Salmonella
Attributes | |
---|---|
Common Name(s) | Salmonellosis |
Scientific Name(s) | Salmonella |
Physical Attributes | Gram-negative, facultative anaerobic, motile (except for S. gallinarum and S. pullorum), rod bacilli |
Geography | World wide |
Mode(s) of Transmission | The feces of people or animals, to other people or other animals, contaminated food |
Likely BW Form(s) | Aerosol; contaminated water and food |
Pathology | Diarrhea, fever, and abdominal cramps, sometimes chills, headache, nausea, and vomiting; a small number develop Reiter's syndrome: pains in their joints, irritation of the eyes, and painful urination; some develop arthritis |
Host(s) | Humans |
Vector/Dormant Form | Food and water especially raw meats; reptiles |
Incubation Period | 12-72 hours |
Fatality | Seldom, less than 1% |
Vaccine | None |
Treatment | Rehydration; if infection spreads to intestines, antibiotics: ampicillin, gentamicin, trimethoprim/sulfamethoxazole, or ciprofloxacin |
Salmonellosis is an infection with a group of bacteria belonging to the genus Salmonella. Salmonella is a Gram-negative, facultatively anaerobic, rod-shaped bacilli that causes diarrheal illness in humans. They are microscopic living creatures that pass from the feces of people or animals to other people or other animals.
Salmonella live in the intestinal tracts of humans and other animals, including birds. Salmonella are usually transmitted to humans by eating foods contaminated with animal feces. Contaminated foods usually look and smell normal. Contaminated foods are often of animal origin, such as beef, poultry, milk, or eggs, but all foods, including vegetables may become contaminated. Many raw foods of animal origin are frequently contaminated, but fortunately, thorough cooking kills Salmonella. Food may also become contaminated by the unwashed hands of an infected food handler, who forgot to wash his or her hands with soap after using the bathroom.
Salmonella may also be found in the feces of some pets, especially those with diarrhea, and people can become infected if they do not wash their hands after contact with these feces. Reptiles are particularly likely to harbor Salmonella and people should always wash their hands immediately after handling a reptile, even if the reptile is healthy. Adults should also be careful that children wash their hands after handling a reptile.
Most persons infected with Salmonella develop diarrhea, fever, and abdominal cramps 12 to 72 hours after infection. Sometimes, the persons experience chills, headache, nausea, and vomiting. The illness usually lasts 4 to 7 days, and most persons recover without treatment although it may be several months before their bowel habits are entirely normal. However, in some persons the diarrhea may be so severe that the patient needs to be hospitalized. In these patients, 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.
A small number of persons who are infected with Salmonella, will go on to develop pains in their joints, irritation of the eyes, and painful urination. This is called Reiter's syndrome. It can last for months or years, and can lead to chronic arthritis which is difficult to treat. Antibiotic treatment does not make a difference in whether or not the person later develops arthritis.
Postenteritis reactive arthritis and Reiter's syndrome have also been reported to occur generally after 3 weeks. Reactive arthritis may occur with a frequency of about 2% of culture-proven cases. Septic arthritis, subsequent or coincident with septicemia, also occurs and can be difficult to treat. There are no vaccines to prevent salmonellosis.
Salmonella infections usually resolve in 5-7 days and often do not require treatment unless the patient becomes severely dehydrated or the infection spreads from the intestines. Persons with severe diarrhea may require rehydration, often with intravenous fluids. Antibiotics are not usually necessary unless the infection spreads from the intestines, then it can be treated with ampicillin, gentamicin, trimethoprim/sulfamethoxazole, or ciprofloxacin. Unfortunately, some Salmonella bacteria have become resistant to antibiotics, largely as a result of the use of antibiotics to promote the growth of feed animals.
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