Can salmonella be prevented

Key facts

• Salmonella is 1 of 4 key global causes of diarrhoeal diseases.
• Most cases of salmonellosis are mild; however, sometimes it can be life-threatening. The severity of the disease depends on host factors and the serotype of Salmonella.
• Antimicrobial resistance is a global public health concern and Salmonella is one of the microorganisms in which some resistant serotypes have emerged, affecting the food chain.
• Basic food hygiene practices, such as "cook thoroughly", are recommended as a preventive measure against salmonellosis.

Salmonella is a gram negative rods genus belonging to the Enterobacteriaceae family. Within 2 species, Salmonella bongori and Samonella enterica, over 2500 different serotypes or serovars have been identified to date. Salmonella is a ubiquitous and hardy bacteria that can survive several weeks in a dry environment and several months in water.

While all serotypes can cause disease in humans, a few are host-specific and can reside in only one or a few animal species: for example, Salmonella enterica serotype Dublin in cattle and Salmonella enterica serotype Choleraesuis in pigs. When these particular serotypes cause disease in humans, it is often invasive and can be life-threatening. Most serotypes, however, are present in a wide range of hosts. Typically, such serotypes cause gastroenteritis, which is often uncomplicated and does not need treatment, but disease can be severe in the young, the elderly, and patients with weakened immunity. This group features Salmonella enterica serotype Enteritidis and Salmonella enterica serotype Typhimurium, the two most important serotypes of Salmonella transmitted from animals to humans in most parts of the world.

The disease

Salmonellosis is a disease caused by the bacteria Salmonella. It is usually characterized by acute onset of fever, abdominal pain, diarrhoea, nausea and sometimes vomiting.

The onset of disease symptoms occurs 6–72 hours (usually 12–36 hours) after ingestion of Salmonella, and illness lasts 2–7 days.

Symptoms of salmonellosis are relatively mild and patients will make a recovery without specific treatment in most cases. However, in some cases, particularly in children and elderly patients, the associated dehydration can become severe and life-threatening.

Although large Salmonella outbreaks usually attract media attention, 60–80% of all salmonellosis cases are not recognized as part of a known outbreak and are classified as sporadic cases, or are not diagnosed as such at all.

Sources and transmission

• Salmonella bacteria are widely distributed in domestic and wild animals. They are prevalent in food animals such as poultry, pigs, and cattle; and in pets, including cats, dogs, birds, and reptiles such as turtles.
• Salmonella can pass through the entire food chain from animal feed, primary production, and all the way to households or food-service establishments and institutions.
• Salmonellosis in humans is generally contracted through the consumption of contaminated food of animal origin (mainly eggs, meat, poultry, and milk), although other foods, including green vegetables contaminated by manure, have been implicated in its transmission.
• Person-to-person transmission can also occur through the faecal-oral route.
• Human cases also occur where individuals have contact with infected animals, including pets. These infected animals often do not show signs of disease.

Treatment

Treatment in severe cases is electrolyte replacement (to provide electrolytes, such as sodium, potassium and chloride ions, lost through vomiting and diarrhoea) and rehydration.

Routine antimicrobial therapy is not recommended for mild or moderate cases in healthy individuals. This is because antimicrobials may not completely eliminate the bacteria and may select for resistant strains, which subsequently can lead to the drug becoming ineffective. However, health risk groups such as infants, the elderly, and immunocompromised patients may need to receive antimicrobial therapy. Antimicrobials are also administered if the infection spreads from the intestine to other body parts. Because of the global increase of antimicrobial resistance, treatment guidelines should be reviewed on a regular basis taking into account the resistance pattern of the bacteria based on the local surveillance system.

Prevention methods

Prevention requires control measures at all stages of the food chain, from agricultural production, to processing, manufacturing and preparation of foods in both commercial establishments and at home.

Preventive measures for Salmonella in the home are similar to those used against other foodborne bacterial diseases (see recommendations for food handlers below).

