Influenza Surveillance Summary: Denton County Hospitals and Providers 17.51% 15.95% 10.94% 7.41% 9.01% 8.08%

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1 DENTON COUNTY PUBLIC HEALTH INFLUENZA SURVEILLANCE PROGRAM CDC WEEK 13, WEEK ENDING APRIL 7, 2017 Epidemiologic Overview Denton County Low influenza activity was reported in Denton County for week positive influenza tests (10 Flu A and 6 Flu B) and 1 hospitalizations were reported by Denton County sentinel providers for week 13. Syndromic surveillance for influenza-like illness (ILI) in Denton County decreased for week 13 when compared to the previous week. Texas Geographic influenza activity in Texas remained at regional for week 13. The percentage of visits for ILI as reported by ILINet providers decreased to 4.6% in week 13 compared to the previous week. The percentage of specimens testing positive for influenza in Texas decreased to 12.6% in week 13 compared to the previous week. US The proportion of outpatient visits for influenza-like illness (ILI) was 2.9%, which is above the national baseline of 2.2%. Six of ten regions reported ILI at or above their region-specific baseline levels. Nine states experienced high ILI activity; five states experienced moderate ILI activity; nine states experienced low ILI activity; and 27 states experienced minimal ILI activity. The geographic spread of influenza in 24 states was reported as widespread; 19 states reported regional activity; five states reported local activity; and two states reported sporadic activity. The percentage of specimens testing positive for influenza in the US was 18.4% and a decrease compared to the previous week The proportion of deaths attributed to pneumonia and influenza (P&I) from the National Center for Health Statistics Mortality Surveillance System for week 11 was 7.3%. This percentage is below the epidemic threshold of 7.4% for week 11. Figure 1. Influenza Surveillance Summary: Denton County Hospitals and Providers Week Ending 2/25/2017 3/4/2017 3/11/2017 3/18/2017 3/25/2017 4/1/ /08/16- CDC Week Present Influenza Tests Performed Weekly Total Positive Influenza Tests Percent Positive Influenza Tests* 17.51% 15.95% 10.94% 7.41% 9.01% 8.08% Positive A Influenza Positive B Influenza Non-differentiated Influenza Influenza Hospitalizations Influenza-associated Pediatric Deaths Influenza-associated Adult Deaths * Percent positive tests only includes positive tests from providers reporting number of tests performed weekly

2 Page 2 of 8 Figure 2. Influenza Positive Tests and Percent Positive, Denton County Hospitals and Providers Flu A Flu B % Positive Positive Influenza Tests Percent Positive October November December January February March April 0 Figure 3. Influenza Positive Tests Reported to CDC by U.S. Public Health Laboratories, National Summary, Season

3 Page 3 of 8 Figure 4. Influenza Positive Tests Reported to CDC by U.S. Clinical Laboratories, National Summary, Season Figure 5. U.S. Virologic Surveillance, Week 13 and Cumulative Data since October 2, 2016

4 Page 4 of 8 Figure 6. ESSENCE Syndromic Surveillance for Influenza-like Illness: Denton County October 1, April 1, 2017 Figure 7. ESSENCE Syndromic Surveillance for Influenza-like Illness: Denton County October 1, 2015 April 1, 2017 Data obtained from hospitals participating in the Electronic Surveillance System for the Early Notification of Community-based Epidemics (ESSENCE) from October 2015 through the present. Depicted are the numbers of persons presenting to Emergency Departments according to patient location (Denton region) with self-reported chief complaints of influenza-like illness.

5 Page 5 of 8 Figure 8. Antigenic Characterization of Influenza Isolates, Since October 1, Influenza A (H1N1) 216 of 217 (99.5%) A/California/7/2009-like Influenza A (H3N2) Influenza B (Yamagata Lineage) Influenza B (Victoria Lineage) 575 of 589 (97.6%) A/Hong Kong/4801/2014- like 242 of 242 (100%) B/Phuket/3073/2013-like* 185 of 201 (92%) B/Brisbane/60/2008-like Influenza Vaccine Composition, Northern Hemisphere: o A/California/7/2009 (H1N1)-like virus o A/Hong Kong/4801/2014-like (H3N2)-like virus o B/Phuket/3073/2013-like virus* o B/Brisbane/60/2008-like virus * Northern Hemisphere quadrivalent influenza vaccine influenza B component Figure 9. Neuraminidase Inhibitor Resistance Testing Results on Samples Collected Since October 1, 2016

6 Page 6 of 8 Figure 10. Pneumonia and Influenza Mortality from the National Center for Health Statistics Mortality Surveillance System: Week ending March 18, 2017 Figure 11. FluSurv-NET Laboratory-Confirmed Influenza Hospitalizations by Age Group, Preliminary data as of March 31, 2017 The FluSurv-NET covers more than 70 counties in the 10 Emerging Infections Program (EIP) states (CA, CO, CT, GA, MD, MN, NM, NY, OR, TN) and three additional states (MI, OH and UT). FluView: Influenza Hospitalization Surveillance Network, Centers for Disease Control and Prevention. Accessed on 4/7/17.

7 Page 7 of 8 Figure 12. FluSurv-NET Laboratory-Confirmed Influenza Hospitalizations: Selected Underlying Conditions Season, Preliminary data as of March 25, 2017 The FluSurv-NET covers more than 70 counties in the 10 Emerging Infections Program (EIP) states (CA, CO, CT, GA, MD, MN, NM, NY, OR, TN) and three additional states (MI, OH and UT). FluView: Influenza Hospitalization Surveillance Network, Centers for Disease Control and Prevention. Accessed on 4/7/17. Figure 13. Weekly Influenza Activity Estimates Reported by State and Territorial Epidemiologists: Week April 1, 2017 Week 13

8 Page 8 of 8 Figure 14. Percentage of Respiratory Specimens that Tested Positive for Influenza: WHO, based on data up to March 19, 2017 Please send inquiries to Briar Deen, MPH Epidemiology Investigator Denton County Public Health at Briar.Deen@dentoncounty.com