Campylobacter Bacteria, Gastroenteritis and Foodborne Illness
Campylobacter and Foodborne Illness or Food Poisoning
Campylobacter is a spiral-shaped 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 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 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. Fortunately, most people recover from campylobacteriosis. Some people experience complications from the infection, however. These complications include reactive arthritis and Guillain-Barré syndrome.
Bacteria and Food Safety
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. 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.
Transmission of Campylobacter
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 also lives in the intestine of some humans without causing any symptoms. On the other hand, fewer than 500 Campylobacter cells - a very small bacterial population - can make some people sick.
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, yet they are often able to withstand this stress. A concentration of oxygen equal to that found in the environment kills them, however. Cooking and pasteurization also 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.
Campylobacter Biofilms Aid Survival
Symptoms of a Campylobacter 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.
The discomfort often starts with stomach pain, a fever and a general feeling of being unwell, which is known as malaise. The infected person may experience a headache, nausea and vomiting as well. Soon after the illness begins the person produces diarrhea, which may be copious and sometimes contains blood, mucus or pus. A diagnosis of Camoylobacteriosis is generally made by identifying the bacteria in a stool sample.
The symptoms of campylobacteriosis 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. 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.
Most cases of campylobacteriosis appear in children, pregnant women and elderly people. Other susceptible people include those with suppressed immune systems. These include people with AIDS, cancer or diabetes or those receiving anti-rejection drugs for an organ transplant. Apparently healthy people at any stage of life may be affected, however.
Treatment 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. This may happen in people whose immune system isn't working properly, such as those with an HIV infection.
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, there are treatments which can relieve symptoms. Most people recover from the disease, but in some people weakness, numbness and fatigue persist.
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 after using a toilet, changing diapers or cleaning up pet feces.
- 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.
- 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. 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.
© 2013 Linda Crampton