The contact between infants/young children and pet animals that may be carrying Salmonella (such as cats, dogs, and turtles) needs careful supervision.

National and regional surveillance systems on foodborne diseases are important means to know and follow the situation of these diseases and also to detect and respond to salmonellosis and other enteric infections in early stages, and thus to prevent them from further spreading.

Recommendations for the public and travellers

The following recommendations will help ensure safety while travelling:

• Ensure food is properly cooked and still hot when served.
• Avoid raw milk and products made from raw milk. Drink only pasteurized or boiled milk.
• Avoid ice unless it is made from safe water.
• When the safety of drinking water is questionable, boil it or if this is not possible, disinfect it with a reliable, slow-release disinfectant agent (usually available at pharmacies).
• Wash hands thoroughly and frequently using soap, in particular after contact with pets or farm animals, or after having been to the toilet.
• Wash fruits and vegetables carefully, particularly if they are eaten raw. If possible, vegetables and fruits should be peeled.

• A guide on safe food for travellers

Recommendations for food handlers

WHO provides the following guidance for people handling food:

• Both professional and domestic food handlers should be vigilant while preparing food and should observe hygienic rules of food preparation.
• Professional food handlers who suffer from fever, diarrhoea, vomiting or visible infected skin lesions should report to their employer immediately.
• The WHO Five keys to safer food serve as the basis for educational programmes to train food handlers and educate consumers. They are especially important in preventing food poisoning. The five keys to Safer Food are:
  • keep clean
  • separate raw and cooked
  • cook thoroughly
  • keep food at safe temperatures
  • use safe water and raw materials.

• Five keys to safer food

Recommendations for producers of fruits, vegetables and fish

The WHO Five keys to growing safer fruits and vegetables: promoting health by decreasing microbial contamination and the Five keys to safer aquaculture products to protect public health provide rural workers, including small farmers who grow fresh fruits and vegetables and fish for themselves, their families and for sale in local market with key practices to prevent microbial contamination.

The Five keys to growing safer fruits and vegetables are:

• Practice good personal hygiene.
• Protect fields from animal faecal contamination.
• Use treated faecal waste.
• Evaluate and manage risks from irrigation water.
• Keep harvest and storage equipment clean and dry.

• Five keys to growing safer fruits and vegetables

The Five keys to safer aquaculture products to protect public health are:

• Practice good personal hygiene.
• Clean the pond site.
• Manage water quality.
• Keep fish healthy.
• Use clean harvest equipment and containers.

• Five keys to safer aquaculture products to protect public health

WHO response

In partnership with other stakeholders, WHO is strongly advocating the importance of food safety as an essential element in ensuring access to safe and nutritious diets. WHO is providing policies and recommendations that cover the entire food chain from production to consumption, making use of different types of expertise across different sectors.

WHO is working towards the strengthening of food safety systems in an increasingly globalized world. Setting international food safety standards, enhancing disease surveillance, educating consumers and training food handlers in safe food handling are amongst the most critical interventions in the prevention of foodborne illnesses.

WHO is strengthening the capacities of national and regional laboratories in the surveillance of foodborne pathogens, such as Campylobacter and Salmonella.

WHO is also promoting the integrated surveillance of antimicrobial resistance of pathogens in the food chain, collecting samples from humans, food and animals and analysing data across the sectors.

WHO, jointly with FAO, is assisting Member States by coordinating international efforts for early detection and response to foodborne disease outbreaks through the network of national authorities in Member States.

WHO also provides scientific assessments as basis for international food standards, guidelines and recommendations developed by the FAO/WHO Codex Alimentarius Commission to prevent foodborne diseases.

Salmonella infection is one of many possible causes of gastroenteritis (also known as ‘gastro’). There are thousands of different types of Salmonella bacteria and they occur in many domestic and wild animals, including birds, sometimes causing illness in them. Two specific types of Salmonella can cause typhoid and paratyphoid fever, which causes a different illness to that described below. Typhoid and paratyphoid infections can be serious and are not common in Australia.

