Fish Microbiology and Quality Assurance

Unit 5 - Foodborne pathogens

5.5. Foodborne gastroenteritis caused by Salmonella
Food poisoning caused by the ingestion of viable cells of genus Salmonella is called Salmonellosis. This is one of the frequently occurring bacterial infections.

Characters
Salmonella are Gram negative, non-spore forming rods that ferment glucose usually producing gas. There are over 2000 serotypes based on antigenic characters and all serotypes are considered potential pathogen. The primary habitat is the alimentary tract of mammals, birds, amphibians and reptiles. Found to be non endemic to intestinal tract of finfishes, crustaceans and mollusks. Because of fecal origin, contaminates food due to pollution with sewage. The most common disease illness associated is gastroenteritis/salmonellosis.

Disease symptoms
A large variety of foods including fish and shellfish are involved in salmonellosis.
Food poisoning symptoms include nausea, vomiting, abdominal cramps, diarrhea, fever and headache. Symptoms occur 6~8 hrs after ingestion of contaminated food. Infective dose varies depending on serotype and ranges from few cells on 105 to cause illness. Persons of all age groups are susceptible. The infection is severe and prolonged among elderly and infants. The likelihood of infection depends on resistance of consumer, infectiveness of salmonella strain and number of organisms ingested. More severe form of infection is typhoid and paratyphoid caused by S.Typhi and S. Paratyphi. Septicemia caused could be fatal

Conditions necessary for outbreak

• Food (fresh / processed) must contain or contaminated with Salmonella
• Must be present in considerable numbers
• Viable organisms must be ingested.

Prevention

• Avoidance of contamination of food from animals, humans, diseased food handlers and carriers.
• Destruction of the organism by heat
• Prevention of growth in foods by keeping at low temperature.
• Avoidance of consumption of warmed left over foods without refrigerator.