Campylobacter Bacteria, Gastroenteritis, and Foodborne Illness
Campylobacter and Foodborne Illness
Campylobacter is an interesting but potentially harmful bacterium that is a major cause of foodborne illness. The bacterium causes inflammation of the gastrointestinal tract, a disorder known as gastroenteritis. Symptoms of the disorder may include nausea, vomiting, cramps, and diarrhea. The infected person may also have a fever. Infection by Campylobacter is called campylobacteriosis.
The CDC (Centers for Disease Control and Prevention) says that in the United States about 1.3 million people are infected by Campylobacter bacteria every year and that about 76 of these people die from the infection. The bacteria are commonly obtained from raw or undercooked poultry, raw, unpasteurized milk, and contaminated water. They may also be obtained from the feces of an infected animal or human.
Campylobacter is one of the most common causes of foodborne illness, which is sometimes known as food poisoning. Fortunately, most people recover from campylobacteriosis. Some people experience complications from the infection, however. These complications include reactive arthritis and Guillain-Barré syndrome.
There are many species of Campylobacter, but the one that most often causes foodborne illness in humans is Campylobacter jejuni. Campylobacter coli is responsible for some cases of the disease.
"Campylo" means curved or twisted in Latin. Campylobacter has rod-shaped cells which are spirally curved, as shown in the first photo in this article. Each cell has a flagellum at one or each end. Flagella are long, whip-like extensions that are used to move a cell through a liquid environment.
The life of Campylobacter isn't completely understood, but some of its biology is known. The bacterium is a microaerophilic organism. It requires oxygen in order to survive, but in a much lower concentration than that found in the atmosphere. It burrows into the mucus layer on top of our intestinal lining and attaches to the epithelial cells under the mucus. Some of the bacteria are able to invade the epithelial cells and destroy the mucosa (the intestinal lining).
Most strains of Campylobacter jejuni produce a toxin called cytolethal distending toxin, or CDT. This toxin causes cells to slowly stretch and eventually die. Strains of a species are slightly different from one another genetically, but they aren't different enough to be classified in different species. In the case of a Campylobacter infection, however, they may be significant.
Transmission of the Bacteria
Campylobacter lives in the digestive tract of animals such as poultry, wild birds, pigs, rodents, cats, and dogs. It often causes no health problems for the affected animal and is a normal part of their intestinal bacterial population. The bacterium is also found in the intestine of some humans who have no symptoms of ill health. It's uncertain whether the bacterium is truly commensal in humans, however. Commensalism is a relationship in which one organism benefits and the other is unaffected.
Although they generally live in an animal's intestine, the bacteria may contaminate the meat (muscle) of a farm animal during slaughtering. In 2011, an organization called NARMS found that 47% of the raw chicken that they tested contained Campylobacter. NARMS stands for National Antimicrobial Resistance Monitoring System for Enteric Bacteria. It's run by several public health agencies, including the CDC.
The bacteria are sometimes present in water that contains animal or human feces. The contaminated water may infect humans if they come into contact with it. Fecal contamination is one reason why it's important to clean up pet stool carefully and why we should wash our hands after defecating. Campylobacter may also infect a cow's udder and enter her milk. In addition, the milk may become contaminated if the udder has feces on its surface.
Unlike illnesses caused by some other important food pathogens, such as Salmonella and E. coli, campylobacteriosis tends to occur in isolated incidents instead of widespread outbreaks. Outbreaks of campylobacteriosis do occasionally appear, however. The disease is more common in summer than in winter.
Campylobacter can survive in a bird's body at a temperature of about 42°C and in our body at a temperature of around 37°C. It can survive refrigeration for a short period. Its numbers are decreased when contaminated food is frozen. When infected meat is removed from an animal the bacteria are exposed to an increased level of oxygen. They are often able to withstand this stress, at least for a while. The tolerance to oxygen seems to depend on the strain of the bacterium, however. Cooking and pasteurization destroy the bacteria.
Scientists have discovered that the bacteria can form biofilms on lab surfaces that mimic those found in food processing facilities. A biofilm consists of layers of bacteria covered by a protective slime. The bacteria in a biofilm are attached to each other and/or to the surface instead of moving freely around. Biofilm formation protects Campylobacter from a high oxygen concentration. Scientists have also discovered that bacteria can be shed from the biofilm under suitable environmental conditions. This means that they could enter raw food placed on the surface.
