You always hear about the dangers of eating undercooked chicken. In this lesson, we will examine Campylobacter, one common cause of bacterial food-borne infection acquired by eating raw poultry.
Food-borne Illness Pop Quiz
Welcome, class. Today, before I begin my lecture, I want to start with a pop quiz. Please close all books and notes. Ready? Which bacteria is responsible for the most cases of food-borne diarrhea in the United States? I’ll give you a minute to think.
All done?Ok. Pencils down. Let’s take a look at a few of your answers. Some of you probably guessed Salmonella. That’s a good guess, with the United States having about 42,000 cases a year, but there are more prevalent bacteria.
The majority of you probably guessed E. coli, that contaminant scourge of leafy greens and peanut butter that sickens about 265,000 Americans yearly. But, E. coli is also incorrect.The correct answer is the bacteria Campylobacter. Never heard of Campylobacter? Don’t feel so bad.
Most people have never heard of it, but there is a decent chance you or someone you know has had it. Every year, about 1.3 million people in the U.S.
will be infected by Campylobacter.
Campylobacter is a genus of gram-negative, motile, curved, rod-shaped bacteria that cause the most cases of bacterial food-borne infection in the United States. These bacteria have flagella that are used for motility and a gram-negative cell wall, characterized by a thin layer of peptidoglycan and an outer membrane.Campylobacter is the cause of a food-borne infection. Remember, a food-borne infection is an illness that results from consuming actively growing pathogens associated with food products.
The disease symptoms are a result of the growth and metabolism of Campylobacter inside your body.Three species of Campylobacter are important pathogens in humans or livestock. C. fetus is a major cause of abortions and infertility in sheep and cattle, but rarely, if ever, directly impacts human health. C. coli and C. jejuni are both confirmed human pathogens.
Most illnesses are caused by C. jejuni, so from this point forward, I will use the term Campylobacter to refer to C. jejuni.
Campylobacter is a normal member of the bacterial community in the intestines of poultry, like chickens and turkeys. The bacteria don’t cause disease in these birds, but they are the primary source of infection for humans. Most cases of Campylobacter food-borne infection result from eating raw or undercooked chicken, or using utensils contaminated by raw chicken. In fact, eating fewer than 500 Campylobacter cells is usually enough to cause disease.
Even one drop of raw chicken fluids can contain this many bacteria.Poultry is the most common source of infection, but you can catch Campylobacter from a few other sources. Campylobacter has been found in raw pork, clams and shellfish. Recently, more and more cases have been popping up that have been linked to consuming unpasteurized milk products.
It is also possible, although less likely, to catch Campylobacter from contact with contaminated pet feces. There have also been cases linked to contaminated non-chlorinated water. Fortunately, large, widespread outbreaks are rare.
The majority of cases are sporadic and isolated to only one or two people. Still, about 1.3 million people will get Campylobacter this year, and an estimated 76 of those people will die from the disease.
Symptoms of Campylobacter
So, what exactly does Campylobacter do to you?After taking two large bites from your chicken drumstick, you realize it’s not quite cooked all the way. You’ve just swallowed several hundred to several thousand tiny Campylobacter cells.
The bacteria are able to pass through your stomach, enter your small intestine and begin invading the cells that line the walls of the intestine.There, the Campylobacter begin to grow and divide. For two to seven days, you feel totally normal, but those bacterial cells are beginning to produce toxins and irritate and destroy your intestinal lining. The toxins and tissue irritation are causing inflammation as your immune system starts attacking the bacteria.
What happens next depends on how many Campylobacter you consumed and how healthy you and your immune system are. For most healthy people, symptoms will be mild and only consist of some watery diarrhea. If you consumed a lot of bacteria or your immune system is not quite up to par, the diarrhea can become more severe, profuse and bloody. You might also have a high fever (over 104 degrees Fahrenheit), headaches, malaise, nausea and cramps.The vast majority of infected people will develop some variation of these symptoms.
About 1 in 1,000 sufferers will develop something more severe, called Guillain-Barre syndrome. For reasons not fully understood, Campylobacter infection can trigger an autoimmune disease where the body’s own immune system starts attacking its nerves. What results is paralysis that can last for weeks.
Patients usually require intensive medical care, but most recover.
Diagnosis and Treatment
Diagnosing Campylobacter requires examining fecal samples for the bacteria. Some doctors might choose to grow the fecal bacteria in a lab in order to more positively identify Campylobacter infection. These bacteria have very specific growth requirements, including a high temperature of 42 degrees Celsius, a low oxygen concentration and a higher than normal carbon dioxide concentration.
Growth in these conditions can positively identify Campylobacter.Since the symptoms could be mistaken for any number of common diseases, and most often, the patient only experiences mild diarrhea, most cases of Campylobacter go undiagnosed and untreated. Fortunately, Campylobacter usually runs its course on its own without treatment in about a week.
For diagnosed cases, the antibiotic erythromycin is frequently given, but it seems to only reduce the length of time Campylobacter is shed in the patient’s feces, not how long the active infection lasts.I mentioned earlier that Campylobacter kills about 76 people a year. These deaths are almost always due to the patient having some additional medical condition that is made worse by the bacterial infection.
Almost any serious, chronic medical condition that taxes the body can make a person more susceptible to a fatal Campylobacter infection.Prevention of Campylobacter is as simple as it gets. You should always thoroughly cook your food, don’t reuse cooking implements for both raw and cooked food, always wash your hands after handling raw meat and practice proper personal hygiene.
Let’s review. Campylobacter is a genus of gram-negative, motile, curved, rod-shaped bacteria that cause the most cases of bacterial food-borne infection in the United States.
There are three major species of Campylobacter that impact humans, but C. jejuni is the most common cause of disease.People get Campylobacter by consuming food contaminated with the bacteria. The most common source is raw or undercooked poultry, like chicken. Once consumed, the bacteria invade the walls of the small intestine, causing irritation and inflammation. Most people will develop only mild diarrhea.
In more severe cases, high fevers, headaches and profuse, bloody diarrhea can occur.In very rare cases, Campylobacter infection can cause Guillain-Barre syndrome. This disease is characterized by the immune system attacking the body’s nerves, leading to paralysis. Most cases of Campylobacter run their course in about a week without treatment. The antibiotic erythromycin is often given to reduce the amount of bacteria shed in the feces, but it has little to no impact on the length of infection.
After you’ve completed this lesson, you will be able to:
- Identify the structure of Campylobacter
- Describe how humans can become infected with Campylobacter
- List the mild and more severe symptoms of Campylobacter
- Explain how Campylobacter is diagnosed and whether it can be treated