None — Foodborne Illness: Salmonella
The Centers for Disease Control and Prevention estimates, each year, about 9.4 million people get sick from contaminated food. About 55,961 of them are hospitalized and 1,351 die.
The USDA reports the leading cause of bacterial-related food illness in the U.S. is salmonella. About one million Americans get sick from salmonella annually, more than 19,000 are hospitalized and more than 370 people die. The annual cost of medical treatment for salmonella-related food illness is $365 million.
The Infection
Salmonella bacteria contamination can be acquired from two main sources – food and animals. The most common food sources are eggs and poultry. Reptiles (turtles, lizards and snakes), frogs and birds are the most common animal sources. People can acquire the salmonella bacteria if they eat contaminated food, touch a contaminated animal or have contact with contaminated animal droppings. The bacteria can also be spread from one person to another through improper hand washing after using the bathroom.
The incubation period for salmonella is one to three days. The symptoms typically include diarrhea, fever, stomach cramps and vomiting, and last from four to seven days. Not everyone gets sick from salmonella and some people have only very mild symptoms. Jeffrey Jahre, M.D., Chief of Infectious Diseases at St. Luke's Hospital in Bethlehem, PA, says infants, young children, pregnant women, the elderly and people with weakened immune systems are most at risk for developing severe complications from salmonella.
Reducing Risk At the Source
The CDC estimates that eggs and poultry account for nearly half (47 percent) of all foods associated with salmonella outbreaks. Salmonella bacteria in the housing environment can contaminate the outer shell of the eggs or get inside through pores in the egg's shell. More importantly, chickens can carry the bacteria in their digestive tract. The birds don't get sick from the bacteria, so there are no signs of infection. But the salmonella bacteria can enter a hen's eggs before the shell forms, contaminating the egg from the inside.
To reduce the risk for widespread infections, the Food and Drug Administration now requires egg producers with 50,000 or more birds to test the eggs and animal environment for salmonella contamination. These regulations took effect on July 10, 2010. Producers of smaller flocks will be required to adhere to the guidelines by July 9, 2012.
A New Test
Shelley Rankin, Ph.D., Microbiologist with the University of Pennsylvania School of Veterinary Medicine in Kennett Square, PA says the traditional test for salmonella bacteria in poultry houses and eggs is very effective, but takes about 10 days to get results. By that time, if the tests have come back positive for salmonella, the eggs have typically reached consumers. Producers must then issue a recall.
A new test, called The TaqMan® Salmonella Enteritidis Detection Kit, can be used to test both the hen house environment and egg. More importantly, the results are available within 48 hours. The hope is, with the faster turn around time, contaminated eggs can be kept out of the food supply, greatly reducing the risk for illness among consumers.
Rankin explains the environmental part of the test involves dragging a prepared gauze pad through the animal manure (because the bacteria will be excreted in the bird feces). If the manure tests positive for the bacteria, the eggs are also tested. That requires taking a sampling of at least 20 disinfected eggs, cracking the shells, mixing the contents to break the yolks and testing the solution. If salmonella is found in the eggs, they are sent to a pasteurization plant. That process heats the eggs and kills the bacteria, making the eggs safe to eat.
Consumers can also take steps to reduce the risk of getting sick from salmonella in eggs. The CDC recommends keeping eggs refrigerated at 40 degrees F or lower, discarding dirty or cracked eggs, thoroughly washing all utensils and dishes that have contact with raw eggs and cooking eggs thoroughly. People who eat foods made with raw or undercooked eggs should only use pasteurized eggs.
Research compiled and edited by Barbara J. Fister