Overview 

Salmonella infection, commonly referred to as salmonellosis, is a bacterial infection. Salmonellosis is often self-limiting, but can lead to severe complications, often individuals aged over 65 years of age and under 12 months are at high risk of serious illness from salmonellosis. Salmonellosis accounts for 93.8 million foodborne illnesses and 155,000 deaths per year globally.¹ Due to the high number of cases and deaths, it’s known to be a significant global public health issue.

Salmonellosis is caused by salmonella that affects the intestinal tract. There are roughly 2500 salmonella serotypes (a variation of bacteria within the same species and subspecies). Currently, the most common serotypes in human disease include salmonella enteritidis and Typhimurium.² Salmonella typically live in the intestines of humans and animals and are released through stools (feces). Humans become infected through contaminated water or food, making Salmonella a form of food poisoning transmitted via the fecal-oral route.

Causes of salmonella

The most common way to get salmonellosis is from raw meat, undercooked poultry, raw eggs, dairy products, and seafood. Approximately 85% of the cases were associated with the consumption of contaminated food.³

You can also get salmonella through cross-contamination, contained water, contact with infected animals (almost any animal can have salmonella), and person-to-person transmission also can cause salmonellosis. This is known as typhoid fever which is caused by salmonella typhimurium. This is related to the bacteria that causes salmonella food poisoning.

Symptoms of salmonella

Most people will develop symptoms within 6-72 hours after becoming infected. This is known as the incubation period, the time from picking up the bacteria to presenting clinical symptoms. Salmonellosis usually lasts between 4-7 days, although diarrhea may last up to 10 days, and it may take several months before bowels return to normal stool habits. Symptoms include: 

• Nausea
• Vomiting
• Diarrhea
• Chills
• Headache
• Blood in the stool
• Fever (temperature above 38 degrees celsius)

How are salmonella infections diagnosed?

Diagnosing salmonella often requires testing a specimen, such as feces or blood. Many different illnesses have symptoms like salmonella, so these tests will specifically identify the bacteria within your body. However, most people have recovered from their symptoms by the time the results return.

Management and treatment for salmonella

There is usually no treatment required for salmonellosis, as it typically resolves on its own. However, if you have salmonella, you should get plenty of rest, drink plenty of water or clear fluids to prevent dehydration, consume low-fat natural yogurts and probiotic products to help restore the bowels to normal function. Paracetamol can help with fever symptoms, and ibuprofen can be used for aches and pains. In severe cases, where the infection spreads beyond the intestinal tract into areas like the blood, bones, liver, spleen, and the central nervous system. Therefore, different forms of treatment may be required for each complication.

Potential complications of salmonella infections

• Salmonella Septicaemia (Sepsis): This is where the presence of salmonella bacteria in the blood triggers an inflammatory response. This life-threatening condition can lead to multiple organ failure. Symptoms include high fever, chills, abdominal swelling, flushed skin, increased heart rate, confusion, and hyperventilation. It often requires intravenous antibiotics for prompt treatment
• Reactive arthritis (formerly known as Reiter disease): Known to be caused by salmonella,¹ this immune-mediated syndrome results in joint pain and swelling, inflammation of the eyes (conjunctivitis), and painful urination. Treatment includes anti-inflammatory medicines such as ibuprofen, antibiotics and physiotherapy.
• Gastrointestinal complications: Chronic diarrhea, irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD) can develop after salmonellosis. One study demonstrated that salmonella is a significant risk factor for IBS, but also for dyspepsia (chronic indigestion). After a one year follow-up, 1 in 7 and 1 in 10 subjects developed IBS or dyspepsia.⁴ IBS causes abdominal pain, bloating and altered bowel habits. Whereas, dyspepsia causes pain or burning in the stomach, bloating nausea after eating, and an early feeling of fullness (satiety) when eating. 

