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PubMedDate not supplied

[The possibility of the detection of one more tick-borne infection--babesiosis--on the territory of Russia].

A total of 739 taiga ticks of ixodes persulcatus species, obtained in the recreational zone of St. Petersburg, were studied for the presence of Babesia sp. with polymerase chain reaction. All these ticks underwent the preliminary examination for the presence of Borrelia (3 species), Ehrlichia (2 species) and tick-borne encephalitis (TBE) virus. In 7 cases Babesia were detected among 413 ticks containing other pathogens. Among 326 ticks no Babesia were detected, as well as no other pathogens. All ticks having Babesia were also found to contain Borrelia species: B. afzelii, B. garinii, or both (1 case). In one female tick, in addition to Babesia, also B. garinii and TBE virus were determined. The data thus obtained should draw special attention not only of parasitologists, epidemiologists and microbiologists studying ticks obtained from natural sources, but also of clinicists who should consider the possibility of mixed infection, when one infection may mask the presence of some other infection, in particular babesiosis. Due to rare occurrence of Babesia in ticks and the presence of mixed infection difficulties may arise in the detection of Babesia.

Animals↗
PubMed2003

[Behavioral therapy of ticks with negative reinforcement in children].

Thirty-two children suffering from motor and vocal ticks exhibited weakness and distonia of ticks-prone muscles were examined. Based on the results obtained earlier, a complex of physical exercises has been worked out and conducted for 20 days. The patients were divided into 3 groups: 1st (n = 10) group did the exercises daily for training the ticks-prone muscles; the 2nd one (n = 10) exercised only after tick's appearance--negative reinforcement; 3rd group (n = 12) did exercises after tick's appearance as well but on irregular basis--probable negative reinforcement. In the 1st group, the exercising resulted in muscle strengthening and decrease of tick's number. The patients of the 2nd group got rid of ticks for 20 days. The probable tick's reinforcement in children of the 3rd group did not change pathological muscle activity. The central mechanisms of cortical plasticity in behavioral therapy of ticks are discussed.

Adolescent↗
PubMed2005

Altitudinal distribution limit of the tick Ixodes ricinus shifted considerably towards higher altitudes in central Europe: results of three years monitoring in the Krkonose Mts. (Czech Republic).

The aim of the study was to monitor present status of the Ixodes ricinus tick vertical distribution in the Krkonose Mts. (Czech Republic) and evaluate its potential changes. Two methods were used: monitoring of tick presence on dogs in 2001-2002 and direct monitoring of host-seeking ticks by flagging on two vertical transects reaching from 620 to 1270 m above sea level (a. s. l.) and from 600 to 1020 m in 2002-2003. Moreover ticks were monitored by flagging at another 13 localities situated in 800-1299 m a. s. l. in 2003. Both monitoring methods revealed an obvious shift in altitudinal distribution limit of the tick I. ricinus in the Krkonose Mts. They both showed that ticks recently penetrate even up to a timberline (approximately 1250 m a. s. l.). The number of recorded host-seeking ticks rapidly decreased with increasing altitude. Whereas the average number of recorded nymphs converted per 60 minutes of flagging reached 15.2-25.7 nymphs in 700-799 m a. s. l. and 3.3-23.3 in 800-899 m, it was 4-9.6 nymphs in 900-999 m, 1.5-1.7 nymphs in 1000-1099 m and only 0.2 nymph in 1100-1299 m a. s. l. The observed shift of the tick altitudinal distribution limit at the same time results in extension of areas with potential risk of tick-borne diseases.

Altitude↗
PubMed2006

Seasonal activity of the common European tick, Ixodes ricinus (Linnaeus, 1758), in the forested areas of the city of Olsztyn and its surroundings.

UNLABELLED: Common European ticks, Ixodes ricinus, have been found in forest areas situated within the boundaries of big cities, and in areas changed by anthropogenic pressure. Monitoring I. ricinus, in the areas used by the public for recreation and leisure, makes it possible to assess the risk of infection with the diseases they transmit. The objective of this study was the comparison of the seasonal activity of ticks, I. ricinus, in the afforested areas of the city of Olsztyn and its surroundings. MATERIAL AND METHODS: This survey was conducted at sites located in the afforested areas of Olsztyn and within the Warmiński Forest situated about 15 km from Olsztyn. Ticks, I. ricinus, were caught every 10-14 days from April to October 2001 by the commonly applied method of flagging. During each catch, the temperature (T) and relative humidity (%RH) was measured with a thermohygrometer, 1 m above the duff level. RESULTS: The tick population density at the Warmiński Forest site was higher than that at the sites within the city limits (116.8 and 20.5 ticks per 100 m2, respectively). Two peaks of tick activity were recorded in this area--the spring peak in June and the autumn peak (much lower) in September. The activity of ticks in the afforested area within the city limits was much lower--only one (spring) peak occurred, which at most sites was observed in June. At all sites, included in the study, the peak activity of ticks was observed in April. CONCLUSION: The study suggests that the afforested areas outside the city are more dangerous to people than the area within the city because of the large number of ticks there.

