Prevention Of Tick-borne Diseases Research Articles

High throughput discovery and characterization of tick and pathogen vaccine protective antigens using vaccinomics with intelligent Big Data analytic techniques

ABSTRACTIntroduction: The incidence of tick-borne diseases (TBDs) is growing worldwide, and vaccines appear as the most effective and environmentally sound intervention for the prevention and control of TBDs.Areas covered: The vaccinomics approach combines omics technologies and bioinformatics for the characterization of tick-host-pathogen molecular interactions and the development of next-generation vaccines. The two main challenges of the vaccinomics approach are the integration and analysis of omics datasets, and the development of screening platforms for the identification of candidate protective antigens. To address these challenges we propose the application of intelligent Big Data analytic techniques for the high throughput discovery and characterization of tick and pathogen derived candidate vaccine protective antigens.Expert commentary: This innovative approach should improve the development and efficacy of vaccines for the control and prevention of TBDs.

The Tick Project: Testing Environmental Methods of Preventing Tick-borne Diseases

Prevention of tick-borne diseases in humans is challenging. To date, no prevention strategies have been shown to be consistently effective. Here, we describe the design of a new large-scale study, involving hundreds of households in Dutchess County, New York, testing whether environmental interventions, applied intensively and over 4 years, can prevent human cases.

Tick-borne disease occupational risks and behaviors of Florida Fish, Wildlife, and Parks Service employees – A health belief model perspective

Early research indicates that outdoor workers, such as park rangers and land managers, are at greater risk of tick-borne disease (TBD) infection because of their repeated occupational exposure to ticks, yet few studies have sought to determine predictors of personal protective behavior in this population. The purpose of this study was to identify within the framework of the Health Belief Model, relevant demographic and psychosocial predictors of TBD personal protective behaviors (PPB) among Fish and Wildlife, and State Parks employees in the U.S. State of Florida. Following informed consent, an e-survey was used to obtain cross-sectional data from 631 study participants. Seven scales and one index of items were adopted to operationalize the independent variables in this study. Study findings revealed that only twenty-five percent of respondents reported receiving occupational risk training about TBD from their employer. ‘Checking for ticks on skin’ was the TBD PPB most adopted by study participants, while the least adopted TBD PPB was ‘tucking pants into socks’. We found the most significant predictors of checking for ticks on skin to be ‘high specific knowledge of TBD PPB’, ‘high perceived risk for TBD’, ‘high intention of taking action to prevent tick bites’, and ‘high perceived self-efficacy for taking action to prevent tick bites’. This study represents a response to the collective call for TBD research focused on the unique issues in Florida. Study findings suggest that occupational training of employees should tailor interventions toward males. Such efforts should focus on increasing specific knowledge of TBD PPB. Management implicationsManagers of nature-based destinations for which exposure to ticks poses a significant risk to employees will find it useful to develop interventions for reducing tick exposure among employees using the following guidelines:I.Educational curriculum for occupational training programs should be tailored to increasingly target behavior modification among male employees.II.Content for curriculum to be used in training programs should emphasize specific, rather than general knowledge of tick-borne disease personal protective behavior. Suggestions for content includes the social, economic and health risks of TBD, specific action that can be taken to prevent TBDs, benefits of taking preventive action, role of checking for ticks, tucking shirts into pants and overall TBD PPB in TBD prevention.

Knowledge and preventive behaviors towards tick-borne diseases in Delaware

Delaware is among the top 10 states in the United States with the highest incidence for Lyme disease. The Delaware Division of Public Health (DPH) therefore has been working diligently to prevent and control tick-borne diseases through a variety of interventions including awareness campaigns and educational programs. To assess if tick-borne disease related information is reaching Delawareans through these programs, DPH in collaboration with Delaware State University administered an anonymous survey to 1755 participants in all three of Delaware counties during May 2017. The questionnaire assessed individuals’ general knowledge about tick-borne diseases and performance of selected tick-borne disease prevention methods Overall, participants’ knowledge of tick-borne diseases was poor; only 38.4% of respondents stated that ticks were problematic in Delaware and only 12.7% of respondents “strongly agreed” that Lyme disease is a problem in Delaware. A little over half of the respondents (51.6%) indicated having seen advertisements/infomercials/flyers for protection from ticks or the disease agents spread by ticks; the most common places for viewing these advertisements were doctor’s offices and through social media. The reported frequency of performing preventive behaviors was variable and disparities were observed by age, race, gender and county of residence. Existing public health communication efforts on tick-borne diseases in Delaware do not appear to be having the desired effect. This study provides important baseline information to rethink communication channels for education and more effectively guide future tick-borne disease awareness campaigns.

