E. coli O157 infection can cause a range of symptoms, from mild diarrhoea to bloody diarrhoea with severe abdominal pain. On rare occasions, it can also cause more serious medical conditions and can be caught by eating contaminated food or by direct contact with animals with the bacteria. It can also be passed from an infected individual to another person if hand and toilet hygiene is poor.
Dr Isabel Oliver, director of PHE's field epidemiology service, said: "At this stage, we are not ruling out other food items as a potential source."
PHE was first alerted to the outbreak at the end of June. Dr Oliver said people could help protect themselves from possible infection by washing their hands before eating and handling food and by thoroughly washing vegetables and salads that they were preparing to eat.
E. coli O157 is found in the gut and faeces of many animals, particularly cattle, and can contaminate food and water. Outbreaks of E. coli O157 are rare compared with other food-borne diseases.
Avoiding E. coli O157 infection
§ Wash hands thoroughly after using the toilet, before and after handling food, and after handling animals
§ Remove any loose soil before storing vegetables and salads
§ Wash all vegetables and fruits that will be eaten raw
§ Store and prepare raw meat and unwashed vegetables away from ready-to-eat foods
§ Do not prepare raw vegetables with utensils that have also been used for raw meat
§ Cook all minced meat products, such as burgers and meatballs, thoroughly
§ People who have been ill should not prepare food for others for at least 48 hours after they have recovered
Source - PHE & BBC