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Previously, a high prevalence of piroplasms has been reported from Florida pumas (Puma concolor coryi) from southern Florida. In the current study, we describe the biological characteristics of a novel Babesia species in Florida pumas. Ring-stage trophozoites were morphologically similar to trophozoites of numerous small babesids of felids including B. leo, B. felis, and Cytauxzoon felis. Parasitemias in Florida pumas were very low (<1%) and hematologic values of 25 Babesia-infected Florida pumas were within normal ranges for P. concolor. Phylogenetic analysis of near full-length 18S rRNA gene, ß-tubulin, cytochrome c oxidase subunit I, cytochrome c oxidase subunit III, and cytochrome b gene sequences indicated that this Babesia species is a member of the Babesia sensu stricto clade and is related to groups of Babesia spp. from carnivores or ungulates, although the closest group varied by gene target. Internal transcribed spacer (ITS)-1 region sequences from this Babesia sp. from 19 Florida pumas were 85.7-99.5% similar to each other and â¼88% similar to B. odocoilei. Similarly, an ITS-2 sequence from one puma was 96% similar to B. bigemina and 92% similar to a Babesia sp. from a red panda (Ailurus fulgens). Infected pumas were positive for antibodies that reacted with B. odocoilei, B. canis, and B. bovis antigens with titers of 1:256, 1:128, and 1:128, respectively. No serologic reactivity was noted for Theileria equi. No molecular evidence of congenital infection was detected in 24 kittens born to 11 Babesia-infected female pumas. Pumas from other populations in the United States [Louisiana (n = 1), North Dakota (n = 5) and Texas (n = 28)], British Columbia, Canada (n = 9), and Costa Rica (n = 2) were negative for this Babesia sp. Collectively, these data provide morphologic, serologic, genetic, and natural history data for this novel Babesia sp. which we propose the name Babesia coryicola sp. nov. sp. This is the first description of a felid-associated Babesia species in North America.
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Powassan virus (POWV) is an emerging tick-borne encephalitic virus in Lyme disease-endemic sites in North America. Due to range expansion and local intensification of blacklegged tick vector (Ixodes scapularis) populations in the northeastern and upper midwestern U.S., human encephalitis cases are increasingly being reported. A better understanding of the transmission cycle between POWV and ticks is required in order to better predict and understand their public health burden. Recent phylogeographic analyses of POWV have identified geographical structuring, with well-defined northeastern and midwestern clades of the lineage II subtype. The extent that geographic and genetically defined sublineages differ in their ability to infect and be transmitted by blacklegged ticks is unclear. Accordingly, we determined whether there are strain-dependent differences in the transmission of POWV to ticks at multiple life stages. Five recent, low-passage POWV isolates were used to measure aspects of vector competence, using viremic and artificial infection methods. Infection rates in experimental ticks remained consistent between all five isolates tested, resulting in a 12-20% infection rate and some differences in viral load. We confirm that these differences are likely not due to differences in host viremia. Our results demonstrate that blacklegged ticks are susceptible to, and capable of transmitting, all tested strains and suggest that the tick-virus association is stable across diverse viral genotypes.
