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Climate Change, Introduced
Pests and Vector-Borne
Diseases
Michael Niemela
California Department of
Public Health, Vector-Borne
Disease Section
Overview
CDPH’s Vector-Borne Disease Section.
What is Climate Change?
Introduction to vector-borne disease
• Dengue
Introductions of Aedes albopictus to U.S.
and CA.
Linking the preceding topics.
Redding
Vector-Borne Disease Section
Offices
Sacramento Headquarters
Santa Rosa
CLOSED
Elk Grove
Richmond Lab
S.L.O.
CLOSED
6 4 Field Offices and
Laboratory plus HQ in
Sacramento
Ontario
Field Offices: 14
Lab: 4
HQ: 5
VBDS' Function
The Vector-Borne Disease Section
(VBDS) protects the health and wellbeing of Californians from diseases
transmitted to people from insects and
other animals.
VBDS Responsibilities and
Activities
Develop and implement statewide vector-borne
disease surveillance, prevention, and control
programs.
Coordinate preparedness activities for detection and
response to introduced vectors and vector-borne
diseases, such as West Nile virus and the Aedes
albopictus mosquito.
Conduct emergency vector control when disease
outbreaks occur, 2010 Plumas Eureka State Park.
VBDS Responsibilities and
Activities
Oversee the Vector Control Technician Certification
and Continuing Education programs.
Provide information, training, and educational
materials to governmental agencies and the public.
Oversee Special Local Need permits on
restricted use of public health pesticides.
Mosquito-Borne Diseases
West Nile virus
Western equine encephalomyelitis
St. Louis encephalitis
Malaria
Dengue
Yellow fever
Tick-borne diseases
Lyme disease
Rocky Mountain spotted fever
Ehrlichiosis
Relapsing fever
Colorado tick fever
Babesiosis
Rodent-Borne Diseases
Plague
Hantavirus cardiopulmonary syndrome
Rat bite fever
Lymphocytic choriomeningitis
Injurious and Nuisance Pests
Bed bugs
Body and head lice
Africanized honey bees
Red imported fire ants
Yellow jackets
Triatoma
Climate Change
What is Climate Change?
Climate change (a.k.a. global warming) is
significant statistical, lasting change of
weather over decades or longer spans of
time.
• Local
• Global
Not from seasonal or single events.
Climate Forcings
Factors that can shape climate:
• Variations is solar radiation
• Deviations in the earth’s orbit
• Mountain building/continental drift
• Changes in greenhouse gas
concentrations
Human Influences
Changes in the concentration of the key greenhouse gases carbon dioxide (a) and methane
(b) since preindustrial times.
Sutherst R W Clin. Microbiol. Rev. 2004;17:136-173
Effects of Climate Change No
So Simple to Predict…
Many confounding factors of human origin:
– Land use patterns: urban, farming, land
cover
– Rate of agricultural and industrial
development
– water management
– cultural and behavioral factors, etc.
– civil unrest, war, famine
Positive feedback cycles: More X = more Y.
More Y = more X.
Drivers of global change considered in relation to
potential changes in the status of vector-borne diseases.
Sutherst R W Clin. Microbiol. Rev. 2004;17:136-173
Effects of Climate Change No
So Simple to Predict…
Global effect not uniform: Detriment to
some areas, a benefit to others.
Incomplete knowledge and few long-term
studies.
Concurrent ecological cycles that are
complex and vary between regions.
• El Niño/La Niña,
• Solar output
Global Temperature
Temperature Increase
U.K.’s Hadley Centre for Climate Change “Business as Usual Prediction”
NOAA’s Prediction
Mosquito-Borne Diseases
http://www.google.com/imgres?q=dengue&um=1&hl=en&safe=active&sa=N&rls=com.microsoft:en-us&biw=1680&bih=866&tbm=isch&tbnid=3PDoJlm517-70M:&imgrefurl=http://www.dengue-fever-symptoms.com/&docid=lM31_6PNhUNGvM&imgurl=http://www.dengue-feversymptoms.com/images/dengue%252520fever%252520symptoms.gif&w=356&h=356&ei=p_wzT9iXJeWqiQKwkoW3Cg&zoom=1&iact=rc&dur=78&sig=113004992271279760932&page=1&tbnh=152&tbnw=163&start=0&ndsp=28&ved=1t:429,r:2,s:0&tx=123&ty=104
Dengue Virus
Arbovirus. Most common vector-borne virus.
Causes dengue fever (headache, fever, retroorbital pain, rash, bleeding) and dengue
hemorrhagic fever.
Four virus serotypes (DEN-1, 2, 3, 4)
– Recovery from infection by one provides lifelong
immunity against that serotype
– Confers only partial and transient protection
against subsequent infection by the other three
– Evidence suggest that sequential infection
increases the risk of more serious disease
resulting in DHF
Dengue Virus
DHF has become a leading cause of
hospitalization and death among children in
several countries.
No vaccine.
Incidence of dengue increasing world wide
– 40% or 2.5 billion people globally are at risk for dengue
– Estimated 50-100 million infections annually worldwide
• Up to a quarter of those are hemorrhagic fever (DHF)
• 25,000 fatalities per year
Fever Cage
Dengue Vectors
Aedes aegypti
Yellow Fever Mosquito
Aedes albopictus
Asian Tiger Mosquito
Aedes albopictus/aegypti
Considered “domestic” mosquitoes.
Container breeders – difficult to
eradicate.
Happily breed in tires, and very small
containers, flower pot basins, cans, etc.
Sprinklers, improper water management.
