[Show abstract][Hide abstract] ABSTRACT: The etiological agents that cause human babesiosis (Babesia microti) and Lyme disease (Borrelia burgdorferi) share a common tick vector (Ixodes scapularis Say) and rodent reservoir (Peromyscus leucopus), but because the geographical distribution of babesiosis is more restricted than Lyme disease, it was not considered a nationally notifiable disease until 2011. Although recent studies have shown dramatic increases in the number of cases of babesiosis and expansion of its range, little is known about infection and coinfection prevalence of these pathogens in the primary tick vector. Of the 478 I. scapularis nymphs collected within six Monmouth County, NJ, municipalities between 2004 and 2006, 4.0 and 10.0% were infected with B. microti and B. burgdorferi, respectively, while 2.9% were coinfected. Analysis of the 610 I. scapularis adults collected during the same period yielded an infection prevalence of 8.2% for B. microti and 45.2% for B. burgdorferi, while 6.2% were coinfected. The potential public health importance of these findings is discussed.
Full-text · Article · Mar 2013 · Journal of Medical Entomology
[Show abstract][Hide abstract] ABSTRACT: We conducted field trials to compare the relative repellent activity of two natural product compounds (nootkatone and carvacrol) with commercially available plant-derived (EcoSMART organic insect repellent) and permethrin-based (Repel Permanone) repellents against adult Ixodes scapularis Say and Amblyomma americanum (L.) (Acari: Ixodidae) by using treated coveralls. One day after treatment, nootkatone and carvacrol provided 100% repellency of I. scapularis adults, with nootkatone maintaining complete protection through 3 d, whereas carvacrol showed steadily declining repellency against I. scapularis during the 7-d course of the trials. Nootkatone was at least as effective against host-seeking A. americanum as against I. scapularis through 3 d. Carvacrol provided little protection against A. americanum adults. Both natural compounds performed well initially in comparison with the commercial products. After 7 d, nootkatone was the most effective against both species followed in order of activity by Permanone, EcoSMART, and carvacrol. Nootkatone seems to have offer considerable potential as a clothing repellent against both I. scapularis and A. americanum.
Full-text · Article · Jan 2012 · Journal of Medical Entomology
[Show abstract][Hide abstract] ABSTRACT: A field trial was conducted in a Lyme disease-endemic area of New Jersey to determine the efficacy of a doxycyline hyclate rodent bait to prophylactically protect and cure small-mammal reservoirs and reduce infection rates in questing Ixodes scapularis ticks for Borrelia burgdorferi and Anaplasma phagocytophilum. The doxycycline-laden bait was formulated at a concentration of 500 mg/kg and delivered during the immature tick feeding season in rodent-targeted bait boxes. The percentage of infected small mammals recovered from treated areas after 2 years of treatment was reduced by 86.9% for B. burgdorferi and 74% for A. phagocytophilum. Infection rates in questing nymphal ticks for both B. burgdorferi and A. phagocytophilum were reduced by 94.3% and 92%, respectively. Results from this study indicate that doxycycline-impregnated bait is an effective means of reducing infection rates for B. burgdorferi and A. phagocytophilum in both rodent reservoirs and questing I. scapularis ticks.
Full-text · Article · Dec 2011 · The American journal of tropical medicine and hygiene
[Show abstract][Hide abstract] ABSTRACT: We used two standard tick collection methods to test the relative effectiveness of two natural product compounds (nootkatone and carvacrol, classified as an eremophilene sesquiterpene and a monoterpene, respectively, that are derived from botanical sources) with commercially-available plant-derived (EcoSMART Organic Insect Repellent, comprised of plant essential oils) and permethrin-based (Repel Permanone) repellents against Ixodes scapularis Say and Amblyomma americanum (L.). Cloth drags were equally effective in sampling both species of host-seeking nymphs, whereas CO, traps attracted primarily A. americanum. All four repellents performed well on drags, with nootkatone and Permanone Repel (100% repelled through 14 d) slightly more effective than carvacrol and EcoSMART (90.7% and 97.7% repelled at 14 d, respectively) at repelling I. scapularis nymphs. Although the same trend in percent repellency was noted in the CO2 trap trial against both A. americanum nymphs and adults, EcoSMART outperformed Permanone in repelling A. Americanum nymphs after 14 d in the drag trial. Generally, the effectiveness of all repellents tested declined over time. The use of tick drags and CO2 traps was rapid, inexpensive, and easy to use in determining the relative effectiveness of repellents in the field.
