Melting of crystallites in a solid porous matrix and the application limits of the Gibbs-Thomson equation.

A thermodynamic model is proposed to describe the melting of lamellar crystallite in a solid medium. This model includes a modification of the Gibbs-Thomson equation to make it applicable to the above-mentioned crystallites. The need for such modification is supported experimentally by studying the impact of the surroundings on the melting point of the crystallites. In particular, the application of the model to nanocrystals in open-porous systems makes it possible to determine the analytical relations for the melting point, the heat of melting, and the inverse effective size of the pores. The fitting of the experimental data with these functional relations then allows for the calculation of the nanocrystalline density, pressure in the nanocrystal, and difference in the surface tension coefficients at the nanocrystal-matrix interface and melt-matrix interface, as well as the difference in the surface entropies per unit area at the nanocrystal-matrix and melt-matrix interfaces.

[POLYMORPHISM IN THE PHENOTYPIC STRUCTURE OF A POPULATION OF TAIGA TICK AND ITS EPIDEMIOLOGICAL SIGNIFICANCE].

The paper presents the results of 10-year (2005-2014) observations of an Ixodespersulcatus Schulze population. The purpose of this investigation was to trace long-term changes in the structure of the taiga tick population from the proportion of specimens with external skeletal anomalies and to assess a relationship between the pattern of imago phenotypic variation and the virus percentage of a carrier. There were a total of reports of the external skeletal structure of 1123 females gathered from plants to a flag in an area at 43 km from the Baikal Road connecting Irkutsk and the settlement of Listvyanka (Irkutsk Region). The proportion of specimens with anomalies averaged 37.8 +/- 1.88%. Four-to-seven varying anomalies were annually recorded. There was a preponderance of scutum impairment (an average of 17.0 +/- 3.08% of all females) that was a conglomerate of prominences and indentations along the entire clypeus surface and that was denoted P9. The nature of a change in the proportion of ticks with two anomalies (average monthly registration rate, 2.5 +/- 0.66%) is exhibited by three-year high-frequency oscillations whereas the specimens with P9 anomalies fail to show so clear cycling. The percentage of virus-containing taiga ticks was individually determined estimating the level of tick-borne encephalitis virus antigen by an enzyme immunoassay. A total of 4022 ticks were examined. The male and female data were pooled. There was a positive correlation between the change in the proportion of females with P9 anomaly and the infection of ticks in the examined population (Spearman's correlation coefficient, 0.88; P < 0.01). This supports the earlier observation of the greater epidemiological significance of the imago of a taiga tick with external skeletal anomalies particularly with considerably marked ones.

Shotgun microbial profiling of fossil remains.

Millions to billions of DNA sequences can now be generated from ancient skeletal remains thanks to the massive throughput of next-generation sequencing platforms. Except in cases of exceptional endogenous DNA preservation, most of the sequences isolated from fossil material do not originate from the specimen of interest, but instead reflect environmental organisms that colonized the specimen after death. Here, we characterize the microbial diversity recovered from seven c. 200- to 13 000-year-old horse bones collected from northern Siberia. We use a robust, taxonomy-based assignment approach to identify the microorganisms present in ancient DNA extracts and quantify their relative abundance. Our results suggest that molecular preservation niches exist within ancient samples that can potentially be used to characterize the environments from which the remains are recovered. In addition, microbial community profiling of the seven specimens revealed site-specific environmental signatures. These microbial communities appear to comprise mainly organisms that colonized the fossils recently. Our approach significantly extends the amount of useful data that can be recovered from ancient specimens using a shotgun sequencing approach. In future, it may be possible to correlate, for example, the accumulation of postmortem DNA damage with the presence and/or abundance of particular microbes.

Detection of tick-borne pathogens in ticks from migratory birds in the Baltic region of Russia.

We report the finding of tick-borne encephalitis (TBE)-virus in indigenous Ixodes ricinus (L.), 'Candidatus Neoehrlichia mikurensis' in exotic Ixodes frontalis (Panzer) and Rickettsia aeshlimannii in exotic Hyalomma marginatum Koch subadult ticks detached from 18.5% (107/577) infested migratory birds in the Baltic region of Russia. This is the first record of human pathogenic 'Candidatus N. mikurensis' in I. frontalis ticks. Moreover, seven other pathogens were identified in I. ricinus ticks. Spotted Fever Group rickettsiae were the predominant pathogen group and were detected only in nymphs. Future investigations are warranted to further characterize the role of birds in the epizootiology of tick-borne pathogens in this region.

[The present knowledge of tick-borne encephalitis vectors].

