Ability of Ixodes persulcatus, Haemaphysalis concinna and Dermacentor silvarum ticks to acquire and transstadially transmit Borrelia garinii

In China, the ability of Ixodes persulcatus, Haemaphysalis concinna and Dermacentor silvarum to transmit Borrelia spirochetes was determined under laboratory conditions. Results showed that all three tick species can acquire spirochetes by feeding on infected mice. However, the capability of the three species to maintain spirochetes was different. Only I. persulcatus is able to maintain spirochetes alive during molting, and subsequent tick stages transmitted the infection to naive mice. In H. concinna and D. silvarum ticks, spirochetes could not survive after the digestion period of blood and after the molting process was finished, spirochetes were no longer detected. Contrary to H. concinna and D. silvarum, I. persulcatus should be considered the principal vector of Lyme disease in north China.     

Ixodid ticks of Pavlodar Province and their participation in the circulation of tularemia infection

Investigations carried out in Pavlodar Province have shown that 7 species of ixodid ticks, Ixodes crenulatus, I. lividus, I. persulcatus, I. laguri laguri, Dermacentor marginatus, D. reticulatus, Haemaphysalis concinna, and one brought species, Hyalomma asiaticum, parasitize domestic animals and wild mammals. Maximum activity of pasture ticks of the genus Dermacentor falls on the end of April--beginning of May, that of H. concinna on the beginning of June. The growth in the abundance of pasture ticks, recorded during the last years, is favoured by the increase in the cattle live stock, its seasonal movements and pasture area reduction. Natural nidi of tularemia become more active. Since 1977 221 cultures of tularemia agent have been isolatid from pasture ticks. H. concinna takes the most active part in the infection circulation.     

Tick infection rates with Borrelia Ixodes ricinus versus Haemaphysalis concinna and Dermacentor reticulatus in two locations in eastern Germany

Unfed nymphal Ixodes ricinus, Haemaphysalis concinna, and adult Dermacentor reticulatus were collected in two locations of Saxony in July and September 1991 by flagging. In July, the abundance of nymphal I. ricinus was about 2-3 times higher than that of nymphal H. concinna, a time of the year when nymphs of both species are reported to have a seasonal peak of activity. No D. reticulatus were flagged concurrently. In September, host-seeking activity of nymphal I. ricinus was again quite high as was that of adult D. reticulatus but only low numbers of nymphal H. concinna were collected. The flagged ticks were individually examined for Borrelia by an indirect immunofluorescence assay (I. ricinus: n = 414; H. concinna: n = 96; D. reticulatus: n = 116). The prevalence of Borrelia (probably B. burgdorferi) in I. ricinus varied from 12.1% to 21.0%. No borreliae were found in H. concinna. Of the examined D. reticulatus from one site (n = 97) 11.3% contained either B. burgdorferi or a related Borrelia. This may be the first finding of Borrelia in an Eurasian Dermacentor species.     

The taxonomic aspects of the transmission of the causative agent of Lyme disease

According to world literature data 17 species of ixodid ticks have been studied for natural infection with the Lyme disease agent. Analysis of the data on the level of the infection, transovarial and transphase transmission has shown that main biological vectors of Borrelia burgdorferi are the species of the subgenus Ixodes s. str. - I. ricinus, I. persulcatus (Eurasia), I. dammini, I. pacificus (North America). Potential vectors are I. scapularis, I. dentatus, Amblyomma americanum, Dermacentor variabilis. Single isolations were registered for I. neotomae, Haemaphysalis leporispalustris, D. occidentalis. Nonidentified spirocheta was isolated from A. americanum, D. variabilis, D. parumapertum, Rhipicephalus sanguineus. No agent was isolated from I. cookey, D. albipictus, R. reticulatus, H. concinna. On the basis of comparative and ontogenetic data the species from a group of main vectors: I. ricinus, I. persulcatus, I. pacificus had been attributed by me to the phyletic group persulcatus before Lyme disease was discovered and its causative agent isolated. The question whether I. scapularis belongs to the group persulcatus was also discussed at that time but left open due to somewhat aberrant structure of gnathosoma at preimaginal phases (Filippova, 1969, 1971, 1973). 6 Palaearctic, 2 Indomalayan and 3 Nearctic species were referred to the group persulcatus at the time. I. dammini was described later, in 1979. Gnathosoma of its preimaginal phases has an intermediate structure between I. scapularis and other species of the group persulcatus. Sexually mature phase and nymph of I. dentatus have much in common with Palaearctic members of the group, I. pavlovskyi, I. kazakstani, I. kashmicus. Preimaginal phases of I. scapularis and nymph of I. dentatus were studied by me on the collection material. Thus, it is possible to speak of the belonging of main vectors of B. burgdorferi to a common phyletic group within the subgenus Ixodes s. str. and, therefore, of common origin of ecological medium for the agent. At the same time each species of the vector is an evolutionally developed difference of ecological medium for B. burgdorferi. Roots of the group persulcatus could originate as far as in Paleocene before the land connection between North America and Europe disappeared. Conditions for the existence of recent species, however, appeared considerably later and their flourishing is dated by Pliocene. The main epidemiological role belongs now to I. ricinus, I. persulcatus, I. dammini, I. pacificus.(ABSTRACT TRUNCATED AT 400 WORDS)     