Salmonella infection is a notifiable condition 1

How Salmonella is spread

Salmonella infection usually results from ingestion of the bacteria from contaminated food, water or hands. Eggs, milk, meat or poultry are particularly high risk foods. Fruit and vegetables may also be contaminated, especially if manure has been used as fertiliser.

People may become infected if they transfer animal faeces containing Salmonella bacteria from their hands to their mouths, for example, if eating after touching animals and failing to wash their hands.

Person-to-person spread may occur when hands, objects or food become contaminated with faeces from people who are infected and the bacteria are then taken in by mouth by another person.

Signs and symptoms

Symptoms may include:

• fever
• diarrhoea
• loss of appetite
• headache
• stomach cramps
• nausea and vomiting.

Sometimes there may be blood or mucus in the faeces. Dehydration is a serious complication. The illness may be particularly severe in young children, the elderly and people with immune suppression.

A small percentage of people may develop arthritis after having a Salmonella infection.

Diagnosis

Diagnosis is made by growing Salmonella bacteria from a faecal specimen or by detecting Salmonella in a faecal sample using a PCR (polymerase chain reaction) test in a pathology laboratory.

Incubation period

(time between becoming infected and developing symptoms)

6 to 72 hours, usually 12 to 36 hours.

Infectious period

(time during which an infected person can infect others)

The faeces are always infectious when symptoms are present. Some people continue to carry Salmonella bacteria in the bowel and shed them in the faeces for months after recovering.

Treatment

Recovery from Salmonella infection usually occurs within a week and antibiotic treatment is not normally required. However, a doctor may prescribe antibiotics for young infants, the elderly and in some other situations. See also Typhoid and paratyphoid.

Gastroenteritis is a common illness, which can be particularly serious in young children.

The following are general recommendations for the treatment of gastroenteritis:

• Give plenty of fluids. Oral rehydration solution is highly recommended for children with mild to moderate dehydration. It is available at pharmacies and should be administered following the instructions on the packaging.
• Mildly unwell children should be given their usual fluids more often. Carbonated (fizzy) drinks or undiluted juice should be avoided.
• Medicines to prevent vomiting or diarrhoea should not be given (especially in children), except where specifically advised by a doctor.
• Breastfed babies should continue to be breastfed throughout their illness.
• Children on formula or solid diets should restart their normal diet (including full strength lactose containing milk) following rehydration with oral rehydration solution.
• Children who are hungry or ask for food should be given small portions of their usual foods, but avoid foods high in sugar or fat.

Seek medical advice if any of the following symptoms occur:

• Signs of dehydration, such as thirst and decreased urination, lethargy, dry mouth, feeling faint on standing
• fever
• severe abdominal pain
• bloody diarrhoea.

• Signs of dehydration, such as thirst and decreased urination, lethargy, dry mouth, sunken eyes, feeling faint on standing
• fever
• abdominal pain
• bloody diarrhoea
• any symptoms in a child less than 12 months of age.

Prevention

• Exclude people with Salmonella infection from childcare, preschool, school and work until there has been no diarrhoea for 24 hours. If working as a food handler in a food business, the exclusion period should be until there has been no diarrhoea or vomiting for 48 hours.
• Infants, children and adults with Salmonella infection should not swim until there has been no diarrhoea for 24 hours.
• Cook meat thoroughly, until the juices run clear.
• Do not purchase dirty or cracked eggs.
• Strict food handling procedures should be used when preparing dishes containing raw or incompletely cooked eggs, such as homemade ice cream and mayonnaise.
• Do not consume unpasteurised milk.
• Follow good food handling procedures.
• Follow good hand washing and keeping areas clean procedures.
• Recognise the risk of Salmonella infections in pets. Chickens, ducklings, tropical freshwater fish and turtles are particularly risky for small children.
• Hand washing after handling raw meat, (especially chicken) or raw eggs
• Always wash fruit (including melons) and vegetables before eating. If home grown, wash them before bringing them into the house.
• Infected people who no longer have symptoms should take special care with hand washing if they are involved in food preparation or in caring for patients in hospital, the elderly or children.
• Babies and small children without diarrhoea who are not toilet trained should wear tight fitting waterproof pants or swimming nappies in swimming pools and changed regularly in the change room. When faecal accidents occur, swimming pools should be properly disinfected.

