Vector Of Lyme Disease Research Articles

First Detection of Lyme Disease Spirochete Borrelia burgdorferi in Ticks Collected from a Raptor in Canada

During a pan‒Canadian tick‒host study, the authors detected the spirochetal bacterium Borrelia burgdorferi sensu lato, which causes Lyme disease, in ticks from a raptor. Lyme disease is one of a number of zoonotic, tick‒borne diseases causing morbidity and mortality worldwide. Larvae of the avian coastal tick, Ixodes auritulus, were collected by wildlife rehabilitators from a Cooper’s hawk, Accipter cooperii, on Vancouver Island, British Columbia. Using PCR [polymerase chain reaction] amplification of the linear plasmid ospA gene of B. burgdorferi, 4 (18%) of 22 larvae were positive. Since these engorged I. auritulus larvae had not had a previous blood meal and B. burgdorferi is rarely transmitted from infected female ticks to their progeny, authors propose that Cooper’s hawks are reservoir‒ competent hosts of B. burgdorferi. Authors’ tick‒host discovery provides the first report of bird‒feeding ticks on a Cooper’s hawk, and exhibits the premier record of B. burgdorferi‒positive ticks on a raptor. Not only are passerine (perching) and gallinaceous (chicken‒like) birds included in the wide dispersal of Lyme disease vector ticks, raptors also now are implicated in the dissemination of B. burgdorferi‒infected ticks. Although I. auritulus does not bite humans, this tick species plays an integral role in the four‒tick enzootic cycle of B. burgdorferi along the West Coast of America. In essence, raptors and I. auritulus ticks may help to amplify this infectious agent in nature, and increase the likelihood of people contracting Lyme Disease, especially in coastal areas.

Emergence of Ixodes scapularis and Borrelia burgdorferi, the Lyme disease vector and agent, in Ohio.

Lyme disease, the most common vector-borne disease in the United States, is caused by a tick-borne infection with Borrelia burgdorferi. Currently, Ohio is considered by the Centers for Disease Control and Prevention (CDC) to be non-endemic for Lyme disease. The low incidence of Lyme disease in this state was largely attributed to the absence of the transmitting vector, Ixodes scapularis, commonly known as the blacklegged tick. However, a tick surveillance program established by Ohio Department of Health indicated that the number of I. scapularis in Ohio had increased sharply in recent years, from 0 - 5 ticks per year during 1983–2008 to 15 in 2009, 40 in 2010, and 184 in 2011. During the fall deer hunting season, examination of deer heads submitted to Ohio Department of Agriculture found 29 I. scapularis from 7 counties in 2010 and 1,830 from 25 counties in 2011. As of 2012, the tick had been found in 57 of the 88 counties of Ohio. In addition, all three active stages (larva, nymph, and adult) of I. scapularis were found in Tiverton Township of Coshocton County, demonstrating the presence of established tick populations at this central Ohio location. Of 530 nymphal or adult I. scapularis analyzed by quantitative polymerase chain reaction (qPCR), 32 (6.1%) tested positive for the B. burgdorferi flaB gene, ranging from 36 to 390,000 copies per tick. Antibodies to B. burgdorferi antigens were detected in 2 of 10 (20%) field-captured Peromyscus leucopus from Tiverton Township, and in 41 of 355 (11.5%) dogs residing in Ohio. Collectively, these data suggest that the enzootic life cycle of B. burgdorferi has become established in Ohio, which poses risk of Lyme disease to people and animals in the area.

Population genetic structure of the Lyme disease vector Ixodes scapularis at an apparent spatial expansion front

Modeling and empirical evidence suggests that Lyme disease is undergoing geographic expansion from principal foci in the midwestern and northeastern United States. Virginia is at the southern edge of the current expansion zone and has seen dramatic rise in human Lyme disease cases since 2007, potentially owing to a recent increase in vector abundance. Ixodes scapularis is known throughout the eastern US but behavioral or physiological variation between northern and southern lineages might lead northern-variant ticks to more frequently parasitize humans. We hypothesized that recent spatial and numerical increase in Lyme disease cases is associated with demographic and/or spatial expansion of I. scapularis and that signals of these phenomena would be detectable and discernable in population genetic signals. In summer and fall 2011, we collected nymphal I. scapularis by drag sampling and adult I. scapularis from deer carcasses at hunting check stations at nine sites arranged along an east–west transect through central Virginia. We analyzed 16S mtDNA sequences data from up to 24 I. scapularis individuals collected from each site and detected a total of 24 haplotypes containing 29 segregating sites. We found no evidence for population genetic structure among these sites but we did find strong signals of both demographic and spatial expansion throughout our study system. We found two haplotypes (one individual each) representing a lineage of ticks that is only found in the southeastern United States, with the remaining individuals representing a less genetically diverse clade that is typical of the northern United States, but that has also been detected in the American South. Taken together, these results lead us to conclude that I. scapularis populations in Virginia are expanding and that this expansion may account for recent observed increases in Lyme disease.

