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PubMed2002

Taxonomic status of Ixodes didelphidis (Acari: Ixodidae).

Ixodes didelphilis Fonseca & Aragão was described in Brazil in 1952 as a new tick species that differed from Ixodes loricatus Neumann by the spiracular plate pattern. We have reared four tick colonies from different geographic areas in the laboratory that were started from single engorged females originally identified as I. didelphidis (BMG, colony ) and I. Iocicatus (CSP, PSP, and TRJ colonies). We analyzed the spiracular plate morphology of F1 adult ticks from each tick colony, compared their biological 11th, and performed a molecular analysis of the second internal transcribed rDNA spacer (ITS2) to test the validity of the species I. didelphidis. The spiracular plate analysis of laboratory F1 adult ticks yielded single females from the four colonies showed variations that invalidate morphological parameters for differentiation of loricatus and I. didelphidis. Biological data of the BMC, CSP, and TRJ colonies were similar. The biology ofthe PSP colony was not evaluated. The ITS2 sequence variations observed between the tick colonies ranged from 1.3 to 4.9%, and the similarity tree constructed by the neighbor-joining method with nucleotide distances showerl that the distances between the samples were similar to what is expected for intraspecific variations found in other ticks species. The morphological and biological results, in conjunction with the ITS2 analysis, supported the conspecificity I. loricatus and I. didelphidis.

Animals↗
PubMed2003

Deer density and the abundance of Ixodes scapularis (Acari: Ixodidae).

The abundance of Ixodes scapularis Say (Ixodes dammini Spielman, Clifford, Piesman & Corwin), the vector tick of the Lyme disease spirochete and other human pathogens, is related to the presence of its primary reproductive stage host, white-tailed deer (Odocoileus virginianus Zimmerman). However, this relationship has not been quantified in terms that would guide wildlife management in areas in which the public is, or is likely to become, exposed to infected ticks. In this study, deer density and tick abundance were measured in an emergent area for Lyme disease at three spatial scales using estimation methods appropriate for each. Simple linear regression was used to relate (1) the number of ticks found on deer at tagging stations in southern Maine to harvest-derived estimates of the density of deer within the towns in which they were killed, (2) tick densities estimated from fall flagging counts to deer densities estimated from pellet group counts made within multiple transects distributed through 5.2-km2 study sites, and (3) tick counts to pellet group counts within the individual transects. At the broadest scale, ticks on deer decreased with elevation and distance from the coast and increased with deer density, although deer and tick presence were only weakly related. Among the 5.2-km2 study sites and within individual transects, tick abundance related more strongly to deer pellet group counts. Few ticks were collected at deer densities <7/km2.

Animals↗
PubMed2003

Vector competence of Ixodes pacificus and I. spinipalpis (Acari: Ixodidae), and reservoir competence of the dusky-footed woodrat (Neotoma fuscipes) and the deer mouse (Peromyscus maniculatus), for Borrelia bissettii.

We investigated the experimental vector competence of Ixodes pacificus Cooley and Kohls and Ixodes spinipalpis Hadwen and Nuttall, and the reservoir competence of the dusky-footed woodrat (Neotoma fuscipes Baird) and the deer mouse (Peromyscus maniculatus [Wagner]), for Borrelia bissettii Postic, Marti Ras, Lane, Hendson, and Baranton. Both rodent species are capable reservoirs for B. bissettii; infection rates for I. pacificus or I. spinipalpis nymphs fed as larvae on infected animals ranged from 50 to 57%. Moreover, both I. pacificus and I. spinipalpis are efficient vectors of B. bissettii. Viable infections were recorded from all rodents known to be exposed to one or more infected nymphs of I. spinipalpis (seven deer mice, two white mice) or I. pacificus (seven deer mice). In contrast, none of four New Zealand white rabbits fed upon by 90 I. pacificus nymphs with a probable B. bissettii infection rate of >50% became infected or seroconverted. The attachment and feeding success of laboratory-reared nymphs similarly confined with deer mice in muslin-covered wire-mesh cages for 24 h ranged from 0% for I. pacificus to 17-73% for I. spinipalpis. Notably, the I. pacificus nymphs were physiologically capable of feeding; nymphs failing to attach to rodents fed readily when placed in feeding capsules upon rabbits. We conclude that the dusky-footed woodrat and the deer mouse are capable experimental reservoir hosts of B. bissettii, and that both I. spinipalpis and I. pacificus are efficient experimental vectors of B. bissettii. However, the reluctance of I. pacificus nymphs to feed on certain rodents may limit its importance as an enzootic vector of B. burgdorferi sensu lato spirochetes.

