MASSACHUSETTS DEPARTMENT OF PUBLIC HEALTH GUIDE TO SURVEILLANCE, REPORTING, AND CONTROL
Shiga toxin-producing Escherichia coli

Section 1 
ABOUT THE DISEASE

A. Etiologic Agent

Shiga toxin-producing E. coli (STEC) are a group of bacteria that express potent emteric toxins called Shiga toxin 1 (Stx1) and Shiga toxin 2 (Stx2). Stx1 is essentially identical to the toxin produced by Shigella dysenteriae. These bacteria are also called verocytotoxic E. coli (VTEC) or enterohemorrhagic E. coli (EHEC).  The toxins are released when bacteria reproduce in the gastrointestinal tract and then destroy intestinal epithelial cells. The most common STEC identified in North America is E. coli O157:H7, although other STEC strains have been implicated in a number of large outbreaks, most notably a large outbreak in Europe in 2011 caused by E. coli O104:H4. 

B. Clinical Description

Infection with STEC can result in a wide spectrum of clinical manifestations. An individual may be asymptomatic, may have mild non-bloody diarrhea, or may have grossly bloody diarrhea.  Abdominal cramps, nausea, and vomiting may also be present. Fever is usually absent. The average incubation period is 3-4 days, with a range of 1-10 days. Most people get better within 5-7 days. In some cases, however, the patient may progress to hemolytic uremic syndrome (HUS) or thrombotic thrombocytopenic purpura (TTP), which are blood clotting disorders that can result in renal failure and death. 

C. Vectors and Reservoirs

While cattle appear to be the most significant reservoir for STEC, these organisms live in the guts of other ruminant animals, including goats, sheep, deer, and elk. Humans can serve as a reservoir for person-to-person spread. 

D. Modes of Transmission

These bacteria must be ingested to cause infection. This can happen when people eat or drink something contaminated with STEC that is not properly cooked or pasteurized or through direct contact with animals and their environment. STEC can also be spread from person-to-person if someone who is infected does not thoroughly wash his or her hands with soap or water before preparing food for others. Spreading STEC this way is more common in families and day care centers than in schools and restaurants.  

E. Incubation Period

An average of 3-4 days, with a range of 1-10 days. 

F. Period of Communicability or Infectious Period

People are infectious for as long as they excrete STEC in their stool. The duration of excretion is typically one week or less in adults but up to three weeks in one third of children. The infectious dose for STEC is very low.  

G. Epidemiology

Over 250,000 STEC infectious occur each year in the United States. Approximately one third are caused by E. coli O157:H7; non-O157 STEC cause the rest.  However, these are just estimates, as not all STEC infections are diagnosed. Many infected people do not seek medical care; many of those who do seek care do not provide a stool specimen for testing, and some laboratories may not test for non-O157 STEC. 

H. Bioterrorist Potential

This organism is a category B agent. Category B agents are considered second highest priority agents. These are organisms that are moderately easy to disseminate; that result in moderate morbidity and low mortality rates; and that require enhanced diagnostic capacity and disease surveillance.
 
Section 2
REPORTING CRITERIA AND LABORATORY TESTING

A. What to Report to the Massachusetts Department of Public Health (MDPH)

•	The isolation of Shiga toxin-producing E. coli from a clinical specimen;

•	Isolation of E. coli O157 from a clinical specimen;

•	Identification of Shiga toxin or Shiga toxin genes in a clinical specimen using a culture independent diagnostic test (CIDT);

•	Identification of an elevated antibody titer to a known Shiga toxin-producing E. coli serotype;

•	Detection of E. coli O157:H7 or STEC/EHEC in a clinical specimen using a CIDT;

•	The onset of acute renal insufficiency within three weeks of acute bloody or non-bloody diarrhea;

•	Diagnosis of post-diarrheal hemolytic uremic syndrome (HUS) or thrombotic thrombotopenic purpura (TTP).
Note: See Section 3C for information on how to report a case.
B. Laboratory Testing Services Available

The Massachusetts State Public Health Laboratory (MA SPHL) will test stool specimens for the presence of Shiga toxin-producing organisms and will also perform confirmatory testing and speciation (and serotyping, when possible) on isolates from clinical specimens submitted by other laboratories. In addition, the MA SPHL requests submission of all isolates of Shiga toxin-producing organisms for typing for disease surveillance purposes. 

For more information about testing, call the MA SPHL Clinical Microbiology Laboratory at (617) 983-6607.
In addition, the MA SPHL Food Microbiology Laboratory, at (617) 983-6616, will test implicated food items from case clusters or outbreaks. See Section 4D for more information.

