[The results of the serological examination of medium-sized mammals in the natural foci of arbovirus infections in central Siberia]. / Rezul'taty serologicheskogo obsledovaniia srednikh mlekopitaiushchikh v prirodnykh ochagakh arbovirusnykh infektsii Srednei Sibiri.

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 7.6 +/- 2.4%, respectively) and in the squirrel, there is a close seasonal relation between the parameters of immune interbred and those virophoricity of taiga tick nymphs.

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. Extirpation of the tick without the cement plug, even very soon after the attachment, did not prevent the transmission by Ixodes ricinus, Ixodes persulcatus or Dermacentor reticulatus to mice. This was within 1 hour in the case of the TBE virus and after 20-22 h of attachment, in the case of Borrelia and I. persulcatus. The epidemiological significance of these findings is discussed.

[The reaction of the tick Hyalomma asiaticum (Acarina, Ixodidae) to 1- to 4-GHz microwaves]. / Reaktsiia kleshscha Hyalomma asiaticum (Acarina, Ixodidae) na mikrovolny 1--4 GGts.

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. The efficiency of the biological action of microwaves is enhanced by impairments in the natural developmental rhythm of the tick.

[The functioning of foci of mixed tick-borne infections on Russian territory]. / Funktsionirovanie ochagov smeshannykh kleshevykh infektsii na territorii Rossii.

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. Evidence is presented for that the Borrelia-infected nymphal ticks display the specific behavioral and viral susceptible features that are physiologically peculiar to older Borrelia-free individuals. It is concluded that the prevalence of Borrelia in the populations of ticks in the foci of mixed infections is associated with their property to suppress viral reproduction in the Borrelia-infected ticks.

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. persulcatus-TBEV interface.

[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]. / Izmenenie bakteritsidnoi aktivnosti tsementiruiushchei fraktsii sliuny kleshchei iksodi pod vliianiem prisutstviia virusa kleshchevogo éntsefalita.

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. persulcatus-TBE virus interface.

[The characteristics of the distribution of the causative agent of Lyme disease and of the behavior of infected ticks of the genus Ixodes]. / Ob osobennostiakh rasprostraneniia vozbuditelia bolezni Laima i povedeniia zarazhennykh im kleshchei roda 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. ricinus was 3-4 times more and the number of detection of Borrelia-infected specimens was 9 times higher than in the regions, where I. persulcatus was absent. The hypothesis is proposed, that the tick I. persulcatus is a carrier and source of the most virulent and acarotropic Borrelia form. It is stated, that the reaction of the Borrelia-infected Ixodes ticks (I. persulcatus and I. ricinus) on the plant odour is changed. It is supposed that such changed plant odour-dependent behavior would be able to be enhancer of the I. persulcatus--I. ricinus Borrelia exchange process.

[An attempt at the serological examination of small mammals in a natural focus of tick-borne encephalitis in central Siberia]. / Opyt serologicheskogo obsledovaniia melkikh mlekopitaiushchikh v prirodnom ochage kleshchevogo éntsefalita srednei Sibiri.

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 3.3 +/- 1.9/0.0 for asian mice (6.2 +/- 3.3/0.0 for males and 0.0/0.0 females), 1.4 +/- 1.4/2.8 +/- 2.0 in striped field mice (0.0/0.0 males and 3.2 +/- 3.2/6.4 +/- 4.5 females), and 0.5 +/- 0.3/5.7 +/- 1.0 in red-backed mice (0.3 +/- 0.3/6.3 +/- 1.4 males and 0.7 +/- 0.5/5.1 +/- 1.3 females).

[Changes in the acaricidal properties of organophosphorus compounds under the influence of magnetic resonance treatment]. / Izmenenie akaritsidnykh svoistv fosfororganicheskikh soedinenii pod vliianiem magnitorezonansnoi obrabotki.

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]. / Itogi ispytaniia dilora v bor'be protiv taezhnogo kleshcha.