Animals↗
PubMed2003

Reduced abundance of Ixodes scapularis (Acari: Ixodidae) and the tick parasitoid Ixodiphagus hookeri (Hymenoptera: Encyrtidae) with reduction of white-tailed deer.

The principal vector for the pathogens of Lyme disease, human granulocytic ehrlichiosis, and human babesiosis is the tick Ixodes scapularis Say. A chalcid wasp, Ixodiphagus hookeri, in the family Encyrtidae parasitizes populations of the tick on several islands or other geographically isolated sites in New England with high densities of these ticks and white-tailed deer (Odocoileus virginianus), the principal host for adult I. scapularis. Deer densities were reduced at a forested tract in Bridgeport and the Bluff Point Coastal Reserve in Groton, Connecticut, from levels exceeding 90 animals per km2 in 1992 (Bridgeport) and 1994 (Bluff Point) to 17 and 10 animals per km2, respectively, by fall 2001. Tick densities declined with sustained reductions in the population of white-tailed deer. Similarly, prevalence of tick parasitism by Ixodes hookeri declined at both sites from 30 to 25% to <1.0% and was significantly correlated with previous year's deer density at both sites (r(s) = 0.933 and r(s) = 0.867, P < or = 0.0001) and with nymphal tick densities at Bridgeport (r(s) = 0.867, P < or = 0.0001), but was not as well correlated with tick densities in Groton. The virtual disappearance of I. hookeri in this study corresponds with a lack of I. hookeri in mainland I. scapularis at comparable deer and tick densities, suggesting that there is a threshold deer density of approximatley 10-20/km2, with corresponding tick densities necessary for I. hookeri to successfully parasitize I. scapularis.

Animals↗
PubMed2003

Bartonella henselae in Ixodes ricinus ticks (Acari: Ixodida) removed from humans, Belluno province, Italy.

The potential role of ticks as vectors of Bartonella species has recently been suggested. In this study, we investigated the presence of Bartonella species in 271 ticks removed from humans in Belluno Province, Italy. By using primers derived from the 60-kDa heat shock protein gene sequences, Bartonella DNA was amplified and sequenced from four Ixodes ricinus ticks (1.48%). To confirm this finding, we performed amplification and partial sequencing of the pap31 protein and the cell division protein ftsZ encoding genes. This process allowed us to definitively identify B. henselae (genotype Houston-1) DNA in the four ticks. Detection of B. henselae in these ticks might represent a highly sensitive form of xenodiagnosis. B. henselae is the first human-infecting Bartonella identified from Ixodes ricinus, a common European tick and the vector of various tickborne pathogens. The role of ticks in the transmission of bartonellosis should be further investigated.

Animals↗
PubMed2004

Detection of Anaplasma phagocytophilum DNA in Ixodes ticks (Acari: Ixodidae) from Madeira Island and Setubal District, mainland Portugal.

A total of 278 Ixodes ticks, collected from Madeira Island and Setubal District, mainland Portugal, were examined by polymerase chain reaction (PCR) for the presence of Anaplasma phagocytophilum. Six (4%) of 142 Ixodes ricinus nymphs collected in Madeira Island and 1 nymph and 1 male (2%) of 93 I. ventalloi collected in Setubal District tested positive for A. phagocytophilum msp2 genes or rrs. Infection was not detected among 43 I. ricinus on mainland Portugal. All PCR products were confirmed by nucleotide sequencing to be identical or to be most closely related to A. phagocytophilum. To our knowledge, this is the first evidence of A. phagocytophilum in ticks from Setubal District, mainland Portugal, and the first documentation of Anaplasma infection in I. ventalloi. Moreover, these findings confirm the persistence of A. phagocytophilum in Madeira Island's I. ricinus.

Anaplasma phagocytophilum↗
PubMed2006

Host usage and seasonal activity patterns of Ixodes kingi and I. sculptus (Acari: Ixodidae) nymphs in a Colorado prairie landscape, with a summary of published North American host records for all life stages.

