In Ida-Viru County and Tallin, five people in the same family aged between 15 and 72, contracted dysentery and the original source of infection is unknown, the Health Board said.
The first person became ill at the end of October, and within a month other members of the family became infected through contaminated objects, food or surfaces.
Irina Dontchenko, an advisor to the Department of Infectious Disease Monitoring and Epidemic Control at the Health Board, says one of the ways that shigellosis, or dysentery, can be contracted is as a result of non-compliance with food hygiene requirements.
"One source of danger may be unwashed vegetables and fruits or dirty hands," said Donschenko, who said it is worth washing vegetables and fruits with running water.
Dysentery is spread through eating contaminated food. In most cases, the pathogen appears in salads, prepared foods, raw fruits and vegetables, and water, through dirty hands.
The disease is particularly prevalent in developing countries and endangers tourists.
As a rule, dysentery is relatively mild, but symptoms can be worse if it is caused by Shigella dysenteriae. Then the sickness begins with acute high fever and abdominal pain, followed by normal, then bloody diarrhoea.
Symptoms can appear after half a day and range from moderate abdominal pain to high fever.
Editor: Helen Wright