Useful links

1 – In South Australia the law requires doctors and laboratories to report some infections or diseases to SA Health. These infections or diseases are commonly referred to as 'notifiable conditions'.

Remember to follow the Clean, Separate, Cook, and Chill guidelines to help keep you and your family safe from Salmonella. Be especially careful to follow the guidelines when preparing food for young children, people with weakened immune systems, and older adults.

Don’t let Salmonella make you or your loved ones sick. Take a look at these five facts and CDC’s tips for lowering your chance of getting a Salmonella infection.

1. You can get aSalmonellainfection froma variety of foods. Salmonella can be found in many foods, including sprouts and other vegetables, eggs, chicken, pork, fruits, and even processed foods, such as nut butters, frozen pot pies, chicken nuggets, and stuffed chicken entrees. Contaminated foods usually look and smell normal, which is why it is important to know how to prevent infection.
2. Salmonellaalso can spread from animals to people and from people to people. Always wash your hands after contact with animals. Also wash your hands after using the toilet, changing diapers, or helping someone with diarrhea clean up after using the toilet. If you have a Salmonella infection, you should not prepare food or drinks for others until you no longer have diarrhea.
3. Salmonellaillness is more common in the summer. Warmer weather and unrefrigerated foods create ideal conditions for Salmonella to grow. Be sure to refrigerate or freeze perishables (foods likely to spoil or go bad quickly), prepared foods, and leftovers within 2 hours (or 1 hour if the temperature outside is 90°F or hotter).
4. Salmonellaillness can be serious and is more dangerous for certain people. Anyone can get a Salmonella infection, but some people are more likely to develop a serious illness, including children younger than 5, older adults, and people with immune systems weakened from a medical condition, such as diabetes, liver or kidney disease, and cancer or its treatment.
5. Salmonellacauses far more illnesses than you might suspect. For every person with a Salmonella illness confirmed by a laboratory test, there are about 30 more people with Salmonella illnesses that are not reported. Most people who get food poisoning do not go to a doctor or submit a sample to a laboratory, so we never learn what germ made them sick.

Pets and other healthy animals, including those at petting zoos, farms, fairs, and even schools and daycares, can carry Salmonella and other germs that make people sick. The following tips will help you stay safe when it comes to our feathery, furry, and scaly friends.

• Wash your hands thoroughly with running water and soap after touching pets and other animals, or their food, water, poop, belongings (such as toys and bowls), or habitats (such as beds, cages, tanks, coops, stalls, and barns).
• Don’t put your hands in your mouth after petting or playing with animals. Keep other items that have come into contact with animals out of your mouth.
• Don’t kiss cats, dogs, chickens, turtles, lizards, or other pets or animals.
• Don’t let children younger than age 5, people with weakened immune systems, or older adults touch high-risk animals (like turtles, frogs, chickens, or ducks) or their belongings or habitats.
• Never eat or drink around high-risk animals or in areas where they live and roam.
• Clean your pet’s bed, cage, terrarium, or aquarium and its contents (such as food and water bowls) outdoors. If you must clean your pet’s habitat indoors, use a bathtub or large sink that can be cleaned and disinfected. Avoid using a kitchen sink, if possible.
• Take your pet to the veterinarian regularly. By keeping your pet healthy, you also help to keep yourself and your family healthy.

Rod Brouhard is an emergency medical technician paramedic (EMT-P), journalist, educator, and advocate for emergency medical service providers and patients.

Andy Miller, MD, is board-certified in internal medicine and infectious disease. He is an associate professor at Weill Cornell Medicine in New York City.

