U.S. Food Safety: Foodborne Illnesses a Menu for Disaster

TUESDAY Jan. 15, 2008 -- Foodborne illness can strike at any time and be caused by any number of different pathogens. Here is a rundown of the most common bacterial offenders, and what you can do to protect yourself:

E. COLI 0157:H7

There are many strains of the bacteria known as Escherichia coli, or E. coli. Most are harmless, four or five can cause disease, and one, in particular, can be fatal.

E. Coli 0157:H7 has been implicated in several deadly outbreaks. The U.S. Centers for Disease Control and Prevention estimates that 73,000 infections and 61 deaths are attributable to E. coli 0157:H7 each year in the United States, not as much as other pathogens, but infinitely more high-profile.

"E. coli 0157:H7 is the media star, but it's actually not that many cases per year," said Helene Andrews-Polymenis, an assistant professor of microbial and molecular pathogenesis at Texas A&M Health Science Center College of Medicine.

Most human infections result from eating uncooked ground beef (cattle carry the pathogen in their intestines without getting sick). It can also be acquired from consuming contaminated dairy products, vegetables, unpasteurized juice, person-to-person contact, and swimming in or drinking water contaminated with sewage. The bacteria also lives in deer, goats and sheep and is a permanent resident of many petting zoos.

Infection with E. coli 0157:H7 can result in bloody diarrhea lasting two to eight days and sometimes even kidney failure. There are ways to prevent transmission of the bacteria, namely good food hygiene.

"There's always going to be a small risk, but practicing good food hygiene is your best defense," said Andrews-Polymenis.

SALMONELLA

Salmonella, another bacteria, can cause bloody diarrhea in humans. Some 40,000 cases of salmonellosis are reported in the United States each year, although the CDC estimates that, because milder cases are not diagnosed or reported, the actual number of infections may be 30 or more times greater. Approximately 600 people die each year after being infected.

The risk of infection is greater in the summer than winter, and children, the elderly and immuno-compromised individuals are most at risk for serious complications.

Like E. coli, people become infected by eating contaminated foods, usually ground beef, eggs, improperly pasteurized dairy products, undercooked pork and, increasingly, poultry products.

"We're seeing salmonella increasing in broiler chickens," said Dr. Robert Tauxe, the CDC's deputy director of the division of foodborne bacterial and mycotic disease.

Prevention methods are similar to those for E. coli, with the added caution not to eat raw eggs or anything containing raw eggs (even cookie dough) and to make sure all meat is cooked thoroughly. Breast-feeding infants can also prevent infection.

BOTULISM

Botulism is a disease caused by the bacterium Clostridium botulinum. The organism thrives in environments which lack oxygen, such as improperly canned goods, and produces a nerve toxin that can cause paralysis, including respiratory paralysis.

"It can be very, very dangerous," said Andrews-Polymenis. Often, botulism is found in home-canned foods with low acid content, such as asparagus, green beans, beets and corn, the CDC states.

Only about 25 cases of foodborne botulism are reported in the United States each year, but it's important that strict hygienic procedures be followed when canning at home. "If their canned food doesn't reach the proper heat or pressurization, then they're in danger," Andrews-Polymenis said.

Also, avoid giving raw honey to infants under the age of 1 as this can be a source of infection.

CAMPYLOBACTER

Campylobacter is one of the most common bacterial causes of diarrheal illness in the United States. More than 1 million people in the United States, or 0.5 percent of the population, are thought to be infected each year.

Again, the organism can cause diarrhea (including bloody diarrhea), cramping, abdominal pain and fever as well as nausea and vomiting. An estimated 100 people die each year, and others may develop arthritis or Guillain-Barre syndrome, an autoimmune disease which can lead to paralysis.

Campylobacter tends to strike in single, sporadic cases rather than large outbreaks. Most cases are associated with handling raw poultry or eating raw or undercooked poultry meat. Some 80 percent to 100 percent of chickens in the United States are carriers of this bacterium.

"There's nothing glamorous or high-tech about preventing these things," said Andrews-Polymenis. "It's all about good preventive maintenance."

LISTERIA

The incidence of Listeria infection, caused by eating food contaminated with the bacterium Listeria monocytogenes, is on the wane, said Tauxe.

Pregnant women, newborns and adults with compromised immune system are more vulnerable to this infection, characterized by fever, muscle aches and sometimes nausea or diarrhea. The infection can spread to the nervous system, resulting in headache, confusion, loss of balance or convulsions.

Some 2,500 people in the United States become ill each year with listeriosis, and about 500 die.

Listeria is usually killed by cooking and pasteurization but can be present in certain ready-to-eat foods such as hot dogs and deli meats.

VIBRIO VULNIFICUS

Infection with this bacterium, which is in the same family as the bugs that cause cholera, usually comes from eating contaminated seafood. Infection can cause vomiting, diarrhea and abdominal pain in healthy people. In immuno-compromised people, it can infect the bloodstream, resulting in septic shock. About half of the people who develop a bloodstream infection will die. From 1988 to 1995, there were 300 reported cases of infection from the Gulf Coast states, where most of the cases occur. Infection can be prevented by avoiding raw oysters or other raw shellfish, and avoiding cross-contamination of cooked seafood and other foods with raw seafood and juices from raw seafood.

OTHER OFFENDERS

Shigella is a bacteria found naturally in the intestinal tracts of humans and other primates. But people who eat food or drink water contaminated by Shigella can become ill with shigellosis. Food contaminated with Shigella usually comes from water polluted by human sewage or if handled by a person infected with Shigella or by cross-contamination.

Hepatitis A is a virus that causes illness characterized by sudden onset of fever, malaise, nausea, anorexia, and abdominal discomfort, followed in several days by jaundice. Cold cuts and sandwiches, fruits and fruit juices, milk and milk products, vegetables, salads, shellfish, and iced drinks are commonly implicated in outbreaks, according to the U.S. Food and Drug Administration. Water, shellfish, and salads are the most frequent sources. Infected workers in food processing plants and restaurants are a common source of the food contamination as well.

Norwalk virus is a virus that can cause viral gastroenteritis, acute nonbacterial gastroenteritis, food poisoning, and food infection and is transmitted mostly by contaminated water, sometimes by contaminated food. Shellfish, particularly raw clams and oysters, and salad ingredients, are the foods most often implicated in Norwalk outbreaks.

Posted: January 2008


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