Botulism

Botulism is a very rare but serious foodborne illness that's usually related to home-preserved foods.

Botulism is caused by the bacterium Clostridium botulinum, with a range of illnesses in humans and animals.

What are the symptoms?

Symptoms usually appear within 12 to 36 hours (within a minimum and maximum range of 4 hours to 8 days) after eating contaminated preserved foods. Symptoms of botulism usually start with weakness of the muscles that control the eyes, face, mouth, and throat. This weakness may spread to the neck, arms, torso, and legs. Botulism also can weaken the muscles involved in breathing, which can lead to difficulty breathing and even death.

How is it treated?

Botulism can be treated and with appropriate care most people recover fully.

If a doctor suspects that someone has botulism, they will be referred to hospital where tests can be arranged for bacteria and toxins.

The affected person will be monitored and if necessary given the anti-toxin called ‘Botulism Immune Globulin Intravenous’ (BIGIV), which if given early in the course of the illness significantly reduces the time of intensive care required. The neurotoxin effects wear off over time but the affected person may require intensive care and ventilation during this process. Supplies of anti-toxin are available overseas if required.

How is botulism illness prevented?

Many cases of botulism are preventable. Cases of foodborne botulism have happened after people ate home-bottled, preserved, or fermented foods that were contaminated with toxin. Contamination can happen when food is handled improperly when it is made, when it is stored, or when it is used by consumers.

Foods with low acid content are the most common sources of home-bottling related botulism cases. Examples of low-acid foods are:

New sources of foodborne botulism continue to be identified.

If you preserve, bottle, can, or ferment your own foods, you can reduce the chance of these foods giving you, your family, or friends botulism by:

• Following safe home bottling instructions.

• Following all instructions for washing, cleaning, and sterilising items used in bottling and canning.

• Refrigerating homemade oils infused with garlic or herbs and throwing away any unused oils after 4 days.

• Refrigerating any canned or pickled foods after you open them.

Information sources and further information

• Botulism - Health New Zealand | Te Whatu Ora

• Clostridium botulinum - Ministry for Primary Industries

• Home-canned foods - protect yourself from botulism - Centers for Disease Control and Prevention

• Botulism - World Health Organization