Ixodid ticks (Acari: Ixodidae) infesting humans in Tokat Province of Turkey: species diversity and seasonal activity

Ixodid ticks (Acari: Ixodidae) are the major vectors of pathogens threatening animal and human health. Tokat Province, Turkey, is a suitable habitat for extended tick activity with its moderate climate and vegetation. In the present study, we surveyed humans visiting health centers to determine the species diversity, geographical distribution, and seasonal activity of ixodid ticks infesting them. Out of 5,999 adult ticks collected from humans from April to September, 2008, 800 ticks were identified to species, while the remaining were identified to genus according to their distinct morphological characteristics. Hyalomma marginatum, Hyalomma detritum, Rhipicephalus bursa, Rhipicephalus (Boophilus) annulatus, Haemaphysalis punctata, Dermacentor marginatus, and Ixodes laguri were the most prevalent tick species among 24 ixodid tick species infesting humans in the region. One of these tick species, Hyalomma isacii was identified as a new record for the ixodid tick fauna of Turkey. Hyalomma species were the most abundant in summer, while Dermacentor and Ixodes species displayed the lowest frequency. Hyalomma aegyptium infestation was very common on humans in the province. Results indicated that a variety of ixodid tick species infest humans depending on the season in the target area. It is possible that a variety of ixodid tick species may contribute to the spread of tick‐borne diseases such as Crimean‐Congo haemorrhagic fever virus (CCHFV), which is endemic in the region.     

Mammals as hosts of Ixodid ticks (Acarina,Ixodidae)

Trophic association between adult ticks of the world fauna with their mammal hosts (511 tick species out of 650 species of Ixodidae of the world fauna) are reviewed. Specific tick species parasitize on representatives of 22 (out of 27) mammal orders, but species of Paucituberculata, Notoryctemorphia, Peramelemorphia, Scandentia, and Dermoptera have no specific parasites. The highest number of tick species was recorded from Artiodactyla and rodents. Mammals, on which representatives of all the 14 genera of the family parasitize, provide the diversity of the ixodid tick fauna. The conclusion on the priority of ecological factors in comparison with phylogenetic status of hosts in the formation of specific characteristics of ticks confirms Balashov’s (1982) concept on the character of host-parasite association between ticks and mammals.     

Characteristics of acquired resistance of lambs to mature ticks Hyalomma asiaticum asiaticum (experimental studies)]

A new method was employed for studies of parasite-host relationships between ixodid ticks and their hosts. It has been established that ixodid ticks are able to desensibilize the reactive sensibility of the host and to satiate themselves without unhibiting the latter. Every day and long parasitism of the ticks on cattle (in nature) and increasing doses of secretion of the ticks' saliva (sensibilizer) lead apparently to the weakening of the host's organism (desensitization). However, under laboratory conditions in hosts a resistence to bites of ixodid ticks can appear.     

Characteristic features of the ranks genus and subgenus, and an intercalary rank "species complex" in ixodid ticks (Acari: Ixodidae)

The work was carries our from the standpoint of the morphological conception of species. Vast collections of the Zoological Institute of the Russian Academy of Science testify to the existence of hiatuses in both genera and subgenera of Palearctic ixodids at all active phases of their ontogenesis. The fact that the subgenera of Palearctic genera have been well studies is notes, and composition of the subgenera is presented. The question of a taxonomic intercalary rank "species complex" is considered in detail in the context of the coevolution between some complexes of closely related species of ixodid ticks and some closely related species (genospecies, strains) of pathogens. The question of the taxonomic rank "species complex" in ixodid ticks as a phyletic species association is postulated on the basis of comparative ontogenetic data. Nomenclature status of the intercalary association "species complex" is specified in conformity with the fourth edition of the International Code of Zoological Nomenclature. Species composition of most studied complexes is presented. Some variants of morphological differentiation between species complexes within subgenus are considered. Significance of the taxonomic concept "species complex" for zoological. parasitological, and medical aspects of the ixodid ticks study was evaluated. Prognostic significance of the rank "species complex" for the study of the relationships between ixodid ticks and pathogens is discussed.     

