A. Desiree LaBeaud, MD, MS

1. 3/9/2016
A World Gone Viral: Arboviral
Emergence in Recent Decades
A. Desiree LaBeaud, MD, MS
Stanford University

2. +What are Arboviruses?
 Arthropod-borne viruses
 Require a blood sucking arthropod
to complete the life cycle
 Often zoonotic
 At least 500 viruses
 Diverse: 8 viral families
• Togaviridae, Flaviviridae, and
Bunyaviridae

3. +Arboviral Importance
 Every year, over 1 million people die from mosquito-
borne diseases
• Children are at high risk
 West Nile virus: widespread transmission of an
‘exotic’ pathogen and the substantial health impact
 Recent introduction of more deadly arboviruses and
their potential threat
 Global distribution, limited by vector range

4. +

5. +Dramatic Resurgence
 Last 20 years: dramatic resurgence or
emergence of epidemic arboviral diseases in
humans and animals
 Epidemics caused by arboviruses:
• Thought to be under control:
‒ Dengue, yellow fever
• Expanded geographic distribution:
‒ West Nile, Rift Valley fever, chikungunya

6. +Disease Emergence: Influences of Modern Life
Urbanization
Deforestation/Reforesta
tion
Land Reclamation
Irrigation Projects
Military Activities/War
 Natural Disasters
 Extreme Weather Events
 Climate Change
 Reduced/Ineffective
Vector Control
 Increased Transportation

7. +Effects of Globalization
 Almost 2 billion people travel aboard
commercial airlines every year

8. +Be a virus,
See the world!
Gary Larson’s view
of infectious
diseases from
FARSIDE
Man’s
Blood
You are from Italy. Wow!!
You have beautiful eyes….
Hey everyone,
we are going to Rome!!!

10. + Western Hemisphere Debut
 Flavivirus
 1999: cluster of encephalitis was reported
in NYC
 Over the next 3 years WNV spread
• 2000: 21 cases; 3 states
• 2001: 66 cases; 10 states
• 2002: 4156 cases; 39 states
 2003: largest NA arboviral epidemic
• >9000 human cases and 100s of
deaths
Gubler CID

11. + WNV Human Cases 2015

12. Dengue
3/9/2016Preparedness for the Zika Virus: A Public Health Emergency
Flavivirus
400 million
cases yearly
4 serotypes
Spread by
Aedes aegypti
Can be deadly
Vaccine coming

13. 3/9/2016Preparedness for the Zika Virus: A Public Health Emergency

14. + Spread of Dengue in US
 Laredo, TX: 1999
• 50% exposed to dengue
 Brownsville, TX: 2005
• Autochthonous spread
• 38% seropositive
 Key West, FL: 2009-2010
• First cases outside TX since 1945
• Locally acquired
 2013: South Texas, Florida
• Long Island, NY
CDC. MMWR. Aug 2007.

15. +Chikungunya virus (CHIKV)
 Togavirus, ssRNA positive-sense virus
 Transmitted by Aedes aegypti and Aedes
albopictus
 Causes a non-specific febrile illness
 Joint symptoms usually last weeks, but can last
years

16. +Chikungunya Emergence
de Lamballerie X. Virology J. Feb 2008

17. +Spread into the Developed World
Chikungunya virus outbreaks:
• 2004 Indian Ocean island/East Africa
• 2006 India
• 2007 Autochthonous spread in Italy
New vector: Aedes albopictus
New virus: mutation in chikungunya
virus (A226V) improved virus
survival in Aedes albopictus and
also increased its virulence
Tsetsarkin KA. PLoS Pathogens. Dec 2007.

18. + CHIKUNGUNYA: 2013-Present

19. +CHIKV: Unwanted Souvenir
 At least 1 million cases of CHIKV have been
confirmed in patients living in the Caribbean
 First time that local transmission of CHIKV has
been reported in the Americas
• At least 1.6 million cases
 9 million Americans travel to the
Caribbean each year
• CHIKV will be more frequent in the U.S.

20. +
UNITED STATES of AMERICA
MEXICO
COLOMBIA
VENEZUELA
BRAZIL
PERU
BOLIVIA
HONDURAS
NICARAGUA
ECUADOR
GUYANA
SURINAME
FRENCH
GUIANA
COSTA RICA
PANAMA
GUATEMALA
CUBA
PARAGUAY
ARGENTINA
URUGUAY
CHILE
GUYANA
SURINAME
FRENCH GUIANA
PANAMA
COSTA RICA
NICARAGUA
HONDURAS
GUATAMALA
EL SALVADOR
BELIZE
Countries in the
Americas where
chikungunya
cases have been
reported:
Mexico, Belize,
Brazil, Colombia,
Honduras, Costa
Rica, Colombia,
El Salvador,
Ecuador,
French Guiana,
Guatemala,
Guyana, Nicaragua,
Panama, Paraguay,
Suriname,
Venezuela
Countries and territories
in the Americas where
chikungunya cases
have been reported:
Anguilla, Antigua and Barbuda, Aruba,
Bahamas, Barbados, British Virgin
Islands, Cayman Islands, Curacao,
Dominica, Dominican Republic,
Grenada, Guadeloupe, Haiti, Jamaica,
Martinique, Montserrat, Puerto Rico,
Saint Barthelemy, Saint Kitts and Nevis,
Saint Lucia, Saint Martin, Saint Vincent
and the Grenadines, Sint Maarten,
Suriname, Trinidad and Tobago, Turks
and Caicos Islands, US Virgin Islands

21. +Why does this keep happening?
 Global travel allows for imported cases
 Climate change allows for vector migration and adaptation
 Urbanization versus resource-limited regions
• Neglected diseases occur in neglected areas

22. Up to 5 million years of healthy life lost each year
LaBeaud et al., Pop Health Metrics 9:1, 2011
Early mortality and long-term, related chronic conditions worth more DALYs
Severely underestimated; Very little data

23. +Why are we constantly taken off guard?
Disease outbreaks of never-heard-of organisms
seem far away
Reactive not proactive climate
• Funding
• Media
Many scarier diseases
• Rift Valley fever virus

24. + Prevention
Avoid exposure to mosquitoes
• Repellents: DEET and picaridin, permethrin
• Wear long-sleeved shirts and long pants
• Use air conditioners and/or window screens
• Clean out standing water for source reduction
Abstain or practice safe sex
Nucleic acid screening of blood

25. + Behavior Change

26. +Conclusions
 Arboviruses are common in all parts of the world and
are causing large outbreaks
 Outbreaks devastate by both direct pathogen effects and
bystander effects on food, shelter, and care
 Co-circulation of dengue, chikungunya, and Zika is
anticipated for the first time in the Americas
 Small, local U.S. outbreaks of Zika likely to mirror DENV
and CHIKV
 More proactive approach is needed to combat continued
arboviral emergence

27. +Thank you for your attention