What Is Salmonella?

Overview

Salmonella infection, commonly referred to as salmonellosis, is a bacterial infection that affects the digestive tract. Salmonella bacteria (primarily Salmonella enterica) typically live in the intestines of both humans and animals and are released  on defecation, and infection usually occurs upon eating the infected meat. Salmonella is therefore classified as a form of food poisoning, which occurs after you have had food or water contaminated with faeces. Some undercooked foods can also cause Salmonella infection. Food and hand hygiene are crucial to preventing bacterial Salmonella growth, spread, and ingestion.

Causes of salmonella

Salmonella bacteria are a group of bacteria that cause food poisoning. Salmonella bacteria are commonly found in:

• Undercooked poultry (e.g., chicken or turkey)
• Raw meat 
• Raw eggs
• Unpasteurised milk 
• Seafood 

As Salmonella bacteria can appear in several food substances, it is important that uncooked food is handled with care. Cross-contamination from these food sources to other sources can happen if food is not properly handled. Exposure to the Salmonella bacteria can happen even in foods that are not typically colonised by the bacteria. For example, whilst vegetables are safe, if they have been exposed to Salmonella bacteria through poor food handling this could make them unsafe as well. Properly cooked food will have a lower likelihood of causing infection. 

Signs and symptoms of Salmonella

Most people who have salmonellosis will start to get symptoms 12 to 72 hours after becoming infected. The illness itself usually lasts between 4 and 7 days. The signs and symptoms of salmonella infection are similar to those of food poisoning, such as:

• Nausea
• Vomiting
• Diarrhoea
  • Diarrhoea is often watery 
  • Can be severe 
  • Blood in faeces indicates severe infection and medical help should be sought immediately 
• Fever (temperature above 38⁰C) 
• Feeling unwell
  • Tiredness
  • Body aches 
  • Chills 
  • Weakness 
• Abdominal cramps/abdominal pain 
• Headache 

Experiencing the above symptoms may also be indicative of other conditions, such as;

• typhoid fever
• appendicitis
• or other forms of food poisoning 

Management and treatment for salmonella

There is usually no specific treatment required. Symptoms tend to resolve within a few days without requiring treatment and most cases can be taken care of at home. It is important to encourage fluid intake, as salmonellosis can cause loss of water from the body (either through diarrhoea or vomiting) and can lead to dehydration. 

Most people do not require treatment with medication for salmonella. If, however, you are experiencing other symptoms, medication may be necessary. For example, paracetamol can be given for a fever and ibuprofen for aches and pains. There are a few instances in which the doctors might advise for a course of antibiotics to be given, such as:

• Children less than 6 months of age
• People over the age of 65
• People with abnormal heart valves 
• People with If the child has a weakened immune system, or is taking medication that might make their immune system weaker (immunocompromised)
• If the salmonella infection spreads throughout the body
  • Usually, salmonellosis is contained within the intestinal tract however, if it spreads then medical treatment may be required

FAQs

How is salmonella infection diagnosed?

Certain tests can be done to detect salmonella infection:

• Stool (faeces) sample
  • Involves sending a sample of faeces to be tested
  • Scientists look for evidence of the salmonella bacteria in your faeces 
• Blood test
  • If doctors suspect that the infection has spread into your blood, they can do a blood culture to detect this 

How can I prevent salmonella?

The governing body in the UK for disease control and prevention is the Food Standards Agency. They have advised the 4C’s of food hygiene when it comes to reducing the risk of salmonella infection: chilling, cleaning, cooking, and preventing cross-contamination.

Chilling

• Freeze food that you are not using
• Avoid defrosting at room temperature
  • Try to defrost the food in a container in the fridge
    • Defrosting in the fridge will minimise the bacterial growth that occurs 
  • Check the guidance on the food packaging to see how to best defrost the item/the time it will take 

Cleaning

• Wash your hands thoroughly after exposure to any source of salmonella infection, including:
  • going to the toilet (faecal matter)
  • changing nappies
  • handling food that could have salmonella bacteria in it, etc
• Washing any work surfaces that have come into contact with contaminated food
  • The bacteria require a temperature of above 70⁰C to be killed, so it is advised to wash surfaces with hot, soapy water 
• Regularly wash dishcloths, sponges, tea towels and oven gloves
  • Dirty, damp cloths are a breeding ground for salmonella bacteria
• Do not wash raw meat
  • Washing raw meat can cause splashes of contaminated water to spread throughout your kitchen 
• Use cleaning products that have antibacterial properties 