Birds as hosts of ixodid ticks (Acarina,Ixodidae)

rophic relations between ixodid ticks of the world fauna parasitizing as adults on birds are analyzed. These ticks include 60 out of 650 species of the family Ixodidae and belong to the genera Ixodes, Haemaphysalis, and Amblyomma. Relations between birds and ticks of the genus Ixodes are most ancient. Colonial marine birds seem to be the first hosts of ixodid ticks in the class of birds. Trophic specialization of ticks is not associated with bird taxa, because in most cases no tick specificity is caused by either phylogenetic features of hosts, or specific environmental conditions.     

Ticks Feeding on Humans: A Review of Records on Human-Biting Ixodoidea with Special Reference to Pathogen Transmission

In this article, literature records of argasid and ixodid ticks feeding on humans worldwide are provided in view of increased awareness of risks associated with tick bites. Ticks can cause paralyses, toxicoses, allergic reactions and are vectors of a broad range of viral, rickettsial, bacterial and protozoan pathogens. Approximately 12 argasid species (Argas and Ornithodos) are frequently found attached to humans who intrude into tick-infested caves and burrows. Over 20 ixodid tick species are often found on humans exposed to infested vegetation: four of these are Amblyomma species, 7 Dermacentor spp., 3 Haemaphysalis spp., 2 Hyalomma spp. and 6 Ixodes species. Personal protection methods, such as repellents and acaricide-impregnated clothing are advised to minimize contact with infected ticks. Acaricidal control of ixodid ticks is impractical because of their wide distribution in forested areas, but houses infested with soft ticks can be sprayed with acaricidal formulations. Attached ticks should be removed without delay. The best way is to grasp the tick as close to the skin as possible with fine tweezers and pull firmly and steadily without twisting. Finally, despite the fact that most people who are bitten destroy the offending tick in disgust, it is recommended that they preserve specimens in ethanol for taxonomic identification and detection of pathogens by molecular methods.     

Saliva-activated transmission (SAT) of Thogoto virus: dynamics of SAT factor activity in the salivary glands ofRhipicephalus appendiculatus,Amblyomma variegatum,andBoophilus microplus ticks

Thogoto (THO) virus is transmitted from infected to uninfected ticks when co-feeding on uninfected guinea-pigs, even though the guinea-pigs do not develop a detectable viraemia. This form of non-viraemic transmission is potentiated by a factor (s) secreted by the saliva of ticks and hence has been termed saliva-activated transmission (SAT). The synthesis of the SAT factor by the salivary glands of three ixodid tick species was determined by placing uninfected nymphal ticks on guineapigs that were subsequently inoculated with a mixture of THO virus and salivary gland extract (SGE) derived from one of the tick species. SAT factor activity was measured by determining the number of nymphs that acquired THO virus. For the three-host ixodid species,Rhipicephalus appendiculatus andAmblyomma variegatum, maximum enhancement of THO virus transmission was observed when salivary glands were derived from uninfected, female ticks that had fed for a period of 6 or 8 days, respectively. In contrast, when salivary glands were derived form uninfected femaleBoophilus microplus, a one-host ixodid tick species, enhancement of THO virus transmission was observed throughout the tick feeding period. Thus, the natural feeding behaviour of ticks appears to be an important factor in determining the relative importance of these vectors in mediating SAT.     

History of the species range of ixodid ticks,vectors of pathogens with natural nidality (Acari,Ixodidae), as a prerequisite of their intraspecific biodiversity

Morphological, taxonomic, and some ecological aspects of intraspecific biodiversity of five ixodid species transmitting pathogens with natural nidality, with extensive ranges of different types are examined. Causal relations of ixodid intraspecific biodiversity with the origin of the species ranges are considered.     

