Tick bite prevention and control Howard S. Ginsberg, Ph.D. USGS Patuxent Wildlife Research Center Coastal Field Station, Woodward Hall PLS University of Rhode Island Kingston, RI 2881 USA hginsberg@usgs.gov
Lyme disease Overall increase in the number of human cases from 1982 through 25 see: Piesman & Eisen. 28. Annual Review of Entomology 53:323-343.
Trends in numbers of Lyme cases reported to the CDC, by state at sites of original reports 5 4 3 2 1 CT R 2 =.19 199 1995 2 25 21 1 8 6 4 2 RI R 2 =.649 199 1995 2 25 21 NY R 2 =.115 6 5 4 3 2 1 199 1995 2 25 21
Trends in numbers of Lyme cases reported to the CDC, by state adjacent to sites of original reports MA 4 R 2 =.833 3 2 1 199 1995 2 25 21 4 3 NJ R 2 =.753 2 1 199 1995 2 25 21 4 3 PA R 2 =.6362 2 1 199 1995 2 25 21
Tick Bite Prevention and Control Discussion Points: 1) Geographical dimensions of tick bite and associated health concerns in the southeastern U.S. distribution of ticks and tick-borne pathogens to help focus efforts geographically 2) Targeting tick control efforts what can be done, and getting people to do it? 3) Effectiveness of tick control efforts in southern environments 4) Prioritize research questions related to tick management in the southern U.S.
Approaches to managing ticks and tick-borne pathogens - Self-protection precautions - Habitat manipulation - Manipulation of host populations - Biological control - Pesticide applications - broadcast - host-targeted
Self protection precautions Avoidance Repellents Vaccination
Habitat distribution of Ixodes scapularis 4 3 ADULTS PER SAMPLE 2 1 WOODS SHRUB MEADOW.8.6 NYMPHS PER SAMPLE.4.2 WOODS SHRUB/MEADOW plotted from Ginsberg & Ewing. 1989. Journal of Medical Entomology 26:183-189.
Lyme disease incidence among Fire Island National Seashore staff (n~55) Before intervention: Seroconversion appx. 12% per year Intervention: Identification of high-risk habitats; active Safety Committee requiring buddy system for tick checks, protective clothing in high-risk habitats, use of repellents, tick check, showering and changing into fresh clothes after work day, easy access to medical attention. After intervention: No cases of Lyme disease for subsequent two years. One case the third year.
Effects of education on self-protection practices and tick bite Significance of change between first and second visit Intervention protective behavior tick bite Protective clothing at home.3.18 away from home.7.3 Repellent at home.1.27 away from home <.1.21 Reported self-efficacy at tick protection <.1.77 modified from: Malouin et al. 23. American Journal of Epidemiology 157:139-151.
from: Ginsberg. 1993. American Journal of Epidemiology 138:65-73.
Habitat manipulation Backyard environment Backyard barriers Clear paths
Manipulation of host populations White-tailed deer: - hunting - exclusion by fencing
Nymphal Ixodes scapularis inside and outside of deer exclosures, Fire Island National Seashore, NY MEAN NO. TICKS PER SAMPLE 4 3 2 1 ** * * INSIDE OUTSIDE 1994 1995 1996 1997 1998 1999 2 from: Ginsberg et al. 24. Environmental Entomology 33:1266-1273.
Nymphal Amblyomma americanum inside and outside of deer exclosures, Fire Island National Seashore, NY (** p <.1) 3 2 Outside Inside 1 ** ** ** 1994 1995 1996 1997 1998 1999 * 2 from: Ginsberg et al. 22. Journal of Vector Ecology 27:215-221.
Fluctuation of Ixodes scapularis populations at three northeastern sites 3 NYMPH DENSITY 2 1 1987 1988 1989 199 1991 1992 1993 1994 from: Ginsberg et al. 1998. Science 281:349-35. Fire Island Prudence Island Westchester
Biological control parasitoid wasps Ixodiphagus hookeri nematodes Steinernema glaseri fungi Verticillium lecanii bacteria Bacillus thuringiensis
Metarhizium anisopliae from: Zhioua et al. 1997. Journal of Parasitology 83:815-818.
Metarhizium anisopliae Potential nontarget effects Hippodamia convergens from : Ginsberg et al. 22. Environmental Entomology 31:1191-1196.