Estimated Effects of Projected Climate Change on the Basic Reproductive Number of the Lyme Disease Vector Ixodes scapularis

Background: The extent to which climate change may affect human health by increasing risk from vector-borne diseases has been under considerable debate.Objectives: We quantified potential effects of future climate change on the basic reproduction number (R0) of the tick vector of Lyme disease, Ixodes scapularis, and explored their importance for Lyme disease risk, and for vector-borne diseases in general.Methods: We applied observed temperature data for North America and projected temperatures using regional climate models to drive an I. scapularis population model to hindcast recent, and project future, effects of climate warming on R0. Modeled R0 increases were compared with R0 ranges for pathogens and parasites associated with variations in key ecological and epidemiological factors (obtained by literature review) to assess their epidemiological importance.Results: R0 for I. scapularis in North America increased during the years 1971–2010 in spatio-temporal patterns consistent with observations. Increased temperatures due to projected climate change increased R0 by factors (2–5 times in Canada and 1.5–2 times in the United States), comparable to observed ranges of R0 for pathogens and parasites due to variations in strains, geographic locations, epidemics, host and vector densities, and control efforts.Conclusions: Climate warming may have co-driven the emergence of Lyme disease in northeastern North America, and in the future may drive substantial disease spread into new geographic regions and increase tick-borne disease risk where climate is currently suitable. Our findings highlight the potential for climate change to have profound effects on vectors and vector-borne diseases, and the need to refocus efforts to understand these effects.Citation: Ogden NH, Radojević M, Wu X, Duvvuri VR, Leighton PA, Wu J. 2014. Estimated effects of projected climate change on the basic reproductive number of the Lyme disease vector Ixodes scapularis. Environ Health Perspect 122:631–638; http://dx.doi.org/10.1289/ehp.1307799

The effectiveness of permethrin-treated deer stations for control of the Lyme disease vector Ixodes scapularis on Cape Cod and the islands: a five-year experiment.

BackgroundThe use of animal host-targeted pesticide application to control blacklegged ticks, which transmit the Lyme disease bacterium between wildlife hosts and humans, is receiving increased attention as an approach to Lyme disease risk management. Included among the attractive features of host-targeted approaches is the reduced need for broad-scale pesticide usage. In the eastern USA, one of the best-known of these approaches is the corn-baited “4-poster” deer feeding station, so named because of the four pesticide-treated rollers that surround the bait troughs. Wildlife visitors to these devices receive an automatic topical application of acaricide, which kills attached ticks before they can reproduce. We conducted a 5-year controlled experiment to estimate the effects of 4-poster stations on tick populations in southeastern Massachusetts, where the incidence of Lyme disease is among the highest in the USA.MethodsWe deployed a total of forty-two 4-posters among seven treatment sites and sampled for nymph and adult ticks at these sites and at seven untreated control sites during each year of the study. Study sites were distributed among Cape Cod, Martha’s Vineyard, and Nantucket. The density of 4-poster deployment was lower than in previous 4-poster studies and resembled or possibly exceeded the levels of effort considered by county experts to be feasible for Lyme disease risk managers.ResultsRelative to controls, blacklegged tick abundance at treated sites was reduced by approximately 8.4%, which is considerably less than in previous 4-poster studies.ConclusionsIn addition to the longer duration and greater replication in our study compared to others, possible but still incomplete explanations for the smaller impact we observed include the lower density of 4-poster deployment as well as landscape and mammalian community characteristics that may complicate the ecological relationship between white-tailed deer and blacklegged tick populations.

Adverse moisture events predict seasonal abundance of Lyme disease vector ticks (Ixodes scapularis).

