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Food Poison Journal Food Poisoning Outbreaks and Litigation: Surveillance and Analysis

Shiga Toxin-Producing Escherichia coli (STEC) Cases in Central Missouri

Screen Shot 2012-04-14 at 7.05.59 PM.pngOn April 5, 2012, the Missouri Department of Health and Senior Services (DHSS) issued a Health Advisory entitled “Shiga Toxin-Producing Escherichia coli (STEC) Cases in Central Missouri” (http://health.mo.gov/emergencies/ert/alertsadvisories/pdf/advisory4512.pdf). This Health Update provides additional information on the situation.

DHSS is continuing to investigate an increase in cases of Shiga toxin-producing Escherichia coli (STEC) in Central Missouri during late March and early April, 2012. Thirteen cases of E. coli O157:H7 have been identified with onset of illness during this time period. Seven of the thirteen cases have matching pulsed-field gel electrophoresis (PFGE) patterns; three cases have pending PFGE results, which are expected next week.

Of the seven cases with matching PFGE patterns, five have reported consumption of raw dairy products from the same farm. In addition, one of the cases for whom PFGE results are pending also reported raw dairy consumption from the same farm. One of the cases a two-year old child reportedly developed hemolytic uremic syndrome (HUS), a severe, life- threatening condition that may result in permanent kidney damage in some of those who survive. It was previously reported that a seventeen month-old child also had HUS, but this case has been found to have a different PFGE pattern.

There are three additional symptomatic cases under investigation for whom laboratory results are pending, or not available.

The investigation is ongoing and the source of infection has not been confirmed. All potential sources of exposure are being considered, but, as stated above, it is known that six cases have consumed unpasteurized milk and/or raw milk products from the same farm before onset of their illness. Missouri law specifically allows a farmer to sell raw milk or cream in Missouri, either at the farm where it originated, or after being delivered to the customer for that individual’s own use.

DHSS recommends that any person who has signs or symptoms of STEC infection should seek medical care. Health care providers should determine if testing for STEC infection is warranted.

Symptoms of STEC infection include severe stomach cramps, diarrhea (which is often bloody), and vomiting. If there is fever, it usually is not very high. Most patients’ symptoms improve within 5–7 days, but some patients go on to develop HUS, usually about a week after the diarrhea starts. The classic triad of findings in HUS is acute renal damage, microangiopathic hemolytic anemia, and thrombocytopenia.

Use of antibiotics in patients with suspected STEC infection is not recommended until complete diagnostic testing can be performed and STEC infection is ruled out. Some studies have shown that administering antibiotics to patients with STEC infection might increase their risk of developing HUS. However, clinical decision making must be tailored to each individual patient. There may be indications for antibiotics in patients with severe intestinal inflammation if perforation is of concern.

Guidelines to optimize detection and characterization of STEC infections include the following:

  • All stools submitted for testing from patients with acute community-acquired diarrhea should be cultured for STEC O157:H7. These stools should be simultaneously assayed for non-O157 STEC with a test that detects the Shiga toxins or the genes encoding these toxins.
  • Clinical laboratories should report and send E. coli O157:H7 isolates and Shiga toxin-positive samples to the Missouri State Public Health Laboratory (MSPHL) as soon as possible for additional characterization.
  • Specimens or enrichment broths in which Shiga toxin or STEC are detected, but from which O157:H7 STEC isolates are not recovered should be forwarded as soon as possible to MSPHL so that non- O157:H7 STEC can be isolated.
  • It is often difficult to isolate STEC in stool by the time a patient presents with HUS. Immunomagnetic separation (IMS) has been shown to increase recovery of STEC from HUS patients. For any patient with HUS without a culture-confirmed STEC infection, stool can be sent to the Centers for Disease Control and Prevention (CDC) through MSPHL. In addition, serum can be sent to CDC through MSPHL for serologic testing for common STEC serogroups.

The benefits of adhering to the recommended testing strategy include early diagnosis, improved patient outcome, and detection of all STEC serotypes.

DHSS reminds all residents:

  • Be aware of the risks of drinking raw (unpasteurized) milk or eating products made from raw milk.
  • Read the label. Make sure the milk you consume is pasteurized. If the word “pasteurized” does not appear on a product label, it may contain raw milk.

Medical providers are required to report, within one day, suspected or diagnosed cases of the following: Shiga toxin-producing E. coli (STEC), other Shiga toxin-positive organisms that have not been characterized, and all cases of post-diarrheal HUS. Reports can be made to the local public health agency, or to DHSS at 800/392- 0272 (24/7). In addition, laboratories are required to submit isolates or specimens positive for E. coli O157:H7, or for other Shiga toxin-positive organisms, to MSPHL for epidemiological and confirmation purposes.