Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “TICKS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 199 records · Page 11Linked to original sources
PubMedDate not supplied

[Intrapopulation differences in the infectivity of adult Ixodes persulcatus P. Sch. with the tick-borne encephalitis virus and an assessment of its total content in ticks].

At the present stage of investigations on the role of vectors in foci of tick-borne encephalitis and of other transmissible infections it is necessary not only to operate with extensive indices of arthropod infection rate but also to take into account the degree of their infection. It has been demonstrated that adult empty Ixodes persulcatus ticks at the time of activation differ significantly by the degree of their infection with tick-borne encephalitis virus. In the Khabarovsk Territory, annual changes in the relative and absolute numbers of infected ticks did not lead to sharp variations in the virus population portion associated with ticks. It is suggested that vector individuals containing different virus doses are of different functional importance in providing long-term existence of virus population.

Animals↗
PubMed1967

The relationship between the tick-borne encephalitis virus and the ticks and mammals of the Tribec mountain range.

The basic problem in the study of tick-borne virus diseases is to establish where the virus is maintained in nature. In general, this focus will be found where there are large and relatively stable populations of ticks, small rodents and insectivores. In the Tribec region the principal vector of tick-borne encephalitis (TBE) is Ixodes ricinus, although other species can circulate the virus under suitable conditions. The virus can persist during winter either in starving nymphs or adults or in non-starving larvae or nymphs. It can also persist in hibernating mammals, but this is a less important mechanism. Among the mammals, the insectivores (hedgehogs, shrews and moles) and certain rodents are hosts of ticks and reservoirs of TBE virus of great importance. During spring, game and farm animals play an important role and birds are important hosts when the number of small mammals is low. Thus the survival of TBE virus depends on a complex interaction of varying populations of tick vectors and vertebrate hosts that occur in different habitats influenced by different environmental conditions.

Animals↗
PubMed1997

Predation of livestock ticks by chickens as a tick-control method in a resource-poor urban environment.

The possible use of chickens as predators of livestock ticks was studied. Chickens were allowed to scavenge for 3 h among tick-infested cattle in a typical township backyard during the milking period. Boophilus decoloratus, Hyalomma marginatum rufipes, Rhipicephalus evertsi evertsi and Otobius megnini were recovered from the crops and gizzards at necropsy. The numbers of ticks ingested ranged from 0-128, with an average of 28.81 (+/- 8.42) per chicken. This study has confirmed that chickens are natural predators of livestock ticks and that chickens can be used as part of an integrated tick control plan in urban cattle-management systems in resource-poor communities in South Africa.

Animals↗
PubMed2026

Harnessing survey data across multiple demographic groups in Illinois to assess survey questions and reveal insights about ticks and tick-borne disease risk: a meta-comparison study.

BACKGROUND: Ticks and tick-borne diseases (TTBDs) are major public and veterinary health issues, existing at the intersection of behavioral, environmental, ecological, climatic, and entomological factors. Knowledge, attitudes, and practices (KAP) surveys have become an insightful tool to yield information regarding the behavioral factors that can predispose individuals to TTBDs. Here we present a unique meta-comparison study of six KAP surveys on TTBDs conducted in Illinois among various demographics: farmers, Extension workers, general public, veterinary, human medicine, and public health professionals. Our goals were multi-fold: (a) to develop an approach to compare KAP surveys used across several stakeholders on a subject of public health concern (i.e., TTBD risk), (b) to analyze the usefulness of questions for revealing information on TTBDs across varied demographic groups in Illinois, and (c) to reveal qualitative insights from the open text survey responses across these surveyed groups. METHODS: We conducted comparative and item response theory (IRT) analysis of all the surveyed questions, which yielded a final set of 39 questions on knowledge and practices, most of them with discriminatory power. Independent textual analysis of the survey responses led to the development of eight separate sub-categories across three main super categories: ticks and tick-borne disease (TBD) risk, TBD treatment and management, and TBD prevention. RESULTS: This study not only introduces a novel approach for comparing multiple KAP surveys on the topic of TTBDs, but also highlights gaps regarding TTBD knowledge, perceptions, and prevention measures among a variety of stakeholders and calls for tailored training and awareness campaigns to reduce the burden of TBDs in the Midwestern US. This meta-comparison approach unveils additional insights from the combined analyses of the KAP surveys. We also discuss perspectives of the surveyed demographics, their experiences with TTBDs, and provide recommendations for future public health efforts. CONCLUSION: These results can guide public health campaigns around TBDs in the United States and help reduce the increasing burden of TBDs on humans and animals.