Risk factors for tick exposure in suburban settings in the Northeastern United States

Prevention of tick-borne diseases requires an understanding of when and where exposure to ticks is most likely. We used an epidemiologic approach to define these parameters for residents of a Lyme-endemic region. Two persons in each of 500 Connecticut households were asked to complete a log each night for one week during June, 2013. Participants recorded their whereabouts in 15min increments (indoors, outdoors in their yard, outdoors on others’ private property, or outdoors in public spaces) and noted each day whether they found a tick on themselves. Demographic and household information was also collected. Logs were completed for 934 participants in 471 households yielding 51,895 time-place observations. Median participant age was 49 years (range 2–91 years); 52% were female. Ninety-one participants (9.8%) reported finding a tick during the week, with slightly higher rates among females and minors. Household factors positively associated with finding a tick included having indoor/outdoor pets (odds ratio (OR)=1.7; 95% confidence interval (CI): 1.1–2.9), the presence of a bird feeder in the yard (OR=1.9; CI:1.2–3.2), and presence of an outdoor dining area (OR=2.2; CI:1.1–4.3). Individual factors associated with finding a tick on a given day were bathing or showering (OR=3.7; CI:1.3–10.3) and hours spent in one’s own yard (OR=1.2, CI:1.1–1.3). Nineteen participants found ticks on multiple days, more than expected assuming independence (p<0.001). Participants who found ticks on multiple days did not spend more time outdoors but were significantly more likely to be male than those finding ticks on a single day (p<0.03). Our findings suggest that most tick exposures in the study area occurred on private property controlled by the respective homeowner. Interventions that target private yards are a logical focus for prevention efforts.

Tick-Borne Zoonoses in the United States: Persistent and Emerging Threats to Human Health.

In the United States, ticks transmit the greatest diversity of arthropod-borne pathogens and are responsible for the most cases of all vector-borne diseases. In recent decades, the number of reported cases of notifiable tick-borne diseases has steadily increased, geographic distributions of many ticks and tick-borne diseases have expanded, and new tick-borne disease agents have been recognized. In this review, we (1) describe the known disease agents associated with the most commonly human-biting ixodid ticks, (2) review the natural histories of these ticks and their associated pathogens, (3) highlight spatial and temporal changes in vector tick distributions and tick-borne disease occurrence in recent decades, and (4) identify knowledge gaps and barriers to more effective prevention of tick-borne diseases. We describe 12 major tick-borne diseases caused by 15 distinct disease agents that are transmitted by the 8 most commonly human-biting ixodid ticks in the United States. Notably, 40% of these pathogens were described within the last two decades. Our assessment highlights the importance of animal studies to elucidate how tick-borne pathogens are maintained in nature, as well as advances in molecular detection of pathogens which has led to the discovery of several new tick-borne disease agents.

Prevention of tick-borne diseases: an overview.

Ticks are closely related to mites and belong to the class Arachnida, which also includes spiders. There are two morphologically and biologically distinct groups of ticks: the ‘soft ticks’ ( Argasidae ) and the ‘hard ticks’ ( Ixodidae ). The most common hard tick in Europe is the castor bean (or sheep) tick, Ixodes ricinus (Figure 1). Not only is this the most abundant tick species, but it can also transmit a variety of pathogens that cause human disease including tick-borne encephalitis (TBE) and Lyme borreliosis.1–3 This renders I. ricinus one of the most dangerous animals in Europe. Figure 1. Nymph of Ixodes ricinus on fingertip. © V Fingerle, Oberschleissheim, Germany. I. ricinus prefers warm, humid environments and tends to be found in locations where humidity exceeds 80% relative humidity (RH). This means that their ideal habitats include woodlands with low scrub, especially along the outskirts of woods and clearances, and also in marshy areas, city parks, and gardens. The ticks are quite passive in their search for a host. They lie in ambush on the tip of a blade of grass (or other plant material) with their front legs out in a behaviour known as ‘questing’ (Figure 2), waiting for a host to pass by in order to latch on to. When ‘questing’, they sway their forelegs back and forth exposing a structure known as the ‘Haller’s organs’. These organs are located towards the end of the first pairs of legs and are able to detect various host odours, humidity, body heat, vibrations, and carbon dioxide. Contrary to popular belief, I. ricinus does not climb very high in the foliage (maximum height is 1.5 m), nor does it jump or fly. In the juvenile stages (larvae and nymphs), it has an extremely broad host range, including small mammals and birds, whereas …