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Vírus da Encefalite Transmitidos por Carrapatos , Encefalite Transmitida por Carrapatos , Ixodes , Animais , Ixodes/virologia , Vírus da Encefalite Transmitidos por Carrapatos/genética , Vírus da Encefalite Transmitidos por Carrapatos/classificação , Vírus da Encefalite Transmitidos por Carrapatos/fisiologia , Encefalite Transmitida por Carrapatos/transmissão , Encefalite Transmitida por Carrapatos/virologia , Humanos , Feminino , Vetores Aracnídeos/virologiaRESUMO
Borrelia burgdorferi, a Lyme disease spirochete, causes a range of acute and chronic maladies in humans. However, a primary vertebrate reservoir in the United States, the white-footed deermouse Peromyscus leucopus, is reported not to have reduced fitness following infection. Although laboratory strains of Mus musculus mice have successfully been leveraged to model acute human Lyme disease, the ability of these rodents to model B. burgdorferi-P. leucopus interactions remains understudied. Here, we compared infection of P. leucopus with B. burgdorferi B31 with infection of the traditional B. burgdorferi murine models-C57BL/6J and C3H/HeN Mus musculus, which develop signs of inflammation akin to human disease. We find that B. burgdorferi was able to reach much higher burdens (10- to 30-times higher) in multiple M. musculus skin sites and that the overall dynamics of infection differed between the two rodent species. We also found that P. leucopus remained transmissive to larval Ixodes scapularis for a far shorter period than either M. musculus strain. In line with these observations, we found that P. leucopus does launch a modest but sustained inflammatory response against B. burgdorferi in the skin, which we hypothesize leads to reduced bacterial viability and rodent-to-tick transmission in these hosts. Similarly, we also observe evidence of inflammation in infected P. leucopus hearts. These observations provide new insight into reservoir species and the B. burgdorferi enzootic cycle.IMPORTANCEA Lyme disease-causing bacteria, Borrelia burgdorferi, must alternate between infecting a vertebrate host-usually rodents or birds-and ticks. In order to be successful in that endeavor, the bacteria must avoid being killed by the vertebrate host before it can infect a new larval tick. In this work, we examine how B. burgdorferi and one of its primary vertebrate reservoirs, Peromyscus leucopus, interact during an experimental infection. We find that B. burgdorferi appears to colonize its natural host less successfully than conventional laboratory mouse models, which aligns with a sustained seemingly anti-bacterial response by P. leucopus against the microbe. These data enhance our understanding of P. leucopus host-pathogen interactions and could potentially serve as a foundation to uncover ways to disrupt the spread of B. burgdorferi in nature.
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Borrelia burgdorferi , Reservatórios de Doenças , Doença de Lyme , Camundongos Endogâmicos C3H , Camundongos Endogâmicos C57BL , Peromyscus , Animais , Peromyscus/microbiologia , Camundongos , Doença de Lyme/microbiologia , Doença de Lyme/transmissão , Doença de Lyme/veterinária , Borrelia burgdorferi/fisiologia , Borrelia burgdorferi/genética , Reservatórios de Doenças/microbiologia , Modelos Animais de Doenças , Ixodes/microbiologiaRESUMO
This clinical insights article examines reasons behind the increase in tick-borne diseases and what clinicians should know about diagnosis and mitigation.
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Doenças Transmitidas por Carrapatos , Humanos , Doenças Transmitidas por Carrapatos/epidemiologia , Doenças Transmitidas por Carrapatos/prevenção & controle , Animais , Carrapatos , Fatores de RiscoRESUMO
Ixodes scapularis ticks are an important vector for at least six tick-borne human pathogens, including the predominant North American Lyme disease spirochete Borrelia burgdorferi . The ability for these ticks to survive in nature is credited, in part, to their ability to feed on a variety of hosts without excessive activation of the proinflammatory branch of the vertebrate immune system. While the ability for nymphal ticks to feed on a variety of hosts has been well-documented, the host-parasite interactions between larval I. scapularis and different vertebrate hosts is relatively unexplored. Here we report on the changes in the vertebrate transcriptome present at the larval tick bite site using the natural I. scapularis host Peromyscus leucopus deermouse, a non-natural rodent host Mus musculus (BALB/c), and humans. We note substantially less evidence of activation of canonical proinflammatory pathways in P. leucopus compared to BALB/c mice and pronounced evidence of inflammation in humans. Pathway enrichment analyses revealed a particularly strong signature of interferon gamma, tumor necrosis factor, and interleukin 1 signaling at the BALB/c and human tick bite site. We also note that bite sites on BALB/c mice and humans, but not deermice, show activation of wound-healing pathways. These data provide molecular evidence of the coevolution between larval I. scapularis and P. leucopus as well as expand our overall understanding of I. scapularis feeding. Significance: Ixodes scapularis tick bites expose humans to numerous diseases in North America. While larval tick feeding enables pathogens to enter the tick population and eventually spread to humans, how larval ticks interact with mammals has been understudied compared to other tick stages. Here we examined the transcriptomic response of a natural I. scapularis rodent host ( Peromyscus leucopus ), a non-native I. scapularis rodent host ( Mus musculus ), and an incidental host (humans). We find that there are differences in how all three species respond to larval I. scapularis , with the natural host producing the smallest transcriptomic signature of a canonical proinflammatory immune response and the incidental human host producing the most robust signature of inflammation in response to the larval tick. These data expand our understanding of the pressures on ticks in the wild and inform our ability to model these interactions in laboratory settings.
