How to test for Botulism?

April 21, 2010

Botulism is a serious food poisoning caused by the toxins of C.botulinum. It is caused by eating food infected with these toxins.

Symptoms of botulism food poisoning usually appear within 18 to 36 hours after eating contaminated food, but sometimes they may occur within 6 hours or even take 10 days to manifest.

The symptoms are varied and are often difficult to recognize because they are not always connected with abdominal diseases. Your mouth and throat may feel dry and sore, you may have a headache accompanied by blurred and double vision, droopy eyelids and dilated pupils, muscle weakness which leads to dizziness, a weak grip, difficulty in talking, swallowing and breathing. This progresses to respiratory and total paralysis. You might even have a few mild abdominal symptoms like nausea, vomiting, abdominal pain, constipation or diarrhea, and sometimes urine retention.

Since various other diseases such as a stroke, myasthenia gravis (which causes weakening and drooping of eyelids) or Guillain-Barre syndrome (which causes muscle paralysis) have many similar symptoms, special tests are conducted to rule out these conditions and confirm a botulism infection. A tensilon test, nerve conduction test (called electromyography or EMG), a brain scan and spinal fluid examination may be ordered to check whether the symptoms could be caused by myasthenia gravis.

However, if several persons who have eaten from the same food container are displaying similar symptoms, botulism would strongly be suspected. A test for botulism neurotoxin will be done directly by using mice inoculation techniques or mouse neutralization test. This consists of taking samples of a patient’s stool, blood or serum and injecting it into the peritoneal cavity of some mice. An equal quantity of stool, blood or serum from the patient is mixed with multivalent antitoxin and injected into some other mice. Sometimes, some portion of the suspected, infected food is injected into mice. If the mice injected with the infected serum/stool/blood die, and those with the antitoxin-treated fluids live, it confirms infection by botulism. This test usually takes 48 hours for the result to be visible.

Sometimes, the infected food or stool from the patient is cultured in an enrichment medium in an isolated form, to confirm that the toxins of botulism exist. This culture test takes around 7 days.

All these tests are performed at qualified laboratories.

Since the effects of botulism can be serious and even fatal at times it is necessary that treatment commences as soon as possible after the results have come in.

Submitted by M T on April 21, 2010 at 12:47

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