Campylobacter jejuni are bacteria that can cause campylobacteriosis: a foodborne illness common worldwide that causes stomach upset with nausea, diarrhea and abdominal pain. While many cases are mild, severe reactions and complications do occur.

What is Campylobacter jejuni infection?

Campylobacteriosis is a common foodborne illness. It is a leading bacterial cause of gastroenteritis (stomach upset with nausea and diarrhea) around the world. While most infections cause mild illness, a small percentage may lead to Guillain-Barré syndrome (GBS), a severe disorder in which the body’s own immune system attacks the nerves and causes muscle weakness.

Causes of Infection

Campylobacter jejuni are bacteria that lives in the intestinal tracts of animals like chickens. They spread to humans through:

• Consumption of undercooked or raw poultry
• Unpasteurized dairy products
• Contaminated water sources
• Direct contact with infected animals, including livestock and pets

Who is at risk for Campylobacteria jejuni infection?

While Campylobacteria infection can affect individuals of all ages, certain groups are more vulnerable:

• Young children under 4 years old
• People between 15 and 44 years old
• Immunocompromised individuals and the elderly

Symptoms of Campylobacter Jejuni Infection

Common signs of infection include:

• Diarrhea, which may be bloody
• Abdominal pain and cramping
• Fever and nausea
• Vomiting (less common)

Symptoms typically develop about three days after exposure, but can range from one to seven days.

Campylobacter Jejuni Diagnosis

A Campylobacter infection is confirmed by testing the stool of someone who is suspected to be infected, using one of the following diagnostic tests:

• Stool culture – Culturing the bacteria under specific conditions.
• Enzyme immunoassay (EIA) – Detects the body’s immune response (antibodies) to Campylobacter.
• Polymerase chain reaction (PCR) – Identifies Campylobacter DNA.

Treatment Options

• Mild cases: Most infections resolve on their own with proper hydration and electrolyte replenishment.
• Severe cases and high-risk patients: Antibiotics, particularly macrolides like azithromycin, may be necessary for those with severe symptoms, bloody diarrhea or weakened immune systems. Fluoroquinolones are an alternative option. In Southeast Asia, there are high rates of resistance to fluroquinolones, so azithromycin is preferred. Treatment is typically three days.
• Avoidance of antimotility agents: Antimotility agents are drugs, such as loperamide, that relieve diarrhea by slowing bowel movements. These drugs can prolong the infection and should generally be avoided.

How do you prevent Campylobacter jejuni infection?

To reduce the risk of Campylobacter infection, follow these precautions:

• Thoroughly cook poultry to eliminate bacteria.
• Avoid consuming unpasteurized dairy products.
• Wash hands properly after handling raw meat.
• Drink only clean, safe water.
• Maintain good kitchen hygiene to prevent cross-contamination.

Potential Complications

Although most cases are mild, severe complications can occur:

• Guillain-Barré syndrome (GBS): Around 1 in 1,000–5,000 individuals infected with Campylobacter develop GBS within one to three weeks.
• Miller Fisher syndrome (variant of GBS): Causes eye muscle paralysis and coordination issues.
• Reactive arthritis: Some individuals experience joint inflammation following infection.
• Irritable bowel syndrome and post-infectious colitis: Persistent diarrhea, bloating and abdominal pain.
• Bacteremia: In rare cases, the infection can spread to the bloodstream.

Guillain-Barré Syndrome and Campylobacter Jejuni: Molecular Mimicry

After being infected with Campylobacter jejuni, the immune system responds by creating antibodies against the invading bacteria. Some variants of this bacteria also have a chameleon-like property: the surface, the lipooligosaccharides, closely resembles a structure found on nerve cells (the gangliosides). As a result, the immune system mistakenly attacks the nerves, leading to Guillain-Barré syndrome (GBS). This confusion occurs through a process called molecular mimicry, in which the bacteria imitate the human body’s own cells. Campylobacter jejuni infections are responsible for approximately 30% of all GBS cases, including both acute motor axonal neuropathy (AMAN) and acute inflammatory demyelinating polyneuropathy (AIDP) subtypes.

Many people who develop GBS after a C. jejuni infection never experience noticeable symptoms of food poisoning. Even without obvious illness, the immune system can still misfire and damage the nerves.

Common Clinical Symptoms of Guillain-Barré Syndrome:

Clinical symptoms usually appear within three days to six weeks of the infection.

• Tingling and numbness: A prickly or “pins and needles” feeling (paranesthesia) often starts in the fingers and toes before any muscle weakness appears.
• Muscle weakness: The weakness usually starts in the legs and spreads upward (ascending muscle paralysis) to the arms. It happens on both sides of the body at the same time.
• Loss of reflexes: Doctors may check reflexes (like the knee-jerk reflex), and in most people with GBS, these reflexes are missing.
• Pain: Some people feel pain in their limbs or back.
• Breathing problems: In more severe cases, GBS can make it hard to breathe.
• Facial and speech issues: In rare cases, individuals may experience trouble moving their face, swallowing or speaking.
• Progression: Symptoms get worse over a period of 12 hours to four weeks, then usually stop getting worse and stay stable before improving (clinical plateau).

When to See a Doctor

Seek medical attention if you experience:

• Severe or prolonged diarrhea
• High fever and dehydration symptoms
• Bloody stool
• Severe or persistent abdominal pain