Cases Of Lyme Disease Research Articles

Assessing the infection rates and pathogenesis of Borrelia burgdorferi in wild rodents and ticks in Western Maryland

Abstract Lyme disease is the most prevalent vector-borne disease in the United States. The causative agent is the spirochete Borrelia burgdorferi. Many rodents are reservoir species that carry B. burgdorferi, through which immature ticks (Ixodes sp.) readily transmit the bacteria. Human cases of Lyme disease have dramatically increased over the past 10 years due to tick range expansion. Incidence has expanded from its New England origin into the Midwest and Mid-Atlantic. We hypothesized that Western Maryland is a prime candidate for B. burgdorferi expansion. To prepare, we sought to (1) determine the incidence of B. burgdorferi infection in wild rodent and tick populations in Western Maryland, (2) identify simple and quick methods for diagnosing B. burgdorferi infection in the field, and (3) gain insight into the pathogenesis of B. burgdorferi in wild rodent populations. DNA was extracted from 67 rodent blood samples and 202 ticks, collected from sites in Western Maryland. Approximately 35.14% of these samples tested positive for B. burgdorferi by PCR. Blood samples were tested for the presence of anti-B. burgdorferi antibody using SNAP 3Dx tests, a rapid ELISA-based veterinary diagnostic. Interestingly, the SNAP 3Dx tests were successful in identifying B. burgdorferi infection in both wild mice and chipmunks, suggesting that the capture antibody used in these canine tests is cross-reactive. Finally, whole B. burgdorferi bacteria were identified on frozen sections of wild mouse spleen by immunofluorescence. Bacteria were found throughout the red pulp and in splenic germinal centers of infected mice. Studies are underway to further characterize the infected cells in these samples.

Tick bite and Lyme disease-related emergency department encounters in New Hampshire, 2010-2014.

Lyme disease (LD) is a common tick-borne disease in New Hampshire (NH). While LD is a reportable condition and cases are counted for public health surveillance, many more people receive care for tick bites or diagnoses of LD than are reflected in surveillance data. NH's emergency department (ED) data system was queried for tick bite and LD-related encounters. Chief complaint text was queried for words related to LD or tick bites. International Classification of Diseases 9th Revision (ICD-9) codes were queried for the LD diagnosis code (088.81). Emergency department patient data were matched to reportable disease data to determine the proportion of ED patients reported to the health department as a suspected LD case. Data were analysed to calculate frequencies for key demographic and reporting characteristics. From 2010 to 2014, 13,615 tick bite or LD-related ED encounters were identified in NH, with most due to tick bites (76%). Of 3,256 patients with a LD-related ED encounter, 738 (23%) were reported to the health department as a suspected LD case. The geographic distribution of ED patients was similar to reported LD cases; however, the regions of the state that experienced higher rates of ED encounters were different than the regions that observed higher rates of reported LD cases. Seasonal distribution of ED encounters peaked earlier than reported LD cases with a second peak in the fall. While age and sex distribution was similar among ED patients and reported LD cases, the rates for children 5years and younger and adults 65years and older were greater for ED encounters. Patients frequently visit the ED to seek care for tick bites and suspected LD. Results of ED data analyses can be used to target education, in particular for ED providers and the public through timely distribution of evidence-based educational materials and training programmes.

The allocation of time and risk of Lyme: A case of ecosystem service income and substitution effects.

Forests are often touted for their ecosystem services, including outdoor recreation. Historically forests were a source of danger and were avoided. Forests continue to be reservoirs for infectious diseases and their vectors - a disservice. We examine how this disservice undermines the potential recreational services by measuring the human response to environmental risk using exogenous variation in the risk of contracting Lyme Disease. We find evidence that individuals substitute away from spending time outdoors when there is greater risk of Lyme Disease infection. Individuals facing a higher risk of infection substitute away from outdoor leisure. On average individuals spent 1.54 fewer minutes outdoors at the average, 72 U.S. Centers for Disease Control and Prevention (CDC), confirmed cases of Lyme Disease. We estimate lost outdoor recreation of 9.41 hours per year per person in an average county in the North Eastern United States and an aggregate welfare loss on the order $2.8 billion to $5.0 billion per year.