中华硬蜱凝血酶抑制剂的分离纯化与活性

通过凝胶过滤和反相高压液相层析。从200只半饱吸血的中华硬蜱(Ixodide sinesis)唾液腺中分离纯化得到一凝血酶抑制剂。用飞行质谱测定其分子量为6．356kDa,与其他蜱类来源的凝血酶抑制剂分子量不同,提示为一新蛋白分子。该抑制剂对凝血酶有强烈的抑制活性,对激活的第X因子和胰蛋白酶有微弱的抑制活性。其发现将为发展疫苗、生物控制中华硬蜱提供资料和目标抗原。     

Distribution and phylogenetic analyses of an endangered tick,Amblyomma sphenodonti

Abstract

In this study we investigate the geographic distribution, genetic diversity, and phylogenetic relationships of an endangered tick, Amblyomma sphenodonti (Family Ixodidae). Amblyomma sphenodonti and its host, the tuatara (Sphenodon), are found only on small offshore islands around New Zealand. Our results show that Amblyomma sphenodonti has a more severely restricted geographic distribution than its host, as it was found on only eight of 28 islands (four out of 12 island groups) where tuatara still live. The prevalence of A. sphenodonti is likely to have been affected by low host density and fluctuations in host population size as tuatara populations became isolated on offshore islands. Analysis of A. sphenodonti cytochrome oxidase 1 (CO1) sequences indicated a lack of gene flow between islands, with fixed differences in CO1 sequences between islands, but almost no genetic diversity within island populations. A similar phylogenetic pattern to that observed in tuatara mtDNA was observed, indicating co‐evolution of two species, at least since the Pleistocene. Phylogenetic analysis using 18S rRNA sequences suggest that A. sphenodonti is not closely related to other Amblyomma species, and that a separate genus for this species may be warranted. However, data from other ixodid ticks are required before the distinctiveness of A. sphenodonti can be confirmed and the phylogenetic relationships among ixodid ticks fully understood.     

Sexual transmission of the tick-borne encephalitis virus in ixodid ticks (Ixodidae)

Sexual transmission of tick-borne encephalitis virus from infected ixodid males to noninfected females is shown: in Ixodes persulcatus in 50% (6 of 12) and in Hyalomma anatolicum in 6.2% (1 of 16). The sexual transmission of tick-borne encephalitis virus is shown to provide a transmissible transfer of the virus into eggs in ixodid ticks. Electron microscope studies of the sexual system of ixodid males infected with the virus have revealed numerous morphologically mature virus particles in lumens of endoplasmic reticulum, in vacuoles of Golgi complex of spermatocytes and in association with tubular elements of spermatids.     

Identification of two forms of cyclophilin from the hard tick Haemaphysalis longicornis

We have shown here the identification and characterization of two cyclophilin, cyclophilin A (CyPA) and B (CyPB), from the ixodid tick, Haemaphysalis longicornis. Both CyPA and CyPB contain the conserved peptidyl-prolyl isomerase (PPIase) domain, with CyPA consisting of 188 amino acids and CyPB of 216 amino acids. CyPA and CyPB share 50–67% amino acid sequence identity with the cyclophilins of other organisms, and are found in multiple organs throughout the developmental stages of ixodid ticks. In addition, recombinant CyPA and CyPB exhibited PPIase activity that could be inhibited by the cyclic peptides cyclosporin A (CsA). Silencing of CyPA through RNA interference has led to a significant reduction in the body weight of engorged ticks and their failure to lay eggs, in contrast to CyPB whose silencing did not result in any detectable phenotypic changes. Our results indicate that CyPA represents the major cyclophilin protein in H. longicornis involved in blood ingestion, viability, and oocyte development. This is the first report of cyclophilin proteins from ixodid and argasid ticks.     

A method for extraction and analysis of high quality genomic DNA from ixodid ticks

Currently, no published methods describe the extraction of high molecular weight genomic DNA from ixodid ticks (Acari: Ixodidae) and commonly used methods of extraction are not well adapted for use with members of this family. A method for extraction of minimally degraded genomic DNA from ixodid ticks that can be completed in one or two days is described. The method produces DNA which is of sufficient size (>24 kb) for use in Southern analysis and which is readily digestible by restriction endonucleases. Southern analysis using a cytochrome P450 gene probe, demonstrates the success of our method with genomic DNA extracted from two species of Ixodidae, the lone star tick, Amblyomma americanum (Linnaeus) and the cattle fever tick, Boophilus microplus (Canestrini).     

Gluttony and sex in female ixodid ticks: how do they compare to other blood-sucking arthropods?

