Four botulism cases in the Bay of Plenty from bottled sea snails

Botulism symptoms include double vision, difficulty swallowing or talking, muscle weakness, and difficulty breathing. Photo / File

Four people from the Bay of Plenty were hospitalised by botulism in May after sharing food at one of their homes which included home-preserved bottled sea snails.

Toi Te Ora Public Health medical officer of health Dr Neil de Wet said botulism was identified in the one bottle of the home-preserved sea snails and was the cause of the illnesses.

All the leftover snails from this bottle were collected by Toi Te Ora Public Health.

"There were no other bottles of this prepared, given to or shared with others, and so there is not a further risk to anyone else," de Wet said.

Botulism was a rare but potentially serious illness caused by a toxin produced by bacteria called Clostridium botulinum.

On rare occasions, the bacteria could contaminate home-preserved bottled foods if the bottling process was not quite right.

The toxin was a nerve toxin and could cause symptoms such as double vision, difficulty swallowing or talking, muscle weakness, and difficulty breathing.

Symptoms usually appeared within 12 to 36 hours, within a minimum and maximum range of four hours to eight days, after eating contaminated preserved foods.

Symptoms of botulism usually started 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 could also weaken the muscles involved in breathing, which could lead to difficulty breathing, which could be fatal.

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

If a doctor suspected that someone had botulism, they would be referred to hospital where tests could be arranged for bacteria and toxins.