Possible Symptoms of an Infection
Campylobacter causes gastroenteritis, a condition in which the stomach and intestine are inflamed and irritated. Some people call the condition "stomach flu", although it has nothing to do with influenza. Symptoms range from mild to severe. They may include:
- stomach pain (often the first symptom)
- a fever
- a general feeling of being unwell (malaise)
- a headache
- diarrhea (sometimes copious and may contain blood, mucus, or pus)
The symptoms of the disease begin from one to ten days after the bacteria enter the body. This gap between ingestion of the bacteria and appearance of the illness is called the incubation period. Once the symptoms appear they generally last for two to five days, but they sometimes stay for up to ten days.
A diagnosis of Camoylobacteriosis is generally made by identifying the bacteria in a stool sample. It's important to realize that a person may still be releasing Campylobacter in their stool even when they no longer have symptoms of the infection.
In any illness, a doctor should be consulted when symptoms are severe, persistent, or recurrent. The symptoms listed above could be caused by a factor other than Campylobacter. A doctor will make a diagnosis and prescribe appropriate treatment.
Possible Treatments for Campylobacteriosis
Often campylobacteriosis treatment isn't necessary because the body deals with the problem by itself, but supportive care is needed while the patient's immune system is doing its job. It's important to drink water during an infection, since water is lost from the body in both vomiting and diarrhea. Electrolyte replacement may also be needed.
Anyone with severe symptoms or ones that don't disappear quickly should seek a doctor's advice. If someone becomes seriously dehydrated after heavy vomiting and diarrhea they may need emergency treatment. A doctor may prescribe an antibiotic to fight the bacteria, although this is generally done only in special circumstances.
Although fatalities are rare, some infections do kill people. The most dangerous situation is the appearance of the bacteria in the bloodstream, a condition known as bacteremia. This may happen in people whose immune system isn't working properly, such as those with an HIV infection.
Most cases of campylobacteriosis appear in children, pregnant women, and elderly people, whose immune systems may not be working at full efficiency. Susceptible people with suppressed immune systems include those with AIDS, cancer, or diabetes or those receiving anti-rejection drugs for an organ transplant. Healthy people at any stage of life may experience the disease, however.
Possible Complications of Infection
Complications of a Campylobacter infection are not common, but they do occur. These complications include meningitis (inflammation of the membranes around the brain), a urinary tract infection, reactive arthritis (which is usually short-term), and Guillain-Barré syndrome. The CDC says that about one in every thousand reported cases of campylobacteriosis leads to Guillain-Barré syndrome and that up to forty percent of all cases of the syndrome in the United States are caused by Campylobacter.
Guillain-Barré syndrome is a condition in which the body's immune system attacks the nerves, causing weakness, numbness, tingling, and paralysis. It's often preceded by an infection. Although there is no cure for the disorder, treatments that can relieve symptoms exist. Most people recover from the disease, but in some people weakness, fatigue, or numbness persist.
The video below was created by the Food Standards Agency, a government organization in the UK. It shares the common recommendation that we shouldn't wash raw chicken because the process can spread Campylobacter cells from the chicken to work surfaces and other places. The United States Department of Agriculture says that we shouldn't wash any raw meat. Cooking the meat at the right temperature will kill the bacteria that can cause foodborne illness.
Splashing water from washing chicken under a tap can spread the bacteria onto hands, work surfaces, clothing, and cooking equipment. Water droplets can travel more than 50cm in every direction. Only a few campylobacter cells are needed to cause food poisoning.— National Health Service in the UK
A 2017-2018 Outbreak of Campylobacteriosis
From January 2017 to the end of February 2018, an outbreak of campylobacteriosis occurred in the United States. In September 2018, the CDC reported the results of their investigation of the outbreak. In the United States, Camylobacteriosis became a nationally notifiable disease in 2015. This means that doctors must report their diagnosis to the government. The CDC is a government organization.
- 118 people in 18 states were affected (based on the cases that were diagnosed).