Section 3
REPORTING RESPONSIBILITIES AND CASE INVESTIGATION

A. Purpose of Surveillance and Reporting

•	To identify transmission sources of public health concern (e.g., a restaurant, a widely distributed food product, or a contaminated public water supply), and to stop transmission from such sources.
•	To identify whether the case may be a source of infection for other persons (e.g. a diapered child, daycare attendee, or food handler), and if so, to prevent further transmission. 

B. Laboratory and Health Care Provider Reporting Requirements

STEC is reportable to the local board of health (LBOH). The MDPH requests that health care providers immediately report to the LBOH in the community where the case is diagnosed, all confirmed or suspected cases of STEC, as defined by the reporting criteria in Section 2A.

Laboratories performing examinations on any specimens derived from Massachusetts residents that yield evidence of STEC infection shall report such evidence of infection directly to the MDPH within 24 hours. 

C. Local Board of Health (LBOH) Reporting and Follow-Up Responsibilities

Reporting Requirements

MDPH regulations (105 CMR 300.000) stipulate that STEC is reportable to the LBOH and that each LBOH must report any confirmed case of STEC or suspected case of STEC, as defined by the reporting criteria in Section 2A. Cases should be reported to the MDPH Bureau of Infectious Disease and Laboratory Sciences (BIDLS), Office of Integrated Surveillance and Informatics Services (ISIS) using MAVEN. 
The most up-to-date reporting requirements can be found at:
http://www.mass.gov/eohhs/gov/departments/dph/programs/id/epidemiology/rdiq/reporting-diseases-and-surveillance-information.html

Case Investigation

It is the responsibility of the LBOH to complete questions in each of the question packages in MAVEN by interviewing the case and others who may be able to provide information.  Please try to complete the case investigation and follow-up within 24 hours.

Calling the provider
If the case was hospitalized (i.e. reporting facility is a hospital), call infection control at the named hospital. A list of infection preventionists can be found in the help section of MAVEN. If the case was seen at a clinician’s office, ask to speak to a nurse working with the ordering provider. You should confirm that the patient was notified of the diagnosis and let them know that you will be calling the case for further information.

Calling the case or parent/guardian of the case 
Before calling the case, review the disease fact sheet by clicking on the Help Button located in MAVEN and all the information in this chapter. The call may take 10-15 minutes, so in order to maximize the chance of getting the information needed, it might be good to note the potential length of the call with your contact, and offer the opportunity to call back when it is more convenient. Asking questions about how the case or child is feeling may get the case or parent/guardian talking. If you are unable to answer a question they have, don’t hesitate to call the Division of Epidemiology and Immunization at 617-983-6800 for assistance, and call the case back with the answer later. People are often more than willing to talk about their illness, and they may be very happy to speak with someone who can answer their questions. 
Using MAVEN
Administrative Question Package 
Monitor your “Online LBOH Notification for Immediate Disease” workflow in MAVEN for any new cases of STEC. An MDPH Epi-of- the-Day (EOD) will review all new cases and request immediate follow up for STEC.  Once a new event appears in this workflow, open the Administrative Question Package (QP) and under the “Local Health and Investigation” section, answer the first question “Step 1 - LBOH acknowledged” by selecting “Yes”.   The “LBOH acknowledged date” will then auto populate to the current day.  Completing this first step will move the event out of this workflow and into your “Online LBOH notified but Case Report Forms (CRF) are pending” workflow. Note the date you started your investigation by answering “Step 2 – Investigation started” as “Yes” and then note the date where shown.  Record your name, agency, and phone numbers where shown in “Step 3 - LBOH/Agency Investigator.” 

Demographic Question Package
Record all demographic and employment information.  It is particularly important to complete the Race/Ethnicity and Occupation questions.

Clinical Question Package
Complete the “Diagnosis/Clinical Information” section, providing the diagnosis date, symptom information and date of symptom onset and other medical information.  

Risk Exposure/Control & Prevention Question Package
Complete all questions to evaluate high-risk exposures the case had during the seven days prior to becoming ill. The risk question package includes a brief food history that focuses on high-risk foods associated with STEC infection.
Completing your Investigation
1.	If you were able to complete a case investigation and follow-up is complete, mark “Step 4 – Case Report Form Completed” as “Yes” and then choose Local Board of Health (LBOH) –Ready for MDPH review for the Completed by variable. 
2.	If you have made several attempts to obtain case information but have been unsuccessful (e.g., the case or health care provider does not return your calls or respond to a letter, or the case refuses to divulge information or is too ill to be interviewed), please complete “Step 4 - Case Report Form Completed” as “No” and then choose a primary reason why the case investigation was not completed from the choices provided in the primary reason answer variable list.
3.	If you are not online for MAVEN you may submit a paper case report form. After completing the form, attach laboratory report(s) and fax or mail (in an envelope marked “Confidential”) to ISIS. The confidential fax number is (617) 983-6813. Call ISIS at (617) 983-6801 to obtain a copy of the case report form and to confirm receipt of your fax.

