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Climate Change, Introduced Pests and Vector-Borne Diseases Michael Niemela California Department of Public Health, Vector-Borne Disease Section.

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Presentation on theme: "Climate Change, Introduced Pests and Vector-Borne Diseases Michael Niemela California Department of Public Health, Vector-Borne Disease Section."— Presentation transcript:

1 Climate Change, Introduced Pests and Vector-Borne Diseases Michael Niemela California Department of Public Health, Vector-Borne Disease Section

2 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.

3 Vector-Borne Disease Section Offices Sacramento Headquarters Elk Grove Ontario Richmond Lab Santa Rosa CLOSED Santa Rosa CLOSED Redding 6 4 Field Offices and Laboratory plus HQ in Sacramento S.L.O. CLOSED S.L.O. CLOSED Field Offices: 14 Lab: 4 HQ: 5

4 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.

5 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.

6 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.

7 Mosquito-Borne Diseases West Nile virus Western equine encephalomyelitis St. Louis encephalitis Malaria Dengue Yellow fever

8 Tick-borne diseases Lyme disease Rocky Mountain spotted fever Ehrlichiosis Relapsing fever Colorado tick fever Babesiosis

9 Rodent-Borne Diseases Plague Hantavirus cardiopulmonary syndrome Rat bite fever Lymphocytic choriomeningitis

10 Injurious and Nuisance Pests Bed bugs Body and head lice Africanized honey bees Red imported fire ants Yellow jackets Triatoma

11 Climate Change

12 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.

13 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

14 Human Influences

15 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


17 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.

18 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

19 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

20 Global Temperature

21 Temperature Increase U.K.’s Hadley Centre for Climate Change “Business as Usual Prediction”

22 NOAA’s Prediction

23 Mosquito-Borne Diseases,r:2,s:0&tx=123&ty=104

24 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

25 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


27 Fever Cage

28 Dengue Vectors Aedes albopictus Asian Tiger Mosquito Aedes aegypti Yellow Fever Mosquito

29 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.

30 Egg Rafts vs. Aedes Eggs

31 31 Possible Larval Sources

32 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.


34 Native Distribution Ae. Albopictus



37 Current Distribution Ae. albopictus *as of 2007

38 Discovery in the USA Houston, TX: Harris County Mosquito Control District discovered 1 st 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.

39 C. Moore. 1999. JAMCA 15: 221-227 Distribution Aedes albopictus 1998

40 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.

41 Los Angeles 1946 Military cargo ship with 40 tons of salvaged tires from the Philippines. Several contained water. Larvae and adults were collected.

42 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.

43 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.

44 Los Angeles County 2001

45 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)

46 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).

47 Identified 15 infestations (6 counties) at nurseries

48 Orange County 2004 Orange County VCD received complaints of day-biting mosquitoes in late summer Source: 20' boat shipped from Hawaii in July

49 Local Response Comprehensive surveillance in and around infested areas. Intensive mosquito control operations. Door-to-door neighborhood inspections. Public education.

50 El Monte. L.A. Co., 2011

51 September 2, 2011

52 Through October 4 th, 2011

53 Through October 27 th, 2011

54 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?

55 What Does Climate Change Have to Do With Bugs and Disease?

56 The World is a Smaller Place Air Travel Shipping Routes

57 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.

58 1 1 1 2 1 2 3 1 2 1 8 2 3 2 1 12 1 1 1 9 3 2 1 1 5 2 Location and Count of Imported Dengue Cases in California 2010-2011 CountyCount San Diego12 Santa Clara9 Orange8 San Mateo5 Los Angeles3 Riverside3 Solano3

59 Climate Change, Disease and Vectors

60 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.

61 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.

62 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.

63 Pesticides

64 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

65 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.).

66 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.

67 Questions?? Michael Niemela California Department of Public Health (916) 686-8411

68 Distribution Aedes aegypti

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