One study has demonstrated a connection between salmonella typhimurium infection and IBD development.⁵ The two most common chronic diseases for IBD is Crohn’s disease and ulcerative colitis. As both these conditions are autoimmune disorders (immune system attacks normal, self-cells within the body). Treatment is often given to control the immune system such as adalimumab. 

• Salmonella meningitis: A rare but severe form of bacterial meningitis, which presents a high prevalance of morbidity.⁶ Symptoms include severe headache, sensitivity to lights (photophobia), confusion, fever, and a stiff neck. Salmonella meningitis can lead to long term-neurological damage and may be fatal if not treated promptly. Treatment of salmonella meningitis is difficult, and there is no consensus on the best approach. Drugs often used are cholram-phenicol, ampicillin and co-trimoxazole.
• Salmonella osteomyelitis: This rare complication, occurring in approximately 0.8% of all salmonella infections.⁷ Salmonella osteomyelitis involves infection of the diaphysis of long bones, usually the femur and humerus. Symptoms include severe bone pain, fever, and redness or swelling over the affected area. This condition used to be incurable, but now treatment typically involves surgery to remove necrotic bone tissue and a course of antibiotics.
• Endocarditis: Inflammation of the inside lining of the heart chambers and heart valves (endocardium) can cause symptoms like aching joints and muscles, chest pain, fatigue, shortness of breath and fever. If untreated, it can lead to heart failure, valve damage, and strokes. The majority of people with this are usually successfully treated with antibiotics. Although, sometimes surgery may be required to fix or replace damaged heart valves.

Prevention Strategies

• Thoroughly wash hands, use soap and water especially after handling food, using the bathroom, or coming into contact with animals
• Prepare food safely, keep kitchen surfaces clean, avoid cross-contamination and ensure all meat especially poultry is cooked properly. Poultry, meat, seafood and eggs should reach an internal temperature of 73.8 degrees celcisus
• Store food properly, refrigerate perishables and avoid consuming raw dairy products.
• Drink treated water
• Use caution when swimming, and avoid swallowing water from pools, lakes or other bodies of water that may be contained
• Be careful when handling animals. For example, wash hands after contact with farm animals, pets, animal feces, and animal environments

FAQs

Can salmonellosis be fatal?

Yes, salmonella globally caused 155,000 deaths. Salmonella infections are especially dangerous if complications like septicaemia develop. Early treatment is crucial!

How can I prevent salmonella infection?

Preventive measures can be followed such as good hygiene, adequate food handling and cooking, and avoiding the consumption of contaminated food and water.

Can pets carry salmonella?

Yes, pets, particularly reptiles like turtles, lizards, frogs and snakes can be carriers of salmonella and transmit it to humans. Therefore, if you come into contact with these animals or clean their habitats make sure you thoroughly wash your hands

What should I do if I suspect I have a salmonella infection?

Generally, individuals with salmonella do not require treatment, as it’s self-limiting (a condition which can resolve without treatment). However, you should seek medical attention immediately if the symptoms become severe and may require antibiotics. 

What are salmonella feces like?

If you have salmonellosis, your diarrhea typically will have a strong odor, sometimes you may also have blood and it will usually be very runny.

Summary

Salmonella infection occurs following infection by Salmonella bacteria, typically salmonella enterica. These bacteria are a large group of bacteria that exist in various places like feces, animals, raw, etc. Salmonellosis can result in various symptoms which are those of food poisoning. This is often resolved by the body without treatment. However, salmonellosis can result in a variety of serious complications, especially in vulnerable populations such as young children, the elderly and people with weakened immune systems. This is because salmonella can spread from the intestines to the bloodstream. If you believe you are experiencing any further symptoms like the ones mentioned above for the various complications, you should seek medical attention immediately. Also, if the affected person is an infant, young child, elderly or someone with a weakened immune system, seek medical attention if the illness lasts more than a few days, associated with high fever or bloody stools, and has dehydration, with signs of dark-colored urine and a dry mouth/tongue.