Effectiveness of pesticide applications broadcast host-targeted
Table 4. Acaricides with products labeled for the control of ticks in the residential landscape. Chemical Some brand names* Chemical type and usage Bifenthrin Talstar Ortho product Pyrethroid insecticide. Available as liquid and granular formulations. Products available for homeowner use and commercial applicators. Carbaryl Sevin Carbamate insecticide. A common garden insecticide for homeowner use, some products are for commercial use only. Cyfluthrin Tempo Pyrethroid insecticide. Available for commercial Powerforce and homeowner use with concentrates and ready to spray (RTS) products. Deltramethrin Suspend A pyrethroid insecticide for commercial applicators DeltaGard G. lambda- Scimitar A pyrethroid insecticide for commercial applicators. cyhalothrin Demand Permethrin Astro Pyrethroid insecticide. There are concentrates Ortho products and ready to spray (RTS) products. Most are for Bonide products Tengard SFR Others homeowner use, a few are for commercial use only. Pyrethrin Pyrenone Natural pyrethrins with the synergist piperonyl Kicker butoxide (PBO) or insecticidal soap provide limited Organic Solutions All tick control. A combination of pyrethrin and Crop Commercial & PBO with either insecticidal soap or silicon dioxide Agricultural Multipurpose (from diatomaceous earth) was found effective Insecticide against ticks in one trial. ( from: Stafford. 24. Tick Management Handbook. CT Agr. Exp. Stn.)
Targeting broadcast applications in space Tick stage habitat Black-legged tick adult 1.5 up in vegetation, especially along animal trails nymph leaf litter closed canopy woods and thickets Lone star tick adult throughout vegetation in wooded and open habitats nymph similar to adults American dog tick adult throughout vegetation in wooded and open habitats, especially along animal trails
Targeting broadcast applications in time
Host-targeted methods Rodents Permethrin-treated cotton balls Bait boxes Deer 4-poster
INTEGRATED PEST MANAGEMENT Traditional agricultural model Keep pests below Economic Injury Level: COST / BENEFIT = 1 Vector-borne diseases Minimize number of cases: COST-EFFICIENCY ANALYSIS
IPM for tick-borne diseases purpose of management examples analysis decision-making protect commodity ticks on cattle, cost/benefit lower vector numbers larval ticks in effective, costcausing nuisance efficient manner in tourist area manage vector-borne ticks carrying costdiseases of humans Lyme disease, efficiency Rocky Mountain Spotted Fever allocate available resources to maximally lower the number of human cases of disease
IPM for tick-borne diseases of humans Integrate techniques so as to efficiently lower probability of exposure to pathogen P e = 1 (1 k v ) n P e = probability of being bitten by at least one infected vector k v = proportion of vectors infected with pathogen (=prevalence) n = number of vector bites
Probability of exposure to pathogen PROBABILITY OF EXPOSURE 1.8.6.4 k v =.5 k v =.25 k v =.1.2 k v =.1 5 1 15 2 NUMBER OF TICK BITES Modified from: Ginsberg. 1993. American Journal Of Epidemiology 138:65-73
Fire Island, New York Initial choice Initial conditions: P e =.12 k v =.321 n =.33 Technique Efficacy Source Resulting P e self-protection lowers n 92% Dattwyler pers. comm..96 PTC lowers k v 86% Ginsberg 1992.15 barrier lowers n 64% Carroll et al. 1992.45 exclude deer lowers n 35% Ginsberg et al. 24.78
Fire Island, New York Integrating techniques After implementing self-protection program: P e =.1 k v =.321 n =.26 Technique Efficacy Resulting P e PTC lower k v 86%.12 barrier lower n 64%.36 exclude deer lower n 35%.66
Efficient integration of management methods - 1 Efficacy linear: Declining marginal efficacy: PROPORTIONAL REDUCTION 1.8.6 low er n or k v.4.2.2.4.6.8 1 COST 1.8 lower n or k v.6 P e.3.2.4.2.2.4.6.8 1 COST P e 1.8.6.4.2 n=5 kv=.5 n=5 kv=.5.2.4.6.8 1 n =5 k v =.25 n=5 kv=.5 n=5 kv=.5.1 n =5, k v =.1 low er k.2.4.6.8 1 v low er n COST
Efficient integration of management methods - 2 LOWERING k v TWICE AS EXPENSIVE LOWERING k v TWICE AS EXPENSIVE One method more expensive: 1.8.6 lower n lower k v.4.2.2.4.6.8 1 COST P e 1.8.6.4.2 n =1 k v =.25 n =5 k v =.25 n =1 k v =.1 n =5 k v =.1 lower k v.2.4.6.8 lower 1n COST Different methods have different efficacy schedules 1 low er k.8 v.6.4.2 low er n.2.4.6.8 1 COST P e 1.8.6.4.2 low er kv.2.4.6.8 low er n1 COST
Integrated Pest Management Comparisons of management techniques Efficacy/cost of management Efficient integration of methods Applicability Environmental effects
Efficient management of vector-borne diseases Conservation Well-targeted interventions: Less need for large-scale, broad-spectrum control measures (minimizes nontarget effects) Public health Greater cost-effectiveness: Fewer people get sick