Diversity of tick species biting humans in an emerging area for Lyme disease.

Smith, Robert P.; Lacombe, Eleanor H.; Rand, Peter W.; Dearborn, Richard G.

doi:10.2105/ajph.82.1.66

Cited by 40 publications

(17 citation statements)

References 30 publications

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“…Biting of humans by I. dentatus is extremely rare in comparison to the numbers of bites people receive from I. scapularis and D. variabilis in the United States (16,51) and has been reported for at least 19 people across Michigan (61, 63); North Carolina (27); West Virginia (22); Washington, DC (53); Connecticut (2); and Maine (31). Given the paucity of direct human biting by the cryptic vector, epidemiological significance of a cryptic cycle is contingent upon the presence of a bridging vector that will share hosts with the cryptic vector and bridge the pathogen to humans.…”

Section: Discussionmentioning

confidence: 99%

Diverse Borrelia burgdorferi Strains in a Bird-Tick Cryptic Cycle

Hamer

Hickling

Sidge

et al. 2011

Appl Environ Microbiol

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The blacklegged tick Ixodes scapularis is the primary vector of the most prevalent vector-borne zoonosis in North America, Lyme disease (LD). Enzootic maintenance of the pathogen Borrelia burgdorferi by I. scapularis and small mammals is well documented, whereas its "cryptic" maintenance by other specialist ticks and wildlife hosts remains largely unexplored because these ticks rarely bite humans. We quantified B. burgdorferi infection in a cryptic bird-rabbit-tick cycle. Furthermore, we explored the role of birds in maintaining and moving B. burgdorferi strains by comparing their genetic diversity in this cryptic cycle to that found in cycles vectored by I. scapularis. We examined birds, rabbits, and small mammals for ticks and infection over a 4-year period at a focal site in Michigan, 90 km east of a zone of I. scapularis invasion. We mist netted 19,631 birds that yielded 12,301 ticks, of which 86% were I. dentatus, a bird-rabbit specialist. No resident wildlife harbored I. scapularis, and yet 3.5% of bird-derived ticks, 3.6% of rabbit-derived ticks, and 20% of rabbit ear biopsy specimens were infected with B. burgdorferi. We identified 25 closely related B. burgdorferi strains using an rRNA gene intergenic spacer marker, the majority (68%) of which had not been reported previously. The presence of strains common to both cryptic and endemic cycles strongly implies bird-mediated dispersal. Given continued large-scale expansion of I. scapularis populations, we predict that its invasion into zones of cryptic transmission will allow for bridging of novel pathogen strains to humans and animals.

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Section: Discussionmentioning

confidence: 99%

Diverse Borrelia burgdorferi Strains in a Bird-Tick Cryptic Cycle

Hamer

Hickling

Sidge

et al. 2011

Appl Environ Microbiol

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“…Our work documents the establishment of I. scapularis populations followed by the emergence of B. burgdorferi on an island on the coast of Maine where neither had previously been found (Rand et al 1991;Smith et al 1992). In this report, we include the unique description of the evolution of B. burgdorferi strain diversity within a newly established population of hard ticks in the isolated setting of island ecology.…”

Section: Introductionmentioning

confidence: 86%

Genotypic Diversity of an Emergent Population ofBorrelia burgdorferiat a Coastal Maine Island Recently Colonized byIxodes scapularis

MacQueen

Lubelczyk²,

Elias³

et al. 2012

Vector-Borne and Zoonotic Diseases

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The recent range expansion of Ixodes scapularis has been accompanied by the emergence of Borrelia burgdorferi. The development of genetic diversity in B. burgdorferi at these sites of emergence and its relationship to range expansion is poorly understood. We followed colonization of I. scapularis on a coastal Maine island over a 17-year period. B. burgdorferi's emergence was documented, as was expansion of ospC strain diversity. Ticks collected from rodents and vegetation were examined for the presence of B. burgdorferi. Sequencing and reverse line blot were used to detect B. burgdorferi ospC major groups (oMG). No I. scapularis were found until year four of the study, after which time they increased in abundance. No B. burgdorferi was detected by darkfield microscopy in I. scapularis until 10 years into the study, when 4% of adult ticks were infected. Seven years later, 43% of adult ticks were infected. In 2003, one oMG accounted for 91% of B. burgdorferi strains. This "founder" strain persisted in 2005, but by 2007 was a minority of the 7 oMGs present. Given the island's isolation, gene flow by avian introduction of multiple strains is suggested in the development of B. burgdorferi oMG diversity.