Animals↗
PubMedDate not supplied

[The frequency of generalized infection in adult fasting ticks of the genus Ixodes in foci of borreliosis in Russia and the USA].

A total of 740 adult Ixodes persulcatus ticks were collected from the vegetation by flagging in Russian foci where Borrelia afzelii and B. garinii circulate, and 156 I. dammini ticks were collected in northwestern USA regions in foci with B. burgdorferi s.str. circulation. Smears prepared from the internal organs of ticks were stained according to Romanovsky-Giemsa and analyzed under a microscope at a x 1125 magnification. All borreliae in 250 microscopic fields were counted, and concentration of microbial bodies per 100 microscopic fields was determined. The general level of infection by Borrelia in both vectors was similar: 26.2 x 3.2 in I. persulcatus and 26.3 +/- 7 in I. dammini. However, the proportions of ticks with generalized infections differ considerably (12.9 +/- 4.8 in I. persulcatus compared with 2.4 +/- 4.8 in I. dammini; significance of difference t = 3.1). We did not reveal any definite increase in the proportion of ticks with borreliae in the salivary glands among ticks with high concentrations of microbial bodies in the gut. In 25 I. persulcatus ticks with generalized infections, series of actual numbers of borreliae (per 100 microscopic fields) found in the gut and salivary glands did not correlate with one another (r = -0.23). These results confirm our previous conclusion (Korenberg, 1994) that frequencies of generalized infection in main vectors of different ixodid tick-borne borrelioses are also different, which is probably due to peculiarities of relationships between spirochetes of each species and corresponding tick vectors. These factors can be responsible for differences in the ways of horizontal and vertical transmission of pathogens belonging to the group under study.

Animals↗
PubMedDate not supplied

[The place of ixodid ticks (Ixodidae) in forest ecosystems].

The ticks Ixodes ricinus and I. persulcatus are the dominant tick species in the forest ecosystems of the temporary zone of Eurasia. They occur within their areals in every types of forests except arid and marsh biotopes. The density of tick populations per square unit exceed many times those of dominant species of mammals and birds living in the same ecosystems. In optimal conditions the abundance of hungry larvae per 1 square km varies from hundreds of thousands to several millions, that of nymphs-from thousands to several hundreds of thousands, and that of imago counts several thousands. The number of larvae and nymphs simultaneously feeding on rodents or shrews usually not exceeds several specimens. However, in case of 50-100% infection rate of hosts and long seasonal period of parasitizing the greater part of individuals in the main host population is repeatedly attacked by ticks and therefore supports a significant number of parasites. Despite of annual fluctuations of ticks and hosts abundance the parasitic systems formed by them are characterized by high stability in time and space. The high resistance of the tick parasitic systems to the influence of unfavorable factors is caused by several independent and duplicated systems of tick's interaction with their hosts and environment. The ticks and their hosts together with agents of the tick borne encephalitis, Lime disease, babesiosis and other transmissive infections form the three component parasitic systems of higher rank. These systems are referred to as the natural foci of diseases and their geographical distribution in general lines coincide with species areals of I. ricinus and I. persulcatus.

Animals↗
PubMed1994

Factors affecting the distributions of the ticks Amblyomma hebraeum and A. variegatum in Zimbabwe: implications of reduced acaricide usage.

