From the TN Department of Health
Summary: The Tennessee Department of Health (TDH) is issuing this Health Alert Network (HAN) Health Advisory to
1) alert clinicians regarding an increase in Shiga-toxin producing E. coli (STEC) and
2) request reporting of cases to TDH. TDH is investigating increased reports of illness caused by STEC. Many of these illnesses have been linked to contact with farm animals at petting zoos and other agritourism businesses.
Background: Exposures that may result in STEC illness include contact with cattle or other ruminant animals such as sheep and goats, consumption of contaminated food, consumption of unpasteurized (raw) milk, consumption of water that has not been disinfected, or contact with the feces of infected people. Illness can begin between 1-10 days after exposure, and most people recover within 5-7 days with mild infection.
Patients suspected of having STEC should not be placed on antibiotics as some studies have shown that it can increase the risk of the patient developing Hemolytic Uremic Syndrome (HUS), a life-threatening complication that occurs in about 5-10% of all STEC cases. Common STEC symptoms include watery or bloody diarrhea, severe abdominal cramps, nausea, vomiting, and possibly fever. STEC infections can become severe, especially in young children.
If you suspect someone is ill with STEC, consider animal exposures in patients’ histories and order laboratory testing where appropriate. If the patient is positive for STEC, please follow the TDH reportable disease guidance located below.
The symptoms of STEC infections vary for each person but often include severe stomach cramps, diarrhea (often bloody), and vomiting. If there is fever, it usually is not very high (less than 101˚F/less than 38.5˚C). Most people get better within 5–7 days. Some infections are very mild, but others are severe or even life-threatening.
Around 5–10% of those who are diagnosed with STEC infection develop a potentially life-threatening complication known as hemolytic uremic syndrome (HUS). Clues that a person is developing HUS include decreased frequency of urination, feeling very tired, and losing pink color in cheeks and inside the lower eyelids. Persons with HUS should be hospitalized because their kidneys may stop working and they may develop other serious problems. Most persons with HUS recover within a few weeks, but some suffer permanent damage or die.
The time between ingesting the STEC bacteria and feeling sick is called the “incubation period.” The incubation period is usually 3-4 days after the exposure, but may be as short as 1 day or as long as 10 days. The symptoms often begin slowly with mild belly pain or non-bloody diarrhea that worsens over several days. HUS, if it occurs, develops an average 7 days after the first symptoms, when the diarrhea is improving.
STEC live in the guts of ruminant animals, including cattle, goats, sheep, deer, and elk. The major source for human illnesses is cattle. STEC that cause human illness generally do not make animals sick. Other kinds of animals, including pigs and birds, sometimes pick up STEC from the environment and may spread it.
Infections start when you swallow STEC—in other words, when you get tiny (usually invisible) amounts of human or animal feces in your mouth. Unfortunately, this happens more often than we would like to think about. Exposures that result in illness include consumption of contaminated food, consumption of unpasteurized (raw) milk, consumption of water that has not been disinfected, contact with cattle, or contact with the feces of infected people. Some foods are considered to carry such a high risk of infection with E. coli O157 or another germ that health officials recommend that people avoid them completely. These foods include unpasteurized (raw) milk, unpasteurized apple cider, and soft cheeses made from raw milk. Sometimes the contact is pretty obvious (working with cows at a dairy or changing diapers, for example), but sometimes it is not (like eating an undercooked hamburger or a contaminated piece of lettuce). People have gotten infected by swallowing lake water while swimming, touching the environment in petting zoos and other animal exhibits, and by eating food prepared by people who did not wash their hands well after using the toilet. Almost everyone has some risk of infection.
Non-specific supportive therapy, including hydration, is important. Antibiotics should not be used to treat this infection. There is no evidence that treatment with antibiotics is helpful, and taking antibiotics may increase the risk of HUS. Antidiarrheal agents like Imodium® may also increase that risk.
HOW CAN STEC INFECTIONS BE PREVENTED?
WASH YOUR HANDS thoroughly after using the bathroom or changing diapers and before preparing or eating food. WASH YOUR HANDS after contact with animals or their environments (at farms, petting zoos, fairs, even your own backyard).
COOK meats thoroughly. Ground beef and meat that has been needle-tenderized should be cooked to a temperature of at least 160°F/70˚C. It’s best to use a thermometer, as color is not a very reliable indicator of “doneness.”
AVOID raw milk, unpasteurized dairy products, and unpasteurized juices (like fresh apple cider).
AVOID swallowing water when swimming or playing in lakes, ponds, streams, swimming pools, and backyard “kiddie” pools.
PREVENT cross contamination in food preparation areas by thoroughly washing hands, counters, cutting boards, and utensils after they touch raw meat. To learn more about how to protect yourself from E. coli, see CDC’s feature, E. coli Infection.