The most important aspects of the relationships of tick-borne encephalitis virus and its vectors--Ixodes ticks. These include the establishment of a rule of viral exchange between the co-fed ticks, which makes its reverse transfer from nymphs to larvae possible; enhancement of tick aggressiveness under the influence of the incremental concentrations of the virus increasing their epidemiological danger; the association of the spread of viral genospecies with the genetic structure of tick populations; the emergence of phenotypically different vector subpopulations with new vector properties (under the influence of anthropogenic factors); and the elucidation of a possible role of the virus as an enhancer in mixed viral and bacterial infections of tick vectors.

[The effects of global climatic changes on bloodsucking ectoparasites and pathogens they transmit].

The present global climatic changes, regardless of their causes and duration, are of paramount importance from the ecological perspective. The influence of these changes on Russian population health attracts the attention of experts. The most important changes have already taken place in the high and middle latitudes, occupied by Russia. The article covers a probable impact of global changes on the distribution of bloodsucking arthropods as the vectors of inoculable disease agents, their abundance and vector capacity, and the role of migratory birds in their spreading. For Russia, the most important is to forecast the condition of the population of gnats, malaria vectors in particular, as well as ticks, the latter group being the vectors of tickborne infections ranging from the Baltic Sea to the Pacific Ocean. Analysis of the changes in mean annual temperatures during the past century by the example of Minsk, an East European city, demonstrates its nearly 1.5-fold increase. Minsk in Belarus, as well as many big cities in Russia, such as St. Petersburg, Yekaterinburg etc., present the so called "warm islands". Global increase in temperatures, winter ones first of all, especially in megapolises, leads to outbreaks of inoculable diseases transmitted by bloodsucking vectors in urbanized territories, with a noticeable north shift of their natural ranges. Recent epidemics of West Nile fever in New York City, USA, as well as in Krasnodar and Volgograd, Russia, can serve as examples. Increased mean summer temperatures, as well as prolonged warm and humid periods, facilitate malaria transmissions. The periods of possible successful transmission of tick-borne infections is prolonged likewise, with a north-west shift of their ranges. Thus, Japanese encephalitis outbreaks are expected in Russian Primorye and in the south of Sakhalin Island. Among known and still revealed tick-borne diseases, an increased role is going to be played by mixed viral as well as bacterial infections.

Early influence of the steppe tribes in the peopling of Siberia.

The Yakuts, Middle Age Turkic speakers (15th-16th centuries), are widely accepted as the first settlers of the Altai-Baikal area in eastern Siberia. They are supposed to have introduced horses and developed metallurgy in this geographic area during the 15th or 16th century A.D. The analysis of the Siberian grave of Pokrovsk, recently discovered near the Lena River (61 degrees 29' N) and dated by accelerator mass spectrometry from 2,400 to 2,200 years B.P., may provide new elements to test this hypothesis. The exceptional combination of various artifacts and the mitochondrial DNA data extracted from the bone remains of the Pokrovsk man might prove the existence of previous contacts between autochthonous hunters of Oriental Siberia and the nomadic horse breeders from the Altai-Baikal area (Mongolia and Buryatia). Indeed, the stone arrowhead and the harpoons relate this Pokrovsk man to the traditional hunters of the Taiga. Some artifacts made of horse bone and the pieces of armor, however, are related to the tribes of Mongolia and Buryatia of the Xiongnu period (3rd century B.C.). This affinity has been confirmed by the match of the mitochondrial haplotype of this subject with a woman of the Egyin Gol necropolis (Mongolia, 2nd/3rd century A.D.) as well as with two modern Buryats. This result allows us to postulate that contacts between southern steppe populations and Siberian tribes occurred before the 15th century.

[Possible types of tick-borne diseases and the predictive role of history data in their diagnosis (parasitological aspects of the problem)]. / Vozmozhnye varianty zabolevanii kleshchevymi infektsiiami i prognosticheskaia rol' anamneza v ikh diagnostike (parazitologicheskie aspekty problemy).

The paper discusses the proven and probable role of different tick-borne pathogens and their combinations in the occurrence of zoonotic diseases. The variants of coexistence of various combinations of 7 proved disease agents (3 species of Borrelia, 2 species of Ehrlichia, Babesia, and TBE virus) with different, if might to be, disease agents, such as rickettsiae of two groups, which do not belong to the Borrelia burgdorferi sensu lato group spirochetes, are analyzed. The difference of their development and the time of transmission after of the vector Ixodes persulcatus Schulze attachment are considered. Based on the their own hypothesis that one tick specimen is able to be the vector of only three human pathogenic agents simultaneously, the authors examined the possible number of combinations of pathogens, which might be obtained by a patient after 1 tick attachment. Proper history data are recommended as a tool for making a correct diagnosis, wherein the time of attachment has to be a main factor. For example, it should be taken into account that TBE virus might be transmitted only some minutes after attachment by not only a female tick, but also a male one. Mixed infection of virus plus Borrelia might develop only following some hours of attachment (most probably after 18-24 hours). The very similar situation has to be considered to lead to virus-Borrelia-Ehrlichia (or Rickettsia) coinfection. Any combination with Babesia involvement may appear not earlier than 24-36 hours after mixed infected tick attachment (or even later). It is necessary to consider a possible role of apathogenic microorganisms which are present in the most of vector specimens in nature and which might be injected with infected tick saliva may play a possible role in the manifestation of disease and in the prediction of their possible influence.