- Out of the 107 people for whom hospitalization records were available, 26 people were admitted to a hospital.
- Nobody died.
Despite the lack of deaths, a worrying discovery was made. In laboratory tests, researchers found that the bacterium was resistant to all of the antibiotics commonly used to treat Campylobacter infections, including macrolides and quinolones. These are major categories of antibiotics.
While the fact that the patients in the outbreak described above recovered is great news, the fact that the bacteria were resistant to common antibiotics isn’t. Antibiotic resistance is becoming a serious problem today. If the patients in the outbreak had problems in their immune system or if supportive treatments by doctors hadn’t been successful, some patients may not have recovered. It’s true that deaths from a Campylobacter infection are uncommon, but they do occur. If the bacterium becomes more virulent, we may be in trouble.
Although antibiotic resistance is a natural process due to changes in bacterial genomes over time, researchers say that we are speeding the process up by the overuse or inappropriate use of antibiotics. The use of antibiotics when they aren’t required in humans and the use in animals in an attempt to prevent disease and improve marketability are having serious effects.
A Link to Pet Store Puppies
The 2017-2018 outbreak of campylobacteriosis was linked to pet stores. The CDC collected some interesting data related to the outbreak.
- 99 percent of the patients who were surveyed reported recent content with a dog.
- 95 percent reported recent contact with a pet store puppy.
- 29 of the 118 people who became ill were pet store employees.
- Store records examined by the CDC showed that 142 of 149 investigated puppies had one or more courses of antibiotics while at the store that housed them.
The CDC says that the discovery of drug administration raises the concern that "antibiotic use might have led to development of resistance". The organization found treatment records for 134 puppies. 78 of these puppies received vaccination for prophylaxis (prevention); 54 for prophylaxis and treatment; and 2 for treatment only. The medium length of antibiotic administration was 15 days.
Dogs can carry Campylobacteria without becoming sick. Some individuals do become sick when exposed to the bacteria, however. This is especially true for puppies, as is the case for human children.
How to Prevent a Campylobacter Infection
Using good hygiene procedures when preparing or eating food is vital in order to prevent a Campylobacter infection. The most important points are to cook food properly and to wash hands, equipment, and surfaces thoroughly and frequently.
- Wash hands with soap and water for twenty seconds before preparing or eating food.
- Supervise young children when they are washing their hands
- Wash hands immediately after using a toilet, changing diapers, cleaning up pet feces, and—at least in the case of children and other susceptible people—after petting animals from outside the home. Some health agencies recommend that children wash their hands after petting any animal.
- Wash cutting boards, utensils, and countertops properly after cutting raw meat. Consider using separate cutting boards for raw meats and other foods.
- After cloths have been used to clean countertops, wash the cloths thoroughly.
- Also wash hands after touching raw meat juices.
- Don't let children touch plastic-wrapped raw chicken in case liquid is leaking from the package. Only a small drop of contaminated liquid is needed to cause an infection.
- Refrigerate meats promptly.
- Separate raw meats and other foods in the refrigerator. Don't position meats in a way that allows their juices to drop on to other foods.
- Don't defrost meats at room temperature
- Make sure that all poultry and other meat is thoroughly cooked.
- Don't eat raw or lightly cooked eggs.
- Don't eat raw or unpasteurized dairy products.
- Drink water from a safe source and avoid water from unsafe sources.
Preventing Foodborne Illness
The rules listed above are important for preventing other cases of foodborne illness in addition to campylobacteriosis. Becoming sick from food poisoning can be horrible, as I know from a memorable incident in my childhood when my whole family became ill. It can sometimes be dangerous as well, especially for susceptible people. It's an excellent idea to get into the habit of following safety procedures when preparing food.
Campylobacter and Campylobacteriosis from the CDC (Centers for Disease Control and Prevention)
Campylobacter fact sheet from WHO (World Health Organization)
Facts about Guillaine-Barre syndrome from the Mayo Clinic
Why you should never wash raw chicken from the NHS (National Health Service)
Washing food and food safety from the USDA (United States Department of Agriculture)
Analysis of drug-resistant Campylobacter infection in 2017-2018 from the CDC
Campylobacter in dogs from PetMD
Questions & Answers
© 2013 Linda Crampton