Shigellosis

What is Shigellosis?

Shigellosis is an infection of the bowel (or gastro-enteritis) caused by the Shigella bacteria. It is not common in New Zealand and is usually caught overseas. However occasional outbreaks do occur and it is infectious so can spread between close contacts.

What are the symptoms?

Symptoms usually begin 1 - 3 days after ingesting the bacteria and include:

• watery diarrhoea
• fever
• nausea
• abdominal (tummy) cramps
• vomiting (sometimes).

In some cases the faeces (poo) contains blood, mucus and pus.  Dehydration (fluid loss), especially in infants, may be severe.

A person may be contagious for up to one month after the illness.  In rare cases, a person may go on to be a carrier and excrete the bacteria in their faeces for months.

How are people infected?

Infected humans are the main source of Shigella bacteria.  Common ways in which people are infected include:

• direct contact with someone who is infected with the bacteria
• eating food that has been contaminated by an infected person
• drinking water or ice that is contaminated by sewage.

How is it treated?

Usually only fluid replacement and rest are needed. Antibiotics can be given if necessary.  Your family doctor will take faecal (poo) samples and notify the local public health service if they suspect shigellosis.

How do I protect myself and others?

Spread of the illness may be prevented by:

• Washing hands thoroughly after going to the toilet, and especially before eating and before feeding infants.
• Children with diarrhoea should be kept away from other children.
• Anyone nursing or looking after an infected child should pay special attention to their own personal hygiene, particularly hand washing.
• An infected person should not swim in a public swimming pool or spa, paddling pool or share bath water with anyone.

People travelling to developing countries should consider the following to reduce their risk:

• Use only bottled water (or water that has been boiled) for drinking and brushing teeth.
• Ask for drinks without ice unless it known to be made from safe water.
• Avoid uncooked food apart from fruits, vegetables and nuts that can be peeled or shelled.
• Make sure food has been thoroughly and freshly cooked and is piping hot when served.

A good general rule for travellers is boil it, cook it, peel it or leave it.

Do I need to take time off work, school or preschool?

Everyone with this infection should stay away from work, school or preschool while they have symptoms. Most people can return to work after they have been completely free of symptoms for 48 hours.

The following people require clearance before they can return to work, school or preschool:

• food handlers (that is, people who prepare or handle food that will be eaten by others)
• health care professionals
• teachers
• school children
• preschoolers in day care centres, crèches or kindergartens.

Clearance means a person must have two consecutive negative faecal specimens taken at least 48 hours apart and at least 48 hours after stopping antibiotics if these have been prescribed.

Food handlers who are close contacts of someone who has shigellosis also need clearance before returning to work but this requires only one negative sample. 

The Medical Officer of Health (public health doctor) will make sure that anyone with shigellosis and their contacts receive relevant advice on clearance testing and returning to work. 

Talk to your family doctor for more information regarding shigellosis.

Resources

• Ministry of Health