We examined host usage and seasonal activity patterns of the nymphal stage of the ticks Ixodes kingi and I. sculptus within a prairie rodent community in north-central Colorado. Ixodes kingi was commonly encountered on both northern grasshopper mice (Onychomys leucogaster) and thirteen-lined ground squirrels (Spermophilus tridecemlineatus), whereas I. sculptus frequently infested S. tridecemlineatus but was absent from O. leucogaster. Low numbers of ticks of both species were collected from deer mice (Peromyscus maniculatus) and Ord's kangaroo rats (Dipodomys ordii). Nymphal loads of I. kingi and I. sculptus increased dramatically on commonly infested rodent species from spring (May-June) to summer (July-August). Further, rodents trapped on prairie-dog towns tended to experience increased nymphal loads of I. kingi (O. leucogaster, S. tridecemlineatus) but decreased loads of I. sculptus (S. tridecemlineatus) following plague epizootics among prairie dog populations. A summary of published North American host records revealed that I. kingi has been recorded from humans, domestic animals (cat, dog), 17 species of carnivores, 40 species of rodents, and four species of lagomorphs, and that I. sculptus has been recorded from humans, domestic animals (cat, dog, goat), 13 species of carnivores, 34 species of rodents, and three species of lagomorphs. In accordance with our observations from Colorado, I. kingi commonly has been found to infest heteromyid and murid rodents (such as grasshopper mice), whereas I. sculptus most frequently has been collected from ground-dwelling sciurid rodents, especially Spermophilus ground squirrels. The potential roles of I. kingi and I. sculptus as enzootic vectors of human pathogens, particularly the agents of tularemia (Francisella tularensis), Q fever (Coxiella burnetii), and Colorado tick fever (CTF virus), are discussed.

Animals↗
PubMed2001

Use of a sentinel host system to study the questing behavior of Ixodes spinipalpis and its role in the transmission of Borrelia bissettii, human granulocytic ehrlichiosis, and Babesia microti.

Ixodes spinipalpis maintains Borrelia bissettii spirochetes in Colorado in a cycle involving wood rats and deer mice. This tick has been described as nidicolous, remaining either attached to its rodent hosts or in the rodent nest. Nidicolous ticks pose little risk of pathogen transmission to humans if they do not actively quest for hosts. To investigate the questing potential of I. spinipalpis, sentinel mice were placed in an area where I. spinipalpis had been commonly found on wood rats and deer mice. Concurrently, wild rodent populations were trapped and analyzed for Lyme disease spirochetes, the agent of human granulocytic ehrlichiosis (aoHGE), and Babesia microti. A total of 122 I. spinipalpis larvae and 10 nymphs were found on 19% of 244 sentinel mice. In addition, 4 sentinel mice became infested with Malaraeus telchinus or Orchopeas neotomae fleas. Questing I. spinipalpis were positively associated with woody shrubs and negatively associated with sunny and grassy areas. Four sentinel mice became infected with aoHGE after having been fed upon only by I. spinipalpis larvae. One sentinel mouse became infected with B. bissettii after having an I. spinipalpis nymph feed on it, and one sentinel mouse became coinfected with aoHGE and B. bissettii after it was fed upon by a single I. spinipalpis nymph. These sentinel mouse conversions suggest the possibility that the aoHGE is transovarially transmitted by I. spinipalpis, and that I. spinipalpis is capable of simultaneously transmitting B. bissettii and the aoHGE. The findings that I. spinipalpis quest away from rodent nests and will attach to and infect sentinel mice may be of public health importance. It suggests the potential transmission of the agents of human granulocytic ehrlichiosis and Lyme disease to other hosts by I. spinipalpis, in regions of the western United States where Ixodes pacificus is not found.

Animals↗
PubMed2001

Short report: Thai tick typhus, Rickettsia honei, and a unique rickettsia detected in Ixodes granulatus (Ixodidae: Acari) from Thailand.

A unique Rickettsia species (Rickettsia thailandii sp. nov.) was identified in an Ixodes granulatus by use of polymerase chain reaction heteroduplex mobility assay by use of segments of the citrate synthase gene. This tick was collected from Rattus rattus from Nakhon Ratchasima province in 1970. Another I. granulatus was infected with Thai tick typhus strain TT-118, Rickettsia honei sp. nov. Stenos, Roux, Walker & Raoult; this tick was removed from a R. rattus collected 4 years later from the same province. Ixodes granulatus is the first tick species in Australasia shown to be infected with R. honei and the unique Rickettsia species.

Animals↗
PubMed1999

Dispersal and distribution of the tick Ixodes uriae within and among seabird host populations: the need for a population genetic approach.

The aim of this study was to characterize the spatial distribution of the tick Ixodes uriae within and among populations of its seabird hosts and to consider the potential insight that could be gained by a population genetic approach to the issue of dispersal of this tick. Analyses of data collected around the Avalon Peninsula, Newfoundland, indicated that both the prevalence and mean abundance of ticks varied significantly among sample locations. Whereas ticks were found on all 4 host species examined (Rissa tridactyla, Uria aalge, Alca torda, Fratercula arctica), infestation prevalence and mean abundance differed among the species. On R. tridactyla, ticks were significantly aggregated at the among-nest scale and nestling infestation was spatially autocorrelated. Conversely, ticks were not aggregated among chicks within nests. These results enabled us to make a priori predictions regarding tick dispersal and host specificity and suggest there may be spatial structure of Ixodes uriae populations at both macro- and microgeographic scales. Investigating the population genetic structure of ticks within and among populations of hosts with different breeding biologies should provide direct insight into the metapopulation dynamics of such a spatially structured system.