The central issue dealt with here is the role of copulation in the control of feeding behaviour in ticks and some haematophagous insects. Female ticks of the family Ixodidae normally engorge to approximately 100 x their unfed body weight, and then drop from the host, produce and lay eggs, and die. Virgins, on the other hand, normally do not exceed 5-40% (depending on species) of the normal engorged body weight. But instead of detaching voluntarily at that point most virgins remain fixed to the host for extended periods, waiting for males to find them so they can complete engorgement. Virgin haematophagous insects, and virgin ticks of the family Argasidae display little, if any, reduction in blood meal size compared to mated females, at least not during the first ovarian cycle. During subsequent ovarian cycles, meal size in some virgin insects may be somewhat reduced depending on how many eggs are retained in the reproductive tract, but the reduction is not nearly to the same extent as that observed for virgin ixodid females. The stimulatory effect of copulation on engorgement in the latter is caused by a pair of proteins (voraxin alpha and beta) produced in the testis and transferred to the female with the spermatophore. Here, I propose why it might be adaptive for an ixodid female to remain small until mated. The hypothesis is suggested from the facts that ixodid ticks remain attached to the host for days (rather than minutes), and that virgin ticks, above a certain critical weight, lose all opportunity for producing viable offspring should they be groomed off the host prematurely, or should the host die while ticks are still attached.     

Experience in the absolute calculation of pasture ixodid ticks (Parasitiformes, Ixodidae) on the eastern macroslopes of Sikhoté-Alin]

A new technique is suggested for absolute registration of adult ixodid ticks with an improved furrow plough. Due to this the number of ticks can be estimated per square unit to various biotopes. As a result of registrations conducted in 1973 the density of ticks populations from the main landscape zones of eastern Sikhote-Alin (from watershed spruce-abietic forests to coastal oak woods) was estimated for the first time.     

Experimental infection of ixodid ticks with Karshi virus

The ixodid ticks Hyalomma asiaticum, H. anatolicum, Dermacentor niveus were infected experimentally with Karsha virus. The virus replication has been proved to occur in the tick's organism. The titre of the virus grows gradually in infected ticks. Entering the tick's gut during its feeding virus particles penetrate into the gut walls where primary multiplication and accumulation of the virus take place.     

The coevolution of ixodid ticks and terrestrial vertebrates

Paleontologic and zoogeographic data speak in favour of Mesozoic origin of ixodid ticks. The absence of strict restrictions for the feeding on unusual species of hosts has caused the domination of polyphagy and oligophagy over monophagy among ixodid ticks. The same peculiarities of ixodid ecology are responsible for a restricted part or absence of phylogenetic parallelism with hosts in their evolution. Primary food relations with reptiles are, apparently, preserved only in the genus Aponomma and in many species of Amblyomma while hosts for most species of other genera are mammals and, to a lesser extent, birds. The number of potential hosts in these species can be much greater than that of real ones. Restrictions in the distribution of some species are connected rather with direct effect of unfavourable environmental factors on their nonparasitic stages of the life cycle than with the absence of suitable hosts. During the evolution of natural landscapes and at a shorter stages under the influence of successions or anthropogenic factors ixodids easily adapt themselves to feeding on new species of hosts. So the differentiation of primary and secondary hosts of these parasites is rather difficult.     

Correlation of the relative population count of ixodid ticks with various recording methods

Data are given on the relative abundance ratio of 3 species of ixodid ticks obtained by different counting methods.     

The influence of various factors on fluid secretion by in vitro salivary glands of ixodid Ticks.

1. Salivary glands of the female ixodid tick, Dermacentor andersoni, secrete fluid in vitro when bathed in a slightly modified version of the mammalian tissue culture medium 'TC 199'. 2. Rate of salivation in vitro increases with progression of feeding, but there is no comparable increase in dry weight of the salivary glands during the early phase of engorgement. Engorged ticks secreted at only 25% the rate of 90-250 mg ticks, indicating that salivary gland degeneration has already begun in the very early post-engorgement stage. 3. A salivary gland stimulating factor can be detected in the nervous system but not in other tissues. 4. Male salivary glands secrete at only 1/20th the rate of female glands. Thus males probably do not use their salivary glands as osmoregulatory organs. 5. From the uniform lack of response to ACh and uniform response to DA in 7 ixodid tick species, it is suggested that the control of salivation is similar throughout the ixodid family.