Long-term dynamics of density and diversity of ticks (Ixodidae) on the natural and disturbed territories

As result of long-years monitoring of density and diversity of Ixodidae living on Tomsk territory and in suburbs it has been shown that at least two species of ticks (I. persulcatus and I. pavlovskyi) inhabit there simultaneously. It has been studied that percent of I. pavlovskyi increased nearby town buildings. In the natural biotopes I. persulcatus is dominated, while I. pavlovskyi is founded rare. It has been shown, that during last 15 years (since 1996 till 2010) density of ticks increase on the town suburbs. The combination of ecological and chemical methods of tick suppression on the limited territory may leads to significant decreasing of ticks density. There is one biotope only, where non-typical for this region species (Dermacentor reticulatus and Haemaphysalis concinna).     

Detection of Babesia spp. DNA in small mammals and ixodic ticks on the territory of north Ural, west Siberia and far east of Russia

Totally, 932 small mammals and 458 questing adult Ixodes persulcatus from Sverdlovsk and Novosibirsk regions and Khabarovsk Territory, as well as 128 Haemaphysalis japonica, 34 H. concinna and 29 Dermacentor silvarum from Khabarovsk Territory were examined for the presence of Babesia by nested PCR based on the 18S rRNA gene. Babesia microti DNA was found in samples of small mammals from all the studied regions--in 36.2% of samples from Sverdlovsk region, 5.3% of samples from Novosibirsk region, and 6.7% of samples from Khabarovsk Territory. The determined B. microti 18S rRNA gene sequences from Novosibirsk region (6 sequences) and from Khabarovsk Territory (10 sequences) were identical to each other and to the sequences of pathogenic for human B. microti US-type, while the determined B. microti 18S rRNA gene sequences from Sverdlovsk region (12 sequences) were identical to those of B. microti strain Munich. B. microti were found most frequently in samples of Myodes spp., they were found also in Microtus spp., Apodemus spp., Sorer spp., and Sicista betulinav. It was shown that one of 347 analyzed I. persulcatus from Novosibirsk region and one of 77 I. persulcatus from Khabarovsk Territory contained B. microti US-type DNA. One I. persulcatus from Novosibirsk region contained B. divergens DNA. In this work B. divergens was for the first time determined in I. persulcatus and B. microti in I. persulcatus in Asian part of Russia. Three different genetic variants of Babesia sensu stricto were found in three H. japonica from Khabarovsk Territory. The first genetic variant was closely related to Babesia sp. revealed in a feral raccoon in Japan (99.9% similarity on the basis of 18S rRNA gene sequences). Two others Babesia genetic variants were most similar to the ovine pathogen Babesia crassa (97.1-97.6% similarity on the basis of 18S rRNA gene sequences).     

Ability of female ixodid ticks to recover from poisoning with DDT in the process of feeding]

Ability of hungary females of Ixodes persulcatus, Haemaphysalis concinna and Dermacentor silvarum to feed and lay eggs after having been exposed to different DDT doses (LD100) has been studied. The ticks heavily injuried but still mobile can feed on the host and lay eggs, i.e. to overcome the poisoning. Clutches laid by these females do not differ from control ones. Loss of mobility deprives the ticks of the ability to fed. An increase in DDT dose (LD100 X 100, experiment with I. persulcatus) does not allow the ticks to feed even if the ability to movement is preserved.     

