[The results of the serological examination of medium-sized mammals in the natural foci of arbovirus infections in central Siberia].

The serological survey of white hares (n = 8), squirrels (n = 118), and Asian chipmunks (n = 486) in the dark coniferous forests of Middle Siberia revealed tick-borne encephalitis virus antihemagglutinins only in the former two species (37.5 +/- 17.1 and 7.

Preliminary studies on virus and spirochete accumulation in the cement plug of ixodid ticks.

We provide evidence that tick-borne encephalitis virus and Borrelia burgdorferi s.l. are accumulated in the cement plug in the host skin within the first few hours after tick attachment.

[The functioning of foci of mixed tick-borne infections on Russian territory].

Based on the studies of behavioral variations in ixodes persulcatus ticks under the influence of their carried pathogens, the authors forward a hypothesis for that there is antagonism between Borrelia and tick-borne encephalitis virus in the vector. Experiments demonstrated that Borrelia-infected ticks had a lower viral sensitivity than did noninfected ticks. There was inhibited viral reproduction in the ticks with double infection.

[The reaction of the tick Hyalomma asiaticum (Acarina, Ixodidae) to 1- to 4-GHz microwaves].

Low-energy microwave radiation in the frequency range in question was found to exert a noticeable biological action on H. asiaticum. Radiation delayed larval hatch by 3-20 days, increased the activity duration of newly moulted larvae by 17-24 days, reduces the survival of hungry larvae and nymphs by 4-10 days.

Bacteriocidal qualities of ixodid tick (Acarina: Ixodidae) salivary cement plugs and their changes under the influence of a viral tick-borne pathogen.

The abundance of bacteriocidal compounds contained in the salivary cement plug of ixodid ticks was changed because of the reproduction of tick-borne encephalitis virus (TBEV) in their bodies. The size of TBEV-infected Ixodes persulcatus Shulze lytic zone surrounding the cement plug enlarged to that of naive ticks, whereas Micrococcus lysodeikticus (Cohn) lytic zones induced by the cement plugs of TBEV-infected Amblyomma hebraeum Koch nymphs or Rhipicephalus appendiculatus Neumann females were reduced, compared with those produced by noninfected specimens. It is possible that an increase of lysozyme production by the primary TBEV vectors (Ixodinae) infected salivary gland cells, compared with suppression of the bacteriocidal qualities of saliva of ticks that are not TBEV vectors in nature (Amblyomminae), is an indication of the specificity of a I.

[Changes in the bactericidal activity of the cementing fraction in ixodid tick saliva under the influence of the presence of the tick-borne encephalitis virus].

It is demonstrated that the abundance of bactericidal compounds in the salivary cement plug of ixodid ticks is changing under the influence of virulent tick-borne encephalitis virus (TBEV) reproduction in their bodies. TBEV infected Ixodes persulcatus cement plug-forming lytic zone size enlarged in comparison with the naive tick one whereas Micrococcus lysodeikticus lytic zones induced by the cement plug of TBEV infected Amblyomma hebraeum nymphs or Rhipicephalus appendiculatus females reduced compared with produced by noninfected specimens. It is supposed that increasing of the lysozyme that production by the main TBEV vectors (Ixodinae ticks) infected salivary gland cells in comparison with suppression of the bactericidal qualities of saliva of the ticks which are not TBEV vectors in the nature (Amblyomminae ticks) is one of markers of the specificity of I.

[The characteristics of the distribution of the causative agent of Lyme disease and of the behavior of infected ticks of the genus Ixodes].

It is demonstrated that in the regions, where Ixodes persulcatus and I. ricinus are sympatric, the incidence and prevalence of Borrelia burgdorferi among the latter tick species is higher. In areas, where the Ixodes persulcatus population infected with Borrelia were met, the percent of infected I.

[An attempt at the serological examination of small mammals in a natural focus of tick-borne encephalitis in central Siberia].

Studies of blood serum samples from Asian mice from a natural focus of tick-borne encephalitis (TBE) in the Krasnoyarsk district, in which agent strains of medium peripheral activity for white mice predominated, in the hemagglutination inhibition test have given negative results. At the same time murine sera were detected with nonspecific inhibitors to TBE virus in low titers (1:10 to 1:20), this being confirmed by enzyme immunoassay. Of the tested in 1988-1991 1047 mice of 11 species the share of sera with nonspecific inhibitors (and, consequently, positive ones) has made up 3.

[Changes in the acaricidal properties of organophosphorus compounds under the influence of magnetic resonance treatment].

The authors demonstrate the possibility of enhancing pesticidal properties of some organophosphorus compounds by their single treatment for 40 min by pulsed magnetic field, 100 kHz, 10-15 microT with 16 Hz sinusoidal modulation. The treatment efficacy is up to 30 days.

[Trial results with dilor in controlling the taiga tick].