No preview · Article · Dec 2011 · Journal of Economic Entomology
[Show abstract][Hide abstract] ABSTRACT: We used published accounts to describe the known statewide distribution of the lone star tick, Amblyomma americanum, in New Jersey and field surveys to characterize the geographical range of A. americanum and selected A. americanum-transmitted pathogens in Monmouth County, the hypothesized northern limit of the species distribution. Ticks were collected using standardized methods from 50 widely dispersed public access areas within 18 municipalities to produce estimates of relative abundance among sites. Collected A. americanum adults were stored at -80 degrees C until processed for DNA extraction. Individual ticks were subjected to polymerase chain reaction analyses to detect the presence of Ehrlichia chaffeensis, E. ewingii, Rickettsia amblyommii, and Borrelia lonestari. The range of A. americanum was generally limited to the southern half of New Jersey. Within Monmouth County, we collected A. americanum from 9 of 18 municipalities (50%) and 24 (48%) of the surveyed properties. We found at least 1 pathogen at 17 (70.8%) sites located within 6 of 9 municipalities, while all 4 target pathogens were detected in 5 of those 6 (83.3%) municipalities. The geographical distribution of A. americanum and its associated pathogens appeared to be restricted to the southern portion of the county. Possible factors governing the distribution are discussed.
Full-text · Article · Sep 2011 · Journal of the American Mosquito Control Association
[Show abstract][Hide abstract] ABSTRACT: We evaluated the ability of dual applications of natural, plant-derived acaricides to suppress nymphal Ixodes scapularis Say and Amblyomma americanum (L.) (Acari: Ixodidae) in a Lyme disease endemic area of New Jersey. An aqueous formulation of 2% nootkatone provided >90% control of I. scapularis through 7 d. Control declined to 80.9% at 14 d, and a second application was made that provided >95% control through the remaining 4 wk of the nymphal season. Nootkatone provided >90% control of A. americanum through 35 d postapplication. Applications of 2% carvacrol and EcoTrol T&O resulted in rapid knockdown of both tick species, but control declined significantly to 76.7 and 73.7%, respectively, after 14 d when a second application was made that extended control of both tick species to between 86.2 and 94.8% at 21 d. Subsequently, control declined steadily in all plots by 42 d postapplication except for I. scapularis in carvacrol-treated plots, where levels of control >90% were observed through 35 d. Of the three compounds tested, 2% nootkatone provided the most consistent results, with 96.5 and 91.9% control of I. scapularis and A. americanum through 42 and 35 d, respectively. The ability of plant-derived natural products to quickly suppress and maintain significant control of populations of these medically important ticks may represent a future alternative to the use of conventional synthetic acaricides. In addition, the demonstrated efficacy of properly-timed backpack sprayer application may enable homeowner access to these minimal-risk acaricides.
No preview · Article · Apr 2011 · Journal of Economic Entomology
[Show abstract][Hide abstract] ABSTRACT: We evaluated the ability of the natural, plant-derived acaricides nootkatone and carvacrol to suppress Ixodes scapularis Say and Amblyomma americanum (L.) (Acari: Ixodidae). Aqueous formulations of 1 and 5% nootkatone applied by backpack sprayer to the forest litter layer completely suppressed I. scapularis nymphs through 2 d. Thereafter, the level of reduction gradually declined to < or =50% at 28 d postapplication. Against A. americanum nymphs, 1% nootkatone was less effective, but at a 5% concentration, the level of control was similar or greater to that observed with I. scapularis through 21 d postapplication. Initial applications of 0.05% carvacrol were ineffective, but a 5% carvacrol formulation completely suppressed nymphs of both species through 2 d and resulted in significant reduction in I. scapularis and A. americanum nymphs through 28 and 14 d postapplication, respectively. Backpack sprayer applications of 5% nootkatone to the shrub and litter layers resulted in 100% control of I. scapularis adults through 6 d, but the level of reduction declined to 71.5% at 28 d postapplication. By contrast, high-pressure applications of 2% nootkatone to the litter layer resulted in 96.2-100% suppression of both I. scapularis and A. americanum nymphs through 42 d, whereas much lower control was obtained from the same formulation applied by backpack sprayer. Backpack sprayer application of a 3.1% nootkatone nanoemulsion resulted in 97.5-98.9 and 99.3-100% reduction in I. scapularis and A. americanum nymphs, respectively, at 1 d postapplication. Between 7 d and 35 d postapplication, the level of control varied between 57.1% and 92.5% for I. scapularis and between 78.5 and 97.1% for A. americanum nymphs. The ability of natural products to quickly suppress and maintain significant control of populations of these medically important ticks at relatively low concentrations may represent a future alternative to the use of conventional synthetic acaricides.
