climate change, introduced pests and vector-borne diseases

Climate Change, Introduced Pests and Vector-Borne

Diseases

Michael NiemelaCalifornia Department of

Public Health, Vector-Borne Disease Section

OverviewCDPH’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.

Vector-Borne Disease Section Offices

Sacramento HeadquartersSacramento Headquarters

Elk GroveElk Grove

OntarioOntario

Richmond LabRichmond Lab

Santa RosaCLOSED

Santa RosaCLOSED

ReddingRedding

6 4 Field Offices and Laboratory plus HQ in Sacramento

S.L.O.CLOSED

S.L.O.CLOSED Field Offices: 14

Lab: 4HQ: 5

VBDS' Function

The Vector-Borne Disease Section (VBDS) protects the health and well-being 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 diseasesLyme disease

Rocky Mountain spotted fever

Ehrlichiosis

Relapsing fever

Colorado tick fever

Babesiosis

Rodent-Borne DiseasesPlagueHantavirus cardiopulmonary syndromeRat bite feverLymphocytic 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-fever-symptoms.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, retro-orbital 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 albopictusAsian Tiger Mosquito

Aedes aegyptiYellow Fever 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

31

Possible Larval Sources

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 DistributionAe. 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.

C. Moore. 1999. JAMCA 15: 221-227

Distribution Aedes albopictus 1998

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

Imported from southern China and Taiwan.

Shipped in 2-3 inches of water.

Containers held about 500 cases with 300 plants in each case.

“Lucky Bamboo” (Dracaena spp)

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

Air Travel

Shipping Routes

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.

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8

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12

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Location and Count of Imported Dengue Cases in California 2010-2011

County CountSan Diego 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.).

SummaryVector-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

Michael.Niemela@cdph.ca.gov

Distribution Aedes aegypti