BackgroundLyme borreliosis (LB) is the most commonly reported vector-borne disease in north temperate regions worldwide, affecting an estimated 300,000 people annually in the United States alone. The incidence of LB is correlated with human exposure to its vector, the blacklegged tick (Ixodes scapularis). To date, attempts to model tick encounter risk based on environmental parameters have been equivocal. Previous studies have not considered (1) the differences between relative humidity (RH) in leaf litter and at weather stations, (2) the RH threshold that affects nymphal blacklegged tick survival, and (3) the time required below the threshold to induce mortality. We clarify the association between environmental moisture and tick survival by presenting a significant relationship between the total number of tick adverse moisture events (TAMEs - calculated as microclimatic periods below a RH threshold) and tick abundance each year.MethodsWe used a 14-year continuous statewide tick surveillance database and corresponding weather data from Rhode Island (RI), USA, to assess the effects of TAMEs on nymphal populations of I. scapularis. These TAMEs were defined as extended periods of time (>8 h below 82% RH in leaf litter). We fit a sigmoid curve comparing weather station data to those collected by loggers placed in tick habitats to estimate RH experienced by nymphal ticks, and compiled the number of historical TAMEs during the 14-year record.ResultsThe total number of TAMEs in June of each year was negatively related to total seasonal nymphal tick densities, suggesting that sub-threshold humidity episodes >8 h in duration naturally lowered nymphal blacklegged tick abundance. Furthermore, TAMEs were positively related to the ratio of tick abundance early in the season when compared to late season, suggesting that lower than average tick abundance for a given year resulted from tick mortality and not from other factors.ConclusionsOur results clarify the mechanism by which environmental moisture affects blacklegged tick populations, and offers the possibility to more accurately predict tick abundance and human LB incidence. We describe a method to forecast LB risk in endemic regions and identify the predictive role of microclimatic moisture conditions on tick encounter risk.

A case of massive infestation of a male green lizard Lacerta viridis/bilineata by castor bean tick Ixodes ricinus (Linnaeus, 1758)

Infestation by ticks affects several vertebrate groups, including reptiles. Castor bean tick Ixodes ricinus is the most widespread tick species. Here we report an impressive tick infestation of a male green lizard Lacerta viridis/bilineata found in 2012 in the vicinity of Bilpa cave in the Kolpa valley, Slovenia. Lizards as tick hosts can play an important role in the life cycle of I. ricinus and may also be potential vectors of Lyme disease.

Purification of a serine protease and evidence for a protein C activator from the saliva of the tick, Ixodes scapularis

The saliva of ticks is critical to their survival as parasites and hematophagous animals. In this study, we have purified an enzyme with trypsin-like activity from the saliva of the tick vector of Lyme Disease, Ixodes scapularis. This enzyme, named as IXOSP (I. scapularis salivary serine protease), is a 29.9 kDa molecule with N-terminus FPxMVxLRIKxR. A BLAST search identified IXOSP as a secreted serine protease (AAY66740) with a conserved catalytic triad His, Asp, and Ser. In vitro studies demonstrated that IXOSP cleaves chromogenic substrates with arginine in the P1 position, by a mechanism inhibited by PMSF or aprotinin. Gene expression studies revealed that IXOSP is expressed at different tick developmental stages, including eggs, and unfed or fed adult tick salivary glands, but not in nymphs or in the midgut. While the physiological substrate for IXOSP remains to be identified, we demonstrated that I. scapularis saliva activate protein C (PC) resulting in the production of activated PC, a potent anticoagulant that also regulates a myriad of inflammatory responses through protease activated receptors. In contrast, the salivary glands of Anopheles gambiae, Anopheles stephensi, Anopheles albimanus, Aedes aegypti, Lutzomyia longipalpis, and Phlebotomus ariasi did not activate protein C. These discoveries are discussed in the context of blood coagulation, inflammation and vector–host interactions.

Functional and Genetic Characterization of Neuropeptide Y-Like Receptors in Aedes aegypti

