McDonald’s shares plunged in after-hours trading after its Quarter Pounder hamburgers were linked to a fatal outbreak of e.coli.

One person died and at least 49 people across 10 US states were taken ill, including a child who was hospitalised with severe kidney complications, according to the US Centers for Disease Control and Prevention (CDC).

Shares in the fast food giant plunged as much as 9pc in after-hours trading after the watchdog said everyone interviewed in connection with the outbreak had reported eating at McDonald’s before falling ill. Most mentioned eating Quarter Pounder hamburgers, the CDC said. 

McDonald’s officials said that initial findings suggest that some illnesses are linked to onions sourced from a single supplier. 

The company has halted distribution of the slivered onions and temporarily removed the Quarter Pounder from menus in the affected states, and also in portions of Idaho, Nevada, New Mexico and Oklahoma.

A McDonald’s spokesman said: “We take food safety extremely seriously and it’s the right thing to do.”

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