The ticks Amblyomma hebraeum and A. variegatum are the main vectors of heartwater, a disease of ruminants caused by Cowdria ruminantium, in the agricultural areas of Zimbabwe. At present, A. hebraeum is widely distributed in the dry southern lowveld, and occurs in at least seven foci in the higher rainfall highveld. Amblyomma variegatum occurs in the Zambezi valley and surrounding dry lowveld areas in the northwest. The distribution of A. hebraeum has changed considerably over the past 70 years, while that of A. variegatum appears to have remained fairly static. The distribution patterns of both species in Zimbabwe display anomalous features; the ticks occur in areas of lowest predicted climatic suitability for survival and development and in areas where the densities of cattle, the most important domestic host, are lowest. The only factor favouring the survival of the species in the lowveld habitats in which they occur is the presence of alternative wildlife hosts for the adult stage. Their absence from more climatically favourable highveld habitats appears to have been the result of intensive acaricide treatment of cattle over a long period and a historic absence of significant numbers of wildlife hosts. Eradication of A. hebraeum and A. variegatum by intensive acaricide treatment of cattle can be achieved in the absence of significant numbers of alternative hosts, because of the long attachment and feeding periods of the adults of these tick species. However, eradication becomes impossible when alternative hosts for the adult stage are present, because a pheromone emitted by attached males attracts the unfed nymphal and adult stages to infested hosts. The unfed ticks are not attracted to uninfested hosts, such as acaricide-treated cattle. Regular acaricide treatment of cattle is expensive and so, for economic reasons, the Government of Zimbabwe is no longer enforcing a policy of strict tick control. It is likely that reduced tick control will result in the spread of Amblyomma ticks to previously uninfested areas. Added to this, recent introductions of various wildlife species to highveld commercial farming areas have created conditions in which the ticks could become established in higher rainfall areas. Amblyomma hebraeum is more likely to spread than A. variegatum, because its adults parasitize a wider range of wildlife hosts (warthogs, medium to large-sized antelope, giraffe, buffalo and rhinoceros), whereas adults of A. variegatum appear to be largely restricted to one wildlife species (buffalo) in Zimbabwe, the distribution of which is now confined to very limited areas of the country, as part of foot and mouth disease control measures.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1984

Boophilus microplus tick burdens on grazing cattle in Colombia.

This study was conducted at Carimagua Research Centre in a well-drained savanna area in the eastern plains of Colombia. The objectives were to note the effect of ecological factors on tick burdens, principally the effect of the environment given by four grasses on the seasonal variations of tick populations. Adult female tick counts were carried out on heifers grazing four pastures and tick larvae on the grass detected by cloth dragging. Tick counts were significantly higher on animals grazing Brachiaria decumbens than those grazing Andropogon gayanus, Melinis minutiflora or native pastures. Tick larvae counts on the grass showed a similar tendency. Introduced grasses and intensification of production will require greater care to control tick infestations since increases in stocking rate and ground coverage could augment tick populations.

Animals↗
PubMed1977

Neuromuscular paralysis caused by tick envenomation.

The Australian scrub-tick Ixodes holocyclus causes a series of significant toxic effects in its victims. The most important feature of tick envenomation is neuromuscular paralysis. Children poisoned by ticks may manifest only local motoneural effects, usually facial paralysis. Progressive ascending flaccid paralysis occurs if the removal of an embedded tick is delayed. The specific neurological features of tick-bite are discussed in the light of a series of 6 children who all showed signs of tick paralysis. Tick venom is known to slow nerve conduction, and may have a botulinum-like effect at the neuromuscular junction. The literature on the neurological effects of tick-envenomation is reviewed.

Australia↗
PubMed2006

Autocidal control of ticks by silencing of a single gene by RNA interference.

Ticks impact human and animal health worldwide and new control methods are needed to circumvent drawbacks of tick control by acaricide application including selection of drug resistant ticks and environmental pollution. Using RNA interference we silenced the expression of a single gene, subolesin, and produced ticks with diminished reproductive performance and prevented successful mating and production of viable offspring. We propose a sterile acarine technique (SAT) for reduction of tick populations by release of subolesin-silenced ticks. Conservation of subolesin among tick species suggests that SAT may be useful for control of many medically and economically important tick species.

Animals↗
PubMed1998

Saliva of Rhipicephalus sanguineus tick impairs T cell proliferation and IFN-gamma-induced macrophage microbicidal activity.

In this study, we investigated tick saliva effects on T cell proliferation, antigen presentation and IFN-gamma-induced macrophage activation, events which are associated with host immune defense mechanisms. Mice repeatedly infested with Rhipicephalus sanguineus ticks, similarly to dogs, did not develop resistance to further infestations. We determined that R. sanguineus tick saliva inhibited, in a dose-dependent manner, both Con-A and specific antigen-induced splenic T cell proliferation. Tick saliva diluted twenty times (64 microg/ml) inhibited Con-A-induced and antigen-specific T cell proliferation in 83% and 69%, respectively. In addition, the inhibition of cell proliferation correlated with a decrease in IL-2 production. Microconcentrator fractionated saliva was tested on a Con-A-induced cell proliferation assay, and showed that one fraction between 3 and 10 kDa and another smaller than 3 kDa can be responsible for the inhibition of T cell proliferation. Although saliva inhibited cell proliferation, it did not impair antigen presentation. Tick saliva further abrogated the killing of intracellular forms of Trypanosoma cruzi by IFN-gamma-activated macrophages. Moreover, saliva-induced macrophage inhibition of IFN-gamma-induced-trypanocidal activity was paralleled with 69% less nitric oxide (NO) production. Finally, tick saliva doubled the production of IL-10 and reduced 84.6% production of IFN-gamma by splenocytes cultured with T. cruzi, suggesting that decreased macrophage NO production may be due to a saliva-induced cytokine imbalance, leading to decreased NO synthase activity. Together, these data indicate that tick saliva can modulate host immune response, thus, contributing to its feeding success and favoring the transmission of tick-borne pathogens.