Full-text · Article · Dec 2009 · Journal of Economic Entomology
[Show abstract][Hide abstract] ABSTRACT: Twenty-five "4-Poster" feeders were placed throughout a 5.2 km(2) study area within a secured military facility situated in a hyperendemic area for Lyme disease in central Monmouth County, New Jersey. Calculated levels of control, relative to untreated areas, peaked at 82.7%, 77.3%, and 94.2% for of host-seeking Ixodes scapularis Say larvae, nymphs, and adults, respectively, within 5 years of deployment. Control of host-seeking Amblyomma americanum (L.) peaked at 99.2%, 89.5%, and 96.9% for larvae, nymphs, and adults, respectively, during the treatment period. Tick burdens on hunter-killed deer were significantly reduced on deer harvested from the treatment area and on deer that had consumed bait corn. Populations of subadult I. scapularis and A. americanum demonstrated some rebound effect following the removal of 4-Posters, but treatment area tick populations remained lower than control area populations 2 years following withdrawal of the 4-Posters. However, control of I. scapularis adults declined to 20.7% by the third fall activity period following removal of the 4-Posters. The posttreatment phase of the study was of insufficient duration to evaluate continued population rebound of adults and subadults during subsequent activity periods.
No preview · Article · Sep 2009 · Vector borne and zoonotic diseases (Larchmont, N.Y.)
[Show abstract][Hide abstract] ABSTRACT: We evaluated the effects of tick control by acaricide self-treatment of white-tailed deer on the infection prevalence and entomologic risk for three Ixodes scapularis-borne bacteria in host-seeking ticks. Ticks were collected from vegetation in areas treated with the "4-Poster" device and from control areas over a 6-year period in five geographically diverse study locations in the Northeastern United States and tested for infection with two known agents of human disease, Borrelia burgdorferi and Anaplasma phagocytophilum, and for a novel relapsing fever-group spirochete related to Borrelia miyamotoi. Overall, 38.2% of adults and 12.5% of nymphs were infected with B. burgdorferi; 8.5% of adults and 4.2% of nymphs were infected with A. phagocytophilum; and 1.9% of adults and 0.8% of nymphs were infected with B. miyamotoi. In most cases, treatment with the 4-Poster device was not associated with changes in the prevalence of infection with any of these three microorganisms among nymphal or adult ticks. However, the density of nymphs infected with B. burgdorferi, and consequently the entomologic risk for Lyme disease, was reduced overall by 68% in treated areas compared to control areas among the five study sites at the end of the study. The frequency of bacterial coinfections in ticks was generally equal to the product of the proportion of ticks infected with a single bacterium, indicating that enzootic maintenance of these pathogens is independent. We conclude that controlling ticks on deer by self-application of acaricide results in an overall decrease in the human risk for exposure to these three bacterial agents, which is due solely to a reduction in tick density.
[Show abstract][Hide abstract] ABSTRACT: Populations of Ixodes scapularis Say nymphs were surveyed at a Lyme disease- endemic area for 8 consecutive yr (1998-2005) to characterize annual changes in abundance. Precipitation and temperature were also monitored over the period 1998-2004 to determine their potential value as predictors of tick abundance. Although both parameters showed annual variation, no statistical differences in the annual abundance of I. scapularis nymphs were observed over the 8-yr period. Our results suggest that precipitation and temperature were not predictive of the abundance of I. scapularis nymphs.
Preview · Article · Sep 2009 · Journal of Medical Entomology
[Show abstract][Hide abstract] ABSTRACT: From 1997 to 2002, the U.S. Department of Agriculture's Northeast Area-wide Tick Control Project used acaricide-treated 4-Poster Deer Treatment Bait Stations in five eastern states to control ticks feeding on white-tailed deer. The objectives of this host-targeted technology were to reduce free-living blacklegged (Ixodes scapularis Say) and lone star (Amblyomma americanum [L.]) tick populations and thereby to reduce the risk of tick-borne disease. During 2002 to 2004, treatments were suspended, and tick population recovery rates were assayed. Subsequently, the major factors that influenced variations in efficacy were extrapolated to better understand and improve this technology. Treatments resulted in significant reductions in free-living populations of nymphal blacklegged ticks at six of the seven sites, and lone star ticks were significantly reduced at all three sites where they were present. During the study, maximal significant (p < or = 0.05) efficacies against nymphal blacklegged and lone star ticks at individual sites ranged from 60.0 to 81.7 and 90.9 to 99.5%, respectively. The major environmental factor that reduced efficacy was the occurrence of heavy acorn masts, which provided an alternative food resource for deer. Although the 4-Poster technology requires 1 or more years to show efficacy, this host-targeted intervention was demonstrated to be an efficacious, economical, safe, and environment-friendly alternative to area-wide spraying of acaricide to control free-living populations of these tick species.
