Aetiology of enzootic staphylococcal infection (tick pyaemia) in lambs. Field investigations into the relationship between tick-borne fever and tick pyaemia.
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Agranulocytosis↗
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Tick, tick, ticking away....
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Anti-Bacterial Agents↗
Tick, tick, tick ... there's a time bomb out there.
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Animals↗
[Ticks of domestic and wild animals in Germany: on the occurrence and biology of the hedgehog tick (Ixodes hexgonus) and the fox tick (Ixodes canisuga)].
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Animals↗
Identification of a glycine-rich protein from the tick Rhipicephalus haemaphysaloides and evaluation of its vaccine potential against tick feeding.
A cDNA coding a glycine-rich protein was identified from the Rhipicephalus haemaphysaloides tick. The cDNA named here as RH50 was 1,823 bp, including a single open reading frame (ORF) of 1,518 nucleotides. The ORF encodes a polypeptide of 506 amino acid residues with a size of 50 kDa, as calculated by a computer. The predicted amino acid sequence of RH50 showed a low homology to sequences of some known extracellular matrix-like proteins. The native protein was identified in both the fed tick salivary gland lysates and extracts of cement material using the serum against the recombinant protein. Reverse transcription polymerase chain reaction results showed that RH50 mRNA was only transcribed in partially fed tick salivary glands, not in unfed tick salivary glands or partially fed tick midgut, fat body, or ovary. The differential expression of RH50 protein in fed tick salivary glands was confirmed by immunofluorescence. The low attachment rate both in the adult and nymphal tick, and the high mortality of immature ticks (nymph) feeding on recombinant RH50-immunized rabbits were found. These results show that the RH50 protein could be a useful candidate for anti-tick vaccine development.
3' Untranslated Regions↗
An updated list of the ticks of Ghana and an assessment of the distribution of the ticks of Ghanaian wild mammals in different vegetation zones.
Twenty one species of ticks belonging to five genera of the family Ixodidae (Order Acari, sub-order Ixodida) - Amblyomma, Haemaphysalis, Hyalomma, Ixodes and Rhipicephalus (including the sub-genus Rhipicephalus (Boophilus)) - were collected from 1260 mammals, representing 29 species, 14 families and 6 orders, in four vegetation zones in Ghana during the period 1971-1978. Four other species were collected from humans in 1977. In all, eight species appeared to be new records for Ghana: Amblyomma tholloni Neumann; Dermacentor circumguttatus Neumann; Haemaphysalis houyi Nuttall & Warburton; Ixodes loveridgei Arthur; Ixodes oldi Nuttall; Ixodes vanidicus Schultze; Rhipicephalus complanatus Neumann; Rhipicephalus cuspidatus Neumann. The updated list of tick species in Ghana given here includes 41 species of ixodid ticks and four species of argasid ticks. Most species have been found in neighbouring regions of West Africa but 56 of the 121 different combinations of ixodid tick species and host species found in the collection described here have not apparently been reported before. The new combinations recorded here bring the total number of different combinations of ixodid tick species and mammalian host species now reported in Ghana to 151. The tick species found on wild mammals in Ghana mostly differed from those reported from domestic stock by other authors. The data showed that different tick species occurred in different vegetation zones and that most species displayed a pronounced preference for certain groups of related host species. Some tick species were found in the savanna feeding mainly on large bovids and/or suids; others were found in forests feeding mainly on small bovids, large rodents or small carnivores.
Animals↗
Prevalence of tick-borne encephalitis virus in Ixodes ricinus ticks in Finland.
Approximately 20 cases of tick-borne encephalitis (TBE) occur annually in Finland. The known endemic areas are situated mainly in the archipelago and coastal regions of Finland, with highest incidence in Aland islands. Ixodes ricinus panels collected in 1996-1997 from two endemic areas were screened for the presence of RNA. Two distinct RT-PCR methods were applied, and were shown to have an approximate detection limit of 10 focus forming doses (FFD)/100 microl. One out of 20 pools (a total of 139 ticks) from Helsinki Isosaari Island and one out of 48 pools (a total of 450 ticks) from Aland were positive with both methods, whereas the remaining pools were negative. The observed overall frequency (0.34%) in ticks in endemic areas of Finland, was similar to the low incidence found by virus isolation in mice in the 1960s (0.5%). Viral RNA was detectable in a diluted sample representing 0.005% of a positive pool of ten nymphs suggesting that the viral RNA load within an infected tick pool was approximately equivalent to 20,000-200,000 FFD. Sequence analysis did not show geographical clustering of the Finnish strains, suggesting an independent emergence of different TBE foci from the south. TBE virus RNA positive ticks were not found in I. ricinus panels consisting of 130 pools (726 ticks) from Helsinki city parks or 41 pools (197 ticks) from Võrmsi Island in Estonia.