Investigation of a Potential Relationship Between Wild Bird Populations and Human Lyme Disease Rate in Connecticut from 1991-2002

Lyme disease is the most common tick-borne disease in North America. Borrelia burgdorferi, is the pathogen, and the black-legged tick carries the bacteria and spreads it when feeding on the blood of animals and humans. At least 70 passerine species and one species of woodpecker in North American are parasitized by immature black-legged ticks. This hypothesis predicts that there would be a positive relationship between Lyme disease rates and bird numbers that infected with the pathogen, and there would be no relationship between Lyme disease rate and bird numbers that not known to be infected with the pathogen. The study depended on the North American Breeding Bird Survey (BBS) to get bird species for 14 routes across Connecticut, and on the Connecticut DHS to get Lyme disease rates for the time period of the study (1991-2002). The range of years was from 1991 to 2002 because of a change in how Lyme disease cases were reported starting in 2003. The bird data were: one group that included all 17 bird species that carry the pathogen, two species separately that are known to become infected by Lyme pathogen (American Robin and Gray Catbird), and a control species not known to carry the pathogen (American Redstart). The study found significant positive relationships between bird numbers and human Lyme disease rate in two routes for the SCLP group, one route for American Robin, three routes for Gray Catbird, and two routes for American Redstart. Only Gray Catbird had a significant negative relationship with human Lyme disease rate in one route. Based on the positive relationships that appeared for American Redstart, the control species, and the few significant relationships for birds known to carry the pathogen, the study rejected the hypothesis that there is a strong relationship between numbers of birds that could be infected with B. burgdorferi and the rate of Lyme disease in people as measured by the methods used in this study.

Prevalence of Borrelia burgdorferi in ticks removed from skin of people and circumstances of being bitten - research from the area of Poland, 2012-2014.

During feeding, the tick sucks blood from the host along with the pathogens that are in the blood, simultaneously exchanging its own pathogens with the host. Humans can also be a host. It is important to understand the most typical circumstances in which people might become infected with Borrelia burgdorferi. This knowledge will help to prepare health education programmes aimed at the prevention of Lyme disease and other tick-borne diseases. The aim of the study was to determine the percentage of ticks infected with Borrelia burgdorferi sensu lato, depending on the circumstances of getting bitten. The research material consisted of ticks acquired from people who had been bitten, and questionnaires completed by these people. 510 ticks were acquired from 257 females and 253 males. Following delivery of a tick for testing, the stage of its development was determined and a molecular assay of Borrelia burgdorferi DNA performed. A positive result of the nested-PCR test was obtained in 78 ticks, which represents 15.30% of all ticks. The infected ticks were collected from male (41 ticks - 52.56%) and female subjects (37 ticks - 47.44%). The biggest number of infected ticks were collected in autumn (54 ticks - 69.23%) and from people who had been into forests (44 ticks - 56.41%). Among the people from whom the infected ticks were acquired, the dominating group included persons over 16 years of age (53 persons - 67.95%) and children aged 0-5 years (16 persons - 20.51%). One in four infected ticks were acquired from the southwestern (20 ticks - 25.64%) and eastern regions of Poland (21 ticks - 26.92%). Infestation of ticks infected with Lyme disease spirochete in this study proved to be variable and depend on the season, the area of tick attack and the region in Poland. The results of the study clearly show that ticks infected with Borrelia burgdorferi inhabit all regions of Poland. The results are consistent with National Institute of Hygiene data which indicates that Lyme disease cases are recorded in all regions of Poland.

Using exploratory data analysis to identify and predict patterns of human Lyme disease case clustering within a multistate region, 2010–2014

Lyme disease is the most commonly reported vectorborne disease in the United States. The objective of our study was to identify patterns of Lyme disease reporting after multistate inclusion to mitigate potential border effects. County-level human Lyme disease surveillance data were obtained from Kentucky, Maryland, Ohio, Pennsylvania, Virginia, and West Virginia state health departments. Rate smoothing and Local Moran's I was performed to identify clusters of reporting activity and identify spatial outliers. A logistic generalized estimating equation was performed to identify significant associations in disease clustering over time. Resulting analyses identified statistically significant (P=0.05) clusters of high reporting activity and trends over time. High reporting activity aggregated near border counties in high incidence states, while low reporting aggregated near shared county borders in non-high incidence states. Findings highlight the need for exploratory surveillance approaches to describe the extent to which state level reporting affects accurate estimation of Lyme disease progression.