[Show abstract][Hide abstract] ABSTRACT: As part of the Northeast Area-wide Tick Control Project (NEATCP), meta-analyses were performed using pooled data on the extent of tick-vector control achieved through seven concurrent studies, conducted within five states, using U.S. Department of Agriculture "4-Poster" devices to deliver targeted-acaricide to white-tailed deer. Although reductions in the abundance of all life-stages of Ixodes scapularis were the measured outcomes, this study focused on metrics associated with I. scapularis nymphal tick densities as this measure has consistently proven to directly correlate with human risk of acquiring Lyme disease. Since independent tick sampling schemes were undertaken at each of the five environmentally distinct study locations, a meta-analytic approach permitted estimation of a single true control-effect size for each treatment year of the NEATCP. The control-effect is expressed as the annual percent I. scapularis nymphal control most consistent with meta-analysis data for each treatment year. Our meta-analyses indicate that by the sixth treatment year, the NEATCP effectively reduced the relative density of I. scapularis nymphs by 71% on the 5.14 km(2) treatment sites, corresponding to a 71% lower relative entomologic risk index for acquiring Lyme disease.
[Show abstract][Hide abstract] ABSTRACT: Spring acaricide applications directed against nymphal Ixodes scapularis have been shown to be effective, but are perceived by the public as having significant adverse environmental impacts, particularly against nontarget organisms. Targeting the adult stage of I. scapularis in the fall would hypothetically result in indirect control of subsequent subadult stages while avoiding other arthropods that are typically inactive during this period. We demonstrate that single fall applications of deltamethrin for 3 consecutive years immediately reduced fall questing adults, while also rapidly reducing the abundance of all postembryonic stages. Deltamethrin applied to the shrub-layer vegetation resulted in levels of control between 97.1% and 100% at 7 days postapplication. Repeated applications against the reproductive stage of I. scapularis progressively reduced the abundance of larvae and nymphs in treated plots, reaching 91.4% and 100% by the conclusion of the study.
Full-text · Article · Jan 2009 · Journal of the American Mosquito Control Association
[Show abstract][Hide abstract] ABSTRACT: We monitored the abundance of Ixodes scapularis Say (Acari: Ixodidae) and the Lyme disease incidence rate after the incremental removal of white-tailed deer, Odocoileus virginianus Zimmermann, within a suburban residential area to determine whether there was a measurable decrease in the abundance of ticks due to deer removal and whether the reduction in ticks resulted in a reduction in the incidence rate within the human population. After three seasons, the estimated deer population was reduced by 46.7%, from the 2002 postfawning estimate of 2,899 deer (45.6 deer per km2) to a 2005 estimate of 1,540 deer (24.3 deer per km2). There was no apparent effect of the deer culling program on numbers of questing I. scapularis subadults in the culling areas, and the overall numbers of host-seeking ticks in the culling areas seemed to increase in the second year of the program. The Lyme disease incidence rate generated by both passive and active surveillance systems showed no clear trend among years, and it did not seem to vary with declining deer density. Given the resources required to mount and maintain a community-based program of sufficient magnitude to effectively reduce vector tick density in ecologically open situations where there are few impediments to deer movement, it may be that deer reduction, although serving other community goals, is unlikely to be a primary means of tick control by itself. However, in concert with other tick control interventions, such programs may provide one aspect of a successful community effort to reduce the abundance of vector ticks.
Preview · Article · Oct 2007 · Journal of Medical Entomology
[Show abstract][Hide abstract] ABSTRACT: In fall 2003, we began testing an integrated control strategy to rapidly achieve and sustain reduced numbers of Ixodes scapularis Say (Acari: Ixodidae) in a residential area. We combined two host-targeted technologies in conjunction with single, barrier acaricide applications to sequentially attack each postembryonic life stage of the tick. Granular deltamethrin applied to the lawn-forest interface of participant properties resulted in 100% control of host-seeking nymphs. Nymphal and larval tick burdens on targeted small mammal hosts at treated properties were reduced by 92.7 and 95.4%, respectively, after the first year (2004) of combined interventions. Over the same period, populations of host-seeking nymphs, larvae, and adults were reduced by 58.5, 24.8, and 77.8%, respectively. After interventions in 2005, tick burdens on small mammals were maintained at similar levels, whereas control of host-seeking nymphs, larvae, and adults increased to 94.3, 90.6, and 87.3%, respectively. Prospects for widespread use of these technologies to protect the public's health are discussed.
