Zika, a mosquito-borne virus, can be passed from a pregnant woman to her fetus, potentially causing microcephaly and other devastating defects. Environmental factors may contribute to the spread of the viruses that cause Zika, dengue, and other tropical diseases, as a changing climate may allow their mosquito carriers to flourish. Though no vaccines exist for Zika or dengue, Rotary clubs can implement service projects to provide education, clean up mosquito habitats, promote prevention, and implement an exciting new method to interrupt mosquitoes’ ability to transmit these viruses.

1. Dr. Jonathan Patz, MD, MPH
Dr. Patz is director of the Global Health Institute at the University
of Wisconsin-Madison. He is a professor and the John P. Holton
Chair in Health and the Environment with appointments in the
Nelson Institute for Environmental Studies and the Department
of Population Health Sciences. For 15 years, Patz served as a
lead author for the United Nations Intergovernmental Panel on
Climate Change (or IPCC)—the organization that shared the
2007 Nobel Peace Prize with Al Gore. He also co-chaired the
health expert panel of the U.S. National Assessment on Climate
Change, a report mandated by the U.S. Congress.

2. Jonathan Patz, Professor & Director
Zika and Dengue: Creating Partnerships to Interrupt Transmission
ROTARY INTERNATIONAL
Atlanta, June 12, 2017
Climate and environment factors in
dengue and Zika resurgence

3. Relationship between temperature and
malaria parasite development time inside
mosquito (“extrinsic incubation period”
or EIP). EIP shortens at higher temps, so
mosquitoes infectious sooner.

4. West Nile Virus Transmission Cycle in
Old World
Dead - end Hosts
?
Mosquito vectors
Culex species
Avian reservoirs
USGS, National Wildlife
Health Center

5. Temperature & arboviral
development rate
Mean quantity of virus within
salivary glands of Culex. tarsalis
female mosquitoes, versus
incubation temperature (°C).
Mean NY99 West Nile Virus titers
in the bodies of infected females
incubated between 14–30°C
Reisen et al. 2014

6. Aedes aegypti (the “small container” mosquito)

7. Transmission of Dengue Virus
by Aedes aegypti
Viremia Viremia
Extrinsic
incubation
period
DAYS
0 5 8 12 16 20 24 28
Human #1 Human #2
Illness
Mosquito feeds /
acquires virus
Mosquito refeeds /
transmits virus
Intrinsic
incubation
period
Illness

9. Synchrony during high temperature for SE Asia
(18 years of data)
Synchronous
Multiannual dengue cycles
Temperature anomaly
(Average lag time ~ 3 to 4
months)
LatitudeLatitude
Month
van Panhuis et al. PNAS, 2015

10. El Niño causing high temperature (SE Asia)
Temperature anomaly
Latitude
Month
Oceanic Niño Index
Month
van Panhuis et al. PNAS, 2015

11. El Niño of 2015
may be the strongest in the
recent hisorical record,
surpassing the 1997-98
event

12. Vectorial capacity for Zika/Dengue
Transmission, S. America
Camindade et al. PNAS, 2016

13. ZIKA VIRUS & el niño
Extreme climate and emerging diseases
Patz et al. (in review)

14. Relationship between temperature and
malaria parasite development time inside
mosquito (“extrinsic incubation period”
or EIP). EIP shortens at higher temps, so
mosquitoes infectious sooner.

15. Peri-urban slums
• Brazil and Colombia have some of
world’s highest “Gini coefficients”

17. Record heat & El Niño
in country with many urban slums:
a perfect storm for Zika emergence ?

19. Observed global warming
About
0.85° C
global
warming
so far
Courtesy: D Liverman

20. CLIMATE
CHANGE
Temperature Rise 1
Sea level Rise 2
Hydrologic Extremes
Urban Heat Island
Effect
Air Pollution &
Aeroallergens
Vector-borne Diseases
Water-borne Diseases
Water resources & food
supply
Mental Health &
Environmental
Refugees
Heat Stress
Cardiorespiratory failure
Respiratory diseases, e.g.,
COPD & Asthma
Malaria
Dengue
Encephalitis
Hantavirus
Rift Valley Fever
Cholera
Cyclospora
Cryptosporidiosis
Campylobacter
Leptospirosis
Malnutrition
Diarrhea
Toxic Red Tides
Forced Migration
Overcrowding
Infectious diseases
Human Conflicts
1 3°C by yr. 2100
2 40 cm “ “
IPCC estimates
Patz, 1998
HEALTH EFFECTS OF CLIMATE CHANGE

21. Our paper in JAMA, 1996

22. Zika and dengue Risk: US
Monaghan et al. 2016

24. Other preventive measures?
• Introducing Wolbachia, a
naturally occuring bacteria
in 60% of all insect species
• Inside the Aedes mosquito,
interferes with transmission
of flaviviruses (dengue,
Zika, and chikungunya)
Prof. Scott O’Neill, Monash University

25. West Nile Virus Transmission Cycle in
Old World
Dead - end Hosts
?
Mosquito vectors
Culex species
Avian reservoirs
USGS, National Wildlife
Health Center