Frequently Asked Questions
New CDC Data on Foodborne Disease Outbreaks
Outbreaks provide important insights into how germs spread, which food and germ combinations cause illnesses, and how to prevent infections. Public health and industry use outbreak data to create information on prevention, education, and policy.
What is campylobacteriosis?
Campylobacteriosis is an infectious disease caused by bacteria of the genus Campylobacter. Most people who become ill with campylobacteriosis get diarrhea, cramping, abdominal pain, and fever within two to five days after exposure to the organism. The diarrhea may be bloody and can be accompanied by nausea and vomiting. The illness typically lasts about one week. Some infected persons do not have any symptoms. In persons with compromised immune systems, Campylobacter occasionally spreads to the bloodstream and causes a serious life-threatening infection.
How common is Campylobacter?
Campylobacter is one of the most common causes of diarrheal illness in the United States. Most cases occur as isolated, sporadic events, not as part of recognized outbreaks. Active surveillance through the Foodborne Diseases Active Surveillance Network (FoodNet) indicates that about 14 cases are diagnosed each year for each 100,000 persons in the population. Many more cases go undiagnosed or unreported, and campylobacteriosis is estimated to affect over 1.3 million persons every year. Campylobacteriosis occurs much more frequently in the summer months than in the winter. The organism is isolated from infants and young adults more frequently than from persons in other age groups and from males more frequently than females. Although Campylobacter infection does not commonly cause death, it has been estimated that approximately 76 persons with Campylobacter infections die each year.
What sort of germ is Campylobacter?
Campylobacter organisms are spiral-shaped bacteria that can cause disease in humans and animals. Most human illness is caused by one species, called Campylobacter jejuni, but human illness can also be caused by other species. Campylobacter jejuni grows best at 37°C to 42°C, the approximate body temperature of a bird (41°C to 42°C), and seems to be well adapted to birds, who carry it without becoming ill. These bacteria are fragile. They cannot tolerate drying and can be killed by oxygen. They grow only in places with less oxygen than the amount in the atmosphere. Freezing reduces the number of Campylobacter bacteria on raw meat.
How is the infection diagnosed?
Many different kinds of infections can cause diarrhea and bloody diarrhea. Campylobacter infection is diagnosed when a culture of a stool specimen yields the bacterium.
How can campylobacteriosis be treated?
Almost all persons infected with Campylobacter recover without any specific treatment. Patients should drink extra fluids as long as the diarrhea lasts. Antimicrobial therapy is warranted only for patients with severe disease or those at high risk for severe disease, such as those with immune systems severely weakened from medications or other illnesses. Azithromycin and fluoroquinolones (e.g., ciprofloxacin) are commonly used for treatment of these infections, but resistance to fluoroquinolones is common. Antimicrobial susceptibility testing can help guide appropriate therapy.
Are there long-term consequences?
Most people who get campylobacteriosis recover completely within two to five days, although sometimes recovery can take up to 10 days. Rarely, Campylobacter infection results in long-term consequences. Some people develop arthritis. Others may develop a rare disease called Guillain-Barré syndrome that affects the nerves of the body beginning several weeks after the diarrheal illness. This occurs when a person's immune system is "triggered" to attack the body's own nerves resulting in paralysis. The paralysis usually lasts several weeks and requires intensive medical care. It is estimated that approximately one in every 1,000 reported Campylobacter illnesses leads to Guillain-Barré syndrome. As many as 40% of Guillain-Barré syndrome cases in this country may be triggered by campylobacteriosis.
How do people get infected with this germ?
Campylobacteriosis usually occurs in single, sporadic cases, but it can also occur in outbreaks, when two or more people become ill from the same source. Most cases of campylobacteriosis are associated with eating raw or undercooked poultry meat or from cross-contamination of other foods by these items. Outbreaks of Campylobacter have most often been associated with unpasteurized dairy products, contaminated water, poultry, and produce. Animals can also be infected, and some people get infected from contact with the stool of an ill dog or cat. The organism is not usually spread from one person to another, but this can happen if the infected person is producing a large volume of diarrhea.