Laboratory and field trials of dilor (beta-dihydroheptachlorine) have demonstrated its high acaricidal characteristics, but this pesticide is not recommended as a means for extermination of Ixodes persulcatus, tick-borne encephalitis virus vectors. The tested compound is characterized by a high persistence, superior even to that of DDT. Dilor metabolites retain their toxicity in the forest up to 4-5 years.

[Differences in the distant transmission of the tick-borne encephalitis virus by ixodid ticks of 2 subfamilies].

Simultaneous but separate feeding of ticks on nonviremic animal (guinea pig) has shown that Amblyomminae ticks are practically unable to transmit distantly tick-borne encephalitis virus (TBEV) to the specimens of their own subfamily and to Ixodinae as well. Ixodes persulcatus and I. ricinus displayed their ability as donors and recipients of TBEV (adults and nymphs) not only for their own subfamily representatives but also as donors for recipients of Amblyomminae subfamily (nymphs and adults of Dermacentor and Rhipicephalus and nymphs of Haemaphysalis).

[A trial at using the systemic action of ivermectin for suppressing the vector capacity of ticks (Ixodidae) infected with the tick-borne encephalitis virus].

Adult Dermacentor marginatus hatched from nymphs infected with TBE virus and poisoned with ivermectin retain their vector abilities. Even small individuals with a 1.5-2 times lesser mass as against the reference mass contain the virus in the body in the same titers and the virions in salivary gland alveoli.

[The participation of birds in the circulation of the tick-borne encephalitis virus in the Asian part of Russia. 1. Natural foci in the Far East].

Virologic examinations of 811 samples of 70 species and of 81 ova from layings of 11 bird species, carried out in natural foci of tick-borne encephalitis (TBE) in the southern Maritime [correction of Primorye] Territory, yielded negative results; serologic examinations revealed a low level of the immune stratum to TBE virus even in the birds feeding on the soil or on grass and shrubberies, that is, belonging to the first and second ecologic groups (0.8 +/- 0.4%).

[Cyclic changes in the population count of the taiga tick in the Stolby preserve].

A harmonic analysis was carried out of Ixodes persulcatus density dynamics over 33 years and the analysis of small mammal density and some climatic factors. It was found that the chronological changes of all the three processes contained cyclic components with the period 5.5 and 11; 3-4; 5.

[Plant smells---important determinants in the behavior and rate of development of ixodid disease vectors].

Experiments with nymphs of Ixodes persulcatus and Dermacentor marginatus have shown that the rate and degree of engorgement, dropping off from the mouse, metamorphosis longevity and weight of emerging imagoes change under plant odour influence. The influence of acetone extract vapours of pepper, poplar buds, linden and aspen was tested. Under the influence of the vapour, acting as an attractant for the adults, engorgement weight of their nymphs and the weight of imagoes emerging from them increased; attractants change the nymph-imago metamorphosis duration as well.

[The results of laboratory and field trials of the action of ektomin on the taiga tick].

Laboratory and field trials of 60% concentrated ectomin emulsion have been conducted. Laboratory experiments on the contact of hungry female individuals of Ixodes persulcatus (Acarina, Ixodidae) with pesticide in the envelopes made of impregnated filter paper have established high imago sensitivity to the preparation--LD50 after a 4-hour contact was 1.10(-6) micrograms/cm2.

[The use of smells of plant origin as indicators of the extensiveness and intensity of ixodid tick infection with the tick-borne encephalitis virus].

It has been shown that, using a simple olfactometer, through which moist air and smell of vegetative origin penetrate into the centre via different ends of the tube, ticks can be divided into two groups, those infected and not infected with tick-borne encephalitis virus. The method yielding a 100% division, is based on opposite changes in the behaviour of virus infected ticks: the attracting smells become repellent and vice versa. Normal reaction to smell measured by the length of the distance covered by an individual tick towards or from the smell source in the olfactometer tube varies in various groups of control and experimental ticks, but correlates with virus titre of ticks.

[Virus exchange between feeding ticks in the absence of viremia in a vertebrate host (distant transmission)].

The data obtained with tick-borne encephalitis virus did not confirm the conclusion made by L. D. Jones et al.

[The possible role of the salivary gland substrate in ixodid ticks as an adjuvant enhancing arbovirus transmission].

Using a model: salivary glands of Dermacentor ticks--tick-borne encephalitis virus--guinea pig--D. marginatus ticks, it became possible to confirm the data of Jones et al. (1989) on the role of a substrate of Rhipicephalus appendiculatus glands as a strong enhancer of orthomyxovirus Togoto transmission during subcutaneous administration of a moderate virus dose to virus-resistant guinea pig.

[Does the suction biting of uninfected ixodid ticks protect against tick-born encephalitis in subsequent bites?].

It has been experimentally established that suction of noninfected preimago and imago of Ixodoidea to sensitive animals (e.g. white mice) does not lead to the elaboration of immunity protection from bites of insects infected with tick-borne encephalitis virus.