Egg Rafts vs. Aedes Eggs
Possible Larval
Sources
31
Ae. Albopictus: Public Health
Concerns
Vector: Dengue, chikungunya, and several
other encephalitis viruses.
Responsible for recent outbreaks of dengue
virus in south Florida, Texas, and Hawaii.
Vicious day-biting mosquito that prefers
mammals.
Establishment would increase risk of
introduction of new mosquito-borne viruses and
pose a severe public health nuisance.
Native Distribution Ae. Albopictus
Current Distribution
Ae. albopictus
*as of 2007
Discovery in the USA
Houston, TX: Harris County Mosquito Control
District discovered 1st breeding population in
August 1985.
1986: Discovered in Louisiana, Tennessee,
Mississippi, Missouri, Illinois, Ohio, Indiana,
Arkansas, and Florida.
1987: Delaware, Kentucky, North Carolina, and
Maryland.
Distribution Aedes albopictus 1998
C. Moore. 1999. JAMCA 15: 221-227
Aedes albopictus
Introductions into California
Biology and behavior highly conducive
to dispersal on cargo.
At least 6 separate introductions into
California in the past 66 years.
Los Angeles 1946
Military cargo ship with 40 tons of
salvaged tires from the Philippines.
Several contained water.
Larvae and adults were collected.
Oakland 1971
Cargo ship with 460 tons of surplus
earthmoving equipment tires from Vietnam.
Several contained water. Larvae and pupae
detected in one tire.
Tires unloaded in Los Angeles by U.S.
Public Health Service quarantine officers.
Two additional tires with immatures
detected.
Alameda County 1987
Alameda County MAD found one larva
in large equipment tires shipped from
Hawaii to a used tire dealer in Oakland.
No additional specimens were
collected in subsequent years
suggesting that the species failed to
become established.
Los Angeles County 2001
“Lucky Bamboo” (Dracaena spp)
Imported from
southern China
and Taiwan.
Shipped in 2-3
inches of water.
Containers held
about 500 cases
with 300 plants in
each case.
Federal Response
CDC press release July 2, 2001
implemented an embargo on importation
of Dracaena shipments in standing water.
Notice of Embargo published in Federal
Register (July 10, Vol. 66, No. 132).
Identified 15 infestations
(6 counties) at nurseries
Orange County 2004
Orange County VCD received complaints of
day-biting mosquitoes in late summer
Source: 20' boat shipped from Hawaii in
July
Local Response
Comprehensive surveillance in and
around infested areas.
Intensive mosquito control operations.
Door-to-door neighborhood
inspections.
Public education.
El Monte. L.A. Co., 2011
September 2, 2011
Through October 4th, 2011
Through October 27th, 2011
What We Know or Don’t…
Mosquito DNA linked to China and not
the Texas form. How did it get there?
Resident said she had been bitten for
“several years”. What is the extent of the
infestation?
Will winter have any effect on the
population? Diapause.
Can we eradicate the infestation?
What Does Climate Change
Have to Do With Bugs and
Disease?
The World is a Smaller Place
Shipping Routes
Air Travel
Locally Acquired Dengue not
Hypothetical
2010: Key West, Florida: 28 cases.
• 5% randomly tested had antibodies or
infection
2005: Brownsville, TX. 25 cases, 16 DHF.
• Tamaulipas State: 1251 cases, 223 DHF
• Previous 5 years, 541 cases, 20 DHF
2001: Hawaii. 153 cases linked to French
Polynesia.
Location and Count of
Imported Dengue Cases in
California 2010-2011
11
1
1
1
2
5
32
1
9
2
County
Count
San Diego
12
2 1
1
1
2
2
1
2
1
1
3
3
8
12
Santa Clara
9
Orange
8
San Mateo
5
Los Angeles
3
Riverside
3
Solano
3
Climate Change, Disease and
Vectors
Effects of Climate Change
Warmer Winters
• Higher survival rates for vectors
Predicted to produce more extreme
weather: Effects of Hurricane Katrina
• Heavy Rains
• Flooding
Displaced people particularly vulnerable
to disease.
Biological Impacts
Warmer temperatures:
• Decreased generation time/gonotrophic
cycles shorter
• Increased rate of biting
• Vectors remain active longer
• Virus becomes infective earlier and
later into the season.
• Caveats to the above.
Introduced Vector Survival
Nature abhors a vacuum:
As territory opens to them,
vectors will move.
As temperature warms,
vectors previously held in
check by temperature will
move north or will survive
introduction.
Immunologically naïve
populations will be
exposed to novel disease
agents.
Pesticides
Responding to Possible Climate Change
Long-term ecological and epidemiological research on
how environmental changes influence disease cycles
Enhanced surveillance
- Appearance of human cases in previously
disease-free areas
- Introduction of new vectors, hosts, or pathogens
- Changing transmission patterns in existing foci
Strengthen public health infrastructure to improve
recognition and response
Responding to Possible Climate Change
Identify potentially vulnerable populations.
Maintain awareness of other changes that could
interact with climate changes to result in emerging
disease risks.
Measures to reduce the spread of disease or disease
vectors and hosts.
Review, evaluate and prepare countermeasures
(vaccines, therapeutic agents, insecticides, etc.).
Summary
Vector-Borne Disease Section: Who we
are and what we do.
Climate change and its potential effects.
Dengue virus.
Aedes albopictus introduction and
consequences.
How climate change, disease and insects
intersect.
Questions??
Michael Niemela
California Department of Public Health
(916) 686-8411
[email protected]
Distribution Aedes aegypti
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