Tick-borne disease preventive practices and perceptions in an endemic area

Lyme disease is the most commonly reported vector-borne illness in the United States. Since the institution of Nationally Notifiable surveillance efforts for Lyme disease in the United States in 1991, there has been a consistent increase in the number of reported cases. Thus, the need for targeted prevention strategies is underscored. The purpose of this study was to investigate knowledge about tick-borne diseases as well as beliefs and practices related to a variety of personal tick-borne disease prevention methods among individuals in southwestern Connecticut, a Lyme disease-endemic area. Between June and September 2014, an anonymous questionnaire was administered to 275 participants through a point-of-contact convenience sample obtained at community events in southwestern Connecticut. The questionnaire assessed individuals’ general knowledge about tick-borne diseases, performance of four selected tick-borne disease prevention methods, and perceived effectiveness and burdensomeness of those four behaviors. Some 80% of participants were female; median age was 55 years (IQR 45–64 years); 30% reported having been treated for a tick-borne illness and 50% reported a family member having been treated for a tick-borne illness. Overall, participants’ knowledge of tick-borne diseases was poor; the average knowledge score was only 57% (SD 22.6%). The reported frequency of performing preventive behaviors was variable. The most commonly reported behavior was performing a tick check (68%); use of tick repellent was the least commonly reported behavior (38%). Those who were more knowledgeable about Lyme disease were more likely to perform tick checks but knowledge score was not significantly associated with any of the other three behaviors studied. Respondents largely believed preventive behaviors to be effective at reducing the risk of tick-borne diseases. Belief that a prevention behavior is effective was highly correlated with performing that behavior but perceived burdensomeness does not appear to influence behavior performance. The reasons for differential uptake of preventive behaviors remains unknown; further study of barriers to performance of personal preventive behaviors is needed to better target public health interventions.

TickNET-A Collaborative Public Health Approach to Tickborne Disease Surveillance and Research.

TickNET, a public health network, was created in 2007 to foster greater collaboration between state health departments, academic centers, and the Centers for Disease Control and Prevention on surveillance and prevention of tickborne diseases. Research activities are conducted through the Emerging Infections Program and include laboratory surveys, high-quality prevention trials, and pathogen discovery.

Investigating the relationship between environmental factors and tick abundance in a small, highly heterogeneous region.

The tick Ixodes ricinus (L.) is the most important vector of tick-borne zoonoses in Europe. Apart from factors related to human behavior, tick abundance is a major driver of the incidence of tick-borne diseases in a given area and related data represent critical information for promoting effective public health policies. The present study analyzed the relationship between different environmental factors and tick abundance in order to improve the understanding of I. ricinus autecology and develop spatial predictive models that can be implemented in tick-borne disease prevention strategies. Ticks were sampled in 27 sites over a four-year period and different environmental variables were studied. Five simple models were developed that explain a large part of variation in tick abundance. Precipitation seems to play the most important role, followed by temperature, woodland coverage, and solar radiation. Model equations obtained in this study may enable the spatial interpolation and extension of tick abundance predicted values to sites of the same area, in order to build regional predictive maps. They could also be useful for the validation of large-scale spatial predictive maps.

Ixodes ricinus and Its Transmitted Pathogens in Urban and Peri-Urban Areas in Europe: New Hazards and Relevance for Public Health.