Longevity of forest and taiga ticks (Ixodidae) infected and non-infected with Borrelia burgdorferi groups

A life longevity of Ixodes ricinus and I. persulcatus have been examined in laboratory conditions. It was found that specimens infected with borreliae live slightly longer than non-infected ones (difference is not reliable); females live 1.5 times longer than males; I. ricinus lives 2-4 times longer than I. persulcatus. It is suggested that I. persulcatus has a higher rate of metabolism than I. ricinus and that the latter species obtains an ability to survive after the last moult two winters and keep an activity in two summer seasons not counting the year of moulting.     

Survey of the vectorial competence of ticks in an endemic area of spotted fever group rickettsioses in Fukui Prefecture, Japan

The prevalence of SFGR in ixodid ticks in the Mt. Arashima-dake area in the northern part of Fukui Prefecture was surveyed, because of strong suspicions that the first case identified in this Prefecture had become infected with R. helvetica in this region. The ticks identified consisted of three genera and six species; I.ovatus, I. persulcatus, I. monospinosus, H. flava, H. japonica and D. taiwanensis. Of all 222 ticks collected, only I. monospinosus ticks (8 of 32 examined) were positive for SFGR isolates, which were genetically identified as R. helvetica. Ticks (157 of all 222) positive for SFGR-DNA fragments consisted of I. monospinosus (14 of 32), I. persulcatus (11 of 55), I. ovatus (3 of 38), H. flava (5 of 21) and H. japonica (2 of 9). Of these, thirteen I. monospinosus, eight I. persulcatus, three I. ovatus, two H. flava and one H. japonica were identified by nucleotide sequences as positive for R. helvetica. DNA fragments from three H. flava and one H. japonica showed greater homology to R. japonica than to R. helvetica or R. asiatica. The present results indicate that it is most likely that the vector tick of R. helvetica infection in Fukui Prefecture is I. monospinosus.     

Ixodes ricinus is the dominant questing tick in forest habitats in Romania: the results from a countrywide dragging campaign

In 2010 and 2011, questing ticks were collected from 188 forested locations in all the 41 counties of Romania using the dragging method. The total of 13,771 ticks collected belonged to eleven species: Ixodes ricinus (86.9?%), Dermacentor marginatus (9.5?%), Haemaphysalis punctata (2.6?%), H. concinna (0.6?%), H. sulcata (0.3?%), H. parva (0.1?%), Hyalomma marginatum (0.02?%), D. reticulatus (0.02?%), I. crenulatus (0.007?%), I. hexagonus (0.007?%) and I. laguri (0.007?%). Ixodes ricinus was present in 97.7?% (n?=?180) of locations, occurring exclusively in 41.7?% of the locations, whereas it was the dominant species in 38.8 % of the other locations, accounting for over 70?% of the total tick community. The following most common questing ticks were D. marginatus, H. punctata and H. concinna. Ixodes ricinus co-occurred with one, two or three sympatric species. The occurrence of D. reticulatus in forested habitats from Romania was found to be accidental.     

The peculiarities of the biology of ticks inhabiting the environs of Tomsk City

The presence of ticks Ixodes persulcatus and I. pavlovskyi occidentalis is revealed in urban parks and the forests directly adjoined to buildings. I. pavlovskyi occidentalis is found to be the dominant species nearby the city. The both species are occurred almost simultaneously, and the peak of their abundance usually falls on 2nd or 3rd ten-day period of May. In the city the ticks species ceased occurring in registers in the end of May, and in the adjacent forests they disappeared in the end of June. I. pavlovskyi occidentalis has not been found in the forests remote from the city at the distance more than 15 kilometers. Besides the above species the ticks Dermacentor reticulatus and Haemaphysalis concinna are occurred rarely in the territory examined.     