Animals↗
PubMedDate not supplied

[Detection of the genotypic heterogeneity of Ixodes persulcatus Schulze (Acari: Ixodidae) of the North-West region of Russia and characteristics of distribution of tick-borne pathogens causing Lyme disease and Ehrlichia infections in various genotypes].

The heterogeneity of the Ixodes persulcatus population in the vicinity of Saint Petersburg was estimated by using malate dehydrogenase (MDH) isoenzyme. There are six MDH genotypes carrying 3 alleles in the Ixodes persulcatus population. The prevalence of Borrelia and Ehrlichia species in the study genotypes was analyzed. There was a difference in the prevalence and intensity of infection. The greatest abundance of Borrelia was described in the genotypes to Genogroup 1 (with allele 1). Among them, heterozygous ticks were most intensively infected. Polymerase chain reaction identified species pathogenic for man. These included 3 species of Borrelia: B. afzelii, B. garinii, and B. burgdorferi sensu stricto and 2 species of Ehrlichia muris and HGE agent. The author are the first to describe HGE agent and B. burgdorfei ss encountered in Russia.

Animals↗
PubMed2001

[Study and prevention of mixed infections, transmitted by Ixodes ticks].

The paper deals with the main aspects of mixed infections transmitted by Ixodes ticks: the biocenotic bases of existence of natural focal mixed infections, the magnitude of their spread, the indices of mixed infestation and the relationships of different causative organisms with Ixodes ticks and reservoir hosts, the spatial relations of mixed parasitic systems, the incidence of tick-borne mixed infections, the problems of their diagnosis and clinical manifestations, as well as the tasks of complex prevention. It is concluded that there is a necessity of applying the comprehensive synecological approach in studying the processes occurring in the focal ecosystems, which requires a definite methodological and structural rearrangement in science organization.

Animals↗
PubMed2001

The occurrence DNA of Babesia microti in ticks Ixodes ricinus in the forest areas of Szczecin.

Babesia microti, an intraerythrocytic protozoan and the etiological agent of human babesiosis, is transmitted by the bite of the tick, Ixodes ricinus. The aim of the present study was to confirm the presence of B. microti by detection of the DNA of these protozoans. The prevalence of B. microti was studied using the PCR method with primers complementary to the gene fragment encoding nuclear small-subunit ribosomal RNA (ss-rDNA). In the course of this study a total of 2095 ticks, Ixodes ricinus, were examined. The mean infection rate was 6.2%. Variable prevalance values were also obtained from six different locations and they were further modified by the seasons of the year. The results confirmed the competence of I. ricinus as a vector of B. microti and that a B. microti-specific PCR can provide a sensitive test for laboratory detection of babesiosis.

Animals↗
PubMedDate not supplied

[Risk of human infection with Ixodes tick-borne relapsing fever in different regional subzones of the Perm region].

Serological and epidemiological surveys covered 2407 persons in 20 populated localities situated in all large geographical and regional subdivisions (subzones) in the Perm Region. Indirect immunofluorescence tests revealed serum immunoglobulins to Borrelia burgdorferi sensu lato. Antibodies in 1:40 or higher dilution were found in nearly 5 to 11% of the dwellers of localities in the subzones of south taiga, coniferous broad-leaved forests, and forest steppe; about 3-7% and 1-6% of them were present in the populations of mountain and middle taigas, respectively. According to the frequency of tick suction and the proportion of an immune interlayer among the population within the Perm Region, four districts were identified by varying risks for infection (epidemic hazard) with Ixodes tick-borne relapsing fever. The populations living in the subzones of south taiga, coniferous, broad-leaved forests, and forest steppe run the greatest risk. An area at average infection risk area corresponds to the south part of a mountain taiga subzone and that at lower risk does to the south part of a middle taiga subzone. There is no possibility of relapsing fever contamination outside the area of Ixodes persulcatus ticks at all. Comparison of their own findings and official statistics has made the authors conclude that there is a great hyperdiagnosis of relapsing fever in the region in question.

Adolescent↗
PubMed2002

Distribution, density and migration dynamics of Ixodes ricinus in an area of the Jurassic mountains of Switzerland.