Taking steps to prevent getting a salmonella infection can save you and your family from being one of the 1.2 million people in the United States who contract this illness each year.   The bacteria responsible for salmonella is spread by contaminated food and by handling animals such as pet turtles that carry it in their feces. Avoid raw or undercooked meat and eggs and ensure raw meat is handled separately from other foods when preparing a meal.

Preventing infection is especially important for those most at risk of a severe illness, including young children, the elderly, and those with weakened immune systems.

While most people get diarrhea that runs its course in a few days, approximately 450 people die every year from acute salmonellosis .

There is no vaccine for salmonella and you can catch the illness multiple times, so it is important to avoid contact with the bacteria.

Transmission

Salmonellosis is an illness that includes diarrhea, fever, and abdominal cramps.   The bacteria are spread in the feces. Some people are healthy but are carriers of the bacteria. Use these tips so you don't give salmonella to others or get it from them:

• Always wash your hands thoroughly after using the toilet, changing diapers, and before preparing food.
• A person who has salmonellosis should not prepare food or pour water for others until they have had no symptoms for 48 hours.
• A person who has salmonellosis should not return to work, child care, or school until they have had no symptoms for 48 hours.
• Don't go swimming if you have had diarrhea in the past 24 hours.

Food Preparation and Handling

There are many food handling practices that are aimed at preventing salmonella infection from food. These practices are important while eating, cooking at home, and preparing food in restaurants.  

Clean

• Wash your hands before and after you handle food items.
• Wash kitchen work surfaces and utensils with soap and water after preparing each food item.
• It is better to use disposable paper towels to clean kitchen surfaces than sponges or cloth towels. If you use cloth towels, they should be washed in hot water in a washing machine after each use.
• Thoroughly wash produce before consuming.
• Peel and discard outer leaves or rinds of fruits and vegetables.
• Scrub hearty vegetables, such as potatoes and carrots, if you want to eat the skin.

Separate

• When shopping, keep raw meat, poultry, and seafood separate from the other items. Store them separately in the refrigerator.
• After contact with raw meat or poultry, wash hands, kitchen work surfaces, utensils, plates, bowls, etc. with soap and water immediately. It is especially important that you don't use unwashed utensils and other items for food that will be served uncooked or for the meat once it has been cooked.
• It is best to have separate cutting boards designated for raw meat and for produce as cleaning may not remove all of the bacteria.
• Don't work with raw poultry or meat and handle an infant (e.g., feed, change diaper) at the same time.

Cook

• Cook poultry, ground beef, and eggs thoroughly before eating. Do not eat or drink foods containing raw eggs or raw unpasteurized milk. Raw eggs may be unrecognized in some foods such as homemade hollandaise sauce, homemade salad dressings, tiramisu, homemade ice cream, homemade mayonnaise, cookie dough, eggnog, and frostings.
• 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. Poultry and meat, including hamburgers, should be well-cooked, not pink in the middle.

Chill

• Keep refrigerators clean and cold (40 F or below for refrigerators).
• Cover and refrigerate produce you have cut.
• Read and follow label instructions such as "Keep Refrigerated" or "Use By" (a certain date).
• Keep prepared fruit salads or other cut produce items in the refrigerator until just before serving. Discard cut produce items if they have been out of the refrigerator for more than four hours.

General

• Mother's milk is the safest food for young infants. Breastfeeding prevents salmonellosis and many other health problems. Wash your hands before breastfeeding your child.
• Don't drink untreated water that could be contaminated by animal waste.

Animal and Pet Contact

While animals may transmit salmonella to anyone, there are groups who are at higher risk and should avoid any contact with animals that commonly carry the bacteria. These groups include infants, children age 5 and younger, adults over age 65, and people with decreased immune function (HIV/AIDS, chemotherapy, organ transplant recipients).

The highest-risk animals are reptiles (turtles, iguanas, other lizards, snakes), amphibians (frogs, salamanders), and live poultry (chickens, ducks, geese, turkeys).

