Salmonellosis (Salmonella Infection)

How Salmonella spreads

Salmonella lives in the intestines of animals, including poultry, cattle, pigs and reptiles. Humans become infected by:

• Undercooked poultry and meat
• Raw or undercooked eggs, including in homemade mayonnaise, cookie dough and sauces
• Unpasteurized milk and dairy
• Contaminated produce: sprouts, melons, leafy greens, cucumbers and others
• Cross-contamination from cutting boards and hands
• Animal contact: turtles, lizards, snakes, chicks, ducklings, and pet food and treats
• Person-to-person spread, especially with poor handwashing

The CDC estimates Salmonella causes about 1.35 million infections and around 420 deaths a year in the US.

Symptoms

• Diarrhea, which may contain blood or mucus
• Fever
• Stomach cramps
• Nausea and vomiting
• Headache and muscle aches
• Chills

Symptoms usually start 12 to 72 hours after exposure and last 4 to 7 days. Bowel habits may take several months to return to normal. People can shed Salmonella in their stool for weeks after recovery.

Who is at risk of severe illness

• Infants and young children under 5
• Adults over 65
• Pregnant women (infection can affect the baby)
• People with weakened immune systems: HIV, cancer treatment, organ transplants, steroids
• People with sickle cell disease
• People taking acid-reducing medicines

In these groups, Salmonella can enter the bloodstream (bacteremia) and infect bones, joints, the brain lining, heart valves or blood vessel grafts.

Complications

• Dehydration, the most common complication
• Bacteremia and focal infections such as osteomyelitis, meningitis and endocarditis
• Reactive arthritis: joint pain, eye inflammation and painful urination weeks after infection
• Irritable bowel symptoms after infection
• Chronic carriage, rare with nontyphoidal Salmonella

Typhoid and paratyphoid fever are caused by different Salmonella types and are covered separately. See typhoid fever.

Diagnosis

Most mild cases are diagnosed from symptoms without testing. A doctor may order:

• Stool culture or PCR panel to identify Salmonella and other germs such as Campylobacter
• Blood cultures for high fever, severe illness or high-risk patients
• Antibiotic sensitivity testing, as resistance is increasing
• Blood tests for dehydration and kidney function

Confirmed cases are reported to public health authorities, who investigate outbreaks.

Treatment

Fluids

• Oral rehydration solution is best for moderate diarrhea, especially in children and older adults
• Water, broth and diluted juices for mild cases
• IV fluids for severe dehydration
• Resume normal eating as soon as you feel able

Medicines

• Antibiotics are not recommended for most healthy people with uncomplicated infection, because they do not shorten illness much and can prolong shedding of the bacteria
• Antibiotics are recommended for severe illness, bloodstream infection, infants under 3 months, adults over 50 with heart or vessel disease, and people with weakened immunity or prosthetic devices. Choice depends on local resistance patterns
• Anti-diarrheal medicines such as loperamide should be avoided with fever or bloody diarrhea, and in children
• Fever and pain relief: acetaminophen (paracetamol) at the label dose

Prevention

• Cook food thoroughly: poultry to 165 °F (74 °C), ground meat to 160 °F (71 °C), and eggs until the yolk and white are firm
• Avoid raw eggs, raw milk and unpasteurized juices
• Wash hands with soap after using the toilet, changing diapers, handling raw meat, and touching animals or their environment
• Prevent cross-contamination: separate cutting boards for raw meat and produce
• Refrigerate food promptly, at 40 °F (4 °C) or below
• Wash produce under running water
• Keep reptiles and backyard poultry away from young children, kitchens and food areas
• Stay home from work, school or childcare while you have diarrhea

Frequently asked questions

What are the symptoms of Salmonella?

Common symptoms are diarrhea (sometimes bloody), fever, stomach cramps, nausea, vomiting, headache and chills. They usually begin 12 to 72 hours after exposure and last 4 to 7 days.

How long does Salmonella last?

Most people recover in 4 to 7 days. Bowel habits may take a few months to return to normal, and you may carry the bacteria in your stool for several weeks after symptoms end.

How do you get Salmonella?

Most infections come from eating undercooked poultry, eggs or meat, unpasteurized milk, or contaminated produce. You can also catch it from reptiles, backyard poultry, pet food, or from infected people through poor handwashing.

Do you need antibiotics for Salmonella?

Usually not. Most healthy people recover with fluids alone, and antibiotics can prolong carriage. Antibiotics are used for severe infections, bloodstream infection, infants, older adults with certain conditions, and people with weakened immune systems.

Is Salmonella contagious?

Yes. It spreads through the fecal-oral route, so careful handwashing is important. People with diarrhea should not prepare food for others, and food handlers, healthcare and childcare workers may need to stay off work until cleared.