BackgroundFemale Aedes aegypti mosquitoes are the principal vector for dengue fever, causing 50–100 million infections per year, transmitted between human and mosquito by blood feeding. Ae. aegypti host-seeking behavior is known to be inhibited for three days following a blood meal by a hemolymph-borne humoral factor. Head Peptide-I is a candidate peptide mediating this suppression, but the mechanism by which this peptide alters mosquito behavior and the receptor through which it signals are unknown.Methodology/Principal FindingsHead Peptide-I shows sequence similarity to short Neuropeptide-F peptides (sNPFs) that have been implicated in feeding behaviors and are known to signal through Neuropeptide Y (NPY)-Like Receptors (NPYLRs). We identified eight NPYLRs in the Ae. aegypti genome and screened each in a cell-based calcium imaging assay for sensitivity against a panel of peptides. Four of the Ae. aegypti NPYLRs responded to one or more peptide ligands, but only NYPLR1 responded to Head Peptide-I as well as sNPFs. Two NPYLR1 homologues identified in the genome of the Lyme disease vector, Ixodes scapularis, were also sensitive to Head Peptide-I. Injection of synthetic Head Peptide-I and sNPF-3 inhibited host-seeking behavior in non-blood-fed female mosquitoes, whereas control injections of buffer or inactive Head Peptide-I [Cys10] had no effect. To ask if NPYLR1 is necessary for blood-feeding-induced host-seeking inhibition, we used zinc-finger nucleases to generate five independent npylr1 null mutant strains and tested them for behavioral abnormalities. npylr1 mutants displayed normal behavior in locomotion, egg laying, sugar feeding, blood feeding, host seeking, and inhibition of host seeking after a blood meal.ConclusionsIn this work we deorphanized four Ae. aegypti NPYLRs and identified NPYLR1 as a candidate sNPF receptor that is also sensitive to Head Peptide-I. Yet npylr1 alone is not required for host-seeking inhibition and we conclude that other receptors, additional peptides, or both, regulate this important behavior.

Spatially-Explicit Simulation Modeling of Ecological Response to Climate Change: Methodological Considerations in Predicting Shifting Population Dynamics of Infectious Disease Vectors.

Poikilothermic disease vectors can respond to altered climates through spatial changes in both population size and phenology. Quantitative descriptors to characterize, analyze and visualize these dynamic responses are lacking, particularly across large spatial domains. In order to demonstrate the value of a spatially explicit, dynamic modeling approach, we assessed spatial changes in the population dynamics of Ixodes scapularis, the Lyme disease vector, using a temperature-forced population model simulated across a grid of 4 × 4 km cells covering the eastern United States, using both modeled (Weather Research and Forecasting (WRF) 3.2.1) baseline/current (2001–2004) and projected (Representative Concentration Pathway (RCP) 4.5 and RCP 8.5; 2057–2059) climate data. Ten dynamic population features (DPFs) were derived from simulated populations and analyzed spatially to characterize the regional population response to current and future climate across the domain. Each DPF under the current climate was assessed for its ability to discriminate observed Lyme disease risk and known vector presence/absence, using data from the US Centers for Disease Control and Prevention. Peak vector population and month of peak vector population were the DPFs that performed best as predictors of current Lyme disease risk. When examined under baseline and projected climate scenarios, the spatial and temporal distributions of DPFs shift and the seasonal cycle of key questing life stages is compressed under some scenarios. Our results demonstrate the utility of spatial characterization, analysis and visualization of dynamic population responses—including altered phenology—of disease vectors to altered climate.

Belowground herbivory in red pine stands initiates a cascade that increases abundance of Lyme disease vectors

There is increasing recognition that infectious disease patterns are often driven by complex underlying ecological processes. In red pine plantations in the Great Lakes region of North America, feeding by rhizophagous insects triggers a cascade that ultimately results in higher densities of blacklegged ticks, Ixodes scapularis, which are the primary vector of the Lyme disease pathogen Borrelia burgdorferi. We sampled 31 plantations in Wisconsin, USA, that were diseased or asymptomatic for a previously described tree mortality syndrome that originates with root infestation. Understory vegetation was greater in diseased stands, as were the proportion of samples containing ticks and the number of ticks per sample. Infection rates with B. burgdorferi were consistent. Tick densities were identical between declining and healthy portions of symptomatic stands, suggesting stand-level factors are responsible, consistent with mammal movement. These results suggest that forest management practices that affect the dynamics of belowground food webs may have implications for human health.

Meningoencephalitis Caused by

In recent years, Borrelia miyamotoi has been detected in Lyme disease vectors worldwide, and human illness attributed to this organism has been

Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry for Rapid Identification of Tick Vectors