The mailing address is:
MDPH, Office of Integrated Surveillance and Informatics Services (ISIS)
305 South Street, 5th Floor
Jamaica Plain, MA 02130
Fax: (617) 983-6813

Section 4
CONTROLLING FURTHER SPREAD

A. Isolation and Quarantine Requirements (105 CMR 300.200)

Foodhandlers with STEC must be excluded from work.

Minimum Period of Isolation of Patient 

After diarrhea has resolved, food handlers may only return to work after submitting two negative stool specimens produced at least 24 hours apart. If the case was treated with an antimicrobial, the stool specimen shall not be collected until at least 48 hours after cessation of therapy. 

Minimum Period of Quarantine of Contacts

Contacts with diarrhea who are food handlers, shall be considered the same as a case and shall be handled in the same fashion. In outbreak circumstances, asymptomatic contacts who are food handlers shall be required to produce two negative stool specimens, taken 24 hours apart. Otherwise, no restrictions. 

Note: A food handler is any person directly preparing or handling food. This could include the food handling facility owner, individual having supervisory or management duties, person on the payroll, family member, volunteer, person performing work under contractual agreement, or any other person working in a food handling facility.  This also includes any person handling clean dishes or utensils. Any person who dispenses medications by hand, assists in feeding, or provides mouth care shall be considered food handlers for the purpose of these regulations. In health care facilities, this includes those who set up trays for patients to eat, feed or assist patients in eating, give oral medications or give mouth/denture care. In day care facilities, schools and community residential programs, this includes those who prepare food for clients to eat, feed or assist clients in eating, or give oral medications. This term does not include individuals in private homes preparing or serving food for individual family consumption. 

B. Protection of Contacts of a Case

None

C. Managing Special Situations
Daycare
Since STEC may be transmitted from person-to-person through fecal-oral transmission, it is important to follow-up carefully on cases of STEC in a daycare setting. General recommendations include:

•	Children with STEC infection who have diarrhea should be excluded and not permitted to re-enter until their diarrhea is resolved and two stool specimens (taken at least 24 hours apart and 48 hours after antimicrobial therapy has been discontinued) are negative for STEC. 

•	Children with STEC infection who have no diarrhea should still be excluded and not permitted to re-enter the daycare until two stool specimens (taken at least 24 hours apart and 48 hours after antimicrobial therapy has been discontinued) are negative for STEC. 

•	Staff with STEC infection who have diarrhea should be excluded until their diarrhea is resolved.

•	Since most staff in childcare programs are considered food handlers, those with STEC in their stool can remain on site, if they do not have diarrhea, but must not prepare food or feed children until they have two negative stool specimens, taken at least 24 hours apart and collected at least 48 hours after completion of antibiotic therapy, if antibiotics are given (per 105 CMR 300.200).

•	Testing should be performed on the stools of any symptomatic contacts in the daycare.

•	In outbreak situations, testing asymptomatic contacts should be considered as well as closing to new admissions. 
School
Since STEC may be transmitted from person-to-person through fecal-oral transmission, it is important to follow-up carefully on cases of STEC in a school setting. General recommendations include:

•	Students or staff with STEC infection who have diarrhea should be excluded until their diarrhea is resolved.

•	Students or staff with STEC who do not handle food, have no diarrhea or mild diarrhea, and are not otherwise sick may remain in school if special precautions are taken.

•	Students or staff who meet the definition of a food handler, as described in Section 4A, and have STEC infection (symptomatic or not) must not prepare food until their diarrhea is resolved and they have two negative stool specimens, taken at least 24 hours apart and collected at least 48 hours after completion of antibiotic therapy, if antibiotics are given (per 105 CMR 300.200). 

Refer to Chapter 8 of the MDPH Comprehensive School Health Manual for complete guidelines on handling diseases spread through the intestinal tract. https://massclearinghouse.ehs.state.ma.us/SCH/SH3001R.html 
Community Residential Programs
Actions taken in response to a case of STEC in a community residential program will depend on the type of program and the level of functioning of the residents.

In long-term care facilities, residents with STEC should be placed on standard precautions until their symptoms subside and they test negative for STEC. Refer to the MDPH Division of Epidemiology and Immunization’s Long Term Care Facilities Infection Control Guidelines (Gastrointestinal Disease) at http://www.mass.gov/eohhs/gov/departments/dph/programs/id/epidemiology/providers/infection-control.html for further information. 