Methods for estimating the demographic structure of the taiga tick (Ixodidae) based on results of standard parasitological observations

A retrospective estimation of the abundance dynamics of the taiga tick Ixodes persulcatus in mixed coniferous and leaf-bearing forests of the Udmurtia Republic in the period 1957-1986 was carried out. A possibility to estimate the absolute number of all stages of I. persulcatus based on relative indices. Females of I. persulcatus lay 20,250 eggs per 1 hectare, and this number of eggs gives birth to 15,000 larvae. From this number, 7870 larvae hibernate and 6550 individuals became fed. The number of nymphs is 5930, among which 5110 individuals live up to spring, and 1390 became fed. The number of adult mites in autumn is 1250; in subsequent spring this number decreases to 780. The mean number of engorged females is 8. The mortality rate of ticks caused by the deficit of hosts increases from preimaginal stages to adults; for larvae, nymphs and imago this index is 16.6, 72.8, and 97.9%, respectively. Quotas of individuals with 3-, 4- and 5-year life cycle among the unfed imago are 70.4, 28.0, and 1.6%, respectively.     

Comparison of Borrelia burgdorferi isolated from humans and ixodid ticks in Hokkaido, Japan.

Four spirochetal isolates (JEM1 to JEM4) were obtained from cutaneous lesions of patients manifesting erythema chronicum migrans in Hokkaido, Japan. In the protein profiles by SDS-PAGE and the reactivities with monoclonal antibodies (H5332 and H9724) by immunoblotting, all the human isolates were identical with the tick isolates from Ixodes persulcatus. These data indicate that I. persulcatus is an important vector of Lyme disease for humans in Japan.     

Reason for fluctuation in the demographic structure of the taiga tick population (Ixodidae) in dark conifer-leaf forests of Kemchug Upland

It was found out, that mean ratio of unfed taiga ticks Ixodes persulcatus having a life cycle of 3-5 and 6 years counts respectively (N = 6) 33.6, 52.8, 13.2 and 0.4%. Data on absolute number of I. persulcatus individuals in the process of onthogenesis is given. It is shown, that mortality of different unfed stages increases from larva to imago. In the autumn-winter period, the mean ratio of eliminated individuals counted 16% of larvae, 20% of nymphs, and 38 of imago. The mortality in the spring-summer period caused mainly by the deficit of hosts and counted for these stages 3, 82 and 98% respectively. Engorged ticks successfully undertake unfavorable conditions both in the spring-summer and autumn-winter periods. Their mean mortality in the period from feeding to moulting does not exceed 12%.     

The correlation variability of the morphometric traits in 4 species of ixodid tick species (Ixodidae)]

Correlation analysis of 10 characters was run in three species of Dermacentor, D. nuttalli, D. ushakovae, D. niveus, and in Ixodes persulcatus, separately for each phase and sex. Correlation coefficients are very low in larvae of all species. In male nymphs correlation coefficients are on the same level in all species while the correlation coefficient level in female nymphs reflects the degree of independence of the development of characters. This defines the degree of manifestation of sexual dimorphism at the nymphal phase: the more rigid the connections between the characters the less number of characters shows sexual differences. At the phase of imago the lowest correlation coefficients are in I. persulcatus. This species displays most distinct differences in the morphology of females and males. On the basis of comparison of correlation and variability coefficients the functional role of the characters is discussed.     

Acarological studies in two protected areas of Central Italy

In the present note are reported the results of preliminary studies on tick distribution in two wildlife areas of Abruzzo (National Park of Abruzzo, a mountainous area, approximately 40,000 ha, in Central Apennines, interesting Abruzzo, Latium and Molise regions) and Latium (Capocotta-Castel Porziano Presidential reserve, on the Tyrrhenian coast, 30 km from Rome). Sampling of ticks from domestic and wild mammals as well as from vegetation, was performed in three different areas of the National Park in 1995. Tick species identified include Rhipicephalus bursa, R. sanguineus, Hyalomma marginatum, Haemaphysalis punctata, Dermacentor marginatus, Ixodes ricinus, I. hexagonus. The presence of I. ricinus was discontinuous and sporadic. In Capocotta estate, samplings were performed bimonthly from March to November 1997 in an restricted area (1 ha) with typical Mediterranean flora and fauna. The following species were collected: I. ricinus, Haemaphysalis concinna, D. marginatus, R. bursa, Hy. marginatum. There was a high dominance of I. ricinus and H. concinna.     

