West Nile Virus Surveillance and Epidemiology United States and Tropical Americas

1. West Nile Virus Surveillance and EpidemiologyUnited States and Tropical Americas J. Erin Staples, MD, PhD Arboviral Diseases Branch Division of Vector-Borne Infectious Diseases Centers for Disease Control and Prevention Fort Collins, CO

2. Overview Surveillance ArboNET Changes over time Epidemiology Incidence and location of WNV in U.S. Demographics Modes of transmission WNV in Tropical Americas Conclusions Future Direction Ongoing assessments Areas for further investigation

3. West Nile Virus Surveillance Formation of ArboNET

4. Response to West Nile Virus in 1999 All lab testing done at CDC Ecologic data collected by state and city health depts Data kept in spreadsheets Identified a need to enhance arboviral disease surveillance on a national level

5. Electronic surveillance system developed by CDC in response to WNV introduction Unique system collecting both human and non-human data Dynamic system which can be adapted

6. Objectives Monitor incidence as well as geographic and temporal spread of WNV and other arboviruses Disseminate information to public health officials, government officials, and the public Promotes prevention and control Stimulates research Evaluate the use of funds and need for additional resources

7. Ecologic data Veterinary cases (e.g., horses) Dead birds Mosquitoes Sentinel (e.g., chicken, horses) Human data Disease cases (e.g. neuroinvasive, fever) Presumptive viremic donors (PVDs) Arboviral Surveillance

8. Adaptation of ArboNET andArboviral Surveillance

9. Adaptation of ArboNET andArboviral Surveillance

10. Adaptation of ArboNET andArboviral Surveillance

11. Adaptation of ArboNET andArboviral Surveillance

12. Adaptation of ArboNET andArboviral Surveillance

13. Adaptation of ArboNET andArboviral Surveillance

14. Changes in WNV Laboratory testing WNV testing initially performed at CDC then transferred to state health depts Commercial assays licensed and used by increasing numbers of commercial and public health labs Less control over confirmation and QA/QC of WNV testing

15. Dissemination of Data Weekly updates posted online and EpiX Weekly updates of USGS maps with number of cases by state and county Regular MMWR updates Annual MMWR summary Peer-reviewed journal articles

17. Percent of all U.S. counties reporting non-human WNV surveillance data to ArboNET by type and year, 2002-2007

18. Numbers of dead birds and mosquitoes tested among counties reporting these data every year, 2002-2007

19. West Nile Virus Epidemiology United States

21. Number of states and counties reporting WNV activity per year, U.S., 1999-2008

22. Counties reporting WNV activity in humans and non-human species, U.S., 2002-2007

23. Non-human Epidemiology United States

24. Culex species Cx. quinquefasciatus Cx. pipiens Cx. tarsalis Cx. restuans Cx. salinarius Aedes species Ae. albopictus Ae. vexans

25. Equine WNV Disease Cases Reported,U.S., 1999-2008

26. Human Epidemiology United States

27. Reported WNV Human Disease Cases U.S., 1999-2008

28. Number WNV Human Disease Cases by Clinical Syndrome, U.S., 1999-2008

29. Estimated Number of WNV Infections and Fever Cases, U.S., 1999-2008 Diagnoses and reporting of WNV fever varies by year and location WNND most reliable indicator of WNV disease activity in humans Based on serosurveys 140 WNV infections per 1 WNND case 28 WNV fever cases per 1 WNND case

30. Incidence of WNND by Year, U.S., 1999-2008

31. Average Annual Incidence of WNND,by County, U.S., 2004-2007

32. Percent of WNND Cases by Month of Onset, U.S., 1999-2007

33. Demographic and Clinical Information WNV Human Disease Cases United States

34. Average Annual Incidence of WNND Cases by Sex and Race, U.S., 1999-2007

35. Average Annual Incidence of WNND by Age Group, U.S., 1999-2007

36. Cumulative Incidence of WNND cases by Age Group and Sex, U.S., 1999-2007

37. Incidence of WNND for Children and Adults, by year, U.S., 1999-2007

38. WNND Clinical Syndrome by Age Cohort,U.S., 1999-2007

39. WNND Severity and Outcome by Age Cohort,U.S., 1999-2007

40. Transmission of WNV Without Mosquitoes As more cases were identified, we started to detect cases being transmitted without mosq, which lead to addition of other variable in ArboNET For example, in 2002, blood transfusion was identified as a mechanism of transmission for WNV infection.As more cases were identified, we started to detect cases being transmitted without mosq, which lead to addition of other variable in ArboNET For example, in 2002, blood transfusion was identified as a mechanism of transmission for WNV infection.

41. WNV Transmission via Blood Transfusions 23 transfusion-associated WNV infections identified in 2002 Beginning 2003, all blood donations screened using NAT on either pooled or individual samples PVDs reported to state health departments which report cases to ArboNET … so all blood donations are screened for WNV.… so all blood donations are screened for WNV.

42. Each year hundreds of WNV PVDs are identified as shows in this slide. Overall, the number of PVDs detected each year parallels the number of WNND cases as shown by the relatively stable ratio of PVDs to WNND cases overtime. Each year hundreds of WNV PVDs are identified as shows in this slide. Overall, the number of PVDs detected each year parallels the number of WNND cases as shown by the relatively stable ratio of PVDs to WNND cases overtime.

43. WNV Transfusion-associated Disease 32 transfusion-associated WNV infections reported in literature Last documented cases in 2006 CDC investigates multiple cases of possible WNV transfusion-associated disease annually Predominantly immunocompromised individuals Unable to substantiate due to lack of retention samples from the original blood unit

44. WNV Transmission by Solid Organ Transplantation Cases of WNV infection from organ transplantation first recognized in 2002 Seven cases of transplant-associated WNV infections documented in the literature 4 cases in 2002, 3 cases in 2005 CDC investigates multiple cases of possible WNV transplant-associated disease annually Most recent case from LA in September 2008 No current guidelines for routine screening of organ donors

45. Other Modes of Transmission Documented in utero transmission of WNV One cases with definitive evidence and three with supportive evidence Breast-feeding associated WNV case

46. Number of Neuroinvasive Disease Cases for by Arboviral Disease, U.S., 1999-2007

47. Non-human and Human Epidemiology Tropical Americas

48. West Nile Virus in Tropical Americas

49. Conclusions - 1 ArboNET developed in response to WNV introduction Non-human activity has helped define the geographic location and spread of WNV WNV human disease may have reached endemic level in the U.S. WNND affects all age groups; causing more deaths and encephalitis in individuals > 50 years

50. Conclusions - 2 WNV has become the most common cause of arboviral neuroinvasive disease in the U.S. WNV activity has also been detected at a lower level in Tropical Americas

51. Future Plans

52. Ongoing Assessments Evaluation of ArboNET and arboviral surveillance Re-evaluation of WNV/Arbovirus case definitions Exploration of the ability of non-human WNV data to predict human WNV disease Determination of risk factors for severe WNV disease Capturing of extended clinical information Economic analysis of WNV vaccine

53. Areas for Further Investigation Assess differences in WNV disease transmission between high and low risk areas Investigate difference in the spread and disease prevalence between U.S./Canada and Latin America/Europe Explore ability of PVDs to predict human WNND Develop guidelines for screening of organ donors for WNV Evaluate the development and use of WNV vaccine for humans

54. Jennifer Lehman Nicole Lindsey Marc Fischer Kristen Janusz Nick Komar Emily Zielinski-Gutierrez Robert Lanciotti John Roehrig