Salmonellosis

Salmonellosis

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ICD-9	003.0
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Salmonellosis is the name name of a group of infectious diseases caused by bacteria of the genus Salmonella, including typhoid fever, paratyphoid fever, and food poisoning.

Salmonella

Salmonella are rod-shaped, gram-negative bacteria, whose main habitat is the intestinal tract of animals. As of December 7, 2005, there are two species within the genus Salmonella: Salmonella bongori (previously subspecies V) and Salmonella enterica (formerly called Salmonella choleraesuis), which is divided into six subspecies, such as

While only two species are recognized, there are numerous serotypes (or serovars). A serovar or serotype is a grouping of microorganisms (or viruses) based on their cell surface antigens, allowing differentiation below the level of species. Serovars may be established based on virulence factors, lipopolysaccharides in gram-negative bacteria, presence of an exotoxin, plasmids, or other characteristics that differentiate two members of the same species (Barron 1996). Various accounts place the number of known serotypes as "over 2,200" (Breslow 2002) and around 4,400 (Ryan and Ray 2004).

However, only a few of these serotypes cause infections in humans, with the majority of cases traced to only five to ten common forms (Breslow 2002). The vast majority of human isolates (>99.5%) are subspecies S. enterica. For the sake of simplicity, the Center for Disease Control and Prevention recommends that Salmonella species be referred to only by their genus and serovar, e.g.,

Salmonella typhi

instead of the more technically correct designation,

Salmonella enterica subspecies enterica serovar Typhi.

Overview

Most persons infected with Salmonella develop diarrhea, fever, vomiting, and abdominal cramps 6 to 72 hours after infection. In most cases, the illness usually lasts 3 to 7 days—most affected persons recover without treatment. However, in some persons the diarrhea may be so severe that the patient becomes dangerously dehydrated and must be taken to a hospital. At the hospital, the patients will receive intravenous fluids to treat their dehydration and medications may be given to provide symptomatic relief, like fever reduction. In severe cases, the Salmonella infection may spread from the intestines to the blood stream, and then to other body sites and can cause death unless the person is treated promptly with antibiotics. The elderly, infants, and those with impaired immune systems are more likely to have a severe illness. Some people afflicted with Salmonellosis later experience reactive arthritis, which can have long-lasting, disabling effects.

The type of salmonella usually associated with infections in humans is called Non-Typhoidal Salmonella. It is usually contracted by ingesting raw or undercooked eggs, or from animals such as:

• Poultry and cattle, if the meat is prepared incorrectly or becomes infected with the bacteria somehow.
• Infected eggs and milk, as well as egg products, when not prepared, handled, or refrigerated correctly.
• Reptiles such as turtles, lizards, and snakes, as they can carry the bacteria on their skin.

Another, rarer form of salmonella is called Typhoidal Salmonella. It is only carried by humans and is usually contracted through direct contact with the fecal matter of an infected person. This kind of salmonella infection can lead to typhoid fever. It therefore mainly occurs in countries that do not have proper systems for handling human waste.

Typhoid fever (or enteric fever) is an illness caused by the bacterium Salmonella typhi (Salmonella enterica Serovar Typhi, which is historically elevated to species status as S. typhi) and less commonly by Salmonella paratyphi. Common worldwide, typhoid fever is transmitted by the feco-oral route, which incorporates ingestion of food or water contaminated with feces from an infected person. Transmission involving infected urine is possible, but much less common (Giannella 1996).

According to the Centers for Disease Control (CDC), typhoid fever is common in most areas of the world except in industrialized regions such as the western Europe, United States, Canada, Japan, and Australia. The CDC advises travelers to the developing world to take precautions, noting that travelers to Asia, Africa, and Latin America have been especially at risk.

Etymology

Both Salmonellosis and the Salmonella type of microorganisms derive their names from a modern Latin coining after Daniel E. Salmon 1850–1914, an American Veterinary surgeon. He had help from Theobald Smith, and they found the bacterium in pigs.

Symptoms

The bacterium induces responses in the animal that it is infecting and this is probably what causes the symptoms rather than any direct toxin. They are usually gastrointestinal including nausea, vomiting, and bloody diarrhea with mucus. Headache, fatigue and rose spots are also possible. These symptoms can be severe especially in the old and very young. Symptoms last generally up to a week, and can appear 6 to 72 hours after bacterium ingestion.

Incidents of salmonellosis

In June 2006, the BBC reported that the Cadbury chocolate manufacturer withdrew a number of products because of possible contamination with salmonella. The problems had been traced to a leaking pipe at a Cadbury plant in Herefordshire in January 2006, though the announcement was not made until June.

In March 2006, The New York Times reported that the U.S. government said that 16.3% of all chickens were contaminated with salmonella. In the mid to late twentieth 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 salmonella colonization. Many different salmonella serovars also cause severe diseases in animals other than human beings.

After bacterial infections, reactive arthritis (aka Reiters Syndrome) can develop. In sickle-cell anemia, osteomyelitis due to Salmonella infection is much more common than in the general population.

In February 2007, the U.S. FDA issued a warning to consumers not to eat certain jars of Peter Pan peanut butter or Great Value peanut butter due to risk of contamination with 'Salmonella Tennessee'. [1]

In March 2007, around 150 people were diagnosed with salmonella-poisoning after eating tainted food at a governor's reception in Krasnoyarsk, Russia. Over 1500 people attended the ball on March 1 and fell ill as a consequence of ingesting salmonella-tainted sandwiches.

References

ISBN links support NWE through referral fees

• Baron, E. J. 1996. Classification. In S. Baron et al., eds., Baron's Medical Microbiology, 4th edition. University of Texas Medical Branch. ISBN 0963117211.
• Breslow, L. 2002. Encyclopedia of Public Health. New York: Macmillan Reference USA/Gale Group Thomson Learning. ISBN 0028658884.
• Centers for Disease Control and Prevention. 2005. Outbreak of multidrug-resistant Salmonella Typhimurium associated with rodents purchased at retail pet stores: United States, December 2003-October 2004. Morbidity and Mortality Weekly Report. Retrieved April 9, 2007.
• Giannella, R. A. 1996. Salmonella. In S. Baron et al., eds., Baron's Medical Microbiology, 4th edition. University of Texas Medical Branch. ISBN 0963117211.
• Ryan, K. J., and C. G. Ray (editors). 2004. Sherris Medical Microbiology, 4th ed. McGraw Hill. ISBN 0838585299.

External links

• CDC website, Division of Bacterial and Mycotic Diseases, Disease Listing: Salmonellosis
• CFIA Website: Salmonellae

See also

• Typhoid fever
• List of foodborne illness outbreaks

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