Anthropogenic Change and the Emergence of Tick-Borne Pathogens in the Northeast US Durland Fish, Ph.D. Yale School of Public Heath Yale School of Forestry and Environmental Studies Yale Institute for Biospheric Studies Center for EcoEpidemiology
TICKS: EXCELLENT VECTORS OF DISEASE AGENTS ZOOPHILIC FEEDING PROLONGED HOST CONTACT PHARMACOLOGIC SALIVA HIGH PATHOGEN PREVALENCE
Diuk-Wasser et al. 2006 J. Med. Entomol. 43:166 CDC HOST-SEEKING TICK SURVEY
Tick-Borne Pathogens of the Northeastern US AGENT DISEASE VECTOR BORRELIA BURGDORFERI LYME DISEASE IXODES SCAPULARIS ANAPLASMA PHAGOCYTOPHILUM ANAPLASMOSIS IXODES SCAPULARIS BABESIA MICROTI BABESIOSIS IXODES SCAPULARIS BORRELIA near MIYAMOTOI UNKNOWN IXODES SCAPULARIS EHRLICHIA CHAFFEENSIS EHRLICHIOSIS AMBLYOMMA AMERICANUM RICKETTSIA RICKETSII TICK-BORNE TYPHUS DERMACENTOR VARIABILIS POWASSAN VIRUS POW ENCEPHALITIS IXODES COOKEI
Emergence of Tick-Borne Pathogens in the Northeastern US Number of Emerging Agents 10 9 8 7 6 5 4 3 2 1 0 2001 1994 1990 1982 1969 1952 1909 1905 1915 1925 1935 1945 1955 1965 1975 1985 1995 2005 Date
Reported Lyme Disease Cases by Year United States, 1982-2002 25,000 20,000 Cases 15,000 10,000 5,000 0 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 Year
Reported Cases of Lyme Disease by Year, United States, 1992-2005 25,000 20,000 15,000 Cases 10,000 5,000 0 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Borrelia burgdorferi RESERVOIRS VECTOR Tamias striatus Ixodes scapularis Peromyscus leucopus Turdus migratorius
POPULATIONS OF Ixodes scapularis ARE DEPENDENT UPON WHITE-TAILED DEER
RE-FORESTATION OF THE NORTHEAST 1900 DEER ABSENT OR RARE 1970 DEER ABUNDANT
REFUGIA FOR IXODES SCAPULARIS CA.1960 0 125 250 500 Kilometers
IXODES SCAPULARIS ROUTES OF EXPANSION 0 125 250 500 Kilometers
Min. Minimum Temperature SD of Maximum Temperature Max Vapour Pressure DATABASE DISTRIBUTION OF IXODES SCAPULARIS Dennis et al. 1998 J. Med. Entomol. 35:629
AUTOLOGISITC MODEL Variables: -Min. Maximum Temp -Mean Maximum Temp -Min. Mean Temp -Mean Minimum Temp -SD of Vapour Pressure Likelihood ratio: p<0.0001 Wald statistic: p<0.0001 Accuracy=95%
RECLASSIFICATION Brownstein et al. 2003 Environmental Health Perspectives 111: 1152-1157.
MODEL PROJECTIONS PRESENT 2020 2050 % CHANGE IN SUITABLE AREA NORTH AMERICA: +69% UNITED STATES: +28% CANADA: +213%
Year 2002 2001 2000 1999 1998 1997 1996 1995 1994 1993 1992 1991 1990 1989 1988 1987 1985 1984 Cohnsteadt, et al. 2007 In prep.
CELLULAR AUTOMATA MODEL FOR DISPERSAL Using host home range location and size to predict spread of ticks For each host: Density Home range: probability of moving from one cell to the other Average tick burden: number moved Legend T 2 1 km Mouse Home Range T 1 Deer Home Range Bird Home Range T 1 Ticks Starting Location
CONCLUSIONS Deer have the most significant role in moving ticks across the landscape Holding deer densities constant, mice may moderate dispersal caused by deer Robins had no significant effect in any modeled scenario Madhav, et al. 2004. J. Med. Entomol. 41:842
SUBURBANIZATION
FOREST FRAGMENTATION (CONNECTICUT) LANDSAT-TM LAND COVER CLASSIFICATION NYMPHAL TICK DENSITY 500 METER BUFFER FRAGSTATS GIS SOFTWARE Patch Size Patch Shape Complexity Patch Isolation Compare indices to sampled tick densities
Forest Fragmentation Predicts Nymphal I. scapularis density PATTERN METRIC ESTIMATE SIGNIFICANCE Patch Size Mean Patch Size -0.0077 P<0.05 Shape Complexity Isolation Mean Shape Index Mean Nearest Neighbor -0.4725 P<0.05 0.0065 P<0.01 Fit log linear models assuming Poisson distribution for nymphal count Brownstein et al. 2005 Oecologia 146: 469
Ixodes scapularis FEEDS ON HUMANS Westchester Co., NY Population 874,866 (1990) 178,889 bites/year (20.4 per 100 person-years) Campbell, et al., 1998. American Journal of Epidemiology 148: 1018-1026
