A further case of E.coli have been confirmed in Orkney, bringing the total number of people with the infection to five.
NHS Orkney said the new case is a "contact" of a patient who has contracted the O157 strain.
Two patients are being treated in hospital while the others have either recovered or are recovering at home. Two suspected cases are also being investigated.
Dr Louise Wilson, Director of Public Health, NHS Orkney, said: "The case confirmed today is a contact of a known case and their infection was identified as a result of our joint investigation. We remain vigilant and are continuing to investigate to find links between the cases."
E.coli O157 is a bacterium which lives in the gut of animals such as cattle, sheep, deer and goats. It can also be carried by pets and wild birds.
In humans, the toxins that the O157 strain produces can cause diarrhoea and kidney failure as well as other illnesses. Young children and older people are said to be at the greatest risk.
Dr Wilson added: "Hygiene plays a vital role in avoiding a wide range of infections. E.coli infections can be food or environment-related, but the symptoms are the same. Some infected people may have mild diarrhoea, or no symptoms at all.
"On average, it takes three to four days for symptoms to develop after swallowing an infectious dose of E.coli O157.
"Symptoms can last up to two weeks, except in cases with complications. Most people get rid of the bacteria after about one week, although children may continue to carry it for longer periods."
