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Infectious disease investigation

We investigate cases of notifiable diseases (particularly food poisoning) in order to ascertain their source and to prevent their further spread and provide advice on infectious diseases to members of the public.

We take cases from GPs, the public, businesses and other local authorities. Once a food poisoning notification is received, we will contact the person with the symptoms and ask them questions regarding:

  • What and where they've eaten prior to their illness
  • Details of their symptoms
  • Whether they've been on holiday abroad
  • Whether or not their GP has taken a faecal sample and
  • Whether anybody else they ate with also experienced any symptoms. We may request that person to provide a faecal sample.

If a person with symptoms is a food handler or health care/nursery worker, who has direct contact or contact through serving food with highly susceptible patients or persons in whom an intestinal infection would have serious consequences, they cannot return to work until they are symptom-free for 48 hours. They must also inform their employer of their symptoms.

Parents or guardians of children aged five years or under or children or adults unable to implement good standards of personal hygiene are advised to stay away from schools or other establishments until they have also been symptom-free for 48 hours.

Food poisoning outbreaks

If a number of people ate at the same venue and have the same food poisoning-type symptoms, this may be due to a Food Poisoning Outbreak. Our investigation into the outbreak will involve:

  • Interviewing people who are ill
  • Interviewing others who ate at the venue but didn't have symptoms
  • Taking faecal and food samples (if appropriate) and
  • Inspecting the implicated venue

Food safety inspection

If there is enough evidence implicating a food premises within the area as a possible source of the outbreak, we may decide to carry out a food safety inspection.

If you believe that you are suffering from food poisoning (i.e. sickness and diarrhoea) please contact us using the details below.

Guidance notes


In conjunction with the Health Protection Unit of South West London we have a provided a number of guidance notes below on the most common gastro-intestinal illnesses.


Related websites

Contact us

Environmental Health Commercial
Merton Council
Civic Centre
London Road

Telephone: 020 8545 3025