Animals↗
The role of host behaviour in tick-host interactions: a domestic host-paralysis tick model.
The aim of this study was to quantify the infestation densities of Karoo and brown paralysis ticks on sheep and goats and explain it in terms of the etho-ecology of these ticks and their domestic hosts. The Karoo paralysis tick usually quests from a vantage point on the vegetation whereas the brown paralysis tick displays an appetence response from the ground and mainly engages hosts that are prostrate. Both tick species are confined chiefly to hilly areas. Temporal differences in the infestation densities of the hosts within and between tick species were evident. These differences were related to disparities in the spatial distribution of the hosts, their activity patterns and the specific appetence responses of the two tick species. Differential climatological conditions affected the quality of forage in areas with a varied topography and the feeding preferences of hosts influenced tick-host sympatry and hence infestation densities.
Animals↗
Effects of tick infestation and tick-borne disease infections (heartwater, anaplasmosis and babesiosis) on the lactation and weight gain of Mashona cattle in south-eastern Zimbabwe.
The effects of ticks and tick-borne disease infections on the lactation and weight gain of Mashona cattle were studied at Mbizi Quarantine Station in the south-eastern lowveld of Zimbabwe. Twenty-nine Mashona cows were allocated to 2 balanced groups and kept in separate paddocks at a stocking rate of one animal per 8 ha. One group received regular acaricide treatment to control bont (Amblyomma hebraeum) and other ticks. The other group was left untreated. The cows were artificially inseminated. The acaricide-treated cows and calves were essentially tick free throughout the experiment, while the untreated cows and calves were continuously tick infested. There was a drought-related decline in tick infestations in the second year of the experiment. Antibodies to Cowdria ruminantium, Babesia bigemina and Anaplasma marginale were detected in cows and calves from both groups, though the untreated group had significantly higher titres to C. ruminantium (P < 0.001). The total, measured amount of milk suckled by untreated calves was significantly more than treated calves (273 kg vs. 241 kg, P < or = 0.05). By interpolating between the twice weekly measurements, it was calculated that over the entire lactation untreated calves suckled an average of 935 kg/hd vs. 837 kg/hd for the treated group. There were no statistical differences in the weights of the 2 groups of calves at birth, weaning, 180 and 210 days post partum (P < 0.05). For cows, there were no statistically significant differences in gestation periods (288 vs. 279 days), reconception rates or weight patterns over time (P < 0.05). The results show that intensive acaricide treatment in areas of Zimbabwe where heartwater is enzootically stable is uneconomical. The maintenance of enzootic stability for tick-borne diseases through minimal tick control is clearly a more economic and practical control option.
Anaplasmosis↗
Effects of tick population dynamics and host densities on the persistence of tick-borne infections.
The transmission and the persistence of tick-borne infections are strongly influenced by the densities and the structure of host populations. By extending previous models and analysis, in this paper we analyse how the persistence of ticks and pathogens, is affected by the dynamics of tick populations, and by their host densities. The effect of host densities on infection persistence is explored through the analysis and simulation of a series of models that include different assumptions on tick-host dynamics and consider different routes of infection transmission. Ticks are assumed to feed on two types of host species which vary in their reservoir competence. Too low densities of competent hosts (i.e., hosts where transmission can occur) do not sustain the infection cycle, while too high densities of incompetent hosts may dilute the competent hosts so much to make infection persistence impossible. A dilution effect may occur also for competent hosts as a consequence of reduced tick to host ratio; this is possible only if the regulation of tick populations is such that tick density does not increase linearly with host densities.
Algorithms↗
Some factors affecting infestation of white-tailed deer by blacklegged ticks and winter ticks (Acari:Ixodidae) in southeastern Missouri.
A total of 5,669 ticks of 4 species was collected from 515 hunter killed, white-tailed deer. Odocoileus virginianus (Zimmerman), in southeastern Missouri from 1993 through 1995. The American dog tick, Dermacentor variabilis (Say) (4 adults), the lone star tick, Amblyomma americanum (L.) (57 adults, 2 nymphs), the blacklegged tick, Ixodes scapularis (Say) (3,120 adults), and the winter tick, Dermacentor albipictus (Packard) (2.059 adults, 436 nymphs, 1 larva) were collected. Patterns of adult D. albipictus and I. scapularies infesting deer were analyzed with respect to upland versus lowland habitat, county, and host sex. Prevalence and intensity of infestation by D. albipictus were higher on bucks than does, and a higher infestation prevalence was recorded for this tick on deer from upland than from lowland habitats. Mean intensities for D. albipictus were not significantly different between counties. Prevalence and mean intensity of infestation for I. scapularis were significantly higher on deer from uplands than lowlands and on bucks than does; mean intensities also differed between counties for this tick. Because adjacent populations, as well as the sex of the host, can differ in infestation rates, differences between local populations of I. scapularis should be recognized to optimize tick surveys and population models.