It only takes a very few Campylobacter organisms (fewer than 500) to make a person sick. Even one drop of juice from raw chicken meat can have enough Campylobacter in it to infect a person! One way to become infected is to cut poultry meat on a cutting board, and then use the unwashed cutting board or utensil to prepare vegetables or other raw or lightly cooked foods. The Campylobacter organisms from the raw meat can get onto the other foods.
How does food or water get contaminated with Campylobacter?
Many chicken flocks are infected with Campylobacter but show no signs of illness. Campylobacter can be easily spread from bird to bird through a common water source or through contact with infected feces. When an infected bird is slaughtered, Campylobacter organisms can be transferred from the intestines to the meat. In 2011, Campylobacter was found on 47% of raw chicken samples bought in grocery stores and tested through the National Antimicrobial Resistance Monitoring System (NARMS). Campylobacter can also be present in the giblets, especially the liver.
Unpasteurized milk can become contaminated if the cow has an infection with Campylobacter in her udder or if the milk is contaminated with manure. Surface water and mountain streams can become contaminated from infected feces from cows or wild birds. Campylobacter is common in the developing world, and travelers to foreign countries are at risk for becoming infected with Campylobacter. Approximately one-fifth (19%) of Campylobacter cases identified in FoodNet are associated with international travel.
What can be done to prevent Campylobacter infection?
Some simple food handling practices can help prevent Campylobacter infections.
- Cook all poultry products thoroughly. Make sure that the meat is cooked throughout (no longer pink) and any juices run clear. All poultry should be cooked to reach a minimum internal temperature of 165°F.
- If you are served undercooked poultry in a restaurant, send it back for further cooking.
- Wash hands with soap before preparing food
- Wash hands with soap after handling raw foods of animal origin and before touching anything else.
- Prevent cross-contamination in the kitchen by using separate cutting boards for foods of animal origin and other foods and by thoroughly cleaning all cutting boards, countertops, and utensils with soap and hot water after preparing raw food of animal origin.
- Do not drink unpasteurized milk or untreated surface water.
- Make sure that persons with diarrhea, especially children, wash their hands carefully and frequently with soap to reduce the risk of spreading the infection.
- Wash hands with soap after contact with pet feces.
Physicians who diagnose campylobacteriosis and clinical laboratories that identify this organism should report their findings to the local health department. If many cases occur at the same time, it may mean that an outbreak has occurred in which many people were exposed to a common contaminated food item or water source. If this food or water is still available, more people could get infected. Public health departments investigate outbreaks to identify the source so that action can be taken to prevent more cases.
What are public health agencies doing to prevent or control campylobacteriosis?
To learn more about how Campylobacter causes disease and its spread, CDC began a detailed active surveillance sentinel system, FoodNet, in five sites in 1996 and subsequently expanded to ten sites. FoodNet monitors the incidence and trends of human Campylobacter infection (as well as other germs transmitted commonly through food) over time and conducts studies to identify risk factors for infection.
The U.S. Department of Agriculture (USDA) conducts research on how to prevent Campylobacter infection in chickens. In 2011, USDA established performance standards to limit Campylobacter contamination of whole broiler chickens in processing plants. The Food and Drug Administration (FDA) has produced the Model Food Code for restaurants. Adherence to it decreases the risk of Campylobacter infection.
The National Antimicrobial Resistance Monitoring System (NARMS), a collaboration among CDC, FDA, USDA, and health departments, tracks changes in antibiotic resistance among Campylobacter from humans, retail meats, and food animals.
PulseNet is a national network whose participants perform standardized molecular subtyping (or “fingerprinting”) of foodborne disease-causing bacteria by pulsed-field gel electrophoresis (PFGE). PFGE can be used to distinguish strains of organisms including Campylobacter at the DNA level. DNA “fingerprints,” or patterns, are submitted electronically to a dynamic database at the CDC. These databases are available on-demand to participants—this allows for rapid comparison of the patterns.