Tick-borne diseases represent major public and animal health issues worldwide. Ixodes ricinus, primarily associated with deciduous and mixed forests, is the principal vector of causative agents of viral, bacterial, and protozoan zoonotic diseases in Europe. Recently, abundant tick populations have been observed in European urban green areas, which are of public health relevance due to the exposure of humans and domesticated animals to potentially infected ticks. In urban habitats, small and medium-sized mammals, birds, companion animals (dogs and cats), and larger mammals (roe deer and wild boar) play a role in maintenance of tick populations and as reservoirs of tick-borne pathogens. Presence of ticks infected with tick-borne encephalitis virus and high prevalence of ticks infected with Borrelia burgdorferi s.l., causing Lyme borreliosis, have been reported from urbanized areas in Europe. Emerging pathogens, including bacteria of the order Rickettsiales (Anaplasma phagocytophilum, “Candidatus Neoehrlichia mikurensis,” Rickettsia helvetica, and R. monacensis), Borrelia miyamotoi, and protozoans (Babesia divergens, B. venatorum, and B. microti) have also been detected in urban tick populations. Understanding the ecology of ticks and their associations with hosts in a European urbanized environment is crucial to quantify parameters necessary for risk pre-assessment and identification of public health strategies for control and prevention of tick-borne diseases.

Protective efficacy of permethrin-treated trousers against tick infestation in forestry workers.

Prevention of tick borne diseases in forestry workers is essentially based on the use of appropriate clothing. The objective of this pragmatic, randomized, controlled trial was to assess the potential benefit of permethrin-treated working trousers for the prevention of tick infestation during forestry work. N=164 male forestry workers were equipped for a period of 16 weeks with permethrin-treated (intervention group-I) or untreated work trousers (control group-II). Subgroups, according to the use of trousers with (I-1, II-1) or without cut protection lining (I-2, II-2) were constituted. Tick infestation (quantity of ticks on the body surface) was assessed by questionnaire after 16 workdays. Control and intervention groups were compared by calculating the infestation rate (percentage of subjects with ticks) and the average number of ticks per workday. The infestation rate in the intervention group was significantly lower than in the control group (36.6 vs. 63.4%, p=0.001; Fisher-test). Further analysis revealed a significant reduction of tick infestation by permethrin treatment only for subjects wearing trousers without the cut protection lining (I-2: 34.2 vs. II-2: 80.0%, p<0.001), while users of cut protection trousers did not benefit from such treated trousers (I-1: 38.6 vs. II-1: 47.6%, n.s.). Similar results were found for comparisons based on the average number of ticks per workday. The use of permethrin-treated trousers does not completely prevent tick infestations. Improvement of tick protection has been shown only for some applications, but not in general. Additional prevention measures are therefore still indispensable.

The speed of kill of fluralaner (Bravecto™) against Ixodes ricinus ticks on dogs.

BackgroundPathogens that are transmitted by ticks to dogs, such as Anaplasma phagocytophilum, Babesia spp., Borrelia burgdorferi sensu latu, and Ehrlichia canis, are an increasing problem in the world. One method to prevent pathogen transmission to dogs is to kill the ticks before transmission occurs. Fluralaner (Bravecto™) is a novel isoxazoline insecticide and acaricide that provides long persistent antiparasitic activity following systemic administration. This study investigated the speed of kill of fluralaner against Ixodes ricinus ticks on dogs.MethodsA total of 48 dogs were randomized to 8 groups of 6 dogs and each dog was infested with 50 female and 10 male I. ricinus ticks. Two days later (day 0), 4 groups received a single treatment of 25 mg fluralaner/kg body weight as Bravecto™ chewable tablets; the dogs in the other 4 groups were left untreated. Separate control and treatment groups were paired at each time point (4, 8, 12, or 24 hours after treatment) for assessment of tick-killing efficacy. At 4, 8, and 12 weeks after treatment, all dogs were re-infested with 50 female I. ricinus ticks and subsequently assessed for live or dead ticks at either 4, 8, 12, or 24 hours after re-infestation. Efficacy was calculated for each assessment time point by comparison of the treatment group with the respective control group.ResultsTick-killing efficacy was 89.6% at 4 hours, 97.9% at 8 hours, and 100% at 12 and 24 hours after treatment. Eight hours after re-infestation, efficacy was 96.8%, 83.5%, and 45.8% at 4, 8, and 12 weeks after treatment, respectively. At least 98.1% tick-killing efficacy was demonstrated 12 and 24 hours after re-infestation over the entire 12 week study period.ConclusionsFluralaner kills ticks rapidly after treatment at 4 hours, and over its entire 12-week period of efficacy, it achieves an almost complete killing effect within 12 hours after tick infestation. The rapid tick-killing effect together with the long duration of efficacy enables fluralaner to aid in the prevention of tick borne diseases.

