Safety Reference Guides

Salmonellae: A Preventable Illness

Summertime... picnics, backyard barbecues, camping and the like can create a breeding ground for food borne illnesses. In recent years, several outbreaks of salmonella have occurred and we would like to help prevent another outbreak, because once is truly enough.

In September and October of 1994, Minnesota, South Dakota and Wisconsin had drastic increases in the number of cases due to Salmonella Enteritidis (SE). These three states during this two-month period had a total of 142 cases reported. The same three states, for all of 1993, had only 303 cases of SE reported. This number may not seem like a lot, but when you consider the symptoms, those infected most likely think one case is too many. Is it possible to get rid of Salmonella completely? No. Salmonellae are found everywhere in nature and is a pathogen to both animals and humans. It is estimated there are two million people in the United States infected each year and it is a common infection throughout other parts of the world.

Common symptoms of SE include diarrhea, abdominal cramps, and fever characterized most of the cases SE reported. These symptoms can lead to a more serious infection of the whole body, known as enteric fever. Fortunately in most cases Salmonella's infection is a self-limiting form of food poisoning or gastroententeritis. When infected with Salmonellae, you will experience symptoms within hours or at the most two days. Symptoms include, in addition to the ones listed above, nausea, vomiting, myalgia (muscle pain) and headache. The onset of symptoms, or incubation period, depends on the amount of bacteria consumed with symptoms lasting anywhere from 2 to 7 days. The cardinal symptom of Salmonellae is diarrhea.

Eggs remain one of the most likely culprits associated with salmonellosis in the United States and several European countries. Can you look at an egg and say, "Aha, this one has Salmonella enteritidis", again the answer is "no". Salmonellae can infect normal-appearing eggs and if eggs are undercooked or eaten raw, then the bacterium can cause illness. During the 1980's, illness related to contaminated eggs occurred most frequently in the northeastern United States, but now illness caused by SE is increasing in other parts of the country as well.

The question that needs to be answered is "How do I prevent or minimize the chance of infection"? Some points to remember are: Make sure to keep eggs refrigerated and discard broken or cracked eggs. Always wash your hands and cooking utensils well with soap and water after contact with raw eggs. Any eggs that are cooked should be eaten promptly and are not to be kept warm for more than two hours. The potato salad at a summer picnic needs to be kept refrigerated or cooled when no longer being eaten. As noted above, you should avoid eating raw eggs including foods such as home-made ice cream, eggnog, Hollandaise sauce or Caesar salad dressing.

Even with what is known about Salmonellae illness, people continue to consume raw foods. Case in point. In 1994 in dodge County, 17 individuals were treated for acute gastrointestinal illness characterized by diarrhea and abdominal cramps. Of these 17 people, 14 admitted to having eaten raw ground beef that was either plain or seasoned with onions and an herb mix during the 72 hours before illness onset. Wisconsin seems to be a hot bed of activity when it comes to gastroenteritis. In June of 2--1, two outbreaks were reported to the Wisconsin Division of Public Health. Both of these outbreaks occurred at summer camps in northern Wisconsin. Although Salmonellae was not to blame in these instances, it was shown that bacteria, which infect the stomach, could be spread by other means than food. The camps, which serve boys aged 10-18 years, are located 80 miles apart. The campus did not share any food preparation facilities or personnel. The only obvious link was that they are run by the same national organization.

Upon investigation it was shown that both sets of campers were infected with "Norwalk-like virus" (NLV), another form of gastroenteritis. Much like the illness associated with Salmonella, NLV has the symptoms of fatigue, nausea, vomiting and diarrhea. Some individuals only had symptoms for a little as two days, once again very similar to Salmonella. As the investigation proceeded, it became evident that the "rustic setting" and lack of hand washing facilities enable the person to person spread of the virus.

During inspection of the camps no major problems with food storage and handling were found. The toilet facilities though were very "rustic" in nature. Campers had to use pit-toilets when nature called, and the toilet area lacked soap but did have cool water for hand washing. The investigation made it clear that certain factors are essential to stopping this type of gastroenteritis. Those are cleansing of environmental surfaces and the availability and use of hand washing facilities.

Technology can only take us so far. We know that eating raw eggs, ground beef or other meats can cause us to become ill. We know that refrigeration can decreased the chance of food poisoning. However we continue undercook meat and leave potato salad out on a hot day. With a little common sense, foresight and willingness to use technology we can protect ourselves from contracting the Salmonellae bacteria.

References:

CDC. Emerging Infectious Diseases Outbreak of Salmonella enteritidis Associated with Nationally Distributed Ice Cream Products - Minnesota, South Dakota, and Wisconsin, 1994 MMWR 43(40); 740-41.

CDC. Division of Bacterial Mycotic Diseases. Disease Information Salmonella enteritidis.

CDC. Outbreak of Salmonella Serotype Typhimurium Infection Associated with Eating Raw Ground Beef - Wisconsin, 1994 MMWR 1995; 44(49); 905-9.

CDC. Norwalk-Like Virus Outbreaks at Two Summer Camps - Wisconsin, June 2001. MMWR 2001; 50(30); 642.3.