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The critical nature of the microbiology laboratory in infectious disease diagnosis calls for a close, positive working relationship between the physician and the microbiologists who provide enormous value to the health care team. This document, developed by experts in both adult and pediatric laboratory and clinical medicine, provides information on which tests are valuable and in which contexts, and on tests that add little or no value for diagnostic decisions. Sections are divided into anatomic systems, including Bloodstream Infections and Infections of the Cardiovascular System, Central Nervous System Infections, Ocular Infections, Soft Tissue Infections of the Head and Neck, Upper Respiratory Infections, Lower Respiratory Tract infections, Infections of the Gastrointestinal Tract, Intraabdominal Infections, Bone and Joint Infections, Urinary Tract Infections, Genital Infections, and Skin and Soft Tissue Infections; or into etiologic agent groups, including arboviral Infections, Viral Syndromes, and Blood and Tissue Parasite Infections. Each section contains introductory concepts, a summary of key points, and detailed tables that list suspected agents; the most reliable tests to order; the samples (and volumes) to collect in order of preference; specimen transport devices, procedures, times, and temperatures; and detailed notes on specific issues regarding the test methods, such as when tests are likely to require a specialized laboratory or have prolonged turnaround times. In addition, the pediatric needs of specimen management are also addressed. There is redundancy among the tables and sections, as many agents and assay choices overlap. The document is intended to serve as a reference to guide physicians in choosing tests that will aid them to diagnose infectious diseases in their patients.
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Survivors of Powassan encephalitis often have persistent neurological disease. A new mouse model replicates some elements of the human disease and demonstrates the presence of viral RNA in the brain as well as myelitis more than 2 mo after the acute infection. The related tick-borne encephalitis and West Nile Neuroinvasive Disease (WNND) also have common neurological sequelae, and models for these better-studied diseases provide evidence for prolonged virus, RNA, and inflammation in some cases, in addition to damage from the acute encephalitic disease. A better understanding of the biological basis for persistent signs and symptoms after Powassan encephalitis, currently a rare disease, could benefit from further studies of the more prevalent flaviviral encephalitides.
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Vírus da Encefalite Transmitidos por Carrapatos , Encefalite Transmitida por Carrapatos , Infecções por Flavivirus , Doenças do Sistema Nervoso , Animais , Camundongos , Humanos , Vírus da Encefalite Transmitidos por Carrapatos/genética , Camundongos Endogâmicos C57BLRESUMO
Near-infrared spectroscopy (NIRS), coupled with modeling and chemometrics, has been used to age grade anopheline and aedine mosquitoes; however, NIRS has not been widely used in field studies to assign mosquitoes to age classes. One reason is the relative cost of NIRS spectrometers. We developed a spectrometer system incorporating a miniature optical engine generating spectra in the shortwave infrared region, calibrated it using laboratory-reared Aedes aegypti, and evaluated its utility to age grade wild-caught cattail mosquitoes, Coquillettidia perturbans. As a refinement of the method, we compared a scoring system based on spectral data point outliers with the typical chemometrics that have been used with NIRS. This inexpensive system (<$3,600) could reliably discriminate between age cohorts of mosquitoes and has the potential for more detailed age grading. Laboratory-reared Ae. aegypti demonstrated a decline in the fraction of spectral outliers with age, and field-collected Cq. perturbans similarly demonstrated such a decline (greater in newly emerged mosquitoes) with date of collection, consistent with their univoltine demography in Massachusetts. We conclude that an economical NIRS system may be able to provide a quantitative dichotomous (young versus old) assessment of field-collected mosquito samples, and thereby may be used to complement abundance-based analyses of the efficacy of adulticiding applications.
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Aedes , Animais , Espectroscopia de Luz Próxima ao Infravermelho/métodos , MassachusettsRESUMO
The burden of ticks and the pathogens they carry is increasing worldwide. Powassan virus (POWV; Flaviviridae: Flavivirus), the only known North American tick-borne flavivirus, is of particular concern due to rising cases and the severe morbidity of POWV encephalitis. Here, we use a multifaceted approach to evaluate the emergence of the II POWV lineage, known as deer tick virus (DTV), in parts of North America where human cases occur. We detected DTV-positive ticks from eight of twenty locations in the Northeast USA with an average infection rate of 1.4 per cent. High-depth, whole-genome sequencing of eighty-four POWV and DTV samples allowed us to assess geographic and temporal phylodynamics. We observed both stable infection in the Northeast USA and patterns of geographic dispersal within and between regions. A Bayesian skyline analysis demonstrated DTV population expansion over the last 50 years. This is concordant with the documented expansion of Ixodes scapularis tick populations and suggests an increasing risk of human exposure as the vector spreads. Finally, we isolated sixteen novel viruses in cell culture and demonstrated limited genetic change after passage, a valuable resource for future studies investigating this emerging virus.