A method for rapid species identification of ticks may help clinicians predict the disease outcomes of patients with tick bites and may inform the decision as to whether to administer postexposure prophylactic antibiotic treatment. We aimed to establish a matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) spectrum database based on the analysis of the legs of six tick vectors: Amblyomma variegatum, Rhipicephalus sanguineus, Hyalomma marginatum rufipes, Ixodes ricinus, Dermacentor marginatus, and Dermacentor reticulatus. A blind test was performed on a trial set of ticks to identify specimens of each species. Subsequently, we used MALDI-TOF MS to identify ticks obtained from the wild or removed from patients. The latter tick samples were also identified by 12S ribosomal DNA (rDNA) sequencing and were tested for bacterial infections. Ticks obtained from the wild or removed from patients (R. sanguineus, I. ricinus, and D. marginatus) were accurately identified using MALDI-TOF MS, with the exception of those ticks for which no spectra were available in the database. Furthermore, one damaged specimen was correctly identified as I. ricinus, a vector of Lyme disease, using MALDI-TOF MS only. Six of the 14 ticks removed from patients were found to be infected by pathogens that included Rickettsia, Anaplasma, and Borrelia spp. MALDI-TOF MS appears to be an effective tool for the rapid identification of tick vectors that requires no previous expertise in tick identification. The benefits for clinicians include the more targeted surveillance of patients for symptoms of potentially transmitted diseases and the ability to make more informed decisions as to whether to administer postexposure prophylactic treatment.

Developing a temperature-driven map of the basic reproductive number of the emerging tick vector of Lyme disease Ixodes scapularis in Canada

A mechanistic model of the tick vector of Lyme disease, Ixodes scapularis, was adapted to a deterministic structure. Using temperature normals smoothed by Fourier analysis to generate seasonal temperature-driven development rates and host biting rates, and a next generation matrix approach, the model was used to obtain values for the basic reproduction number (R0) for I. scapularis at locations in southern Canada where the tick is established and emerging. The R0 at Long Point, Point Pelee and Chatham sites where I. scapularis are established, was estimated at 1.5, 3.19 and 3.65, respectively. The threshold temperature conditions for tick population survival (R0=1) were shown to be the same as those identified using the mechanistic model (2800–3100 cumulative annual degree days >0°C), and a map of R0 for I. scapularis, the first such map for an arthropod vector, was drawn for Canada east of the Rocky Mountains. This map supports current risk assessments for Lyme disease risk emergence in Canada. Sensitivity analysis identified host abundance, tick development rates and summer temperatures as highly influential variables in the model, which is consistent with our current knowledge of the biology of this tick. The development of a deterministic model for I. scapularis that is capable of providing values for R0 is a key step in our evolving ability to develop tools for assessment of Lyme disease risk emergence and for development of public health policies on surveillance, prevention and control.

Geographical and environmental factors driving the increase in the Lyme disease vector Ixodes scapularis.

The population densities of many organisms have changed dramatically in recent history. Increases in the population density of medically relevant organisms are of particular importance to public health as they are often correlated with the emergence of infectious diseases in human populations. Our aim is to delineate increases in density of a common disease vector in North America, the blacklegged tick, and to identify the environmental factors correlated with these population dynamics. Empirical data that capture the growth of a population are often necessary to identify environmental factors associated with these dynamics. We analyzed temporally- and spatially-structured field collected data in a geographical information systems framework to describe the population growth of blacklegged ticks (Ixodes scapularis) and to identify environmental and climatic factors correlated with these dynamics. The density of the ticks increased throughout the study's temporal and spatial ranges. Tick density increases were positively correlated with mild temperatures, low precipitation, low forest cover, and high urbanization. Importantly, models that accounted for these environmental factors accurately forecast future tick densities across the region. Tick density increased annually along the south-to-north gradient. These trends parallel the increases in human incidences of diseases commonly vectored by I. scapularis. For example, I. scapularis densities are correlated with human Lyme disease incidence, albeit in a non-linear manner that disappears at low tick densities, potentially indicating that a threshold tick density is needed to support epidemiologically-relevant levels of the Lyme disease bacterium. Our results demonstrate a connection between the biogeography of this species and public health.

Discovery of antagonists of tick dopamine receptors via chemical library screening and comparative pharmacological analyses

Ticks transmit a wide variety of disease causing pathogens to humans and animals. Considering the global health impact of tick-borne diseases, there is a pressing need to develop new methods for vector control. We are exploring arthropod dopamine receptors as novel targets for insecticide/acaricide development because of their integral roles in neurobiology. Herein, we developed a screening assay for dopamine receptor antagonists to further characterize the pharmacological properties of the two D1-like dopamine receptors (Isdop1 and Isdop2) identified in the Lyme disease vector, Ixodes scapularis, and develop a screening assay for receptor antagonists. A cell-based, cyclic AMP luciferase reporter assay platform was implemented to screen the LOPAC1280 small molecule library for Isdop2 receptor antagonists, representing the first reported chemical library screen for any tick G protein-coupled receptor. Screening resulted in the identification of 85 “hit” compounds with antagonist activity at the Isdop2 receptor. Eight of these chemistries were selected for confirmation assays using a direct measurement of cAMP, and the effects on both Isdop1 and Isdop2 were studied for comparison. Each of these eight compounds showed antagonistic activity at both Isdop1 and Isdop2, although differences were observed regarding their relative potencies. Furthermore, comparison of the pharmacological properties of the tick dopamine receptors with that of the AaDOP2 receptor from the yellow fever mosquito and the human dopamine D1 receptor (hD1) revealed species-specific pharmacological profiles of these receptors. Compounds influencing dopaminergic functioning, such as the dopamine receptor antagonists discovered here, may provide lead chemistries for discovery of novel acaricides useful for vector control.

