1. Public Health Response to Zika Virus in California
James Watt, MD, MPH
Chief, Division of Communicable Disease Control
Presentation to the
California Blood Bank Society
May 6, 2017

2. Disclosure
I have no financial relationships with commercial interests to disclose.

3. Outline Zika epidemiology in California and Mexico
Public health activities to control Zika
Forecast for 2017

4. Zika Cases in California, 2015-17
534 travel-associated Zika cases reported as of April 21, 2017
7 sexually-transmitted cases
111 cases pregnant at the time of diagnosis
334 residents of counties with invasive Aedes
368 potentially viremic while in California

5. Zika Risk in California
Essential ingredients of transmission present
Viremic persons
Vector mosquitoes
Risk of sustained transmission very low
Environmental and housing conditions limit human/mosquito interaction compared to tropical countries
No local transmission of dengue or chikungunya viruses
Limited local transmission possible

6. Travel-Associated Zika Cases in California* 18 87
117 33 13 9 3 6 7 27 35 16 4 2 1 41 5
No reported cases
1-10 reported cases
11-20 reported cases
21+ reported cases
County with Aedes mosquitoes
Updated
*as of April 21, 2017

7. For 2016, 453 Zika cases were reported in California
For 2016, 453 Zika cases were reported in California. The epi cure here illustrates 2016 Zika cases by week or onset or specimen collection for asymptomatic cases. The peak onset for Zika cases in 2016 was weeks 27-34, or July 4th through August 22th. This also correlates with peak travel seasons in late June and early August. The average number of cases reported by epi week decreased to 5 cases a week for the month of December compared to 27 a week for July and August.

8. Exposure Countries for Travel-Associated Zika Cases in California, 2015-2017*
Country
Number of Cases
Mexico
190
Nicaragua 61
Guatemala 49
El Salvador 36
Dominican Republic 26
Costa Rica 25
Puerto Rico
Honduras
Jamaica 14
Colombia 10
updated
*as of April 21, 2017

9. Zika Virus Disease Cases in Mexico, by Month

10. Zika Virus Disease Cases Mexico, April 2016

11. Zika Virus Disease Cases, Mexico, March 2017

12. Travel to California from Zika-Affected Countries--2015
Air
~4.5 million
Final destination airports:
Los Angeles 54%, San Francisco 20%, San Diego 6%
Highest volume occurred in July and August
66.8% of flights originated in Mexico
Sea
1.2 million
Arrival ports:
Long Beach 65%, Los Angeles 20%, San Diego 8%
Land
55 million
California county of entry
San Diego: ~70%, Imperial ~30%
All of the Zika cases reported in California and most of the US are travel related. In million travelers flew into California from Zika affected areas, with 67% of those flights originating in Mexico million travelers entered California by ship and 55 million by a land vehicle. This large number of travelers from Zika affected areas increases the risk of local transmission in California and elsewhere in the US.

13. Public Health Response to Zika in California Is a Collaboration
61 local health departments
77 local vector control agencies
CDPH
CDC
Blood centers
Professional partners

14. National Zika Response Domains
Vector Control and Surveillance
Maternal and Child Health Surveillance and Response
Public Health Surveillance and Epidemiological Investigation
Rapid Birth Defects Monitoring and Follow-up
Laboratory Testing
Travel Health News
Prevention of Sexually Transmitted Zika Virus Infections
Clinician Outreach and Communication
Prevention of Blood Transfusion–transmitted Zika Virus Infections
Risk Communication/Community Education
Specific activities are tied to the national Zika virus threat stage:
Stage 0: no Aedes mosquitoes present (applies to parts of California)
Stage 1a: Aedes mosquitoes present, but low season (current situation for Southern California and Central Valley)
Stage 1b: Aedes mosquitoes present and active (mosquito activity rises with sustained warm temperatures—late spring/early summer in parts of Inland Empire, late summer in most of Southern California)
Stage 2: single household with local transmission
Stage 3: multi-person local transmission (3 or more unrelated cases)

15. Public Health Response Goals
Prevent Zika virus infection in pregnant women
Prevent travel associated infections
Prevent mosquito-borne transmission in California
Reduce the impact of Zika virus infection in pregnancy

16. Prevent Travel Associated Infections in Pregnant Women
Vector Control and Surveillance
Maternal and Child Health Surveillance and Response
Public Health Surveillance and Epidemiological Investigation
Rapid Birth Defects Monitoring and Follow-up
Laboratory Testing
Travel Health News
Prevention of Sexually Transmitted Zika Virus Infections
Clinician Outreach and Communication
Prevention of Blood Transfusion–transmitted Zika Virus Infections
Risk Communication/Community Education
Challenging due to the complex reasons for international travel. Likely to become more challenging as Zika spreads in the border region.
Nevertheless, several prevention opportunities exist:
CDPH and other partners are working to inform pregnant women about travel associated risk and prevention strategies
Directly through public outreach
Through health care providers
Prevent secondary infections
Inform sexual partners of pregnant women of risk and prevention strategies
Prevent transmission through blood transfusion

17. Prevent Mosquito-borne Transmission in California
Vector Control and Surveillance
Maternal and Child Health Surveillance and Response
Public Health Surveillance and Epidemiological Investigation
Rapid Birth Defects Monitoring and Follow-up
Laboratory Testing
Travel Health News
Prevention of Sexually Transmitted Zika Virus Infections
Clinician Outreach and Communication
Prevention of Blood Transfusion–transmitted Zika Virus Infections
Risk Communication/Community Education
The opportunities include:
Monitoring transmission risk
Vector surveillance
Human case surveillance
Rapid detection of local mosquito-bourne infections through
Laboratory testing
Human surveillance
Response to limit spread from infected persons (travel or local infections)
Vector control
Epidemiologic investigation
Public health response
Public education
If transmission occurs, rapid investigation to determine scope of transmission

18. Reduce the Impact of Zika Virus Infection in Pregnancy
Vector Control and Surveillance
Maternal and Child Health Surveillance and Response
Public Health Surveillance and Epidemiological Investigation
Rapid Birth Defects Monitoring and Follow-up
Laboratory Testing
Travel Health News
Prevention of Sexually Transmitted Zika Virus Infections
Clinician Outreach and Communication
Prevention of Blood Transfusion–transmitted Zika Virus Infections
Risk Communication/Community Education
If infections in pregnancy occur, there are opportunities to support infected women, encourage appropriate fetal and infant evaluation, and monitor infected infants.

19. What Is the Future for Zika?
Slide from CDC

20. Chikungunya Experience
Slide from CDC

21. The Future of Zika in California?
Possibly more cases in 2017 than 2016
If transmission increases in Mexico
If virus spreads in Baja California
Increasing cases in the summer, but how much?
Greatest risk of local transmission in summer
Peak of Aedes mosquito activity
Highest levels of travel exposure
Public health response activities continuing
Due to high volume of travel across the land border

22. Thank You