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Because deer are considered to be incompetent reservoirs of the agent of Lyme disease (Borrelia burgdorferi sensu stricto) in the northeastern United States, they may serve as zooprophylactic or "dilution" hosts if larvae of the deer tick vector (Ixodes dammini, "northern" clade of Ixodes scapularis) frequently feed on them. To determine whether host-seeking nymphal deer ticks commonly feed on deer as larvae, we used a real-time PCR host bloodmeal remnant identification assay to identify the host on which these ticks had fed. Nymphal lone star ticks (Amblyomma americanum) were collected simultaneously in our sites and provided an index of the availability of deer in these sites. At 3 of the 4 sites, Ixodes nymphs had fed as larvae on a variety of hosts, including mice, birds, and shrews, but rarely on deer (<6% for all sites); in contrast, lone star tick nymphs had commonly fed on deer (31 to 78%). Deer were common larval hosts for Ixodes ticks (39% of bloodmeals) in only one site. The prevalence of B. burgdorferi in host-seeking nymphal deer ticks was associated with mouse-fed ticks (P = 0.007), but there was no association with deer-fed ticks (P = 0.5). The diversity and prevalence of hosts that were identified differed between deer ticks and lone star ticks that were collected simultaneously, demonstrating that there is no confounding of host bloodmeal identification by contaminating environmental DNA (eDNA). We conclude that deer were not common hosts for larval deer ticks, thus limiting their zooprophylactic role in our sites. IMPORTANCE Because deer are incompetent reservoirs for B. burgdorferi, their presence may modulate the force of enzootic transmission by serving as zooprophylactic or "dilution" hosts. Such an effect would depend on the extent to which subadult deer ticks feed on other hosts. We used bloodmeal analysis on nymphal deer ticks to identify the host upon which larvae had fed. We found that lone star ticks collected at the same time as deer ticks commonly fed on deer, but deer ticks did not. We conclude that deer are not a preferred host for larval deer ticks and, thus, are not necessarily zooprophylactic.
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Borrelia burgdorferi , Ixodes , Doença de Lyme , Animais , Borrelia burgdorferi/genética , Doença de Lyme/prevenção & controle , Doença de Lyme/veterinária , Camundongos , New England/epidemiologia , NinfaRESUMO
In the northeastern United States, the emergence of Lyme disease has been associated, in part, with the increase of small forest patches. Such disturbed habitat is exploited by generalist species, such as white-footed mice, which are considered the host with the greatest reservoir capacity for the agents of Lyme disease (Borrelia burgdorferi sensu stricto) and human babesiosis (Babesia microti). Spatial risk analyses have identified edge habitat as particularly risky. Using a retrotransposon-based quantitative PCR assay for host bloodmeal remnant identification, we directly measured whether the hosts upon which vector ticks fed differed at the edge or within the contiguous small habitat patch. Questing nymphal deer ticks, Ixodes dammini, the northern clade of Ixodes scapularis, were collected from either the edge or within a thicket on Nantucket Island over 3 transmission seasons and tested for evidence of infection as well as bloodmeal hosts. Tick bloodmeal hosts significantly differed by site as well as by year. Mice and deer were identified most often (49.9%), but shrews, rabbits, and birds were also common. Ticks from the edge fed on a greater diversity of hosts than those from the thicket. Surprisingly, mice were not strongly associated with either infection at either sampling site (odds ratio [OR] < 2 for all). Although shrews were not the most common host utilized by ticks, they were highly associated with both infections at both sites (OR = 4.5 and 11.0 for B. burgdorferi and 7.9 and 19.0 for B. microti at the edge and thicket, respectively). We conclude that reservoir hosts may differ in their contributions to infecting ticks between edge and contiguous vegetated patches. IMPORTANCE Habitat fragmentation is thought to be a main factor in the emergence of Lyme disease and other deer tick-transmitted infections. The patchwork of forest and edges promotes altered biodiversity, favoring the abundance of generalist rodents, such as white footed mice, heretofore considered a key tick and reservoir host in the northeastern United States. We used tick bloodmeal analyses to directly identify the hosts from which nymphal deer ticks became infected. We demonstrate that there is considerable microfocality in host contributions to the cohort of infected ticks and that shrews, although they fed fewer ticks than mice, disproportionately influenced the force of pathogen transmission in our site. The venue of transmission of certain deer tick-transmitted agents may comprise a habitat scale of 10 m or fewer and depend on alternative small mammal hosts such as shrews.
