a world gone viral: arboviral emergence in recent decades
TRANSCRIPT
05/02/2023
A World Gone Viral: Arboviral Emergence in Recent DecadesA. Desiree LaBeaud, MD, MSStanford University
+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
+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
+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
+Disease Emergence: Influences of Modern Life
UrbanizationDeforestation/Reforestation
Land Reclamation Irrigation ProjectsMilitary Activities/War
Natural Disasters
Extreme Weather Events
Climate Change
Reduced/Ineffective Vector Control
Increased Transportation
+Be a virus, See the world!
Gary Larson’s view of infectious diseases from FARSIDE
Man’sBlood
You are from Italy. Wow!!You have beautiful eyes….
Hey everyone, we are going to Rome!!!
+ 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
05/02/2023
Dengue
Preparedness for the Zika Virus: A Public Health Emergency
Flavivirus400 million cases yearly
4 serotypesSpread by Aedes aegypti
Can be deadlyVaccine coming
+ 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.
+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
+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.
+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.
+UNITED STATES of AMERICA
MEXICO
COLOMBIA
VENEZUELA
BRAZIL
PERU
BOLIVIA
HONDURAS
NICARAGUA
ECUADOR
GUYANA
SURINAME
FRENCHGUIANA
COSTA RICA
PANAMA
GUATEMALA
CUBA
PARAGUAY
ARGENTINA
URUGUAY
CHILE
GUYANASURINAME
FRENCH GUIANA
PANAMA
COSTA RICA
NICARAGUA
HONDURAS
GUATAMALAEL 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
+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
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 DALYsSeverely underestimated; Very little data
+Why are we constantly taken off guard?Disease outbreaks of never-heard-of organisms seem far awayReactive not proactive climate
• Funding• Media
Many scarier diseases• Rift Valley fever virus
+ PreventionAvoid 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 sexNucleic acid screening of blood
+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