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]. / Razlichiia v distantnoi peredache virusa kleshchevogo éntsefalita iksodovymi kleshchami dvukh podsemeistv.

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). Experimental and literature data analysis permits the authors to conclude that the very important role of TBEV circulation in nature belongs to the distant virus transmission. The absence of such type of virus exchange among Amblyomminae excludes this group of ticks from active virus circulation in TBEV foci.

[A trial at using the systemic action of ivermectin for suppressing the vector capacity of ticks (Ixodidae) infected with the tick-borne encephalitis virus]. / Popytka ispol'zovaniia sistemnogo deistviia ivermektina dlia podavleniia vektornoi sposobnosti kleshchei (Ixodidae), zarazhennykh virusom kleshchevogo éntsefalita.

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. Administration of an oil solution of ivermectin into the stomach of white mice, nymph feeders, in a dose surpassing threefold the dose recommended for intramuscular injection of this agent completely suppressed shedding of intact nymphs but did not suppress it in those infected. The nymph mass, size and mass of adult ticks hatched from them dropped under the effect of ivermectin dosage build-up in both intact and infected ticks, but these processes were slower in ticks infected with TBE virus. The authors suggest that the ticks infected with TBE virus are much more resistant to the process of gamma-aminobutyric acid depression, the mechanism of ivermectin action. They emphasize the necessity of bearing in mind the possible differences in the reactions to systemic poisons of intact and infected ticks when organizing vector control measures.

[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]. / Uchastie ptits v tsirkuliatsii virusa kleshchevogo éntsefalita v aziatskoi chasti Rossii. Soobshchenie 1. Prirodnye ochagi Dal'nego Vostoka.

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%). A difference has been demonstrated between the shares of TBE immune samples in the first and second+third (birds feeding on trees but sometimes on soil) +fourth (feeding on trees, in air, out of forests, on animals) ecological groups of birds, as well as between the first+second and third+fourth groups.

[Cyclic changes in the population count of the taiga tick in the Stolby preserve]. / Tsiklicheskie izmeneniia chislennosti taezhnogo kleshcha v zapovednike "Stolby".

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; 5.5 and 14-16 years, respectively. A long-term prognosis of I. persulcatus density was made based on harmonic synthesis.

[Plant smells---important determinants in the behavior and rate of development of ixodid disease vectors]. / Zapakhi rastenii--vazhnye determinanty povedeniia i skorosti razvitii iksodid-perenoschikov boleznei.

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. Repellent acting odours, as a rule, produce an opposite reaction. The phenomenon of the inversion of the infected D. marginatus reaction to the odour is proved in nymphs. Attractant for naive adult ticks (poplar buds) increased the time of feeding and weight of nymphs in comparison with the control. Just the opposite: nymphs infected with tick-borne encephalitis (TBE) virus produce an opposite reaction--weight decrease under influence of poplar buds as the repellent. Importance of the above phenomena for the ticks distribution and TBE epizootiology is discussed.

[The results of laboratory and field trials of the action of ektomin on the taiga tick]. / Rezul'taty laboratornykh i polevykh ispytanii deistviia éktomina na taezhnogo kleshcha.

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. In field experiments ectomin ensured a 100% effect of hungry Ixodes persulcatus elimination 1-2 days later, with the preparation expenditure no more than 0.05 kg/hectare. The effect was retained throughout one whole season of I. persulcatus activity.

[The use of smells of plant origin as indicators of the extensiveness and intensity of ixodid tick infection with the tick-borne encephalitis virus]. / Ispol'zovanie zapakhov rastitel'nogo proiskhozhdeniia v kachestve indikatorov ékstensivnosti i intensivnosti zarazheniia iksodovykh kleshschei virusom kleshchevogo éntsefalita.

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. It is greater in ticks with a higher level of virus reproducibility. The reaction to smell in infected ticks makes it possible to predict the intensity of their infestation.