Environmental Factors Affecting Survival of Immature Ixodes scapularis and Implications for Geographical Distribution of Lyme Disease: The Climate/Behavior Hypothesis.

Recent reports suggest that host-seeking nymphs in southern populations of Ixodes scapularis remain below the leaf litter surface, while northern nymphs seek hosts on leaves and twigs above the litter surface. This behavioral difference potentially results in decreased tick contact with humans in the south, and fewer cases of Lyme disease. We studied whether north-south differences in tick survival patterns might contribute to this phenomenon. Four month old larvae resulting from a cross between Wisconsin males and South Carolina females died faster under southern than under northern conditions in the lab, as has previously been reported for ticks from both northern and southern populations. However, newly-emerged larvae from Rhode Island parents did not differ consistently in mortality under northern and southern conditions, possibly because of their younger age. Survival is lower, and so the north-south survival difference might be greater in older ticks. Larval survival was positively related to larval size (as measured by scutal area), while survival was positively related to larval fat content in some, but not all, trials. The difference in larval survival under northern vs. southern conditions might simply result from faster metabolism under warmer southern conditions leading to shorter life spans. However, ticks consistently died faster under southern than under northern conditions in the laboratory when relative humidity was low (75%), but not under moderate (85%) or high (95%) RH. Therefore, mortality due to desiccation stress is greater under southern than under northern conditions. We hypothesize that mortality resulting from the greater desiccation stress under southern conditions acts as a selective pressure resulting in the evolution of host-seeking behavior in which immatures remain below the leaf litter surface in southern I. scapularis populations, so as to avoid the desiccating conditions at the surface. If this hypothesis is correct, it has implications for the effect of climate change on the future distribution of Lyme disease.

Geographic Expansion of Lyme Disease in Michigan, 2000-2014.

BackgroundMost Lyme disease cases in the Midwestern United States are reported in Minnesota and Wisconsin. In recent years, however, a widening geographic extent of Lyme disease has been noted with evidence of expansion eastwards into Michigan and neighboring states with historically low incidence rates.MethodsWe collected confirmed and probable cases of Lyme disease from 2000 through 2014 from the Michigan Department of Health and Human Services, entering them in a geographic information system. We performed spatial focal cluster analyses to characterize Lyme disease expansion. We compared the distribution of human cases with recent Ixodes scapularis tick distribution studies.ResultsLyme disease cases in both the Upper and Lower Peninsulas of Michigan expanded more than 5-fold over the study period. Although increases were seen throughout the Upper Peninsula, the Lower Peninsula particularly expanded along the Indiana border north along the eastern shore of Lake Michigan. Human cases corresponded to a simultaneous expansion in established I scapularis tick populations.ConclusionsThe geographic distribution of Lyme disease cases significantly expanded in Michigan between 2000 and 2014, particularly northward along the Lake Michigan shore. If such dynamic trends continue, Michigan—and possibly neighboring areas of Indiana, Ohio, and Ontario, Canada—can expect a continued increase in Lyme disease cases.

Susceptibility of spirochetes Borreliaburgdorferisensulato to antibiotics in vitro

Abstract Empiric therapy has been applied in the treatment of Lyme disease. This therapy is selected following the sensitivity analysis of the proposed drug in all species of bacteria which can cause a similar type of infection and on the basis of the clinical efficacy of antibiotic treatment. Established schemes based on data collected from many centers in the world, including type of antibiotic, dose and duration of his administration, and the stage and form of Lyme disease have been created. Number of in vitromethods of spirochetes susceptibility to antibiotics has been also developed. Unfortunately, the lack of standardization often makes it impossible to compare the results of MIC and MBC. Furthermore, little is known about the interactions of the various antimicrobial substances and spirochetes. There is a need for testing of clinical strains isolated from patients after treatment, which would explain the problems associated with “refractory” cases of Lyme disease. The paper presents the research on the antibiotic-spirochete interactions observed in vitro. 1. Introduction. 2. In vitro culture and growth of Borreliaburgdorferisensulato. 3. In vitro susceptibility of Borreliaburgdorferisensustricto strains to antimicrobial agents. 4. Summary

Controversies in Persistent (Chronic) Lyme Disease.