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Babesia microti , Borrelia burgdorferi , Ixodes , Doença de Lyme , Animais , Babesia microti/genética , Borrelia burgdorferi/genética , Ecossistema , Humanos , Doença de Lyme/veterinária , Mamíferos , Camundongos , CoelhosRESUMO
Powassan virus lineage 2 (deer tick virus) is an emergent threat to American public health, causing severe neurologic disease. Its life cycle in nature remains poorly understood. We use a host-specific retrotransposon-targeted real time PCR assay to test the hypothesis that white-footed mice, considered the main eastern U.S. reservoir of the coinfecting agent of Lyme disease, is the reservoir for deer tick virus. Of 20 virus-infected host-seeking nymphal black-legged ticks 65% fed on shrews and none on mice. The proportion of ticks feeding on shrews at a site is positively associated with prevalence of viral infection, but not the Lyme disease agent. Viral RNA is detected in the brain of one shrew. We conclude that shrews are a likely reservoir host for deer tick virus and that host bloodmeal analysis can provide direct evidence to incriminate reservoir hosts, thereby promoting our understanding of the ecology of tick-borne infections.
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Reservatórios de Doenças/veterinária , Vírus da Encefalite Transmitidos por Carrapatos/fisiologia , Encefalite Transmitida por Carrapatos/veterinária , Musaranhos , Animais , Reservatórios de Doenças/virologia , Encefalite Transmitida por Carrapatos/epidemiologia , Encefalite Transmitida por Carrapatos/transmissão , Massachusetts/epidemiologia , Rhode Island/epidemiologiaRESUMO
Fifty years ago, the index case of human babesiosis due to Babesia microti was diagnosed in a summer resident of Nantucket Island. Human babesiosis, once called "Nantucket fever" due to its seeming restriction to Nantucket and the terminal moraine islands of southern New England, has emerged across the northeastern United States to commonly infect people wherever Lyme disease is endemic. We review the history of babesiosis on Nantucket, analyze its epidemiology and ecology there, provide summaries of the first case histories, and comment on its future public health burden.
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BACKGROUND: Powassan virus (POWV) is a tick-transmitted pathogen that may cause severe encephalitis; experimentally, it can be transmitted within just 15 minutes following a tick bite. The deer tick virus subtype of POWV (DTV) is transmitted by the deer tick and is the likely cause of the increase in the number of POWV cases reported in the United States. However, DTV has only been definitively documented in 6 patients by molecular analysis of the virus. METHODS: Two patients from Connecticut with encephalitis, who had a recent deer tick bite, were evaluated by the relevant serologic tests to determine if they had been infected with POWV. Evaluation also included molecular testing of an adult deer tick that had been removed from one of the patients. RESULTS: We documented neuroinvasive POWV infection in 2 children from Connecticut. Based on the results of testing the tick removed from case 2, this patient was infected by DTV, representing the 7th reported case and the first documented case of DTV infection in a child. Of note, the duration of the tick bites in both cases was very short. CONCLUSIONS: We provide the first clinical and epidemiologic evidence that POWV/DTV can be rapidly transmitted to a human host, that is, within hours of tick attachment, which is distinctive when compared to other deer tick-transmitted infections such as Lyme disease.
