Shigellosis

Shigellosis is transmitted via contaminated food or drinking water. Travellers are advised to follow the well-known advice of “Boil it, cook it, peel it or forget it”, and to generally maintain good personal hygiene.

Pathogen and transmission
Pathology
Distribution and frequency of occurrence
Prevention
Documents and links

Pathogen and transmission

Shigellosis is a bacterial diarrhoeal disease that is caused by one of the four species of the Shigella bacterium: Shigella dysenteriae, S. flexneri, S. boydii and S. sonnei. Infection occurs through direct contact with an already infected person or with food that has been contaminated with infected faeces. Flies can also carry the bacteria from faeces onto food. Contaminated drinking water can cause major shigellosis outbreaks.

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Pathology

The time between infection and the onset of illness is one to three days, or in rare cases up to a week. Fever, nausea, vomiting, stomach pains and bloody and purulent diarrhoea are the typical symptoms. In around one third of cases the diarrhoea is runny, and the person will have up to 20 defecations a day. The resulting major loss of body fluids and mineral salts is a complication that can be dangerous for small children and older individuals. Shigella dysenteriae also produces a toxin which can cause the further complication of substantial bleeding. Some cases of the disease develop very mildly, however, and persons who do not develop complications will tend to recover of their own accord within four to seven days.

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Distribution and frequency of occurrence

Shigellosis occurs all over the world, but is more prevalent in warmer countries with low hygiene standards. In Switzerland between 150 and 250 cases of shigellosis are reported per year.

You can find key figures on the current incidence of shigellosis on the FOPH Infectious Diseases Dashboard (IDD).

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Prevention

There is no vaccine against shigellosis. So in countries with poor hygiene conditions, the tried-and-trusted travel rule of “Boil it, cook it, peel it or forget it” needs to be applied. So:

Only use boiled, filtered or chemically treated water (including for cleaning the teeth).
Only eat thoroughly-cooked food.
Only eat fruit you have peeled yourself.
Do without ice cubes.
Wash your hands frequently.
At a restaurant, if possible order only hot drinks or drinks in their original bottles that are opened at your table.

For further information on the global distribution of shigellosis and ways and means to avoid infection, consult your GP or a doctor specialising in travel medicine.

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