of the brand in June 2007. The Mexican fast casual chain also experienced a significant slide in purchase consideration, a key metric in predicting potential revenue.

Chipotle’s consumer perception was measured by Buzz score, which asks respondents: “If you’ve heard anything about the brand in the last two weeks, through advertising, news or word of mouth, was it positive or negative?”

Prior to the Halloween-time shut down, 8% more adults 18 and over had a positive view on Chipotle than negative. By this past Monday, 19% had a more negative view on Chipotle than positive.

The impact on purchase consideration has been dramatic as well over the past 10 days, Chipotle coming close to hitting the low mark for the year. At Halloween, 24% of all adults 18 and over reported that they would consider purchasing from Chipotle the next time they wanted to buy fast casual food. That percentage dropped to 19%, where it has held since the middle of last week.