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Vírus da Encefalite Transmitidos por Carrapatos , Encefalite Transmitida por Carrapatos , Ixodes , Animais , Criança , Connecticut/epidemiologia , Encefalite Transmitida por Carrapatos/epidemiologia , HumanosRESUMO
Deer tick-transmitted Borrelia burgdorferisensu stricto (Lyme disease) and Babesia microti (babesiosis) increasingly burden public health across eastern North America. The white-footed mouse is considered the primary host for subadult deer ticks and the most important reservoir host for these and other disease agents. Local transmission is thought to be modulated by less reservoir-competent hosts, such as deer, diverting ticks from feeding on mice. We measured the proportion of mouse-fed or deer-fed host-seeking nymphs from 4 sites during 2 transmission seasons by blood meal remnant analysis using a new retrotransposon-based quantitative PCR (qPCR) assay. We then determined the host that was associated with the infection status of the tick. During the first year, the proportion of mouse-fed ticks ranged from 17% on mainland sites to 100% on an island, while deer-fed ticks ranged from 4% to 24%. The proportion of ticks feeding on mice and deer was greater from island sites than mainland sites (on average, 92% versus 43%). Mouse-fed ticks decreased significantly during year 2 in 3 of 4 sites (most were <20%), while deer-fed ticks increased for all sites (75% at one site). Overall, ticks were more likely to be infected when they had fed on mice (odds ratio [OR] of 2.4 and 1.6 for Borrelia and Babesia, respectively) and were less likely to be infected if they had fed on deer (OR, 0.8 and 0.4). We conclude that host utilization by deer ticks is characterized by significant spatiotemporal diversity, which may confound efficacy tests of interventions targeting reservoir hosts.IMPORTANCE White-footed mice are thought to be the most important reservoir host for the deer tick-transmitted pathogens that cause Lyme disease and human babesiosis because they are the primary host for immature ticks. Transmission would be reduced, however, if ticks feed on deer, which are not capable of infecting ticks with either pathogen. By directly measuring whether ticks had fed on either mice or deer using a new quantitative PCR (qPCR) assay to detect remnants of host DNA leftover from the larval blood meal, we demonstrate that host utilization by ticks varies significantly over time and space and that mice often feed fewer ticks than expected. This finding has implications for our understanding of the ecology of these diseases and for the efficacy of control measures.
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Babesia microti/isolamento & purificação , Borrelia burgdorferi/isolamento & purificação , Cervos , Ixodes/microbiologia , Peromyscus , Animais , DNA/análise , Cervos/sangue , Cervos/genética , Cervos/microbiologia , Feminino , New England , Ninfa/microbiologia , Peromyscus/sangue , Peromyscus/genética , Peromyscus/microbiologia , RetroelementosRESUMO
Lyme disease, caused by some Borrelia burgdorferi sensu lato, is the most common tick-borne illness in the Northern Hemisphere and the number of cases, and geographic spread, continue to grow. Previously identified B. burgdorferi proteins, lipid immunogens, and live mutants lead the design of canonical vaccines aimed at disrupting infection in the host. Discovery of the mechanism of action of the first vaccine catalyzed the development of new strategies to control Lyme disease that bypassed direct vaccination of the human host. Thus, novel prevention concepts center on proteins produced by B. burgdorferi during tick transit and on tick proteins that mediate feeding and pathogen transmission. A burgeoning area of research is tick immunity as it can unlock mechanistic pathways that could be targeted for disruption. Studies that shed light on the mammalian immune pathways engaged during tick-transmitted B. burgdorferi infection would further development of vaccination strategies against Lyme disease.
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Borrelia burgdorferi , Ixodes , Doença de Lyme , Carrapatos , Vacinas , Animais , Humanos , Doença de Lyme/prevenção & controle , VacinaçãoRESUMO
Tularemia is a Holarctic zoonosis caused by the gamma proteobacterium Francisella tularensis and is considered to be a vector-borne disease. In many regions, human risk is associated with the bites of flies, mosquitoes, or ticks. But the biology of the agent is such that risk may be fomite related, and large outbreaks can occur due to inhalation or ingestion of contaminated materials. Such well-documented human risk factors suggest a role for these risk factors in the enzootic cycle as well. Many arthropods support the growth or survival of the agent, but whether arthropods (ticks in particular) are obligately required for the perpetuation of F. tularensis remains to be demonstrated. As with most zoonoses, our knowledge of the ecology of F. tularensis has been driven with the objective of understanding human risk. In this review, we focus on the role of the arthropod in maintaining F. tularensis, particularly with respect to long-term enzootic persistence.
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Vetores Artrópodes/microbiologia , Francisella tularensis , Tularemia/transmissão , Animais , Evolução Biológica , Tularemia/epidemiologiaRESUMO
Subtropical lone star tick larvae typically emerge in late summer. We found clusters of host-seeking lone star tick larvae during early June 2018 in New York and Massachusetts, USA. Invasion and persistence of this tick in more northern locations may have been promoted by adaptation to an accelerated life cycle.