Animals↗
PubMed1994

Cholesteryl esters on the body surfaces of the camel tick, Hyalomma dromedarii (Koch, 1844) and the brown dog tick, Rhipicephalus sanguineus (Latreille, 1806).

Cholesteryl esters were found to constitute a major component of the lipids coating the body cuticle of females of the camel tick, Hyalomma dromedarii and the brown dog tick, Rhipicephalus sanguineus. One or more cholesteryl esters, alone or in combination, have been shown to serve as the mounting sex pheromone of several species of ixodid ticks. Consequently, knowledge of these compounds is important for an understanding of the mating behavior of these ticks. Based on thin layer chromatography, cholesterol and cholesteryl esters were the most abundant neutral lipids found on the body surfaces of fed females of these two species. Analysis using HPLC demonstrated significant quantities of the following compounds, tentatively identified as cholesteryl esters (expressed in micrograms per female equivalent), in H. dromedarii: Cholesteryl acetate 18.2; cholesteryl laurate, 6.8; cholesteryl linoleate, 24.8; cholesteryl oleate, 12.9; cholesteryl palmitate, 0.3; and cholesteryl stearate 1.7. In contrast, the same method revealed only 3 cholesteryl esters in extracts of females of R. sanguineus: Cholesteryl acetate, 2.0; cholesteryl linoleate, 8.5; and cholesteryl oleate, 3.0. In both species, two unidentified peaks, with the spectral characteristics of cholesteryl esters, were also observed. Identification of the cholesteryl esters was confirmed: by (1) positive bioassay results with conspecific (H. dromedarii) males and heterospecific (Dermacentor variabilis) males; (2) similarity of ultraviolet spectra between identified sample peaks and authentic standards; and (3) demonstration of cholesterol and the corresponding free fatty acid following enzymatic digestion of each of the HPLC-separated fractions containing the different cholesteryl esters. Comparisons with the cholesteryl ester composition of the mounting sex pheromone of other metastriate Ixodidae are discussed. These findings, along with studies reported previously, suggest that differences in the mounting sex pheromones of ixodid ticks are an important factor in minimizing heterospecific matings in nature.

Animals↗
PubMed2006

Analysis of the long-term dynamics of tick-borne encephalitis (TBE) and ixodid tick-borne borrelioses (ITBB) morbidity in Russia.

As early as in the 1960s, Professor M.P. Chumakov suggested that primary tick-borne encephalitis (TBE) diagnoses made by practicing physicians should be verified by serological or virological methods. Verification showed that a large proportion of TBE cases (included in the official statistics of TBE morbidity) was accounted for by the so-called seronegative forms of the disease. Ixodid tick-borne borrelioses (ITBBs), or infections of the Lyme borreliosis group, which proved to be sympatric to TBE in Russia accounted for an even higher morbidity in past years. Some other tick-borne diseases were still unknown at that time. We analyzed 1062 case histories of patients with febrile diseases acquired through tick bites in the Udmurt Republic, Russia (one of the most hazardous regions with respect to TBE morbidity), recorded from 1965 to 1968, and 1509 similar cases recorded from 1983 to 1988. In the first period, 97 out of 684 cases (14.2%) included in the official statistics of TBE morbidity could be classified as ITBB according to modern case criteria. In the second period, 464 out of 1509 cases recorded as TBE (30.7%) were retrospectively diagnosed as ITBB. No specific diagnosis could be made in 7-17% of the total number of cases interpreted as 'tick-borne' diseases. A similar situation existed in other regions of Russia before 1996 and, as a consequence, the official parameters of annual TBE morbidity in different periods were overestimated by a factor of 1.2-1.6. Here, the long-term dynamics of TBE morbidity in Russia are presented as they appear according to official data and after correction with regard to estimations.

