In addition to Salmonella typhi and Salmonella paratyphi, there are more than 2,200 known Salmonella serotypes. Most are pathogenic. Salmonella is one of the top two recognized bacterial causes of foodborne disease (Campylobacter is the other).

Some history

The first non-typhoidal Salmonella to be isolated was the agent that causes hog cholera – Salmonella Cholerae-suis – described initially in 1885. Each new Salmonella was, at first, named for the disease syndrome; then, as the apparently different “species” became more numerous, they were named for the location (city, state or country) where they were first reported (e.g., Salmonella London, Salmonella Tennessee, Salmonella Java)

What is Salmonella, and where is its natural habitat?

Salmonella inhabits the intestinal tract of virtually all species of insects, warm-blooded animals, fish, reptiles and birds around the world. With just a few exceptions – and humans are the main exceptions – the microbe causes no illness to its animal host.

How is Salmonella transmitted? What is the incubation period of the infection?

Salmonella is transmitted most often through the consumption of contaminated food or water, or by hand-to-mouth contact with a carrier animal, reptile or insect. Secondary person-to-person transmission also can occur. The incubation period usually is 1 to 3 days.

What illnesses are caused by Salmonella? How long does it take to develop?

Salmonella infections most often cause salmonellosis – a form of gastroenteritis. Symptoms usually develop in 1 to 3 days following ingestion of an infective dose of the bacteria, and typically last from 4 to 7 days.

What are the symptoms of salmonellosis?

Symptoms of non-typhoidal Salmonella infections (salmonellosis) usually include diarrhea, fever, cramps and vomiting.

What is the prognosis of Salmonella infections?

The disease is largely self-limiting; however, some patients experience secondary consequences, including endocarditis or bacteremia. Osteomyelitis also is an occasional complication, as is Reiter’s syndrome – a reactive arthritis.

What foods carry Salmonella?

Virtually any food – meat, poultry, dairy, produce, spices, candy, chocolate, – may be contaminated with Salmonella. In addition, small pets – rodents, snakes and lizards – are common carriers of this pathogen. Food items that are Salmonella-free may become contaminated through improper handling (cross-contamination) during preparation.

How can susceptible people protect themselves from infection?

The US Centers for Disease Control and Prevention (CDC) offers some tips for avoiding the spread of Salmonella:

  • Cook poultry, ground beef, and eggs thoroughly. Do not eat or drink foods containing raw eggs, or raw (unpasteurized) milk.
  • If you are served undercooked meat, poultry or eggs in a restaurant, don’t hesitate to send it back to the kitchen for further cooking.
  • Wash hands, kitchen work surfaces, and utensils with soap and water immediately after they have been in contact with raw meat or poultry.
  • Be particularly careful with foods prepared for infants, the elderly, and the immunocompromised.
  • Wash hands with soap after handling reptiles, birds, or baby chicks, and after contact with pet feces.
  • Avoid direct or even indirect contact between reptiles (turtles, iguanas, other lizards, snakes) and infants or immunocompromised persons.
  • Don’t work with raw poultry or meat, and an infant (e.g., feed, change diaper) at the same time.
  • Mother’s milk is the safest food for young infants. Breastfeeding prevents salmonellosis and many other health problems.

For more information on Salmonella and other food-borne pathogens, visit the CDC website or read Food Safety: Old Habits, New Perspectives.