Reports of visits for influenza-like illness (ILI) to sentinel providers. This week, a total of 103 visits for ILI were reported by 10 providers. The median percent of ILI visits in Maryland was 1%. This is below the state baseline of 3.6%.

Sentinel providers are health care providers who report to us the proportion of patient visits for influenza like illness. Because of the great variability in reported ILI proportions among providers each week, the median ILI is used instead of the average. Half of the ILI reports were below the median and half were above.

If you are interested in becoming a sentinel provider, please feel free to contact us at flu@dhmh.state.md or by phone at 410-767-6700.

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Reports of rapid influenza tests from clinical laboratories. During week 16, a total of 734 rapid influenza tests were reported by 26 reporting clinical laboratories. Of these, 28 tests (4%) were positive. NOTE: We have added 10 new clinical labs to our network starting on week 6.

Because the sensitivity and specificity of rapid flu tests vary with the prevalence of influenza in the population*, rapid flu tests performed before the first DHMH lab-confirmed case are not counted as confirmed cases for the purpose of surveillance. Now that the DHMH laboratory has confirmed a case by reference methods, all rapid influenza tests will be counted as confirmed cases.

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Reports of reference testing on submitted specimens from the Public Health Laboratory. During week 16, a total of 10 specimens were submitted for testing at the DHMH laboratory. None of these specimens were positive. This season, a total of 828 specimens have been submitted for testing at the DHMH laboratory. Of these, 321 (39%) have been positive by PCR and/or viral culture.

For the purpose of influenza surveillance, cases are counted as “confirmed” when they are based on more reliable reference test methods (PCR or culture) performed by the DHMH lab, or are based on other techniques such as rapid test for the detection of influenza antigen AFTER the DHMH lab has confirmed its first case of the season.

This is done because the sensitivity and specificity of rapid flu tests vary with the prevalence of influenza in the population*, and are less reliable when prevalence is low.  This season, all positive clinical laboratory results from week 46 onward (4,983) are counted as confirmed cases, and of course, all of the positive DHMH lab results (321).

To date, the CDC laboratory has identified three as type A (H1N1) Brisbane-like, one as A (H3N2) Brisbane-like, and two as type B Florida-like. All three strains are components of this season’s influenza vaccine.  Two type A (H1N1) isolates were found to be resistant to Oseltamivir (Tamiflu ®) but sensitive to Adamantanes and Zanamivir. Interim guidelines on the use of antivirals for influenza can be found at http://tinyurl.com/cdcinterim.

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Reports of hospitalizations due to influenza. No information was submitted as of the time of publication of this report.

To date, there have been 454 (224, 49% adult, and 230, 51% pediatric) hospitalizations for influenza reported to DHMH.

The Emerging Infections Program collects information on a weekly basis from several hospitals in the Baltimore Metro Region on the number of hospitalizations associated with influenza.

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Reports from Maryland residents. A total of 542 participants signed up at www.tinyurl.com/flu-enroll by the end of week 16. Of the 542 residents who received the weekly survey, 259 (48%) responded to it. Among the respondents, 7 (3%) reported flu-like symptoms.
Because there is no baseline to compare these results, and the sample size is small (compared to the population), caution must be taken when interpreting the results.
We continue to recruit participants. Please enroll at the link above or pass on the link to anyone interested.

If you would like to participate in the resident flu tracking survey, please visit THIS SITE [https://www.surveymonkey.com/s.aspx?sm=eIGPl_2bIZTs3qV90lureTog_3d_3d] or email us at flu@dhmh.state.md.us.

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Click Here to Download This Week's Report in PDF Format
Or choose a report below to download and read (also PDF)

To Read the Weekly Flu Report from CDC, Please visit www.cdc.gov/flu/weekly