Encephalitis, Tick-Borne↗
PubMed1991

Dermatologic aspects of tick bites and tick-transmitted diseases.

Dermatologic manifestations of tick bites and tickborne disease are not commonly encountered. However, recognition of the signs and histopathologic conditions of tick bites can be important to the diagnosis and management of small animal diseases. Understanding the local nodular inflammatory reaction to a tick bite can allay the owner's fear that a newly recognized nodule may be a malignant growth. Additionally, recognition of tick bites and pathognomonic dermatologic changes may provide important evidence in making a diagnosis of tick-transmitted diseases.

Animals↗
PubMed2003

The influence of tick behavior, biotope and host specificity on concerted evolution of the platelet aggregation inhibitor savignygrin, from the soft tick Ornithodoros savignyi.

Ticks are obligate blood-feeding parasites that secrete anti-hemostatic components during feeding to enable control of the hemostatic system of the host. Complex interactions at the tick-host interface are an indication of the important role that the host played during tick evolution. The question is to what extent interaction with the host and the environment influences tick evolution. Previously, two isoforms (97% sequence identity) of savignygrin, an alphaIIbbeta3 antagonist, have been described. The presence of both isoforms within 20 random individuals confirmed that these isoforms must be recent gene duplicates. Analysis of the sequence differences between the isoforms shows a Kn/Ks ratio of 1, which indicates neutral selection for the isoforms. However, the biased localization of differences within the 3' end of the genes suggests that concerted evolution acts on the isoforms. Calculation of the divergence date between the isoforms (1.6-5.2 MYA) also indicates purifying selection, as ample time had passed after duplication, for inactivation of one gene copy. We conclude that concerted evolution has functioned to maintain a high copy number of the savignygrins in order for Ornithodoros savignyi to parasitize a wide host range. This contrasts with O. moubata that expresses the savignygrin homolog, disagregin, as a single copy at lower concentration levels and correlates with the confined habitat and consequently narrow host range of O. moubata. Recent "domestication" of O. savignyi due to animal husbandry practices could however, have reduced the selection constraints acting to maintain the gene copies as evidenced by the structural instability of one of the isoforms. Our results suggest that environmental factors and host associations do play an important role in the evolution of anti-hemostatic components in ticks.

Alleles↗
PubMed1995

Cellular and molecular interrelationships between ticks and prokaryotic tick-borne pathogens.

Tick-borne prokaryotic pathogens share a very intimate relationship with the vectors. Ingestion during the bloodmeal places the microbe into the gut lumen whence it must travel to the salivary glands at the right time for transmission during a subsequent feeding. This crucial event requires coordination between pathogen development and arthropod host activities that may be mediated by the expression of genes specific for the vector phase of the pathogen. Invertebrate hormones or factors associated with tick tissues may provide the cues that signal changes in tick physiology that induce necessary steps in the pathogen, such as colonization of ovaries during egg development in preparation for transovarial transmission or dispersion to the salivary glands at the time of a bloodmeal. These hypotheses cannot easily be investigated within the complex environment of the tick, but tick cell culture offers a simplified system with which to examine many of these important interrelationships.

Alphaproteobacteria↗
PubMed1985

Borrelia theileri: isolation from ticks (Boophilus microplus) and tick-borne transmission between splenectomized calves.