Knowledge and prevention of tick-borne diseases vary across an urban-to-rural human land-use gradient

We sought to determine the behavioral risk of exposure to tick-borne diseases across a human land-use gradient in a region endemic for diseases transmitted by the lone star tick. We measured the knowledge, attitudes, and preventive behaviors of visitors to 14 suburban, exurban, and rural recreational parks. A structured interview was conducted to determine respondents’ (n=238) knowledge of tick-borne disease risk, perceived susceptibility to tick-borne disease, and tick bite prevention behaviors. We found significant differences across park types for most personal protective behaviors. Individuals in exurban parks were more likely to perform frequent tick checks and use chemical insect repellents compared to other park types (p<0.001), while suburban park visitors were more likely to avoid tick habitats (p<0.05). Disparities exist in the level of knowledge, perceived personal risk, and use of preventive measures across the human land-use gradient, suggesting that targeted public health intervention programs could reduce behavioral exposure risk by addressing specific gaps in knowledge and prevention.

Effect of owner-controlled acaricidal treatment on tick infestation and immune response to tick-borne pathogens in naturally infested dogs from Eastern Austria

BackgroundTick-borne infections resulting from regular tick infestation in dogs are a common veterinary health problem all over the world. The application of repellent and acaricidal agents to prevent transmission of pathogens is a major protection strategy and has been proven to be highly effective in several trials under laboratory and natural conditions in dogs. Despite such promising results, many dog owners still report tick infestation in their dogs although acaricidal agents are used. Information about the current infection status and changes of the infection status regarding tick-borne diseases (TBD) in dogs treated by the owner’s controlled acaricide application is lacking.MethodsIn this study 30 dogs were each treated with permethrin, fipronil + S-methoprene, or served as untreated controls. Application of the acaricide was performed by the owner who decided when and how often to use the spot on preparation. Over a period of 11 months, dogs were clinically examined and sampled for antibody responses against Babesia canis, Anaplasma phagocytophilum, Borrelia burgdorferi s. l., and TBE virus before the study started, 6 months later and at the end of the investigation period.ResultsThe permethrin acaricide was applied on average 3.40 times within the examination period, whereas the fipronil + S-methoprene medication was applied 3.03 times. Approximately 2/3 of all dogs, independent of the group, had a positive immune response to one or more pathogens. Three dogs developed clinical symptoms of canine babesiosis, all other dogs remained healthy. Individual number of ticks per dog or number of infections per dog did not correlate with the application rate, and the number of ticks per dog did not influence the number of infections per dog. As owners did not apply the acaricides regularly no influence on the number of infections could be documented although the number of ticks was clearly reduced by the application of the spot-on drugs.ConclusionsClinical disease in dogs exposed to tick-borne pathogens is rare, although a humoral immune response reflecting infection is common. More educational training for dog owners is necessary to make the application of acaricides effective regarding the prevention of tick-borne diseases.

Taxonomic and Phylogenetic Relationships Between Neotropical Species of Ticks from Genus &lt;I&gt;Amblyomma&lt;/I&gt; (Acari: Ixodidae) Inferred from Second Internal Transcribed Spacer Sequences of rDNA

The accurate specific identification of ticks is essential for the study, control and prevention of tick-borne diseases. Herein, we determined ribosomal nucleotide sequences of the second internal transcribed spacer (ITS2) of 15 Neotropical hard tick species of the genus Amblyomma Koch found in Brazil. Most of the studied ticks accidentally parasite humans and potentially act as vectors of zoonoses. Lengths of the ITS2 sequences ranged from 956 to 1,207 bp, whereas GC content varied from 62.4 to 66.9%. A matrix of ITS2 divergence was calculated with the ITS2 sequence data obtained showing divergence levels varying from 1.5 to 28.8%. The analysis indicated that this molecular marker can be useful for Amblyomma-specific identification. Phylogenetic inferences based on the ITS2 sequences were used to assess some issues in subgenus taxonomy.