The Centers for Disease Control and Prevention estimates that more than 300 000 new cases of Lyme disease occur each year in the United States and that 10% to 20% of these patients will remain symptomatic despite receiving appropriate antibiotic therapy. Many elements of the disease are poorly understood and have generated considerable controversy. This paper discusses the medical controversies related to posttreatment manifestations and their potential impact on infusion nurses.

Lyme Disease Surveillance in New York State: an Assessment of Case Underreporting.

Despite the mandatory nature of Lyme disease (LD) reporting in New York State (NYS), it is believed that only a fraction of the LD cases diagnosed annually are reported to public health authorities. Lack of complete LD case reporting generally stems from (i) lack of report of provider-diagnosed cases where supportive laboratory testing is not ordered or results are negative (i.e. provider underreporting) and (ii) incomplete case information (clinical laboratory reporting only with no accompanying clinical information) such that cases are considered 'suspect' and not included in national and statewide case counts (i.e. case misclassification). In an attempt to better understand LD underreporting in NYS, a two-part study was conducted in 2011 using surveillance data from three counties. Case misclassification was assessed by obtaining medical records on suspect cases and reclassifying according to the surveillance case definition. To assess provider underreporting, lists of patients for whom ICD-9-CM code 088.81 (LD) had been used were reported to NYS Department of Health (NYSDOH). These lists were matched to the NYSDOH case reporting system, and medical records were requested on patients not previously reported; cases were then classified according to the case definition. When including both provider underreporting and case misclassification, approximately 20% (range 18.4-24.6%) more LD cases were identified in the three-county study area than were originally reported through standard surveillance. The additional cases represent a minimum percentage of unreported cases; the true percentage of unreported cases is likely higher. Unreported cases were more likely to have a history of erythema migrans (EM) rash and were more likely to be young paediatric cases. Results of the study support the assertion that LD cases are underreported in NYS. Initiatives to increase reporting should highlight the importance of reporting clinically diagnosed EM and be targeted to those providers most likely to diagnose LD, specifically providers treating paediatric patients.

Validation of Random Sampling as an Estimation Procedure for Lyme Disease Surveillance in Massachusetts and Minnesota

Many disease surveillance programs, including the Massachusetts Department of Public Health and the Minnesota Department of Health, are challenged by marked increases in Lyme disease (LD) reports. The purpose of this study was to retrospectively analyse LD reports from 2005 through 2012 to determine whether key epidemiologic characteristics were statistically indistinguishable when an estimation procedure based on sampling was utilized. Estimates of the number of LD cases were produced by taking random 20% and 50% samples of laboratory-only reports, multiplying by 5 or 2, respectively, and adding the number of provider-reported confirmed cases. Estimated LD case counts were compared to observed, confirmed cases each year. In addition, the proportions of cases that were male, were ≤12years of age, had erythema migrans (EM), had any late manifestation of LD, had a specific late manifestation of LD (arthritis, cranial neuritis or carditis) or lived in a specific region were compared to the proportions of cases identified using standard surveillance to determine whether estimated proportions were representative of observed proportions. Results indicate that the estimated counts of confirmed LD cases were consistently similar to observed, confirmed LD cases and accurately conveyed temporal trends. Most of the key demographic and disease manifestation characteristics were not significantly different (P<0.05), although estimates for the 20% random sample demonstrated greater deviation than the 50% random sample. Applying this estimation procedure in endemic states could conserve limited resources by reducing follow-up effort while maintaining the ability to track disease trends.

Characterizing Lyme Disease Surveillance in an Endemic State

Lyme disease (LD) is the most common vector-borne disease in Maryland and the United States. Surveillance for LD is valuable for understanding the burden of the disease, particularly to assess whether the disease is spreading and to appreciate who is affected. However, not all cases of LD in Maryland are reported, and surveillance practices vary across each of Maryland's 24 local health departments (LHDs). To better understand this variability and to systematically characterize the surveillance process, we surveyed Maryland's LHDs regarding LD surveillance. The Maryland Local Health Department Lyme Disease Surveillance Survey has been administered annually since 2011. Questions asked each year included whether all LD reports are investigated or only a subset, and how many reports are not entered into the surveillance database. Since 2011, Maryland has lost surveillance personnel for LD. Each year from 2009 to 2012, a median 3598 (range 2462 to 5722) reports were not entered into the surveillance database and hence not investigated. These reports represent 43-55% of all reports received for the year. Over time, more LHDs chose to streamline their LD investigation approach by investigating only those reports that met the criteria for laboratory evidence of infection: in 2008, 5 (21%) LHDs investigated only a subset of LD reports; by 2013, this increased to 15 (63%). There is wide variability across LHDs in how LD investigations are conducted. Maryland LHDs have experienced a loss of LD surveillance personnel with a concomitant increase in the number of LHDs adopting a streamlined approach to investigating cases. These findings underscore the tremendous burden of LD on the public health agencies and highlight the need for alternative approaches that can both reduce burden and preserve surveillance data quality.

