Presentation on theme: "Climate Change, Introduced Pests and Vector-Borne Diseases"— Presentation transcript:
1 Climate Change, Introduced Pests and Vector-Borne Diseases Michael NiemelaCalifornia Department ofPublic Health, Vector-Borne Disease Section
2 Overview CDPH’s Vector-Borne Disease Section. What is Climate Change? Introduction to vector-borne diseaseDengueIntroductions of Aedes albopictus to U.S. and CA.Linking the preceding topics.
3 Vector-Borne Disease Section Offices Sacramento Headquarters ReddingSacramento HeadquartersSanta RosaCLOSEDElk GroveRichmond LabS.L.O.CLOSEDField Offices: 14Lab: 4HQ: 5Ontario6 4 Field Offices and Laboratory plus HQ in Sacramento
4 VBDS' FunctionThe 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 onrestricted use of public health pesticides.
7 Mosquito-Borne Diseases West Nile virusWestern equine encephalomyelitisSt. Louis encephalitisMalariaDengueYellow fever
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.LocalGlobalNot from seasonal or single events.
13 Climate Forcings Factors that can shape climate: Variations is solar radiationDeviations in the earth’s orbitMountain building/continental driftChanges in greenhouse gas concentrations
15 Changes in the concentration of the key greenhouse gases carbon dioxide (a) and methane (b) since preindustrial times.Changes in the concentration of the key greenhouse gases carbon dioxide (a) and methane (b) since preindustrial times. Reprinted from with permission from Intergovernmental Panel on Climate Change (data archived at the Hadley Centre for Climate Prediction and Research).Sutherst R W Clin. Microbiol. Rev. 2004;17:
17 Effects of Climate Change No So Simple to Predict… Many confounding factors of human origin:Land use patterns: urban, farming, land coverRate of agricultural and industrial developmentwater managementcultural and behavioral factors, etc.civil unrest, war, faminePositive 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.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:
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
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 serotypeConfers only partial and transient protection against subsequent infection by the other threeEvidence suggest that sequential infection increases the risk of more serious disease resulting in DHF
25 Dengue VirusDHF has become a leading cause of hospitalization and death among children in several countries.No vaccine.Incidence of dengue increasing world wide40% or 2.5 billion people globally are at risk for dengueEstimated million infections annually worldwideUp to a quarter of those are hemorrhagic fever (DHF)25,000 fatalities per year
28 Dengue Vectors Aedes aegypti Yellow Fever Mosquito Aedes albopictus Asian Tiger 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.
31 Possible Larval Sources Although probably originally a forest edge-adapted species that used bamboo stalks and tree holes for larval habitat, Aedes albopictus has adapted well to life with humans and the multitude of containers they provide.Aedes aegypti and other mosquitoes have a complex life-cycle with dramatic changes in shape, function, and habitat. Female mosquitoes lay their eggs on the inner, wet walls of containers with water. Larvae hatch when water inundates the eggs as a result of rains or the addition of water by people. In the following days, the larvae will feed on microorganisms and particulate organic matter, shedding their skins three times to be able to grow from first to fourth instars. When the larva has acquired enough energy and size and is in the fourth instar, metamorphosis is triggered, changing the larva into a pupa. Pupae do not feed; they just change in form until the body of the adult, flying mosquito is formed. Then, the newly formed adult emerges from the water after breaking the pupal skin. The entire life cycle lasts 8-10 days at room temperature, depending on the level of feeding.It is this life-cycle complexity that makes it rather difficult to understand where the mosquitoes come from.There is a very important adaptation of Ae. aegypti and other dengue vectors that makes controlling their populations a difficult task. Their eggs can withstand desiccation for several months, which means that even if all larvae, pupae, and adults were eliminated at some point in time, repopulation will occur as soon as the eggs in the containers are flooded with water. Unfortunately, there is no effective way to control the eggs in containers.
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. Linthicum et al Known vector of dengue virus in Japan, Southeast Asia, southern China, and Seychelles, perhaps second in importance only to Ae aegypti. It is a competent experimental vector of EEE, Ross River, WEE, Venezuelan EE, Sindbis, and WNV. WNV has been isolated from adults collected in Pennsylvania in 2000 and at least 5 other states in 2001 and 2002.