Animals↗
Far eastern tick-borne rickettsiosis: identification of two new cases and tick vector.
We recently reported the first documented cases of a new rickettsial disease caused by Rickettsia heilongjiangensis in the Russian Far East (Far Eastern tick-borne rickettsiosis). Here we report the amplification of DNA of R. heilongjiangensis from both the skin biopsy of an acutely ill patient and the tick removed from him prior to the disease development. The tick has been identified as Haemaphysalis spp. The clinical picture was that of a spotted fever group rickettsiosis and a seroconversion was noted with R. heilongjiangensis antigen. Screening testing of both species of Haemaphysalis ticks inhabiting Russian Far Eastern regions showed that up to 28.13% of H. concinnae and 4.48% of H. japonica douglasii ticks harbor R. heilongjiangensis. It has been concluded that H. concinnae may serve as the main vector for the transmission of R. heilongjiangensis. H. japonica douglasii ticks harbor several varieties of rickettsiae. DNA of "Candidatus Rickettsia tarasevichiae," previously found in Ixodes persulcatus ticks, was amplified from one male tick. Two sequenced complete gltA genes belong to the novel spotted fever group rickettsial species provisionally called here "Candidatus Rickettsia principis" variants Hjd54 and Hjd61. The rate of infection has been found to be not higher than 1.5%.
Adult↗
Tick avoidance behaviors associated with a decreased risk of anti-tick salivary gland protein antibody seropositivity in military personnel exposed to Amblyomma americanum in Arkansas.
During April through September 1990, 399 military personnel who originated from either Fort Chaffee, Arkansas (n = 236) or Fort Wainwright, Alaska (n = 163) were studied during maneuvers in tick-infested areas at Fort Chaffee. Study subjects completed a questionnaire and had pre- and post-maneuvers serum specimens analyzed for antibodies to several rickettsial and ehrlichial agents and to Amblyomma americanum (lone star tick) salivary gland proteins (anti-tick saliva antibodies [ATSA], a biologic marker of tick exposure). Military rank/grade and home station were associated with pre-maneuvers ATSA seropositivity by enzyme-linked immunosorbent assay (ELISA). Fort Wainwright personnel were more likely to show at least a 50% increase in ATSA levels, compared with subjects from Fort Chaffee, from the pre- to the post-maneuvers specimen (adjusted odds ratio [AOR] = 2.7, 95% confidence interval [CI] = 1.2-6.1). Subjects from Fort Wainwright who did not report use of bed netting were at an increased risk of post-maneuvers ATSA seropositivity (AOR = 4.1, 95% CI = 1.5-11.5). In contrast, subjects from Fort Chaffee who did not report tucking pants into socks were at increased risk of post-maneuvers ATSA seropositivity (AOR = 2.8, 95% CI = 1.1-7.1). Subjects from Fort Chaffee who reported an attached tick bite during maneuvers were more likely to be ATSA-seropositive in the post-maneuvers specimen (AOR = 2.5, 95% CI = 1.2-5.2). Western blot assays revealed large differences in tick salivary gland proteins that were recognized on the post-maneuvers specimen among three randomly selected individuals, and small differences within a single individual who reported a tick bite during maneuvers, comparing pre- and post-maneuvers specimens. The ATSA ELISA seropositivity was not associated with seroconversion to the tick-borne infectious agents.
Adolescent↗
[The use of smells of plant origin as indicators of the extensiveness and intensity of ixodid tick infection with the tick-borne encephalitis virus].
It has been shown that, using a simple olfactometer, through which moist air and smell of vegetative origin penetrate into the centre via different ends of the tube, ticks can be divided into two groups, those infected and not infected with tick-borne encephalitis virus. The method yielding a 100% division, is based on opposite changes in the behaviour of virus infected ticks: the attracting smells become repellent and vice versa. Normal reaction to smell measured by the length of the distance covered by an individual tick towards or from the smell source in the olfactometer tube varies in various groups of control and experimental ticks, but correlates with virus titre of ticks. It is greater in ticks with a higher level of virus reproducibility. The reaction to smell in infected ticks makes it possible to predict the intensity of their infestation.
Animals↗
[Effect of the physiological state of ticks on the intensity of tick-borne encephalitis virus replication in them].