Cooking

• Try to follow guidance on packaging in regards to temperature and time needed to cook
• Before you serve poultry, pork, or minced meat ensure that it is properly cooked
  • It should be cooked all the way through and piping hot
  • When the thickest part of the meat is cut it should not be pink or appear uncooked
  • Any juice that comes from the meat after being cooked should be clear
  • Mince meat will have bacteria all throughout, therefore burgers should not be served rare or pink
  • Whole cuts of meat (such as a steak) have bacteria on the outside, therefore these can be served pink in the middle
• Advised to cook poultry unstuffed
  • Stuffing poultry increases cooking time and the risk of bacterial survival. If poultry is stuffed, it may require cooking for longer than normal

Preventing cross-contamination

• Ensure that you have separate utensils and chopping boards for raw food
  • If your skin gets splashed, ensure you wash it thoroughly before touching the non-contaminated utensils
• Wash the utensils thoroughly once used
• Keep raw meat covered and separate from the cooked food
• Package raw meat and other groceries in separate bags
  • Label these bags so that you always use one set of bags for raw meat to minimise contamination 
  • Try to use washable bags (such as cotton bags or fabric bags)
  • Store raw meat at the bottom of the fridge

There are certain pets that have an increased chance of having Salmonella bacteria present. Therefore, it is important to be careful when handling these pets, and when cleaning out their enclosures. Examples of these pets include:

• Reptiles (e.g., lizards, snakes, tortoises)
• Amphibians (e.g., frogs, toads)

Who is at risk of salmonella?

Salmonella infection can happen to anyone, however, there are certain groups who have a greater risk. Examples of groups with a greater risk of developing salmonellosis include:

• People with a weakened immune system, such as those with:
  • AIDS
  • Sickle cell disease
  • Malaria
  • Medication that can cause immunosuppression 
• Age
  • Children under 5 and people over 65 years of age 
• People with poor hand hygiene 
• People with pets that are a higher risk of salmonella contamination
  • Amphibians
  • Reptiles 
  • Live poultry 
• All pets can increase the risk of exposure to salmonella, for example:
  • If animals are present in places where food is prepared
  • Not washing hands after handling pets 
  • Putting water from a pets tank into a sink which is involved in food preparation 

How common is salmonella?

As reported by the UK health security agency, there were roughly 8,000 cases of salmonella infection reported in 2019.¹ 

If you think that you have contracted food poisoning from eating out then you should report this to your local Environmental Health Office. 

How long do salmonella symptoms last?

Salmonella symptoms typically resolve within 7 days following the start of infection. 

What are the complications of salmonella?

It is quite rare for there to be complications of Salmonella infection. They are more likely in groups of individuals who are at risk (such as those who have a weakened immune system, those with pre-existing conditions, children, and the elderly). Examples of complications that can arise include:

• Imbalance of salts (electrolytes) within your body
  • This is secondary to dehydration, caused by diarrhoea or vomiting
  • If left untreated this can cause damage to the kidneys
  • Most people can avoid this by having a good intake of water 
• Complications that arise from your body reacting to the infection
  • Sometimes the body will react to the infection in an inappropriate manner, leading to other areas of the body being attacked by your antibodies 
  • Examples of this include: reactive arthritis, conjunctivitis or inflammation of the skin
• Spread of the infection to areas other than your intestinal tract
  • This could be the blood (sepsis), heart valves, brain, bones, etc
• Persistent diarrhoea
• Guillain-Barre syndrome

When should I see a doctor?

Usually, salmonella resolves on its own, however, if you are concerned then you should consult with your doctor. Examples of things that might cause concern include:

• Continuous vomiting
• Severe diarrhoea 
• Persistence of symptoms past 7 days 
• Blood in the faeces 
• Severe abdominal pain 
• Persistent high fever 
• Feeling unwell for a prolonged time
• If you have a weak immune system
• If you are elderly
• If you have underlying health conditions 
• If you are pregnant 

If you have any symptoms you are concerned about seek medical help. Salmonella symptoms overlap with other conditions. Thus, it is important to seek medical advice if you are concerned about your health. 

Summary

Salmonella infection occurs following infection by Salmonella bacteria. Salmonella bacteria are a group of bacteria that exist in various places (such as faeces, animals, raw meat, etc.). Symptoms are those of food poisoning (such as diarrhoea, vomiting, abdominal pain, fever, etc.). Salmonella usually resolves by itself, however, if there are concerning features then antibiotics might be given. If you have any concerns about the symptoms you are experiencing, then you should seek medical help promptly.