Taxonomic and Phylogenetic Relationships Between Neotropical Species of Ticks from GenusAmblyomma(Acari: Ixodidae) Inferred from Second Internal Transcribed Spacer Sequences of rDNA

The accurate specific identification of ticks is essential for the study, control and prevention of tick-borne diseases. Herein, we determined ribosomal nucleotide sequences of the second internal transcribed spacer (ITS2) of 15 Neotropical hard tick species of the genus Amblyomma Koch found in Brazil. Most of the studied ticks accidentally parasite humans and potentially act as vectors of zoonoses. Lengths of the ITS2 sequences ranged from 956 to 1,207 bp, whereas GC content varied from 62.4 to 66.9%. A matrix of ITS2 divergence was calculated with the ITS2 sequence data obtained showing divergence levels varying from 1.5 to 28.8%. The analysis indicated that this molecular marker can be useful for Amblyomma-specific identification. Phylogenetic inferences based on the ITS2 sequences were used to assess some issues in subgenus taxonomy.

Foci of tick-borne diseases in Southwest Germany

Presently known tick-borne diseases in Germany include Lyme borreliosis, tick-borne encephalitis (TBE-virus, western subtype), Q-fever, babesiosis and presumably ehrlichiosis. Blood samples of 4,368 forestry workers in the State of Baden-Wuerttemberg (B-W), southwestern Germany, were tested for the presence of antibodies against Borrelia burgdorferi sensu lato, TBE-virus and Ehrlichia spp. (genogroup E. phagocytophila). Furthermore 12,327 ticks ( Ixodes ricinus) collected in various areas of B-W were analysed by PCR and genotyping for the prevalence of pathogen RNA and DNA. The human seroprevalence rates of antibodies to B. burgdorferi sensu lato ranged from 18 % to 52 %, for TBE-virus from 0 % to 43 % and for Ehrlichia spp. from 5 % to 16 % in various counties of the State. The foci of B. burgdorferi and TBE-virus as indicated by antibody prevalence in humans are only partly overlapping with each other. The highest rates of TBE-virus antibodies are in concordance with available clinical data. However antibody prevalence up to 27 % in areas with no reports of clinical cases was found, suggesting that TBE occurs throughout the State of B-W, The prevalence of Ehrlichia spp. antibodies suggests that ehrlichiosis plays a role as a tick-borne disease in Germany, but as long as no clinical data are available, this will remain unclear. Investigations of ticks for TBE-virus (n = 9,189) by nested PCR showed prevalence rates from 0% to 2.3% and for Ehrlichia spp. (n = 1,963) from 2.6% to 3.1%. Examination of ticks (n = 3,138) for the presence of B. burgdorferi sensu lato DNA was performed by PCR and revealed prevalence rates from 13.9% up to 24%. Furthermore 1,106 samples positive for B. burgdorferi sensu lato were used for genotyping. B. afzelii DNA was found in 407 ticks (36.8%), followed by B. garinii (21.9 %), B. valaisiana (13.7%), and B. burgdorferi sensu stricto (9.9 %). Double infection was found in 6.4% and triple infection in 0.8% of the ticks. 10.5% of the positive samples could not be classified. Prevention of tick-borne diseases has to focus on behavioural intervention to reduce individual tick exposure by proper behaviour in the environment, as a large-scale control of the tick population seems impossible and thus reduction of Lyme borreliosis and TBE through tick control is unlikely. Vaccination against TBE-virus should not only be recommended for high endemic areas but also for persons with a high individual risk.

Prevention of tick-borne diseases: the need for a revised strategy.

Prevention of tick-borne diseases: the need for a revised strategy.

Forecasting habitat suitability for ticks and prevention of tick-borne diseases

Climate and vegetation are the major factors affecting the distribution of ticks. Consequently, spatial distributions can be analysed by statistical methods that look for correlations between abiotic factors and known data about tick presence/absence. Remote sensing features can be obtained from a wide database of sensors with different characteristics, then applied to the problem of mapping prediction of tick distribution. Some studies had demonstrated that the use of these abiotic variables from satellite imagery has biological significance, therefore statistical accuracy of these distribution models can be interpreted under an ecological framework. Furthermore, models can be linked to these predictive maps, enabling the forecast of spatial and temporal dynamics of ticks, looking for seasonal patterns of activity and accurate use of acaricide treatments.