Frequent isolation of Francisella tularensis from Dermacentor reticulatus ticks in an enzootic focus of tularaemia

Abstract. A total of 924 questing Dermacentor reticulatus (Fabricius), 504 Ixodes ricinus (L.), sixty Haemaphysalis concinna Koch and 718 mosquitoes (Aedes spp.) were examined in a floodplain forest ecosystem during the 1994-95 outbreak of tularaemia in South Moravia, Czech Republic. Francisella tularensis was not isolated from H.concinna ticks or Aedes spp. mosquitoes, whereas twenty-one isolates were recovered from the other haematophagous arthropods. Dermacentor reticulatus revealed a significantly higher infection rate (2.6%) than I.ricinus (0.2%). This tick species acts as principal vector for tularaemia in the enzootic focus. Monitoring of D.reticulatus for F.tularensis thus seems to be a very efficient approach in the surveillance of tularaemia in the flood-plain forest ecosystems of Europe.     

The meadow tick Dermacentor reticulatus in natural foci of tick-borne encephalitis in Udmurtia

In southern Udmurtia, where occur both Dermacentor reticulatus and Ixodes persulcatus, in the years of high abundance of small mammals feeding periods of larvae and nymphs of these ticks coincide completely. The duration of simultaneous parasitism of preimago of the above ixodid species on animals is of epidemiological significance as far as within this period the infection of young stages of D. reticulatus with the virus of tick-borne encephalitis occurs. This is confirmed by the isolation of I strain of the virus from D. reticulatus collected at the state of engorged nymphs on hosts common with I. persulcatus and moulted in the laboratory.     

Comparative characteristics of lysozymes of different origin

Lysozymes with different molecular weights were isolated from homogenates of ticks or Ixodoidea with a procedure based on specific sorption of the enzyme by chitin. Lysozymes with a molecular weight of 13,800 were isolated from O. moubata, O. papillipes and A. lahorensis and lysozymes with a molecular weight of 15,000 were isolated from H. asiaticum and I. persulcatus. Micrococci and staphylococci proved to be the most sensitive to the lysozymes. E. coli and Salmonella spp. were less sensitive. The activity of the lysozymes from O. moubata, O. papillipes and A. lahorensis was 2 to 4 times as high as that of the yolk lysozyme and 4 to 8 times as high as that of the lysozymes from H. asiaticum and I. persulcatus. The activity of the yolk lysozyme was 2 or more times as high as that of the lysozymes from H. asiaticum and I. persulcatus. The lysozymes were resistant to heating in acid media. In alkaline media a marked loss of the activity was observed.     

Detection of two zoonotic Babesia microti lineages, the Hobetsu and U.S. lineages, in two sympatric tick species, ixodes ovatus and Ixodes persulcatus, respectively, in Japan

The species Babesia microti, commonly found in rodents, demonstrates a high degree of genetic diversity. Three lineages, U.S., Kobe, and Hobetsu, are known to have zoonotic potential, but their tick vector(s) in Japan remains to be elucidated. We conducted a field investigation at Nemuro on Hokkaido Island and at Sumoto on Awaji Island, where up to two of the three lineages occur with similar frequencies in reservoirs. By flagging vegetation at these spots and surrounding areas, 4,010 ticks, comprising six species, were collected. A nested PCR that detects the 18S rRNA gene of Babesia species revealed that Ixodes ovatus and I. persulcatus alone were positive. Lineage-specific PCR for rRNA-positive samples demonstrated that I. ovatus and I. persulcatus carried, respectively, the Hobetsu and U.S. parasites. No Kobe-specific DNA was detected. Infected I. ovatus ticks were found at multiple sites, including Nemuro and Sumoto, with minimum infection rates (MIR) of ～12.3%. However, all I. persulcatus ticks collected within the same regions, a total of 535, were negative for the Hobetsu lineage, indicating that I. ovatus, but not I. persulcatus, was the vector for the lineage. At Nemuro, U.S. lineage was detected in 2 of 139 adult I. persulcatus ticks (MIR, 1.4%), for the first time, while 48 of I. ovatus ticks were negative for that lineage. Laboratory experiments confirmed the transmission of Hobetsu and U.S. parasites to hamsters via I. ovatus and I. persulcatus, respectively. Differences in vector capacity shown by MIRs at Nemuro, where the two species were equally likely to acquire either lineage of parasite, may explain the difference in distribution of Hobetsu throughout Japan and U.S. taxa in Nemuro. These findings are of importance in the assessment of the regional risk for babesiosis in humans.