Botulism

Botulism is a neuroparalytic disease caused by the ingestion of very small amounts of botulinum toxin. An oral dose of 0.005 pg may be lethal for humans. C. botulinum is a spore-producing organism that can grow only in the absence of oxygen. The tough spores are found worldwide in the soil and in the mud of lakes and rivers. When food like fish, vegetables, and meat is contaminated with soil containing the spores and is then left at room temperature, the spores germinate and multiplication of the organism occurs.

Some strains grow in temperatures as low as 3.3° C. During the growth process, a powerful neurotoxin is produced, which, when ingested, results in symptoms of botulism, following an incubation period of 18 to 36 hours. The preformed toxin causes a muscular paralysis with hoarseness, visual disturbances, headache, nausea, vomiting, and difficulty in swallowing and speaking. If left untreated, death from respiratory or cardiac arrest is a real danger. Symptoms may last from several weeks to many months.

A less severe disease is caused in infants ingesting spores of C. botulinum. These spores germinate in the infant’s gut, releasing toxin in the intestine. Symptoms of flaccidity and weakness, with difficulty in feeding, are the presenting symptoms of infantile botulism. Treatment includes administration of antitoxin antibodies to attempt to neutralize the toxins.

Prevention relies on the destruction of spores by thorough heating of all preserved food. This is especially relevant to home-preserved food - the cause of many outbreaks. The high acid content of certain foods prevents the growth of this organism, but preformed toxin retains its activity when added to acid food. As mentioned previously, in an outbreak in England in 1989, the source was contaminated hazelnut puree used to flavor yoghurt. The toxin in food may be destroyed by heating at 85° C for 5 minutes.

Vibrio Parahaemolyticus Food Poisoning

This form of food poisoning is related to the ingestion of undercooked or raw shellfish or fish. Vparahaemolyticus has a predilection for high salinity and grows well in the warmer seas. The shellfish and fish taken from such sites may be contaminated with the organism. When undercooked shellfish are eaten, symptoms of diarrhea and vomiting, fever, and abdominal cramps appear within 16 to 48 hours, resolving in 2 to 7 days. Other halophilic (salt-loving) bacteria, like Vibrio vulnificus, may cause a septicemic infection in people eating raw oysters. Prevention depends on the adequate cooking of seafood.