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SALMONELLAE INFECTIONS SALMONELLOSIS (Salmonella Gastroenteritis)

PATHOGEN:

Salmonellosis is a bacterial disease caused by Gram negative bacteria that do not produce spores and are facultative anaerobes. Salmonella Typhimurium and S. Enteritidis are two serotypes commonly associated with salmonellosis.

RESERVOIR(S):

Many animals carry salmonellae in their GI tracts, including birds, livestock, reptiles, and rodents, and the bacteria are excreted in fecal matter.

TRANSMISSION:

Salmonellosis is a food infection that is usually acquired by eating foods contaminated with the bacteria. Contaminated foods are most often of animal origin, such as undercooked poultry, unpasteurized milk, or undercooked eggs. However, all foods, including vegetables, may potentially become contaminated.

Direct human-to-human transmission is rare because an inoculum of 106-10

8 bacteria per

gram or ml is required to cause disease.

Salmonellosis may also be acquired through ingestion of salmonellae bacteria that are normal flora in many reptiles and are excreted in the fecal material of the animal.

DISEASE:

Common symptoms of salmonellosis include the onset of diarrhea, fever, and abdominal cramps 12 to 72 hours after infection. In most cases, the illness will last 4 to 7 days, with most infected individuals recovering without treatment. However, in some persons the diarrhea may be severe enough to cause dehydration and require hospitalization.

In serious disease, the bacterium may spread from the intestines to the blood stream, and then to other sites in the body causing further complications and possibly even death. The very young, the elderly and the immunocompromised are most at risk for serious disease.

Each year, approximately 40,000 cases of salmonellosis are reported in the United States. The actual number of infections may be much greater than this, due to the fact that many cases go unreported. One estimate puts the number of unreported cases at thirty times greater than the number of reported cases. The CDC estimates that about 600 persons die each year with acute salmonellosis.

TREATMENT:

Salmonella infections are usually self-limiting and often do not require treatment. Persons with severe diarrhea may require rehydration, often with intravenous fluids. Antibiotics are not usually necessary unless the infection spreads from the intestines. Then, the infection can be treated with antibiotics.

VACCINE:

There is no vaccine to prevent salmonellosis.

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PREVENTION:

Poultry, eggs and meat should be well-cooked and persons should avoid consuming unpasteurized dairy products. Cooking kills the bacteria, preventing disease.

Cross-contamination of foods should also be avoided. Uncooked meats should be kept separate from produce, cooked foods, and ready-to-eat foods. Hands, cutting boards, counters, knives, and other utensils should be washed thoroughly after handling uncooked foods.

TYPHOID FEVER PATHOGEN:

Typhoid fever is caused by Salmonella Typhi and S. paratyphi bacteria which are Gram negative bacilli that do not produce spores or toxins.

RESERVOIR(S):

Humans are the only reservoir hosts for S. Typhi and S. Paratyphi . TRANSMISSION:

Typhoid fever is acquired by fecal-oral transmission through ingestion of food or water contaminated with feces or urine from an infected person.

Direct transmission may also occur because the inoculum required to cause infection is 105

bacteria per gram or ml, which is significantly lower than that required for Salmonella gastroenteritis.

The bacterium may colonize the gall bladder, resulting in chronic asymptomatic shedding of the pathogen by convalescent carriers.

DISEASE:

Typhoid fever is a food infection.

Symptoms appear 10-14 days after ingestion of the bacteria and include fever, headache, muscle pain, malaise, and anorexia. Localized gastroenteritis may or may not be present and a non-infectious rash of flat, pink, spots may occur on the upper abdomen and chest, but disappears within hours or days.

The bacteria gain access to the bloodstream and infect other organs including the spleen, liver and gall-bladder.

The bacteria may then re-infect the intestinal tract, resulting in serious disease caused by hemorrhage and perforation of the intestine, meningitis, endocarditis (inflammation of the inner lining of the heart), and septic shock.

The mortality rate for untreated disease is 12-30%.

TREATMENT:

Antibiotic treatment is effective but prolonged antibiotic therapy is required.

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The gall bladder may need to be removed if it is colonized with the bacteria. VACCINE:

The use of the inactivated vaccine has largely discontinued in favor of using live, attenuated vaccines, such as Ty21a, and acellular sub-unit vaccines, such as the V1 polysaccharide vaccine.

PREVENTION:

Cook food or heat water to kill the bacteria.

Wash hands after using the bathroom.

Avoid cross-contamination by hands, utensils and surfaces.