The features of tick-borne encephalitis (TBE) virus reproduction in Ixodes ricinus and Dermacentor anderson ticks were studied in relation to the age of ticks, duration of fasting, feeding, and conditions of keeping the ticks before and after the experiment. Parenteral infection of ticks at various intervals after molting showed that the most favourable conditions for reproduction, survival, transphase and transovarial transmission of the virus occurred when the virus was given to the ticks in the first days after the period of postlarval development followed by feeding the vectors on vertebrates. In this case, owing to increased metabolic activity and intensive organogenesis and histogenesis, the virus persisted in ticks in high titers till the moment of oviposition and penetrated into the egg batch. When the virus was inoculated into old exhausted females (8-18 months) virus titers in ticks were low and penetration of the virus into the egg batch was irregular.
Animals↗
Immunization of cattle against Boophilus annulatus ticks using adult female tick antigen.
Ten crossbred calves (Friesian x Egyptian native) aged between 7-9 months old were used to evaluate the immunizing effect of whole adult B. annulatus tick antigen. A soluble fraction was obtained from extensively disrupted ticks and this fraction was used to vaccinate calves with 1 mg protein antigen. The vaccination protocol for five randomly selected calves involved two immunizations, the first was administered subcutaneously (plus aluminium hydroxide adjuvant) at the beginning of the experiment and the second was given 4 weeks later. At the same time, calves of the control group were injected with phosphate buffered saline (PBS) plus adjuvant. Ticks were counted on animals and the number of eggs laid per tick were counted and hatching percentages were determined. The vaccinated and control animals were skin tested with the antigen and calves were injected in three different sites with 50 microliters of 50, 100 and 200 ng of the antigen. At the same time, control sites were injected with PBS and the diameter of the immune response sites was measured using skin callipers. Immunization of calves showed that vaccination resulted in 73% reduction in the mean tick count. At the same time, immunization reduced the oviposition of ticks from vaccinated calves and the reduction percentage in egg laying was 65%. Vaccination induced a good immunity that could protect calves during the tick season (more than 5 months) as indicated from skin hypersensitivity reaction with the tick antigen.
Animals↗
Identification of a follistatin-related protein from the tick Haemaphysalis longicornis and its effect on tick oviposition.
The identification of ovary-associated molecules will lead to a better understanding of the physiology of tick reproduction and vector-pathogen interactions. A gene encoding a follistatin-related protein (FRP) was obtained by random sequencing from the ovary cDNA library of the tick Haemaphysalis longicornis. The full-length cDNA is 1157 bp, including an intact ORF encoding an expected protein with 289 amino acids. Three distinct domains were present in the deduced amino acids, namely, the follistatin-like domain, KAZAL, and two calcium-binding motifs, EFh. The sequence shows homology with the follistatin-related protein (FRP), which was thought to play some roles in the negative regulation of cellular growth. RT-PCR showed that the gene was expressed throughout the developing stages and mainly in the ovary as well as in fat body, hemocytes, salivary glands, and midgut. This gene was expressed in GST-fused recombinant protein with an expected size. The mouse antiserum against the recombinant protein recognized a 56-kDa native protein in both tick ovary and hemolymph. The recombinant proteins were found to have binding activity for both activin A and bone morphogenetic protein-2 (BMP-2). Silencing of FRP by RNAi showed a decrease in tick oviposition, which is consistent with the effect of a recombinant protein vaccine on the adult tick. These results showed that the tick FRP might be involved in tick oviposition. This is the first report of a member of follistatin family proteins in Chelicerata, which include ticks, spiders, and scorpions.
Activins↗
Extension of Ixodes ricinus ticks and agents of tick-borne diseases to mountain areas in the Czech Republic.
Along with the shift of the hard tick Ixodes ricinus to higher altitudes observed in the Czech Republic a corresponding shift of tick-borne infections to higher altitudes has been expected. Therefore, I. ricinus ticks, mainly nymphs, were investigated for the presence of tick-borne viruses, tick-borne encephalitis (TBE), Tribec and Eyach, and the spirochaete Borrelia burgdorferi sensu lato in the Sumava and Krkonose Mountains (Czech Republic). The TBE virus and different genospecies of B. burgdorferi s.l. were detected by RT-PCR and PCR, respectively. TBE virus was detected in ticks at 620 and 720 m above sea level (a.s.l.), B. burgdorferi s.l. was detected in ticks up to 1065 m a.s.l. Four genospecies of B. burgdorferi s.l. were identified, B. afzelii, B. garinii, B. burgdorferi sensu stricto, and B. valaisiana. Some nymphs carried multiple Borrelia infections. The conditions of tick-borne agents' distribution and potential epidemiological consequences are discussed.
Altitude↗