Anaplasma phagocytophilum RESERVOIRS VECTOR PROCYON LOTOR SCIURUS CAROLINENSIS IXODES SCAPULARIS PEROMYSCUS LEUCOPUS DUMETELLA CAROLINENSIS
EMERGENCE OF HUMAN ANAPLASMOSIS 1987. First case of human infection with Ehrlichia canis, Detroit, MI Maeda, et al. New England Journal of Medicine 316:853-856. 1994. Six cases of granulocytotrophic ehrlichiosis (2 fatal) Minnesota and Wisconsin. Chen et al., Journal of Clinical Microbiology 1995 Human granulocytic ehrlichiosis in Connecticut: Report of a fatal case. Hardalo, et al. Clin Infect Dis.; 21:910-4. 1996 Human granulocytic ehrlichiosis: A case series from a medical center in New York state. AgueroRosenfeld. et. al. Annals of Internal Medicine 125: 904-908 1997. Prevalence of the agent of human granulocytic ehrlichiosis in ticks collected in 1984, NY and CT. Schwartz. et al., New England Journal of Medicine 337: 49-50
INFECTION PREVALENCE IN HOST-SEEKING Ixodes scapularis (%) STAGE SITE N A.p. B.b. BOTH EXP ADULT NY-95 100 53 52 26 27.5 ADULT NY-84 100 32 45 19 14.4 ADULT CT-1 251 8.3 52.6 6.5 4.4 ADULT CT-2 48 12.5 56.3 8.3 7 NYMPH NY-95 73 20 26 5.5 5.2 NYMPH CT-1 442 1.6 32.9 0.2 0.1 NYMPH CT-2 164 1.2 31.2 0 0.3 Schwartz et al. 1997 NEJM 337:49-50
Babesia microti VECTOR RESERVOIR IXODES SCAPULARIS PEROMYSCUS LEUCOPUS
BABESIOSIS EMERGENCE IN CONNECTICUT 1970 Babesiosis in a Massachusetts resident. Western et.al. N Engl J Med 283:854 6. Connecticut Cases 1989 Babesiosis in Eastern Connecticut. CDC MMWR 38:649 50. 2004 Babesiosis in Western Connecticut. Anderson & Magnarelli, Emerging Infectious Diseases 10: 545-546
SPREAD OF BABESIOSIS IN CONNECTICUT 1989 2004 8 km/yr ± 0 5 10 20 Km
PREVALENCE OF IXODES SCAPULARIS-BORNE PATHOGENS (NEW JERSEY) Pathogen % infected ticks B. Burgdorferi 43 A. phagocytophilum 17 B. microti 5 B. burgdorferi & A. phagocytophilum 6 B. burgdorferi & B. microti 2 A. phagocytophilum & B. microti 2 B. burgdorferi, A. phagocytophilum, & B. microti 0 Varde et al. 1998 Emerging Infections Diseases 4: 97-99
Are there I. scapularis-borne Pathogens with Potential for Emergence? FEEDS UPON HUMANS (20.4 per 100 person-years)
0.01 16S TURDI ANDERSONI AFZELII VALAISIANA PHYLOGENY TANUKII LUSITANIAE GARINII BISSETTI BURGDORFERI (N-40 CONTROL) SINICA JAPONICA ANSERINA 87 HERMSII SPOTTED OWL ISOLATE 85 TURICATAE 100 PARKERI FLORIDA DOG CORIACEAE MAXIMUM LIKELIHOOD TREE SELECTED BOOTSTRAP VALUES FROM NEIGHBOR JOINING 61 96 LONESTARI 99 MIYAMOTOI NEW BORRELIA PERSICA CROCIDURAE DUTTONI RECURRENTIS HISPANICA SPANISH ISOLATE
POWASSAN VIRUS VECTOR RESERVOIR http://www.entomology.cornell.edu/medent IXODES COOKEI MUSTELIDS
POTENTIAL FOR EMERGENCE OF POWASSAN VIRUS 1958 Powassan virus: isolation of virus from a fatal case of encephalitis. McLean, et Can Med Assoc J. 80:708-11 1979. Powassan virus in Ixodes cookei and Mustelidae in New England. Main,et al. J Wildl Dis 15: 585 591. 1996 Experimental transmission of Powassan virus (Flaviviridae) by Ixodes scapularis ticks. Costero, et al. Am J Trop Med Hyg 55: 536 546. 1997 A new tick-borne encephalitis-like virus infecting New England deer ticks. Ixodes dammini. Telford, et al. Emerg Infect Dis 3: 165 170 2000 Enzootic transmission of deer tick virus in New England. Ebel, et al. American Journal of Tropical Medicine And Hygiene 63 (1-2): 36-42 2001 Four cases of Powassan encephalitis from Maine and Vermont. Courteny et. al. Journal of the American Medical Association 286: 1962-3
POWASSAN VIRUS VECTOR RESERVOIR VECTOR IXODES COOKEI MUSTELIDS IXODES SCAPULARIS
FISHER Martes pennanti Extinct in mid-atlantic states in 1900 Reintroductions in Pa. and W. Va. Pest status in Connecticut Home range >4,000 ha (males)
POWASSAN VIRUS VECTORS RESERVOIR? IXODES SCAPULARIS IXODES COOKEI MARTES PENNANTI
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