Underreporting of Lyme and Other Tick-Borne Diseases in Residents of a High-Incidence County, Minnesota, 2009.

Lyme disease (LD), anaplasmosis, babesiosis and other tick-borne diseases (TBDs) attributed to Ixodes ticks are thought to be widely underreported in the United States. To identify TBD cases diagnosed in 2009, but not reported to the Minnesota Department of Health (MDH), diagnostic and procedural billing codes suggestive of tick-borne diseases were used to select medical charts for retrospective review in medical facilities serving residents of a highly endemic county in Minnesota. Of 444 illness events, 352 (79%) were not reported. Of these, 102 (29%) met confirmed or probable surveillance case criteria, including 91 (26%) confirmed LD cases with physician-diagnosed erythema migrans (EM). For each confirmed and probable LD, probable anaplasmosis and confirmed babesiosis case reported to MDH in 2009, 2.8, 1.3, 1.2 and 1.0 cases were likely diagnosed, respectively. These revised estimates provide a more accurate assessment and better understanding of the burden of these diseases in a highly endemic county.

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

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.

Seroprevalence of Borrelia burgdorferi antibodies in white-tailed deer from Texas.

Lyme Disease is caused by the bacterial pathogen Borrelia burgdorferi, and is transmitted by the tick-vector Ixodes scapularis. It is the most prevalent arthropod-borne disease in the United States. To determine the seroprevalence of B. burgdorferi antibodies in white-tailed deer (Odocoileus virginianus) from Texas, we analyzed serum samples (n = 1493) collected during the 2001–2015 hunting seasons, using indirect ELISA. Samples with higher sero-reactivity (0.803 and above) than the negative control group (0.662) were further tested using a more specific standardized western immunoblot assay to rule out false positives. Using ELISA, 4.7% of the samples were sero-reactive against B. burgdorferi, and these originated in two eco-regions in Texas (Edwards Plateau and South Texas Plains). However, only 0.5% of the total samples were sero-reactive by standardized western immunoblot assay. Additionally, both ELISA and standardized western immunoblot assay results correlated with an increased incidence in human Lyme Disease cases reported in Texas. This is the first longitudinal study to demonstrate fluctuation in sero-reactivity of white-tailed deer to B. burgdorferi sensu stricto antigens in southern United States. Future ecological and geographical studies are needed to assess the environmental factors governing the prevalence of Lyme Disease in non-endemic areas of the southern United States.

Modeling the Geographic Distribution of Ixodes scapularis and Ixodes pacificus (Acari: Ixodidae) in the Contiguous United States.

In addition to serving as vectors of several other human pathogens, the black-legged tick, Ixodes scapularis Say, and western black-legged tick, Ixodes pacificus Cooley and Kohls, are the primary vectors of the spirochete (Borrelia burgdorferi) that causes Lyme disease, the most common vector-borne disease in the United States. Over the past two decades, the geographic range of I. pacificus has changed modestly while, in contrast, the I. scapularis range has expanded substantially, which likely contributes to the concurrent expansion in the distribution of human Lyme disease cases in the Northeastern, North-Central and Mid-Atlantic states. Identifying counties that contain suitable habitat for these ticks that have not yet reported established vector populations can aid in targeting limited vector surveillance resources to areas where tick invasion and potential human risk are likely to occur. We used county-level vector distribution information and ensemble modeling to map the potential distribution of I. scapularis and I. pacificus in the contiguous United States as a function of climate, elevation, and forest cover. Results show that I. pacificus is currently present within much of the range classified by our model as suitable for establishment. In contrast, environmental conditions are suitable for I. scapularis to continue expanding its range into northwestern Minnesota, central and northern Michigan, within the Ohio River Valley, and inland from the southeastern and Gulf coasts. Overall, our ensemble models show suitable habitat for I. scapularis in 441 eastern counties and for I. pacificus in 11 western counties where surveillance records have not yet supported classification of the counties as established.

