Influenza Surveillance in Maryland:
2008-2009 Season
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Surveillance of influenza in Maryland is coordinated by the Division of Communicable Disease Surveillance in the Office of Epidemiology and Disease Control Programs (EDCP). The influenza surveillance system has several components to it:
- Reports of visits for influenza-like illness (ILI) to sentinel providers. Influenza-like illness is defined by the Centers for Disease Control and Prevention (CDC) as a fever ≥100°F and a cough and/or a sore throat (in the absence of a known cause other than influenza). Sentinel providers are health care providers in Maryland who volunteer each year to provide information on how many patients are visiting their practices with ILI. The providers submit their information every week on-line or via fax. If you are a health care provider, and you would be interested in participating, we would be honored to have you on our team. Please use the contact information at the end of this web page to contact the influenza surveillance coordinator. A more thorough description of the sentinel provider program can be downloaded from here (requires a PDF viewer).
- Reports of rapid influenza tests from clinical laboratories. Clinical laboratories (those who perform lab tests on patients for diagnostic purposes) volunteer each year to provide information on how many rapid flu tests they perform each week and the number of those that are positive. Reporting is done on-line or by fax. If you are the manager or medical director of a clinical laboratory in Maryland, please contact the influenza surveillance coordinator for information on how to participate in this component of influenza surveillance.
- Reports of reference testing on submitted specimens from the Public Health Laboratory. The public health lab reports the number of samples submitted for influenza testing and the results of these tests. A subset of these samples are forwarded for further testing at CDC, where specialized testing can identify the specific strains of influenza being seen in Maryland
- Reports of outbreaks of influenza in schools and other institutions. The Division of Outbreak Investigations receives reports from local health department of outbreaks of respiratory disease in places like schools, hospitals, long-term care facilities, and other such institutions. In fact, outbreak reporting is required in Maryland. An outbreak of respiratory disease is confirmed as an influenza outbreak once a laboratory confirms the presence of influenza.
- Reports of hospitalizations due to influenza. The Emerging Infections Program receives reports on the number of patients admitted with influenza from several hospitals in Maryland. These reports are broken down by age into “child” (<18 years of age) and “adult” (18 years of age and older) categories to give a better perspective of who is being hospitalized with influenza.
- Reports from Maryland residents. This season, for the first time, Maryland residents can contribute to influenza surveillance in Maryland. Residents will initially sign up to participate by giving DHMH some basic information (month and year of birth, county and zip code of residence, and a valid e-mail address). Then, every week, the enrolled residents will receive a weekly reminder to report to DHMH on any symptoms (fever, cough, and/or sore throat) they may have had the previous week. To enroll in the program, please visit http://www.tinyurl.com/flu-enroll.
The information collected via these six components helps determine when influenza begins to circulate in Maryland, what communities are affected by it, how well the seasonal vaccine matches the circulating strains of influenza, and the incidence of ILI in the community. While rapid influenza tests are less sensitive and specific (accurate) when compared to reference tests like polymerase chain reaction (PCR) or viral culture, they do serve as a good indicator in helping to distinguish influenza from other respiratory disease. Also, hospitalization data may give an indication of what groups are most severely impacted by influenza.
Using data from the surveillance system, along with other information like vaccination rates in school children and healthcare workers, it is the aim of EDCP to know more about where influenza is active in Maryland so actions can be taken to reduce its spread. Each week during the influenza season (October - May), EDCP publishes a report of the influenza activity in the State. The report is circulated to health care providers and health authorities all around Maryland. Please click on the links above or below to visit the flu report page.
It is important to remember that all the information submitted is voluntary, that the information only answers questions about the location and activity of the influenza virus, and that the information is not representative of the general population in Maryland.
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