Salmonella infection (salmonellosis) is a common bacterial disease that affects the intestinal tract. Salmonella bacteria typically live in animal and human intestines and are shed through feces. Humans become infected most frequently through contaminated water or food.
Salmonella is divided into two groups:
- Typhoidal Salmonella, which is made up of bacterial strains that cause typhoid fever or paratyphoid fever, including Salmonella Typhi, Paratyphi A, Paratyphi B, and Paratyphi C
- Non-typhoidal Salmonella, which includes all other Salmonella strains
The term Salmonella refers to a family of bacteria known for more than 100 years to cause foodborne illness in humans. In 1885, a research assistant to veterinary surgeon Daniel Salmon discovered the first strain – Salmonella-Salmonella cholera suis – and Dr. Salmon got the credit. Today, the number of known salmonella strains totals more than 2,300, and particular strains of salmonella are now resistant to traditional antibiotics. Typically, none of the strains affects the taste, smell, or appearance of food. Strains that cause no symptoms in animals can sicken people, and vice versa.
Epidemiology at world wide
The incidence of salmonellosis has markedly increased in many countries; however, a paucity of good surveillance data exists. In 2000, approximately 21.6 million worldwide cases of typhoid fever caused 216,500 deaths. The incidence of typhoid fever in south-central Asia, Southeast Asia, and, possibly, southern Africa was high (>100 cases per 100,000 population per year). The rest of Asia, Africa, Latin America, and Oceania (except for Australia and New Zealand) typically see intermediate rates of typhoid fever (10-100 cases per 100,000 population), while the incidence is low in the other parts of the world (< 10 cases per 100,000 population). In countries where typhoid fever is endemic, most cases of the disease occur in children aged 5-19 years and young adults.
Since foods contaminated with Salmonella are not obvious, anyone may consume contaminated foods. Owning pets such as small rodents, chicks, ducklings, turtles and some other reptiles, and some birds may increase the risk of coming in contact with Salmonella bacteria. People who are exposed to many people, such as those living in group housing, may have an increased risk. Children under 5 years of age have the highest reported incidence of infection.
People with medical conditions that lead to immune suppression are at risk for a more severe illness when they do become infected.
You can get salmonellosis by eating food contaminated with salmonella. This can happen in the following ways:
- Food may be contaminated during food processing or food handling.
- Food may become contaminated by the unwashed hands of an infected food handler. A frequent cause is a food handler who does not wash his or her hands with soap after using the bathroom.
- Salmonella may also be found in the feces of some pets, especially those with diarrhea. You can become infected if you do not wash your hands after contact with these feces.
- Reptiles, baby chicks and ducklings, and small rodents such as hamsters are particularly likely to carry Salmonella. You should always wash your hands immediately after handling one of these animals, even if the animal is healthy. Adults should also be careful that children wash their hands after handling reptiles, pet turtles, baby chicks or ducklings, or small rodents.
- Beef, poultry, milk, and eggs are most often infected with salmonella. But vegetables may also be contaminated. Contaminated foods usually look and smell normal.
Causes of salmonellosis
Salmonella infection is usually caused by eating raw or under cooked meat, poultry, eggs or egg products. The incubation period ranges from several hours to two days. Most salmonella infections can be classified as stomach flu (gastroenteritis). Possible signs and symptoms include:
- Abdominal cramps
- Blood in the stool
Signs and symptoms of salmonella infection generally last two to seven days. Diarrhea may last up to 10 days, although it may take several months before bowels return to normal.
A few varieties of salmonella bacteria result in typhoid fever, a sometimes deadly disease that is more common in developing countries.
Diagnosis and test
- Salmonella infection can be detected by testing a sample of your stool. However, most people have recovered from their symptoms by the time the test results return.
- If your doctor suspects that you have a salmonella infection in your bloodstream, he or she may suggest testing a sample of your blood for the bacteria.
Treatment and medications
Salmonella-induced gastroenteritis treatment
- Usually, symptoms will last for about 1 week and will resolve without any treatment. It is important to monitor the hydration levels of the patient by making sure they have an adequate fluid intake. If the doctor suspects the bacteria have entered the bloodstream, or are likely to, they may prescribe antibiotics.
- Antimotility drugs (to stop diarrhoea) generally are discouraged, especially in people with bloody diarrhoea or diarrhoea complicated by a fever.
Typhoid fever treatment
- The Salmonella bacteria that causes typhoid can be killed by antibiotics such as ciprofloxacin or ceftriaxone. However, some strains become resistant to antibiotics after long-term use, and antibiotics have known side effects.
- Additional treatments for typhoid include drinking fluid to prevent dehydration and eating a healthy diet to ensure the absorption of nutrients.
- Wash your hands with soap and warm water before preparing food, before eating food, after going to the toilet, after changing a baby’s diapers, after touching pets and other animals and after gardening.
- Do not keep cooked and raw foods next to each other
- In the fridge, place raw foods in the shelves below ready-to-eat foods
- Thoroughly wash raw fruits and vegetables before eating
- Cook food thoroughly, especially meats
- Keep all cooking utensils and work surfaces clean
- Regularly swap used dishcloths for clean ones
- Beware of drinking untreated water from streams, rivers and lakes
- Do not keep pet reptiles or amphibians inside the house if there are elderly people, pregnant women, very young children or people with weakened immune systems in the household
- If somebody in your household becomes infected with Salmonella, wash all dirty clothes, bedding and towels in the washing machine at the hottest setting possible. Thoroughly clean toilet seats, toilet bowls, all handles in the bathroom, basins and taps after use with a detergent and hot water, followed by a household disinfectant.