Predicting the speed of tick invasion: an empirical model of range expansion for the Lyme disease vector Ixodes scapularis in Canada

Summary1. Over the past two decades, Ixodes scapularis, the primary tick vector of the Lyme disease pathogen Borrelia burgdorferi in North America has expanded its range northward from the USA to colonize new regions in southern Canada. We have previously projected range increases for I. scapularis based on temperature suitability, but to what extent this is matched by actual tick range expansion is unknown.2. Since 1990, I. scapularis ticks have been collected across Canada offering a unique opportunity to track the range expansion of an arthropod vector. We used these data to model time‐to‐establishment for tick populations across Canada to identify factors influencing the rate of spread.3. Our results point to both long‐distance dispersal of ticks by migratory birds and local dispersal by resident hosts as important potential mechanisms underlying patterns of tick range expansion.4. Temperature (accumulated degree days > 0 °C) was the most important determinant of environmental suitability for tick population establishment, suggesting that climate warming may facilitate range expansion.5. Model projections suggest that I. scapularis range will expand c. 46 km year−1 in the coming decade, with climate warming expected to increase the rate of spread. This expansion is likely to result in a substantial increase in human Lyme disease risk, with the proportion of the human population of eastern Canada inhabiting areas with established tick populations increasing from 18% in 2010 to over 80% by 2020.6. This first empirical model of I. scapularis invasion supports theoretical range projections based on climate suitability and provides a unique data‐driven estimate of the speed of northward range expansion for I. scapularis at the continental scale.7. Synthesis and applications. By tracking I. scapularis invasion in Canada over the past two decades, we show that I. scapularis is rapidly expanding its range and is likely to colonize the most densely populated areas of southern Canada in the coming decade. These projections suggest that prompt action is necessary to prepare the Canadian public for a likely epidemic of Lyme disease, with emphasis on focusing surveillance activities to confirm the locations of emerging Lyme disease risk.

Research brief

Accurate information about the spatial pattern of risk of infection with Borrelia burgdorferi, the tick-borne bacterium that causes Lyme disease, is hard to obtain with human case reporting because of under-reporting and misdiagnosis. Now, researchers have constructed a Lyme disease risk map for the eastern USA by using standardised field sampling to estimate the density of B burgdorferi-infected host-seeking Ixodes scapularis (the Lyme disease vector) throughout the tick's range. Their map, which identifies infection risk foci in the northeast and upper midwest regions, should help to guide surveillance, control, and prevention efforts.

Development of a host blood meal database: de novo sequencing of hemoglobin from nine small mammals using mass spectrometry

We report the successful de novo sequencing of hemoglobin using a mass spectrometry-based approach combined with automatic data processing and manual validation for nine North American species with currently unsequenced genomes. The complete α and β chain of all nine mammalian hemoglobin samples used in this study were successfully sequenced. These sequences will be appended to the existing database containing all known hemoglobins to be used for identification of the mammalian host species that provided the last blood meal for the tick vector of Lyme disease, Ixodes scapularis.

Species Distribution Models and Ecological Suitability Analysis for Potential Tick Vectors of Lyme Disease in Mexico

Species distribution models were constructed for ten Ixodes species and Amblyomma cajennense for a region including Mexico and Texas. The model was based on a maximum entropy algorithm that used environmental layers to predict the relative probability of presence for each taxon. For Mexico, species geographic ranges were predicted by restricting the models to cells which have a higher probability than the lowest probability of the cells in which a presence record was located. There was spatial nonconcordance between the distributions of Amblyomma cajennense and the Ixodes group with the former restricted to lowlands and mainly the eastern coast of Mexico and the latter to montane regions with lower temperature. The risk of Lyme disease is, therefore, mainly present in the highlands where some Ixodes species are known vectors; if Amblyomma cajennense turns out to be a competent vector, the area of risk also extends to the lowlands and the east coast.