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“…For example, nymphs recovered from humans included both I. scapularis and Ixodes cookei Packard in Connecticut (Magnarelli and Anderson 1989), both I. scapularis and Amblyomma americanum (L.) in New York and Maryland (Falco 1987, Falco and Fish 1988b, Armstrong et al 2001), and multiple Ixodes spp.— I. cookei, I. scapularis, Ixodes marxi Banks, and Ixodes muris (Bishopp and Smith)—in Maine (Smith et al 1992). Moreover, I. cookei has been reported to bite humans also in Michigan, New York, Vermont, and West Virginia (Hall et al 1991, Sood et al 1997, Walker et al 1998, Lubelczyk et al 2010), and bites by A. americanum occurs commonly in the Mid-Atlantic States (Merten and Durden 2000, Schulze et al 2006, Rossi et al 2015).…”

Section: Risk Measures Based On Collection Of Ticks From Humansmentioning

confidence: 99%

“…Moreover, I. cookei has been reported to bite humans also in Michigan, New York, Vermont, and West Virginia (Hall et al 1991, Sood et al 1997, Walker et al 1998, Lubelczyk et al 2010), and bites by A. americanum occurs commonly in the Mid-Atlantic States (Merten and Durden 2000, Schulze et al 2006, Rossi et al 2015). Ixodes scapularis accounted for most (83–94%) of the nymphs recovered from humans in Connecticut and New York (Magnarelli and Anderson 1989, Falco 1987, Falco and Fish 1988b), whereas they made up only a small proportion (<10%) of the human-biting nymphs in Maine and Maryland (Smith et al 1992, Armstrong et al 2001). Based on data from United States Armed Forces personnel, which may be less reflective of residential settings as compared with the data from civilians presented above, I. scapularis (with no distinction with regards to life stage) accounted for 79–92% of recognized human bites in the Connecticut-Rhode Island-New York-Massachusetts area; ~45% of bites in the Minnesota-Wisconsin-Ohio area; 10–20% of bites in the Mid-Atlantic States of Pennsylvania, New Jersey, Delaware, Maryland, Washington D.C., and Virginia (northern part of the state); and 2–7% of bites in southern Virginia, North Carolina, and South Carolina (Rossi et al 2015).…”

Section: Risk Measures Based On Collection Of Ticks From Humansmentioning

confidence: 99%

Critical Evaluation of the Linkage Between Tick-Based Risk Measures and the Occurrence of Lyme Disease Cases: Table 1.

Eisen

2016

J Med Entomol

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The nymphal stage of the blacklegged tick, Ixodes scapularis Say, is considered the primary vector to humans in the eastern United States of the Lyme disease spirochete Borrelia burgdorferi sensu stricto. The abundance of infected host-seeking nymphs is commonly used to estimate the fundamental risk of human exposure to B. burgdorferi, for the purpose of environmental risk assessment and as an outcome measure when evaluating environmentally based tick or pathogen control methods. However, as this tick-based risk measure does not consider the likelihoods of either human encounters with infected ticks or tick bites resulting in pathogen transmission, its linkage to the occurrence of Lyme disease cases is worth evaluating. In this Forum article, we describe different tick-based risk measures, discuss their strengths and weaknesses, and review the evidence for their capacity to predict the occurrence of Lyme disease cases. We conclude that: 1) the linkage between abundance of host-seeking B. burgdorferi-infected nymphs and Lyme disease occurrence is strong at community or county scales but weak at the fine spatial scale of residential properties where most human exposures to infected nymphs occur in Northeast, 2) the combined use of risk measures based on infected nymphs collected from the environment and ticks collected from humans is preferable to either one of these risk measures used singly when assessing the efficacy of environmentally based tick or pathogen control methods aiming to reduce the risk of human exposure to B. burgdorferi, 3) there is a need for improved risk assessment methodology for residential properties that accounts for both the abundance of infected nymphs and the likelihood of human–tick contact, and 4) we need to better understand how specific human activities conducted in defined residential microhabitats relate to risk for nymphal exposures and bites.

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Diversity of tick species biting humans in an emerging area for Lyme disease.

Cited by 40 publications

References 30 publications

Diverse Borrelia burgdorferi Strains in a Bird-Tick Cryptic Cycle

Diverse Borrelia burgdorferi Strains in a Bird-Tick Cryptic Cycle

Genotypic Diversity of an Emergent Population ofBorrelia burgdorferiat a Coastal Maine Island Recently Colonized byIxodes scapularis

Critical Evaluation of the Linkage Between Tick-Based Risk Measures and the Occurrence of Lyme Disease Cases: Table 1.

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