What is Campylobacter?

Campylobacter is a genus of Gram-negative bacteria that are spiral-shaped and move with a characteristic corkscrew motion. They are microaerophilic, meaning they grow best in environments with low levels of oxygen. Among the various species within this genus, Campylobacter jejuni and Campylobacter coli are the most commonly implicated in human gastrointestinal illness.

Microbiology and Characteristics

These bacteria are oxidase-positive and typically thrive at a temperature range of 37-42°C, resembling conditions found in the intestinal tracts of warm-blooded animals, including poultry, cattle, and humans. When viewed under a microscope, they appear comma or S-shaped. Unlike many other foodborne pathogens, Campylobacter does not multiply in food; instead, it survives until it reaches a suitable host (CDC).

What Foods Can Be Contaminated?

Meat and Poultry

The primary reservoir for Campylobacter is the gastrointestinal tract of birds, especially poultry. Consequently, chicken meat is often contaminated with this bacterium. Raw or undercooked poultry can present a high risk of Campylobacter contamination.

Dairy Products

Unpasteurized milk is another common source of Campylobacter. The bacteria can be present on the udder or teat of the cow, contaminating the milk during the milking process.


Though less common compared to poultry and dairy, contaminated water can also infect seafood such as shellfish.


Vegetables and fruits can become contaminated via contact with soil that contains the bacteria or through cross-contamination during processing or handling.


Untreated water from lakes, streams, or wells can be a potential source of Campylobacter. This is particularly true in areas where agriculture and wildlife have access to water sources.

Ready-to-Eat Foods

Cross-contamination is a significant concern in the kitchen. Ready-to-eat foods can also be contaminated if they come in contact with raw meats or other sources carrying the bacteria.

How Does It Affect Human Health?

Acute Symptoms

In humans, Campylobacter primarily causes a condition known as campylobacteriosis, which is a form of gastroenteritis. The symptoms typically include diarrhea, abdominal cramps, and fever. Vomiting and nausea may also occur. The symptoms usually manifest within 2 to 5 days after exposure and can last for about a week (CDC).

Severe Cases and Complications

In some instances, complications such as dehydration may occur, requiring hospitalization. More severe complications can include hemolytic uremic syndrome (HUS), a type of kidney failure, and Guillain-Barré Syndrome (GBS), a condition that affects the nervous system. Though these severe complications are rare, they are serious and can have long-lasting effects on health.

Susceptible Populations

While anyone can contract campylobacteriosis, certain populations are more susceptible to severe symptoms. These include:

  • Infants and young children
  • Elderly individuals
  • People with compromised immune systems

Immunological Responses

The immune system typically reacts to Campylobacter infection by releasing antibodies. However, immunity to Campylobacter is not fully understood, and reinfections can occur.

How Common is Illness?

Prevalence in the U.S.

According to the Centers for Disease Control and Prevention (CDC), Campylobacter is one of the most common causes of diarrheal illness in the United States. Approximately 1.5 million cases occur annually, but many more go unreported.

Global Incidence

Worldwide, Campylobacter is also a leading cause of bacterial gastroenteritis. It’s estimated by WHO that Campylobacter caused 166 million illness cases, including 96 million food-related illnesses in 2010.

Underreporting and Data Gaps

It’s important to note that many cases go unreported because people with milder symptoms often don’t seek medical attention. Moreover, lack of comprehensive surveillance systems in some countries makes it difficult to get an accurate count.


Outbreaks are generally less common with Campylobacter compared to other foodborne pathogens like Salmonella or E. coli. However, when outbreaks do occur, they are often linked to raw or undercooked poultry, unpasteurized milk, and contaminated water.

Where Does It Come From?

Animal Reservoirs

Campylobacter is naturally found in the digestive tracts of many warm-blooded animals. Poultry, cattle, and swine are significant reservoirs. Wild animals like birds and rodents can also harbor these bacteria.

Environmental Reservoirs

While the bacteria do not multiply outside their host, they can survive in water and soil for a limited period, acting as temporary environmental reservoirs.

Human-to-Human Transmission

Although less common, person-to-person transmission is possible through the fecal-oral route, especially in settings like daycare centers where hygiene practices may be less controlled.

Cross-contamination in Food Handling

Improper food handling can also be a significant source of Campylobacter. Cross-contamination can occur when cutting boards, utensils, or hands that have touched raw meat come into contact with ready-to-eat foods.

Pet Transmission

Pets, especially puppies and kittens, can also carry Campylobacter and could be a source of human infection.

How Is It Affected by Environmental Factors?


Campylobacter is sensitive to high temperatures and is effectively killed when meat is cooked to the recommended internal temperature. However, the bacteria are also capable of surviving freezing temperatures, although their metabolic activity is halted.

Oxygen Levels

Being microaerophilic, Campylobacter prefers environments with low oxygen levels, similar to those found in the gut of animals. It does not survive well in conditions with high levels of oxygen, which is why it does not multiply in foods exposed to air.

pH Levels

The bacterium is sensitive to acidic conditions. Foods that are naturally acidic or those that have been acidified, like pickled vegetables, are generally less conducive for Campylobacter survival.


Campylobacter needs a certain level of moisture to survive. Dry conditions, such as those in dehydrated foods, are not suitable for the bacteria.

Other Environmental Stresses

Exposure to ultraviolet light and certain disinfectants can also effectively kill Campylobacter, making these useful tools in sanitation practices.

How Can It Be Controlled?

Personal Hygiene

Proper handwashing with soap and water can significantly reduce the risk of Campylobacter transmission, especially after handling raw meats or visiting the toilet.

Cooking Practices

Cooking meat, particularly poultry, to a minimum internal temperature of 165°F (74°C) will effectively kill Campylobacter. Using a food thermometer is recommended to ensure that the meat has reached the proper temperature.

Food Handling

  • Avoid cross-contamination by using separate cutting boards and utensils for raw and cooked foods.
  • Wash fruits and vegetables thoroughly.
  • Refrigerate foods promptly.


For dairy and juice products, pasteurization is effective in killing Campylobacter.

Water Treatment

Chlorination and ultraviolet (UV) treatment of water supplies can reduce the risk of Campylobacter contamination.

Veterinary Practices

Farmers can take steps to control the bacterium at the source. This includes biosecurity measures like disinfecting equipment and isolating infected animals.

Consumer Education

Public awareness about safe food handling practices can go a long way in controlling the spread of Campylobacter.

Are There Rules and Regulations?

United States

In the United States, the USDA’s Food Safety and Inspection Service (FSIS) is responsible for ensuring that the nation’s commercial supply of meat, poultry, and egg products is safe. The FSIS has set guidelines on microbiological testing for Campylobacter in poultry products.

European Union

In the European Union, Regulation (EC) No 2073/2005 sets microbiological criteria for foodstuffs, including criteria for Campylobacter in broiler carcasses. The regulation aims to reduce the prevalence of these bacteria in the food chain.

World Health Organization (WHO)

The WHO provides international guidelines and advice on how to handle food safely to avoid Campylobacter contamination. These guidelines are often adopted by countries without a strong existing food safety infrastructure.

Local Regulations

Different states or countries may have their own additional guidelines and regulations aimed at controlling Campylobacter.

Industry Standards

Many food producers and suppliers have implemented Hazard Analysis and Critical Control Points (HACCP) systems to identify and control food safety hazards, including Campylobacter.

Consumer Labels

In some regions, labels like “Free from Campylobacter” are emerging, although the effectiveness of such labels is still a subject of study.