Full-text · Article · Oct 2007 · Journal of Medical Entomology
[Show abstract][Hide abstract] ABSTRACT: To evaluate their potential importance in the transmission of ixodid tick-borne borrelioses in Monmouth County, NJ, we collected host-seeking Ixodes scapularis Say and Amblyomma americanum (L.) (Acari: Ixodidae) adults and nymphs to determine relative encounter frequencies and the infection prevalence of selected Borrelia spp. in their respective tick vectors. We also reviewed records of all ticks submitted for identification by the public in Monmouth County during 2001-2005. Relative abundance of the two species varied markedly among sites. Adult encounter frequencies for the two species were similar; however, A. americanum nymphs were encountered 3 times more frequently than I. scapularis nymphs. Of 435 ticks submitted by the public, 50.1 and 38.9% were I. scapularis and A. americanum, respectively. However, during May through August, the peak Lyme disease transmission season in New Jersey, significantly more submitted ticks were A. americanum (55.9%), compared with I. scapularis (34.1%). Polymerase chain reaction analysis of 94 1. scapularis and 103 A. americanum adults yielded infection prevalences of 31.9% for B. burgdorferi and 5.8% for B. lonestari, respectively. Although the infection prevalence of B. burgdorferi in I. scapularis was considerably higher than the infection prevalence of B. lonestari in A. americanum, the higher encounter frequencies for A. americanum compared with I. scapularis observed in this and other studies may result in increased risk of acquiring exposure to A. americanum-transmitted pathogens. The potential public health implications of these results are discussed.
Full-text · Article · Dec 2006 · Journal of Medical Entomology
[Show abstract][Hide abstract] ABSTRACT: Ambyomma americanum (L.) (Acari: Ixodidae) is an aggressive tick that feeds on humans during all postembryonic life stages. In many regions of the United States, it is the tick most commonly found attached to humans. Public health interest has grown recently, due to the recognition of new human pathogens transmitted by A. americanum and the expanding distribution of the tick. A. americanum is a vector of several bacteria pathogenic to humans. Ehrlichia chaffeensis and Ehrlichia ewingii cause moderate-to-severe febrile illness. "Rickettsia amblyommii," a member of the spotted fever group Rickettsia, also has recently been implicated as a possible human pathogen based on serologic evidence from persons recovering from illness after a tick bite. We have determined the prevalence of infection of Ehrlichia chaffeensis, E. ewingii, "Borrelia lonestari", and R. amblyommii within A. americanum ticks from 29 sites in nine states. Overall infection prevalences were 4.7% for E. chaffeensis (range, 0-27%), 3.5% for E. ewingii (range, 0-18.6%), 2.5% for B. lonestari (range, 0-12.2%), and 41.2% for R. amblyommii (range, 0-84.0%). In addition, 87 ticks (4.3%) were infected with two or more bacteria. This report documents new distribution records for E. ewingii, B. lonestari, and R. amblyommii and underscores the nonhomogeneous distribution of pathogen foci of infection. Additional surveillance throughout the range ofA. americanum is warranted to increase physician and public awareness of the risk of disease to humans from exposure to the agents transmitted by this tick.
Full-text · Article · Dec 2006 · Journal of Medical Entomology
[Show abstract][Hide abstract] ABSTRACT: We live-trapped small mammals and flagged vegetation within wooded natural and residential landscapes to examine how any observed differences in small mammal species composition may influence Ixodes scapularis Say burdens and the abundance of host-seeking ticks. Two years of live trapping showed that Eastern chipmunks, Tamias striatus, were captured with significantly greater frequency in some residential areas than white-footed mice, Peromyscus leucopus, whereas the proportion of white-footed mouse captures was higher or similar to chipmunk captures in the undeveloped natural areas. Both mice and chipmunks seemed to adapt well to managed residential landscapes, with residential sites yielding similar or significantly greater numbers of captures compared with undeveloped sites. In areas where chipmunk captures outnumbered mice, larval tick burdens on mice were either higher or no different than in areas where few or no chipmunks were captured, in contrast to previous studies suggesting that alternate hosts should reduce larval burdens on mice. Chipmunks apparently play an important role in the Lyme disease transmission cycle in these residential settings.
Preview · Article · Dec 2005 · Journal of Medical Entomology