Salmonella is one of the most common enteric (intestinal) infections in the United States. Salmonellosis (the disease caused by Salmonella) is the second most common foodborne illness after Campylobacter infection. It is estimated that 1.4 million cases of salmonellosis occur each year in the U.S.; 95% of those cases are foodborne-related. Approximately 220 of each 1000 cases result in hospitalization and eight of every 1000 cases result in death. About 500 to 1,000 or 31% of all food-related deaths are caused by Salmonella infections each year. Salmonellosis is more common in the warmer months of the year.
Salmonella infection occurs when the bacteria are ingested, typically from food derived from infected food-animals, but it can also occur by ingesting the feces of an infected animal or person. Food sources include raw or undercooked eggs/egg products, raw milk or raw milk products, contaminated water, meat and meat products, and poultry. Raw fruits and vegetables contaminated during slicing have been implicated in several foodborne outbreaks.
Symptoms of Salmonella infection
The acute symptoms of Salmonella gastroenteritis include the sudden onset of nausea, abdominal cramping, and bloody diarrhea with mucous. Fever is almost always present. Vomiting is less common than diarrhea. Headaches, myalgias (muscle pain), and arthralgias (joint pain) are often reported as well. The onset of symptoms usually occurs within 6 to 72 hours after the ingestion of the bacteria. The infectious dose is small, probably from 15 to 20 cells.
Reiterís Syndrome, which includes and is sometimes referred to as ìreactive arthritis,î is an uncommon, but debilitating, result of a Salmonella infection. The symptoms of Reiterís Syndrome usually occur between one and three weeks after the infection. Reiterís Syndrome is a disorder that causes at least two of three seemingly unrelated symptoms: reactive arthritis, conjunctivitis (eye irritation), and urinary tract infection. The arthritis associated with Reiterís Syndrome typically affects the knees, ankles, and feet, causing pain and swelling. Wrists, fingers and other joints can be affected, though with less frequency. With Reiterís Syndrome, the affected person commonly develops inflammation where the tendon attaches to the bone, a condition called enthesopathy. Some people also develop heel spurs, bony growths in the heel that cause chronic or long-lasting foot pain. Arthritis from Reiterís Syndrome can also affect the joints of the back and cause spondylitis, inflammation of the vertebrae in the spinal column. The duration of reactive arthritis symptoms can vary greatly. Most of the literature suggests that the majority of affected persons recover within a year. The condition, can, however, be permanent. For more information, visit the Marler Clark sponsored Web site about Reiterís Syndrome.
Detection and treatment of Salmonella infection
Salmonella bacteria are discovered in stool cultures. Although blood cultures are rarely positive, bacteremia (bacteria in the blood stream) does occur in 5% of adults with Salmonella gastroenteritis and can result in spread to the heart (endocarditis), spleen, bone (osteomyelitis), and joints (Reiterís Syndrome or reactive arthritis). However, blood cultures are often not performed and in most cases the blood stream is not infected. In the stool, the laboratory is challenged to pick out Salmonella from many other similar bacteria that are normally present. In addition, many persons submit cultures after they have started antibiotics, which may make it even more difficult for a microbiology lab to grow Salmonella. So, the diagnosis of salmonellosis may be problematic and many mild cases are culture negative.
Salmonella infections usually resolve in five to seven days, and many times require no treatment, unless the affected person becomes severely dehydrated or the infection spreads from the intestines. Persons with severe diarrhea may require rehydration, often with intravenous fluids. Treatment with antibiotics is not usually necessary, unless the infection spreads from the intestines, or otherwise persists, in which case the infection can be treated with ampicillin, gentamicin, trimethoprim/sulfamethoxazole, or ciprofloxacin. Some Salmonella bacteria have become resistant to antibiotics, possibly as a result of the use of antibiotics to promote the growth of feed animals.
For those persons who develop Reiterís Syndrome, symptomatic treatment with high doses of a nonsteroidal anti-inflammatory drug and steroid injections into affected joints can be helpful in reactive arthritis. For people with severe joint inflammation, injections of corticosteroids directly into the affected joint may reduce inflammation. A small percentage of patients with reactive arthritis have severe symptoms that cannot be controlled with these treatments, in which case medicine that suppresses the immune system, such as sulfasalazine or methotrexate, may be effective. Exercise, when introduced gradually, may help improve joint function. Topical corticosteroids can be applied directly on the skin lesions associated with reactive arthritis.
Preventing Salmonella infection
To prevent salmonellosis, cook poultry, ground beef, and eggs thoroughly before eating. In order to insure that eggs do not contain viable Salmonella they must be cooked at least until the yoke is solid, and meat and poultry must reach 160∫F or greater throughout. Be particularly careful with foods prepared for infants, the elderly, and those with a compromised immune system.
Do not eat or drink foods containing raw eggs, such as homemade eggnog and hollandaise sauce. Avoid drinking raw (unpasteurized) milk or products made from raw milk.
Wash hands, kitchen work surfaces, and utensils with soap and water immediately after they have been in contact with foods of animal origin. Also, wash hands with soap after handling reptiles, amphibians or birds, or after contact with pet feces. Infants and immunocompromised persons should have no direct or indirect contact with such pets.