Salmonellosis overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Salmonellosis is an infection with Salmonella bacteria. Most persons infected with Salmonella develop diarrhea, fever, vomiting, and abdominal cramps 6 to 72 hours after infection. In most cases, the illness 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 sources such as:
- Poultry and cattle, if the meat is prepared incorrectly or somehow becomes infected with the bacteria.
- Infected eggs and milk, as well as egg products, when not prepared, handled, or refrigerated properly.
- Reptiles such as turtles, lizards, and snakes, as they can carry the bacteria on their skin.
- Pet rodents
Cannabis contaminated with Salmonella muenchen was positively correlated with dozens of cases of salmonellosis in 1981.[1]
A rarer form of salmonella called Typhoidal Salmonella can lead to typhoid fever. It is only carried by humans and is usually contracted through direct contact with the fecal matter of an infected person. It therefore mainly occurs in countries that do not have proper systems for handling human waste.
Epidemiology and Demographics
Salmonella serotype Typhimurium and Salmonella serotype Enteritidis are the most common in the United States. Salmonella has been known to cause illness for over 100 years. They were discovered by a American scientist named Salmon, for whom they are named.
Every year, approximately 40,000 cases of salmonellosis are reported in the United States. Because many milder cases are not diagnosed or reported, the actual number of infections may be thirty or more times greater. There are many different kinds of Salmonella bacteria. Salmonella serotype Typhimurium and Salmonella serotype Enteritidis are the most common in the United States.Salmonellosis is more common in the summer than winter.
Children are the most likely to get salmonellosis. The rate of diagnosed infections in children less than five years old is higher than the rate in all other persons. Young children, the elderly, and the immunocompromised are the most likely to have severe infections. It is estimated that approximately 400 persons die each year with acute salmonellosis.
Risk Factors
Every year, approximately 40,000 cases of salmonellosis are reported in the United States. Because many milder cases are not diagnosed or reported, the actual number of infections may be thirty or more times greater. Salmonellosis is more common in the summer than winter. Children are the most likely to get salmonellosis. The rate of diagnosed infections in children less than five years old is about five times higher than the rate in all other persons. Young children, the elderly, and the immunocompromised are the most likely to have severe infections. It is estimated that approximately 400 persons die each year with acute salmonellosis.
Screening
National surveillance is conducted through the public health laboratories for culture-confirmed cases and through the National Notifiable Diseases Surveillance System (NNDSS). Active laboratory- and population-based surveillance is conducted in FoodNet sites.
Causes
Enterobacteriaceae of the genus Salmonella, a gram-negative rod-shaped bacilli. Approximately 2000 serotypes cause human disease.
Natural History, Complications and Prognosis
Sequelae
Estimated 400 fatal cases each year; a few cases are complicated by chronic arthritis.
Transmission
Contaminated food, water, or contact with infected animals.
Symptoms
Diarrhea (sometimes bloody), fever, and abdominal cramps. Occasionally can establish localized infection (e.g., in a joint) or enter the blood.