The bovine spirochete, Borrelia theileri, was detected in Giemsastained blood smears from a splenectomized calf 17 days after exposure to a laboratory colony of the tropical cattle tick, Boophilus microplus. Spirochetes were detected in the hemolymph and ovary of all engorged female ticks examined, indicating a high infection rate in this tick colony. Spirochetes were detected in a 2nd splenectomized calf 15 days after exposure to the larval offspring of ticks from the 1st calf. The only observable effect of infection in the 2 calves was a maximum rectal temperature increase to 40.2 C, which coincided with the first detectable parasitemia. The tick colony did not have any adverse effects, despite extensive multiplication of spirochetes in their tissues.

Animals↗
PubMed1980

Demonstration of Anaplasma marginale Theiler in ticks by tick transmission, animal inoculation, and fluorescent antibody studies.

Cattle were inoculated with a Virginia isolate of Anaplasma marginale Theiler and served as an infective source for laboratory-reared Dermacentor andersoni Stiles and D variabilis (Say) nymphs. Transstadial transmission of A marginale was demonstrated by feeding the newly molted adult ticks of both species on susceptible cattle and by inoculation of gut and salivary gland homogenates collected from adult ticks at postattachment days 5 and 7. Oral secretions collected from the same group of ticks and inoculated into a susceptible cow did not cause infection. Fluorescent antibody studies of infected tick gut and salivary glands were positive, although smears of tick oral secretions were negative for fluorescence.

Anaplasma↗
PubMedDate not supplied

[Differences in the distant transmission of the tick-borne encephalitis virus by ixodid ticks of 2 subfamilies].

Simultaneous but separate feeding of ticks on nonviremic animal (guinea pig) has shown that Amblyomminae ticks are practically unable to transmit distantly tick-borne encephalitis virus (TBEV) to the specimens of their own subfamily and to Ixodinae as well. Ixodes persulcatus and I. ricinus displayed their ability as donors and recipients of TBEV (adults and nymphs) not only for their own subfamily representatives but also as donors for recipients of Amblyomminae subfamily (nymphs and adults of Dermacentor and Rhipicephalus and nymphs of Haemaphysalis). Experimental and literature data analysis permits the authors to conclude that the very important role of TBEV circulation in nature belongs to the distant virus transmission. The absence of such type of virus exchange among Amblyomminae excludes this group of ticks from active virus circulation in TBEV foci.

Animals↗
PubMed1990

Experimental infection of ticks Ixodes ricinus with tick-borne encephalitis virus under different microclimatic conditions.

The influence of environmental temperature and relative air humidity on the development of ticks Ixodes ricinus and their infection rate with tick-borne encephalitis virus was studied. It was found that the temperature influenced significantly the development of ticks, but it did not influence their infection rate. To the contrary, the relative air humidity influenced the infection rate. It is assumed that the intrinsic factors play a primary role in the infection of ticks, while extrinsic factors have a secondary role; they are probably important at border values only.

Animals↗
PubMed1978

The isolation of Central European encephalitis (tick-borne encephalitis) virus from Ixodes ricinus (L.) ticks in southern-Germany.

During the years 1972--1976 a total of 14.692 ticks of the species Ixodes ricinus (L.), (2.738 adults and 11.954 nymphs) was collected. They were taken from five areas where human Central European encephalitis virus (CEE) infections had occurred. By means of, intracerebral (IC) and subcutaneous (SC) isolation experiments with suckling mice 19 agents, exhibiting the pathogenic characteristics of CEE virus, were isolated from these ticks. In neutralization tests with suckling mice these isolates could be identified as CEE virus strains. From the 14.692 ticks at least 1.29% were virus carriers as evidenced by the number of isolated virus strains. By the same reasoning at least 3.6% of the adults and 0.76% of the nymphs must have contained virus. We were successful in each of the five areas, rather distant from each other, to isolate the virus. The favorable ecological conditions for the main vector Ixodes ricinus in the Federal Republic of Germany give rise to the assumption that this medically important tick-borne disease might be permanently present in many areas.

Animals↗
PubMedDate not supplied

[Viremia in patients with tick-borne encephalitis and in persons with attached ixodes ticks].

