What is Biosurveillance?
Biosurveillance is the gathering and analyzing of data from many information sources in order to detect and manage a possible biological outbreak or other public health event, whether naturally occurring or deliberate.
Syndromic surveillance is one type of biosurveillance that provides public health officials with a timely system for detecting, understanding, and monitoring health threats. Syndromic surveillance can be used as an early warning system for respiratory viruses, environmental threats, emerging diseases, bioterrorism, and more. Syndromic surveillance relies on information about a person's signs and symptoms, before a confirmed diagnosis or lab test, which allows for earlier detection of potential public health events across a broad range of conditions.
What makes syndromic surveillance distinct from other public health surveillance systems is that it relies on the receipt of near real time data from various sources (e.g. hospital emergency departments, urgent care centers, poison control centers) for earlier detection of disease outbreaks and conditions of interest compared to traditional surveillance systems.
The epidemiologists in the Office of Preparedness and Response (OP&R) utilize the Maryland Electronic Surveillance System for the Early Notification of Community-based Epidemics, otherwise known as ESSENCE, to conduct syndromic surveillance.
What Type of Data is Received in ESSENCE?
The MD ESSENCE system currently receives the following data:
- Emergency Department (ED) visits
- Urgent Care (UC) visits
- Emergency Medical Services (EMS) calls
- Poison Control calls
- School absenteeism
- Over the counter pharmacy sales of cold medications, allergy medications, and thermometers
What Can Be Done with ESSENCE Data?
MD ESSENCE users can monitor overall trends by categorizing emergency department/urgent care (ED/UC) visits based on chief complaints (short descriptions of signs and/or symptoms that led patients to the ED/UC) and discharge diagnoses. Queries (pre-developed and customizable) can be used on all data sources to monitor for any disease or hazard. MD ESSENCE users review disease activity for evidence of unusual cases or clusters; investigate natural, intentional, or simulated outbreaks; and respond to natural disasters, weather-related threats, and any other public health emergencies.
Examples of syndromic surveillance in action include:
- Monitoring for early signs of outbreaks associated with large scale events, including special events in Washington, DC.
- Characterizing trends in non-fatal drug overdose in Maryland and its jurisdictions.
- Analyzing trends of respiratory illness (COVID, Influenza, and RSV) during the respiratory season.
Who Can Access the Maryland Syndromic Surveillance System?
Only Maryland Department of Health (MDH) and local health department (LHD) epidemiologists and communicable disease staff can access Maryland's syndromic surveillance system (MD ESSENCE). However, syndromic surveillance data for a variety of health conditions, including category A agents, various syndromes, heat and cold-related illness, naloxone administration and non-fatal drug overdoses are available publicly in the
MDH OP&R Syndromic Surveillance weekly reports and
MDH dashboards.
Strengths and Limitations of Syndromic Surveillance:
Strengths:
- Data is gathered in near real time which allows for the earlier detection of unusual patterns of illness.
- Provides a routine baseline level so that it is easier to detect and characterize when something abnormal is happening.
- Can potentially identify illness clusters early, allowing public health agencies to mobilize a rapid response, thereby reducing morbidity and mortality.
- Can be analyzed in combination with traditional public health surveillance data for an enhanced and robust understanding of the burden of illness in a community.
Limitations:
- Data is pre-confirmed and only reflects patterns in suspected, rather than clinically confirmed, illness.
- Data may not be representative of the whole population. For example, data would not include those people who go to a private physician.
- Chief complaints are commonly recorded in a free text field, which may include misspellings or abbreviations. The chief complaint may also lack context; for example, a chief complaint may state “sick” or “feels bad” without mentioning symptoms such as fever or cough.
- Variability in chief complaint terms across health care facilities can make it difficult to measure the exact burden of illness in a community.
How Should MDH ESSENCE Data be Cited?
When using MDH ESSENCE data, please cite:
MD ESSENCE Data, Office of Preparedness and Response (OP&R), Maryland Department of Health.
If you have any questions about syndromic surveillance or the MD ESSENCE system, please contact us at
mdh.essence@maryland.gov.
