Salmonella bongori
Salmonella choleraesuis
Salmonella enterica
Salmonella enteritidis
Salmonella nyanza
Salmonella paratyphi
Salmonella typhi
Salmonella typhimurium
Salmonella virginia Salmonella is a genus of rod-shaped Gram-negative enterobacteria that causes typhoid fever, paratyphoid and foodborne illness. Salmonella does not ferment lactose. It is motile in nature and produces hydrogen sulfide.

Disease-causing salmonellae have recently been re-classified into a single species, Salmonella enterica, which has numerous strains or serovars. Salmonella typhi is a well known serovar that causes typhoid fever. Other salmonellae are frequent causes of foodborne illness, and can especially be caught from poultry and more generally from food that has been cooked or frozen, and not eaten straight away. In the mid to late 20th century, Salmonella enterica serovar Enteritidis was a common contaminant of eggs. This is much less common now with the advent of hygiene measures in egg production and the vaccination of laying hens to prevent samonella colonisation. Many different salmonella serovars also cause severe diseases in animals other than human beings.

Symptoms

See main article Salmonellosis

Symptoms are usually gastrointestinal and can include nausea, vomiting, diarrhoea. These symptoms can be severe especially in the old and very young. Symptoms last generally up to a week, and can appear around 24 hours after ingestion of the bacterium.

The bacterium induces responses in the animal that it is infecting and this is probably what causes the symptoms rather than any direct toxin.

External links

• notes on Salmonella nomenclature
• Taxonomy Browser at the U.S. National Center for Biotechnology Information
• List of Salmonella species at Finland's National Public Health Institute (in Finnish)
• Backgrounder on Salmonella from the Food Safety and Inspection Service of the United States Department of Agriculture