MASSACHUSETTS DEPARTMENT OF PUBLIC HEALTH GUIDE TO SURVEILLANCE, REPORTING, AND CONTROL
Listeriosis

Section 1 
ABOUT THE DISEASE

A. Etiologic Agent

Listeriosis is caused by the bacterium Listeria monocytogenes. 

B. Clinical Description

Manifestations of listeriosis are host-dependent. In older adults and persons with immunocompromising conditions, septicemia and meningitis are the most common clinical presentations. Pregnant women may experience fever and other non-specific symptoms, such as fatigue and aches, potentially followed by fetal loss or bacteremia and meningitis in their newborns. 
 
C. Vectors and Reservoirs

Reservoirs for L. monocytogenes are soil, water, silage, and mammals.

D. Modes of Transmission

Listeria are usually acquired through ingestion of contaminated foods and less commonly through contact with infected animals. Unlike most other foodborne pathogens, Listeria can grow in contaminated refrigerated foods. Rare nursery outbreaks have been reported attributed to contaminated equipment or materials. L. monocytogenes infection may be acquired by the fetus in utero or during delivery. 

E. Incubation Period

A range of 3–70 days has been reported, with a median incubation period of about 21 days.

F. Period of Communicability or Infectious Period

L. monocytogenes may be shed for months in the stool of infected persons. Secondary infections among household contacts have not been identified. Following delivery, mothers of infected newborns may shed L. monocytogenes for 7–10 days in vaginal secretions or in urine. 

G. Epidemiology

Listeria are widely distributed in nature. Most cases of human listeriosis are sporadic, but foodborne and healthcare-associated outbreaks have been documented. Foods particularly associated with infection include unpasteurized milk and milk products (including soft cheeses), processed meats (hot dogs, deli meats, and salads), and contaminated vegetables. Newborns, the elderly, immunocompromised persons, and pregnant women are at greater risk for infection. About 30% of diagnosed cases occur in infants within the first three weeks of life. 

H. Bioterrorist Potential

This pathogen is not considered to be of risk for use in bioterrorism.

Section 2
REPORTING CRITERIA AND LABORATORY TESTING

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

•	The isolation of L. monocytogenes from a normally sterile site (e.g., blood or cerebrospinal fluid [CSF], or less commonly, joint, pleural, or pericardial fluid).

•	In the setting of miscarriage or stillbirth, isolation of L. monocytogenes from placental or fetal tissue.
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) performs confirmatory testing of L. monocytogenes isolates from normally sterile sites, as well as additional testing for disease surveillance purposes to identify genetically related cases that may suggest a common exposure. 

For more information about testing, call the MA SPHL 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 contaminated food product, a restaurant, a contaminated public water supply), and to stop transmission from such sources.

B. Laboratory and Health Care Provider Reporting Requirements

Listeriosis 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 listeriosis, as defined by the reporting criteria in Section 2A.

Laboratories performing examinations on any specimens derived from Massachusetts residents that yield evidence of Listeria 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 listeriosis is reportable to the LBOH and that each LBOH must report any confirmed case of listeriosis or suspected case of listeriosis, 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. 

Calling the provider
Listeriosis cases are usually very ill and hospitalized.  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. In addition to completing the MAVEN question packages, all listeriosis cases should be interviewed with the CDC’s Listeria Initiative Questionnaire, which may take 45 minutes or longer to complete.  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. If the case is too ill to respond to questions, ask to speak with a family member or other proxy to obtain food history information. Asking questions about how the case or child is feeling may get the case or parent 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 listeriosis. An MDPH Epi-of- the-Day (EOD) will review all new cases and request immediate follow up for listeriosis.  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
Accurately record all risk questions in MAVEN.  Review the CDC Listeria Initiative Questionnaire and document in the MAVEN question package any consumption of high risk animal products.  Foods often associated with Listeria include fresh soft cheeses, ice cream and other frozen foods, deli meats, hot dogs, and unpasteurized or inadequately pasteurized milk.  

CDC Listeria Initiative Questionnaire
All listeriosis cases need to be interviewed using CDC’s Listeria Initiative Questionnaire which collects a detailed history on foods consumed during the month prior to illness onset.  This questionnaire is not currently in MAVEN and will be attached to the MAVEN event by the EOD assigned to the case.  This questionnaire should be completed with the case or a family member of the case as soon as possible. The completed questionnaire should be scanned and attached to the MAVEN event or faxed to MDPH.
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)

None

Minimum Period of Isolation of Patient 

None

Minimum Period of Quarantine of Contacts

None  

B. Protection of Contacts of a Case

None

C. Managing Special Situations

Reported Incidence Is Higher Than Usual/Outbreak Suspected

If the number of reported cases of listeriosis 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.

Multi-state Clusters

The Centers for Disease Control and Prevention (CDC) is working to identify multi-state clusters of Listeria 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 consumption. 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 infection with Listeria:

•	Thoroughly cook all meat, including hot dogs, and thoroughly reheat food until steaming hot. 

•	Wash all raw vegetables. Eat cut melon right away or refrigerate it.

•	Avoid raw (unpasteurized) milk or foods made from raw milk.

•	Avoid contamination of cooked or ready-to-eat foods by raw meats or unwashed vegetables. For example, do not let juice from hot dogs and lunch meats get on other foods, utensils, or food preparation surfaces.

•	Wash hands, knives, and cutting boards after handling uncooked foods.

In addition, individuals at high risk for developing listeriosis (e.g., pregnant women or immunocompromised persons, including individuals taking steroids) should:

•	Avoid soft cheeses unless the label says it is made with pasteurized milk (hard cheeses, processed cheeses, cream cheese, cottage cheese, and yogurt need not be avoided).

•	Cook hot dogs and other ready-to-eat meats (such as sliced deli meat, prepackaged cold cuts, or fermented or dry sausages) until they are steaming hot.

•	Only eat sprouts if they are thoroughly cooked.

•	Do not eat refrigerated pate or meat spreads from a deli or meat counter or from the refrigerated section of a store.

•	Do not eat refrigerated smoked seafood unless it is canned or shelf-stable or it is in a cooked dish. 

A Listeriosis Public Health Fact Sheet is available at http://www.mass.gov/eohhs/gov/departments/dph/programs/id/epidemiology/factsheets.html 

ADDITIONAL INFORMATION

The formal CDC surveillance case definition for listeriosis 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. [Listeriosis] 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: 513-516.

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. 354-357

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

“Listeriosis:.” Centers for Disease Control and Prevention. http://www.cdc.gov/listeria/index.html last reviewed December 2016