Other animals that may transmit salmonella include pet birds, rodents (hamsters, guinea pigs, rats, mice), hedgehogs, farm animals, dogs, cats, and horses. The bacteria are primarily found in their feces, but their fur, feathers, bedding, toys, food, feeders, cages, or enclosures will also harbor the germs. These animals can be completely healthy and still carry the bacteria.

Use these tips to reduce your risk and protect people in higher-risk groups:  

• Wash your hands with soap and water after any contact with animals, their enclosures, or their feces. While this applies to any animal or pet, it is especially a concern with reptiles, amphibians, or birds.
• People in high-risk groups should avoid direct or even indirect contact with reptiles, amphibians, and live poultry. These animals should not be kept as pets in households that have members in the high-risk groups, or at daycare facilities, elder care facilities, or medical facilities.
• Don't allow high-risk animals into areas where you commonly eat or drink. Don't eat, drink, or smoke while around those animals.
• Petting zoos or farm visits are best reserved for children over age 5, with supervision.
• Adults in high-risk groups should not clean any pet items or animal waste without wearing disposable gloves. Children age 5 and under should not be given such tasks.
• When washing pets or their items, try to do so outdoors. Do not discard the water in a sink that is used for food preparation. Use bleach to disinfect any sink, tub, or toilet afterward.
• If your child is age 5 or younger, supervise the child around animals. Don't allow contact with your child's face or kissing. Assist your child in handwashing after handling an animal.

Backyard Farming

As keeping chickens and enjoying homegrown eggs is popular, it is important to understand the risks of salmonella from these activities. You should only buy live poultry or chicks from hatcheries certified by the USDA National Poultry Improvement Plan (USDA NPIP).   It's best not to get your poultry from show breeders or other backyard farmers.

Use these tips to avoid getting salmonella:

• Clean your coop regularly, wearing gloves and shoe protectors or shoes you only use in the coop.
• Change the food and water daily.
• Wash your hands after handling a chicken or collecting eggs and do so either outdoors or using a sink that isn't used for food preparation.
• Clean feeding bowls and other items outdoors or in a sink not used for food preparation, disinfecting it with bleach.
• Don't eat, drink, or smoke around your birds.
• Keep your birds out of the house and away from areas, including outdoor patios, where you prepare or eat food.
• Don't allow children under age 5 around your birds and supervise other children and adults so they handle the birds safely.
• If any bird is sick, separate it from the rest of the birds and contact your veterinarian.
• Ensure your birds get all recommended vaccines.
• If you use chicken manure as garden compost, it must be cured for at least 45 days before use.
• Don’t kiss backyard poultry, or snuggle them and then touch your face or mouth.  

Use these tips for homegrown egg safety:

• Collect the eggs each morning and afternoon.
• Washing eggs after collection isn't recommended as the Center for Disease Control (CDC) says that washing in cold water can pull bacteria into the eggs.   Clean them outdoors with a brush or cloth.
• Discard cracked or dirty eggs.
• Refrigerate eggs in two hours or less.
• If you are selling your eggs, follow all local regulations and licensing requirements.
• When eating homegrown eggs, cook them thoroughly and don't consume raw eggs.

Identifying Outbreaks

Public health departments and the CDC require medical facilities to report cases of salmonellosis so they can identify and track outbreaks.   Clinical laboratories send isolates of Salmonella to public health laboratories so the specific type can be determined and compared with other Salmonella in the community. If many cases occur at the same time, it may mean that a restaurant, food, or water supply has a problem which needs correction by the public health department. While many people don't seek medical care for a bout of salmonellosis that runs a typical course, those who do will help with this monitoring for outbreaks.

Information on outbreaks can be seen on the CDC site.

Examples of recent outbreaks include those due to shell eggs, coconut, chicken salad, raw sprouts, kratom, pet guinea pigs, and pet turtles. You can drill down to see the specifics for outbreaks.

If you hear any news reports of recalls of food due to concern for salmonella or foodborne illnesses, check to see whether you have bought the recalled products. Do not consume them.