Staff members who give direct patient care (e.g., feed patients, give mouth or denture care, or give medications) are considered food handlers and are subject to food handler restrictions under 105 CMR 300.200. (See Section 4A for more information.) In addition, staff members with STEC infection who are not food handlers should not work until their diarrhea is resolved.

In residential facilities for the developmentally disabled, staff and clients with STEC must refrain from handling or preparing food for residents until their symptoms have subsided and they have two negative stool specimens, taken at least 24 hours apart and collected at least 48 hours after completion of antibiotic therapy, if antibiotics are given.

Reported Incidence Is Higher Than Usual/Outbreak Suspected

If the number of reported cases of STEC in your city/town is higher than usual or if you suspect an outbreak, investigate to determine the source of infection and the mode of transmission. A common vehicle, such as a food item, should be sought, and applicable preventive or control measures should be instituted. Consult with the epidemiologists at the MDPH Division of Epidemiology and Immunization at (617) 983-6800. They can help determine a course of action to prevent further cases and can perform surveillance for cases across town lines, which would otherwise be difficult to identify at the local level.

Clusters

The Centers for Disease Control and Prevention (CDC) is working to identify multi-state clusters of STEC infection. Cases, which may be part of such clusters, will require additional follow-up and data collection by LBOH. Advice on follow-up activities for such situations will be provided by the MDPH Division of Epidemiology and Immunization staff on a case-by-case basis. 

D. Preventive Measures

Environmental Measures

Implicated food items must be removed from the environment. A decision about testing implicated food items can be made in consultation with the MDPH Food Protection Program (FPP) or the MDPH Division of Epidemiology and Immunization. The FPP can help coordinate pickup and testing of food samples. If a commercial product is suspected, the FPP will coordinate follow-up with relevant outside agencies. To contact the FPP, please call (617) 983-6712.

Note: The role of the FPP is to establish policy and to provide technical assistance with the investigation, such as interpreting the Massachusetts Food Code, conducting a Hazard Analysis and Critical Control Point (HACCP) risk assessment, initiating enforcement actions, and collecting food samples.

The general policy of the MA SPHL is to test only food samples implicated in suspected outbreaks, not in single cases (except when botulism is suspected). The LBOH may suggest that the holders of food implicated in single case incidents either locate a private laboratory that will test food or store the food in their freezer for a period of time, in case additional reports are received. However, a single, confirmed case with leftover food consumed within the incubation period may be considered for testing under particular circumstances.

Personal Preventive Measures/Education

To avoid future exposure, advise individuals to:

•	Always wash their hands thoroughly with soap and water before eating or preparing food, after using the toilet, after changing diapers, and after contact with animals, especially cattle.

•	Wash their own hands as well as the child’s hands in a sanitary manner after changing diapers. 

•	Wash their hands thoroughly and frequently when ill with diarrhea or when caring for someone with diarrhea. Hands should be scrubbed for at least 15-20 seconds after cleaning the bathroom, after using the toilet or helping someone use the toilet, after changing diapers, before handling food, and before eating. 

•	Keep food that will be eaten raw, such as vegetables, from becoming contaminated by animal-derived food products. Wash fruits and vegetables thoroughly, especially those that will not be cooked. 

•	If served an undercooked hamburger or other undercooked ground beef product in a restaurant, send it back for further cooking. 

•	Cook all ground beef and hamburgers to an internal temperature of 1600 F.

•	Drink only pasteurized milk, juice, or cider.

An STEC Public Health Fact Sheet and a Shigella Public Health Fact Sheet are available at http://www.mass.gov/eohhs/gov/departments/dph/programs/id/epidemiology/factsheets.html 

ADDITIONAL INFORMATION

The formal CDC surveillance case definition for STEC is the same as the criteria outlined in Section 2A of this chapter. (The CDC and the MDPH use the CDC case definitions to maintain uniform standards for national reporting.) When reporting to the MDPH, always use the criteria outlined in Section 2A.

Note: The most up-to-date CDC case definitions are available on the CDC website at      https://wwwn.cdc.gov/nndss/case-definitions.html  

REFERENCES

American Academy of Pediatrics. In: Pickering L.K., ed. Red Book: 2015 Report of the Committee on Infectious Diseases, 30th Edition. Elk Grove Village, IL, American Academy of Pediatrics; 2015: 343-347.

CDC. Case Definitions for National Notifiable Disease Surveillance System, 2017. .

Heymann, D., ed. Control of Communicable Diseases Manual, 20th Edition. Washington, DC, American Public Health Association, 2015. 158-163

MDPH. Regulation 105 CMR 300.000: Reportable Diseases, Surveillance, and Isolation and Quarantine Requirements. MDPH, Promulgated January 27, 2017

“Escherichia coli:.” Centers for Disease Control and Prevention. https://www.cdc.gov/ecoli/general/index.html last reviewed December 2014