Chipotle Mexican Grill on Tuesday said the $1 billion in value the chain lost over five days was caused by a single employee coming to work sick. The sniffly staffer spread the norovirus around a suburban Washington DC, store, sickening more than 130 customers. The headlines about the outbreak sent Chopotle’s shares on a five-day slide — cutting more than $1 billion off the Denver company’s market cap. “We conducted a thorough investigation and it revealed that our leadership didn’t follow our protocols,” said Chipotle founder and Chief Executive Steve Ells during a second-quarter earnings conference call on Tuesday. ... (full story)