Animals↗
PubMed2002

Seasonal epidemiology of ticks and aspects of cowdriosis in N'Dama village cattle in the Central Guinea savannah of Côte d'Ivoire.

In the Central Guinea savannah of Côte d'Ivoire, cattle breeding started only approximately 30 years ago. The impact of parasitism on the overall health status and productivity of the trypanotolerant N'Dama cattle in this area is unknown. In close collaboration with national veterinary institutions and local farmers, we studied spectrum, burden and seasonal dynamics of ticks (including aspects of cowdriosis) on N'Dama village cattle. In a longitudinal study, three randomly selected cattle herds (traditional farming type) of one village were examined repeatedly for ticks. Spectrum, burden, seasonal epidemiology of ticks were assessed. In these traditional herds (which lack (ecto)parasite management), all animals were infested by ticks at monthly counts. Five different tick species were identified; the four genera in order of frequency were: Amblyomma (overall prevalence 96%), Boophilus (47%), Hyalomma (<1%) and Rhipicephalus (<1%). Amblyomma variegatum was the most-abundant tick on cattle in all seasons. Seroprevalence of Cowdria ruminantium was 31% (95% CI: 26, 36%). Most of the animals typically carried low tick burdens. N'Dama cattle seem well adapted to their environment and can resist the tick burdens under this traditional farming system.

Animals↗
PubMed1998

Breed-associated resistance to tick infestation in Bos indicus and their crosses with Bos taurus.

The relative resistance to tick infestation of zebu (Bos indicus) in comparison to crossbred (B. indicus x B. taurus) cattle was investigated. B. indicus breeds, all belonging to Tanganyika shorthorn zebu were Meru, Mbullu and Iringa red. Crossbreds were Meru x Friesian and Iringa red x Friesian. Parameters to distinguish between 'tick resistant' and 'tick susceptible' cattle were tick counts on naturally exposed animals, serum complement levels and delayed skin hypersensitivity response to phytohaemagglutinin. Results have shown that pure zebu cattle are less infested with ticks when compared to zebu-taurine crosses under identical field conditions. Zebu cattle also had significantly higher serum complement level than crossbred cattle. While serum complement and tick burden were negatively associated (r = -0.27, P < 0.001), the cutaneous response to phytohaemagglutinin did not vary with tick infestation. The influence of cattle breed on tick infestation and serum complement level is demonstrated.

Animals↗
PubMed2000

A model to simulate the effect of vaccination against Boophilus ticks on cattle.

This paper describes a vaccination model to simulate the effect of cattle vaccination with concealed antigens on Boophilus tick spp. The model considers the vaccination effect in three parts: antibody titer, accumulation of damaging vaccination effects by parasite stages, and the effect of accumulated damage on all tick life stages. Biological parameters for ticks and hosts, as well as parameters describing tick-host interaction, were included. The validity of this model, integrated with the TICKSIM simulation program, was demonstrated for the Bm86-containing vaccine Gavac by comparing simulated and real data for several geographic locations in the Americas. All model parameters were estimated using field data collected in the different geographic locations. The model sensitivity to changes in antibody titer level and titer half-life was studied, and the impact on tick population density of changes in these parameters was evaluated. Simulation results showed that to achieve a higher level of tick control, an increase in the maximum antibody titer levels was more important than extending titer half-life in geographical locations with short seasonal peaks of tick infestation. The TICKSIM program, integrated with the new vaccination model, proved to be a framework for designing and evaluating tick control strategies, including vaccination with GavacTM.

Animals↗
PubMed1999

Survival strategy of tick-borne encephalitis virus: cellular basis and environmental determinants.