An original method of virus isolation developed by the authors made it possible to collect 64 strains of tick-borne encephalitis (TBE) virus isolated from the blood of TBE patients and subjects complaining of sucking Ixodidae ticks. It is demonstrated that only a small part of the tick natural population cause acute TBE. The majority of the strains (54 isolates) of TBE virus have been isolated from the blood of clinically healthy subjects. Half of the strains showed no immunogenic properties in human body. Season infectivity corresponds to monthly virusophority of the ticks.

Adolescent↗
PubMed1997

Ticks and tick-borne diseases as a constraint to sheep and goat production in Italy. Selected features.

The paper reviews basic information on small ruminant production in Italy and on the tick species commonly found on them. A total of 13 Ixodidae species have been reported to parasitise sheep in the country. The tick species were belonging to five genera: Ixodes (two species), Haemaphysalis (four species), Dermacentor (one species), Rhipicephalus (three species) and Hyalomma (three species). The same species, with the exception of Haemaphysalis inermis and Hyalomma detritum have been reported also on goats. Scarse data are available on the impact of tick borne diseases on small ruminants productivity. The zoonotic role which may be played by ticks in transmitting occupationally acquired diseases to people involved in animal husbandry and to common public which may accidentally invade grazing areas is also discussed.

Animal Husbandry↗
PubMed2004

Immune-responsive lysozymes from hemocytes of the American dog tick, Dermacentor variabilis and an embryonic cell line of the Rocky Mountain wood tick, D. andersoni.

Immune-responsive lysozyme encoding cDNAs were identified from two medically important tick species by an expressed sequence tag approach of D. variabilis hemocytes (Dv Lys) and a D. andersoni embryonic derived cell line, DAE100. Comparative sequence analyses indicated the Dermacentor molecules to be products of orthologous genes and to be most similar to arthropod c-type lysozymes. Northern blotting analyses demonstrated that Dv Lys expression levels were most abundant in tick hemocytes and to a much lesser degree in the midgut while barely detectable in ovary, salivary gland, and Malpighian tubule tissues. Involvement of the Dermacentor c-type lysozymes in innate immunity was demonstrated by Escherichia coli challenges of D. variabilis ticks by injection resulting in a temporal profile of significantly elevated transcript abundances above those of naive controls that was similarly observed of the D. andersoni cells co-cultured with E. coli. In contrast to that reported of the digestive gut lysozyme of the soft tick Ornithodoros moubata, Dv Lys levels were not statistically differentially regulated by blood meal digestion. Additionally, given the differences in tissue distribution, sequence characteristics and phylogenetic placements between the Dermacentor and Ornithodoros lysozymes demonstrates that ticks possess differently adapted c-type lysozymes that are spatially and temporally differentially expressed.

Amino Acid Sequence↗
PubMed2006

Gene silencing of the tick protective antigens, Bm86, Bm91 and subolesin, in the one-host tick Boophilus microplus by RNA interference.

The use of RNA interference (RNAi) to assess gene function has been demonstrated in several three-host tick species but adaptation of RNAi to the one-host tick, Boophilus microplus, has not been reported. We evaluated the application of RNAi in B. microplus and the effect of gene silencing on three tick-protective antigens: Bm86, Bm91 and subolesin. Gene-specific double-stranded (dsRNA) was injected into two tick stages, freshly molted unfed and engorged females, and specific gene silencing was confirmed by real time PCR. Gene silencing occurred in injected unfed females after they were allowed to feed. Injection of dsRNA into engorged females caused gene silencing in the subsequently oviposited eggs and larvae that hatched from these eggs, but not in adults that developed from these larvae. dsRNA injected into engorged females could be detected by quantitative real-time RT-PCR in eggs 14 days from the beginning of oviposition, demonstrating that unprocessed dsRNA was incorporated in the eggs. Eggs produced by engorged females injected with subolesin dsRNA were abnormal, suggesting that subolesin may play a role in embryonic development. The injection of dsRNA into engorged females to obtain gene-specific silencing in eggs and larvae is a novel method which can be used to study gene function in tick embryogenesis.

Animals↗