Listeria Outbreak in Ontario, Canada: Summer 2008

On Saturday, August 23rd., 2008, the Public Health Agency of Canada announced that 21 cases of a deadly listeriosis outbreak have been confirmed and another 30 are under investigation. Of the confirmed cases, sixteen have occurred in Ontario, three in British Columbia, one in Saskatchewan and one in Quebec.

Four deaths in Ontario have resulted from the disease so far, along with another on Vancouver Island in British Columbia.

Until recently, this disease has been unknown to most Canadians. Here are some pertinent facts of which we should be aware, in light of the growing outbreak.

Background

Listeria monocytogenes (commonly called listeria) is a type of bacteria which is common in the environment. Animals and humans can carry the bacterium without even knowing it. Farm animals may appear healthy and still be carriers. They may contaminate foods such as meats and dairy products. Listeriosis is a food borne illness.

Foods contaminated with listeria look, smell and taste normal. The bacteria can live and even multiply on food stored in the refrigerator. It can be killed by proper cooking procedures.

Symptoms

Symptoms start suddenly and include persistent fever, chills, muscle and joint pain, fatigue, nausea, vomiting, cramps, diarrhoea, headache, or constipation. At this stage the illness may be mistaken for food poisoning.

If the disease spreads to the nervous system, these further symptoms may be noted: severe headache, stiff neck, confusion, loss of balance and convulsions. Meningitis encephalitis (an infection of the brain or its surrounding tissues) and /or septicemia (blood poisoning) may develop. Either of these conditions can result in death.

Timeline

Symptoms can appear from 2 to 90 days after consuming contaminated food. Average incubation period is three weeks.

Most at risk

Most at risk are pregnant women and their unborn children, those with weakened immune systems and the elderly.

Treatment

There is no vaccine for listeria. The disease is treated by antibiotics. Early diagnosis is critical, especially for those at high risk.
Diagnosis