In an area of the Jurassic mountains of Switzerland ecological aspects of the tick species Ixodes ricinus were studied. In particular, the influence of temperature, humidity and vegetation parameters on tick density and distribution were investigated several times in six different habitat types. This was carried out on two scales; on a small scale, within a habitat type and on a larger scale, where all six habitat types were included. By a marking experiment, aspects of the migration dynamics of the ticks were studied. The densities of the six habitat types differed significantly in most of the cases. An analysis of the distribution pattern within a habitat type showed a contagious distribution mostly for the forests and the forest edge, whereas a random distribution was found as well, mainly for the meadows. But these distribution patterns tend towards randomness with time. On a small scale none of the factors showed an influence on tick distribution, therefore the most important factor on this scale might be the hosts of Ixodes ricinus. On a larger scale, temperature and humidity do in some cases influence tick densities. The marking experiment suggests an extremely high turnover of the ticks in an area with an average host density, probably due to passive transportation by hosts and to activation of resting individuals.

Altitude↗
PubMedDate not supplied

[Ixodes tick-borne borreliosis and tick-borne encephalitis in the Udmurt republic: retrospective analysis of their spread].

The primary clinical-anamnestic and laboratory data on 1,062 cases, registered in Udmurtia in 1965-1968 and caused by the bites of taiga ticks (ixodes persulcatus), were retrospectively analyzed. The study revealed that not less than 27% of these cases could be regarded as cases of Ixodes tick-borne borreliosis (ITBB); formerly they were classified with tick-born encephalitis (TBE) or diseases of unclear etiology. The spread of ITBB on the territory of the Udmurt Republic was shown to be similar to that of TBE.

Animals↗
PubMed2002

[Occurrence of genomic species of Borrelia burgdorferi sensu lato in populations of Ixodes ricinus ticks from West Pomerania].

The aim of this study was to determine the incidence of Borrelia burgdorferi sensu lato infections in Ixodes ricinus ticks from recreational areas of the province of West Pomerania. Ticks (nymphs and adults) were collected between April and October 2000 and 2001 from 10 sampling sites. The presence of the spirochete, Borrelia burgdorferi sensu lato, was confirmed with an indirect fluorescence assay (IFA) and the polymerase chain reaction (PCR). In addition, a nested PCR technique was used to detect one of three genomic species of the bacteria (B. burgdorferi sensu stricto, B. garinii, B. afzelii). A total of 2380 ticks were studied, including 2195 nymphs, 89 females and 96 males. Peak collection was in June of 2000 (330 ticks) and in August of 2001 (156 ticks) (Table 4). Collection was lowest in October of 2000 (93 ticks) and 2001 (127 ticks) (Tables 2 and 4). The mean infection frequency of Ixodes ricinus as determined with PCR was 12.8% in 2000 and 10.9% in 2001. The frequency determined with IFA was 11.6% (2000) and 9.6% (2001) (Tables 1 and 3, Figs. 1 and 2). The nested PCR technique revealed that the dominant genospecies was B. burgdorferi sensu stricto (83.5% of ticks in 2000 and 87.7% in 2001), followed by B. garinii (12% and 10.2% in 2000 and 2001, respectively). B. afzelii was detected in 4.4% (2000) and 2% (2001) of ticks. Co-infection with B. burgdorferi sensu stricto and B. garinii occurred in 3.4% (2000) and 1.8% of ticks (2001). Determination of the genomic species was not possible in approximately 7% of ticks (Tables 5 and 6). The present results show that there is a substantial risk of contacting borreliosis in recreational areas in the vicinity of Szczecin.

Animals↗
PubMedDate not supplied

[Epidemiology of Ixodes tick-borne borreliosis in the north of the Volga-Viatka region].

Among the territories of the Volga-Vyatka Region of Russia, the Kirov Region is characterized by the highest incidence of Ixodes tick-borne borreliosis. Its incidence rates ranged from 10.5 to 48.6 per 100,000 inhabitants. The average long-term regional rate was 8 times as high as the federal one. The bulk of cases was notified in the central regional districts referred to as a southern taiga subarea. The infection with the borreliae I. persulcatus and I. ricinus was 21-29%. Urban inhabitants infected for domestic reasons were prevalent among those who had been ill. Patients aged above 40 years accounted for 64.5%. There was an increase in the proportion of patients referring for medical care for the bites being stuck. Cases of mixed infections (Ixodes tick-borne borreliosis and tick-borne encephalitis) came to be more frequently detected; these constituted about a third of all tick-borne infections.

Adolescent↗