33 We believe that they did not establish either because of aggressive surveillance and control (2001) or that they were a southeast Asian strain unable to survive the winter (2004 OC)
34 Native Distribution Ae. Albopictus Widely distributed in parts of India, eastern Asia and southeast Asia, parts of Japan, New Guinea and most islands in the Indian Ocean
35 With their propensity to trap water, tires have long been recognized as potential habitat for mosquitoes. Pratt et al reported the discovery of mosquito larvae in 3 of 12 ships carrying old tires and other salvage from combat areas of the Pacific to the United States. They reported finding 7 species of non-indiginous species, several known disease vectors. Even dry tires were recognized as potential sources of eggs.Pratt et al Tires as a factor in the transportation of mosquitoes by ships. Military Surgeon 99(6):
37 Current Distribution Ae. albopictus Native to southeast Asia: distribution in blueEstablished populations in green*as of 2007
38 Discovery in the USAHouston, 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.The earliest records of albos in the US were isolated introductions in used tires shipped from Asian ports (Pratt et al 1946).The 1st clearly established population in the USA was in Houston, Harris County, TX on August 2, Initial survey by the Harris Co MCD Aug-Oct 1985 found it widespread in Harris Co, especially the eastern halfA previous collection in Memphis TN suggested the possibility of additional introductions, or very rapid spread from a single focus. Albos were collected or intercepted 3 times previous to 1985 associated with used tires, but breeding populations were never demonstrated. Introduction in Houston presumably also with used tires.The CDC had developed and maintained a collaborative (i.e. included state and local agencies) ovitrap surveillance program for Aedes aegypti since In early 1986 the program was modified and expanded to better detect Aedes albopictus. The trapping quickly revealed widespread infestations in the southern states, but also some lighter infestations in the northern states.14 states positive by 1987The northward and westward spread was slower than the rapid eastward spread, presumably caused by colder temps in the north and drier summers in the west
39 Distribution Aedes albopictus 1998 Figure taken from Chester Moore Aedes albopictus in the United States: current status and prospects for further spread. JAMCA 15(2):The first 14 years ( ). The map illustrates the rapid eastward spread, in two-year increments, from the point of discovery in Houston TX in August 1985 (or at least the pattern of discovery given the potential for multiple introductions in used tire shipments). By 1999, infestations were reported from 26 states east of the Mississippi River (Moore 1999). Current USA distribution is similar (minus California)Current distribution is at least 911 Counties and 26 States.C. Moore JAMCA 15:
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 1946Military cargo ship with 40 tons of salvaged tires from the Philippines.Several contained water.Larvae and adults were collected.Considerable quantities of salvaged material was returned to the USA by the military from combat areas of WWII. Water retaining material such as tires, amphibious vehicles and shell cases provide habitat for mosquitoes. Routine Public Health Service quarantine inspections at Los Angeles detected larval and adult mosquitoes in cargo returning from SE Asia in 1945 (possibly the first published record of mosquitoes being transported in cargo).Albopictus larvae were detected in a shipment of tires from the Philippine Islands on Jan 17, The shipment took 36 days at sea to arrive. The cargo was composed of 40 tons of used tires, several which contained water. Some live adults were also captured. All material that contained water was treated with 5% DDT in kerosene.
42 Oakland 1971Cargo 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.Since about 1966, large quantities of military material has been moved from Vietnam to the USA. This material all has to be clean and treated with insecticide. “Surplus” materials can be purchased by civilan contractors and shipped to the USA on cargo ships and do not need to follow the same requirements for larviciding tires.A ship entered quarantine at Oakland April 2, 1971 with 460 tons of surplus earthmoving equipment tires consigned to a tire dealer in Los Angeles. The US Public Health Service, Center for Disease Control, Foreign Quarantine Program (Burlingame, CA) inspected the cargo and discovered a few of the tires contained water. Two larvae and 3 pupae were discovered in one tire. The ship was remanded to Los Angeles where the tires were unloaded under the supervision of the Public Health Service quarantine officers. Two additional tires containing several larvae and pupae were found. This incident was easily resolved since it was an isolated occurrence.