Although TBE virus can be transmitted in the laboratory by a wide variety of ixodid tick species to a wide variety of vertebrate host species, nevertheless in nature endemic cycles of TBE virus depend principally on just two tick species, Ixodes ricinus in the western and I. persulcatus in the eastern Palaearctic. A complete transmission cycle, from tick to tick via vertebrates, occurs most efficiently between co-feeding ticks in the absence of a systemic viraemia. This non-systemic route depends on TBE virus replication within particular immunocompetent cells in the skin, and only certain vertebrate species, notably Apodemus mice, are susceptible to this. Amongst the potential tick vectors in Europe, only I. ricinus has the correct host relationships and appropriate natural life cycle to support such non-systemic transmission cycles. Within the wide European distribution of this tick-host relationship, only in certain places do larval and nymphal ticks feed together on the same hosts with sufficient coincidence to ensure TBE virus survival. The environmental factors that determine this seasonal coincidence are being identified with the help of remotely-sensed meteorological satellite imagery to create predictive risk maps of TBE foci.

Animals↗
PubMed2004

Tick salivary glands: function, physiology and future.

The salivary glands are the organs of osmoregulation in ticks and, as such, are critical to the biological success of ticks both during the extended period off the host and also during the feeding period on the host. Absorption of water vapour from unsaturated air into hygroscopic fluid produced by the salivary glands permit the tick to remain hydrated and viable during the many months between blood-meals. When feeding, the tick is able to return about 70% of the fluid and ion content of the blood-meal into the host by salivation into the feeding site. This saliva also contains many bioactive protein and lipid components that aid acquisition of the blood-meal. The salivary glands are the site of pathogen development and the saliva the route of transmission. The importance of the multifunctional salivary glands to tick survival and vector competency makes the glands a potential target for intervention. Here we review the cell biology of tick salivary glands and discuss the application of new approaches such as expressed sequence tag projects and RNA interference to this important area in the field of tick and tick-borne pathogen research.

Animals↗
PubMed2000

Tick bite and Lyme borreliosis risk at a recreational site in England.

The risk of tick bite and Lyme borreliosis in a forested area in England with public access was studied over a two-year period. Tick infestation levels were high with more than 1000 members of the public reporting for tick removal at a local clinic. Most of the attached ticks were nymphs (82%) and distinct differences in anatomical sites of attachment were observed in children and adults. Children sustained nymphal bites to the head, neck and axilla region much more frequently than adults (48 vs. 10%), whereas adults were bitten on the lower legs more frequently than children (46 vs. 9%). The vegetation was heavily infested with ticks and high numbers were particularly associated with areas used by deer. The average density of nymphs collected from the vegetation was 14.1 per 10 m2 (range 5.1-43.6). Infection rates of these nymphs determined by PCR and indirect IFA ranged from 5.2-17.0%, and the genospecies Borrelia valaisiana and B. garinii were detected, suggesting that birds may be important reservoir hosts in this area. It is estimated that, at the level of tick challenge observed here, at least 50 persons per year may be bitten by infected ticks at this site. However, no cases of Lyme borreliosis have been reported through the clinic follow-up procedure, and sera from 19 forest workers were negative for antibody to B. burgdorferi sensu lato. Despite the high challenge from tick bites, this particular recreational forest site poses a low risk of infection to the general public, and prophylactic antibiotic treatment or serological testing following a bite is not justified.

Adult↗
PubMed2002

The use of a 4% (w/w) deltamethrin collar (Scalibor ProtectorBand) in the extended control of ticks on dogs.

Deltamethrin (4%, w/w) formulated in a polymer matrix system (Scalibor ProtectorBand, Intervet International BV) was evaluated for the prevention of ticks on dogs. Controlled laboratory trials were conducted, wherein dogs wearing anti-tick collars were compared with control dogs and artificially infested by adult Ixodes ricinus and/or Rhipicephalus sanguineus ticks. The activity of the collars increased from 24 to 48 h post-treatment (pt) wherein tick numbers were reduced to 78.7% for I. ricinus and to 77% for R. sanguineus. The proportion of ticks controlled after the second infestation on D7 pt increased to 99% for I. ricinus and 99.5% for R. sanguineus. For I. ricinus adult ticks, an efficacy of 95.4% was reached over a period of 5.5 months and approximated 90% for R. sanguineus. Hence, the efficacy of the deltamethrin-impregnated dog collar was >90% for 6 months against both tick species. There was no significant difference between the efficacy of the collar against either R. sanguineus or I. ricinus. A subsequent field study wherein 82 dogs were wearing the collar and monitored for tick infestation indicated that the duration of efficacy was between 5 and 6 months.

Animals↗