A School-Based Intervention to Increase Lyme Disease Preventive Measures Among Elementary School-Aged Children.

Purpose: Educational interventions to reduce Lyme disease (LD) among at-risk school children have had little study. The purpose of this study was to evaluate whether a short in-class LD education program based on social learning theory and the Health Belief Model (HBM) impacted a child's knowledge, attitude, and preventive behavior.Methods: Students in grades 2–5 in 19 elementary schools were selected in an area that was highly endemic for LD. The children received an educational intervention or were on a wait list as controls. Their knowledge, attitudes, and self-reported preventive behaviors were surveyed before implementing the program and 1 year later. General linear regression analyses adjusting for age, gender, and baseline variables were used to measure the impact of the intervention.Results: There were 3570 participants in the study: 1562 received the intervention, and 2008 were controls. The mean age for both groups was 9.1 years, with 53% women in the intervention group and 50% women in the control group. The children in the intervention group increased their overall knowledge of LD more than the children in the control group (overall knowledge score improvement, mean difference (SD) 1.38 (1.3) vs. 0.36 (1.3) p < 0.0001). All children in classes receiving the intervention reported an increase in precautionary behavior, positive attitude toward taking precautions, and self-efficacy compared with the wait list controls. Two LD cases were confirmed during the follow-up period, one in the intervention group and one in the controls.Conclusions: These findings demonstrate that a short in-class educational program that includes elements of the HBM, including: (1) awareness and knowledge about the disease, (2) benefits of preventive behavior, and (3) confidence in ability to perform preventive behaviors can improve knowledge, attitude, and self-reported precautionary behavior among at-risk children. www.clinicaltrials.gov: NCT00594997

Incident Tick-Borne Infections in a Cohort of North Carolina Outdoor Workers.

Tick-borne diseases cause substantial morbidity throughout the United States, and North Carolina has a high incidence of spotted fever rickettsioses and ehrlichiosis, with sporadic cases of Lyme disease. The occupational risk of tick-borne infections among outdoor workers is high, particularly those working on publicly managed lands. This study identified incident tick-borne infections and examined seroconversion risk factors among a cohort of North Carolina outdoor workers. Workers from the North Carolina State Divisions of Forestry, Parks and Recreation, and Wildlife (n = 159) were followed for 2 years in a randomized controlled trial evaluating the effectiveness of long-lasting permethrin-impregnated clothing. Antibody titers against Rickettsia parkeri, Rickettsia rickettsii, "Rickettsia amblyommii," and Ehrlichia chaffeensis were measured at baseline (n = 130), after 1 year (n = 82), and after 2 years (n = 73). Titers against Borrelia burgdorferi were measured at baseline and after 2 years (n = 90). Baseline seroprevalence, defined as indirect immunofluorescence antibody titers of 1/128 or greater, was R. parkeri (24%), R. rickettsii (19%), "R. amblyommii" (12%), and E. chaffeensis (4%). Incident infection was defined as a fourfold increase in titer over a 1-year period. There were 40 total seroconversions to at least one pathogen, including R. parkeri (n = 19), "R. amblyommii" (n = 14), R. rickettsii (n = 9), and E. chaffeensis (n = 8). There were no subjects whose sera were reactive to B. burgdorferi C6 antigen. Thirty-eight of the 40 incident infections were subclinical. The overall risk of infection by any pathogen during the study period was 0.26, and the risk among the NC Division of Forest Resources workers was 1.73 times that of workers in other divisions (95% confidence interval [CI]: 1.02, 2.92). The risk of infection was lower in subjects wearing permethrin-impregnated clothing, but not significantly (risk ratio = 0.81; 95% CI: 0.47, 1.39). In summary, outdoor workers in North Carolina are at high risk of incident tick-borne infections, most of which appear to be asymptomatic.

Lyme Disease in Hispanics, United States, 2000-2013.

Hispanics comprise a growing portion of the US population and might have distinct risk factors for tickborne diseases. During 2000–2013, a total of 5,473 Lyme disease cases were reported among Hispanics through national surveillance. Hispanics were more likely than non-Hispanics to have signs of disseminated infection and onset during fall months.