Chipotle Mexican Grill Inc. took another hit today – this time in the wallet.

Shares of the restaurant chain’s stock hit a 52-week low Monday after the Centers for Disease Control and Prevention (CDC) announced five new suspected E. coli cases infecting people in Kansas, North Dakota and Oklahoma, according to media reports.

The CDC said it does not know if the more recent cases are connected to the outbreak linked to Chipotle in late October which affected 53 people, according to media reports. The first cases were reported primarily in Washington and Oregon. Twenty people were hospitalized in that outbreak, according to previous accounts.

Chipotle said it would revise its standards after the initial reports of illnesses surfaced in late October and early November.

But that wasn’t the end of the chain’s foodborne illness woes as 120 people in Boston, most of them Boston College students, reported becoming ill earlier this month after eating at a nearby Chipotle restaurant. According to preliminary tests, the restaurant patrons in Boston were sickened by another disease-causing organism called norovirus, according to reports.

Chipotle fell 3.6 percent to 521.71 in the stock market Monday, Investors.com reported. The stock fell as low as 508.10 intraday, which was the lowest since May 2014.