43 Alameda County 1987Alameda 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.In 1987, staff of the Alameda CMAD collected Ae albopictus larvae from large equipment tires shipped from Hawaii to an Oakland, CA tire dealer (note: Albopictus was believed to have reached the Hawaiian Islands in the late 1800’s). Failure to collect additional specimens in subsequent years suggested that the species failed to become established
44 Los Angeles County 2001Detected initially in June 2001 at the ports of Los Angeles & Long Beach by USDA/APHIS Plant Protection and Quarantine Officer Armanious and Centers for Disease Control and Prevention (CDC) Quarantine Officers Fernandez and Marty, and the Greater Los Angeles County Vector Control District (GLACVCD) in a cargo containerThe Port of Los Angeles includes 29 major cargo terminals, including facilities to handle automobiles, containers, dry bulk products and liquid bulk products. Its six modern container facilities together handle in excess of four million units of cargo containers annually.
45 “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.
46 Federal ResponseCDC 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).Exclusion for ships enroute through July 17
47 Identified 15 infestations (6 counties) at nurseries After the initial discovery of Ae. albopictus, investigations at wholesale nurseries by local mosquito and vector control agencies and county environmental health departments documented additional infestations at 7 locations in Los Angeles County, 1 in Santa Clara County, 2 in San Bernardino County, 3 in Orange County, 1 in San Joaquin County and 1 in San Diego County. All by mid-August.The Rowland Heights nursery was the first discovered and represented the first evidence of albopictus breeding in southern CaliforniaAlbos continued to be detected at certain locations through 2004, but none after. Speculated either an overwintering population, or additional eggs hatching from local containers or new bamboo importsIdentified 15 infestations (6 counties) at nurseries
48 Orange County 2004Orange County VCD received complaints of day-biting mosquitoes in late summerSource: 20' boat shipped from Hawaii in JulyOCVCD received complaints of day-biting mosquitoes in late summer (late Aug or Sept). Inspections revealed albopictus breeding in small containers. Some questioning revealed that a 20ft boat had recently been shipped from Hawaii in a seacontainer. OCVCD assumed that eggs in the hull hatched and develped when flooded by washing the boat. OCVCD staff conducted door to door surveillance throughout the neighborhood looking for sources, eliminating them, and placing ovitraps. Found lots of breeding in neighbors yards (2 houses from the boat house). More breeding found in other yards plus ovitrap positives. One adult was captured 0.6 miles from the index site. Adulticide was applied to selected back yards where habitat appeared conducive to adult harborage.Surveillance continued through 2006, but no evidence of albos was found after Assumed to have been a cold-intolerant strain unable to survive the winter.
49 Local ResponseComprehensive surveillance in and around infested areas.Intensive mosquito control operations.Door-to-door neighborhood inspections.Public education.Continued ovitrap surveillance in 2005 and 2006 detected no more eggs
50 El Monte. L.A. Co., 2011Continued ovitrap surveillance in 2005 and 2006 detected no more eggs
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 Shipping RoutesAir Travel
57 Locally Acquired Dengue not Hypothetical 2010: Key West, Florida: 28 cases.5% randomly tested had antibodies or infection2005: Brownsville, TX. 25 cases, 16 DHF.Tamaulipas State: 1251 cases, 223 DHFPrevious 5 years, 541 cases, 20 DHF2001: Hawaii. 153 cases linked to French Polynesia.
58 Location and Count of Imported Dengue Cases in California 2010-2011 CountyCountSan Diego12Santa Clara9Orange8San Mateo5Los Angeles3RiversideSolano12131122115922121133812
60 Effects of Climate Change Warmer WintersHigher survival rates for vectorsPredicted to produce more extreme weather: Effects of Hurricane KatrinaHeavy RainsFloodingDisplaced people particularly vulnerable to disease.
61 Biological Impacts Warmer temperatures: Decreased generation time/gonotrophic cycles shorterIncreased rate of bitingVectors remain active longerVirus 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.
64 Responding to Possible Climate Change Long-term ecological and epidemiological research onhow environmental changes influence disease cyclesEnhanced surveillance- Appearance of human cases in previouslydisease-free areas- Introduction of new vectors, hosts, or pathogens- Changing transmission patterns in existing fociStrengthen public health infrastructure to improverecognition and response
65 Responding to Possible Climate Change Identify potentially vulnerable populations.Maintain awareness of other changes that couldinteract with climate changes to result in emergingdisease risks.Measures to reduce the spread of disease or diseasevectors and hosts.Review, evaluate and prepare countermeasures(vaccines, therapeutic agents, insecticides, etc.).
66 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.
67 Questions?? Michael Niemela California Department of Public Health (916)