[The possibility of the detection of one more tick-borne infection--babesiosis--on the territory of Russia]. / O vozmozhnosti vyiavleniia eshche odnoi kleshchevoi infektsii--babezioza--na territorii Rossii.

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.

[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]. / Vyiavlenie genotipicheskoi neodnorodnosti populiatsii Ixodes persulcatus Schulze (Acari: Ixodidae) Severo-Zapada Rossii i osobennosti raspredeleniia kleshchevykh patogenov--vozbuditelei bolezni Laima i érlikhiozov v razlichnykh genotipakh.

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.

[Borreliae as possible antagonists of tick-borne encephalitis virus: parasitologic and clinical aspects]. / Borrelii kak veroiatnye antagonisty virusa kleshchevogo éntsefalita: parazitologicheskii i klinicheskii aspekty problemy.

An attempt was made to compare the Borrelia-TBE-virus interface in Ixodes ticks and in patients. The authors suppose that Borrelia might suppress viral replication in ticks and in TBE-susceptible individuals. Whether antibiotics (particularly representatives of the tetracycline group) may be essential in treating tick-borne diseases is also discussed. Examples of antibiotic suppression of Borrelia that made the clinic presentation of encephalitis more severe as a consequence are analyzed and discussed. The calculated risk for borreliosis or tick-borne encephalitis and the actual morbidity rates were compared. Possible reasons for disagreement in the results are also discussed.

Evidence of ehrlichiosis agents found in ticks (Acari: Ixodidae) collected from migratory birds.

Two Ehrlichia pathogens were found in immature Ixodes ricinus (L.) ticks collected from migratory passerine birds in the Curonian Spit area of the Baltic Region of Russia (Kaliningrad enclave). During the spring and fall of 2000, 1,606 passerine birds (eight species) were collected; 6.8% of them (110/1,606) were infested by ticks, and 51.8% (57/110) of tick clusters contained various human pathogenic microorganisms. Human monocytic ehrlichiosis (HME) and human granulocytic ehrlichiosis (HGE) agents were found in 14% (8/57) of cases. Borrelia afzelii, Borrelia garinii, and Borrelia burgdorferi sensu stricto were found in 92.9% (53/57) of the ticks. In five out of eight cases, infection of both Ehrlichia and Borrelia were obtained. In one case, a single nymph contained HME, B. afzelii, and B. garinii. Borrelia burgdorferi s.s. and B. afzelii were found together in one pool of four nymphs and one larva. All agents were identified using polymerase chain reaction and species-specific primers. In 8.8% of the ticks collected from birds in the fall and 22% in the spring, pathogens were isolated from attached co-feeding nymphs and larvae. These data demonstrate that Ehrlichia exchange could occur between co-feeding ticks on animals without systemic infection.

Identification of Ehrlichia spp. and Borrelia burgdorferi in Ixodes ticks in the Baltic regions of Russia.

The presence and distribution of Ehrlichia spp. and Borrelia burgdorferi sensu lato was demonstrated among ixodid ticks collected in the Baltic regions of Russia, where Lyme borreliosis is endemic. A total of 3,426 Ixodes ricinus and 1,267 Ixodes persulcatus specimens were collected, and dark-field microscopy showed that 265 (11.5%) I. ricinus and 333 (26.3%) I. persulcatus ticks were positive. From these samples, 472 dark-field-positive and 159 dark-field-negative ticks were subjected to PCR and subsequent reverse line blot hybridization. Fifty-four ticks (8.6%) carried Ehrlichia species, and 4 (0.6%) carried ehrlichiae belonging to the Ehrlichia phagocytophila complex, which includes the human granulocytic ehrlichiosis agent. The E. phagocytophila complex and an Ehrlichia-like species were detected only in I. ricinus whereas Ehrlichia muris was found exclusively in I. persulcatus, indicating a possible vector-specific infection. Borrelia garinii was found predominantly in I. persulcatus, but Borrelia afzelii was evenly distributed among the two tick species. Only two I. ricinus ticks carried B. burgdorferi sensu stricto, while Borrelia valaisiana and a newly identified B. afzelii-like species were found in 1.7 and 2.5% of all ticks, respectively. Of the dark-field-positive ticks, only 64.8% yielded a Borrelia PCR product, indicating that dark-field microscopy may detect organisms other than B. burgdorferi sensu lato. These observations show that the agent of human granulocytic ehrlichiosis may be present in ticks in the Baltic regions of Russia and that clinicians should be aware of this agent as a cause of febrile disease.

Peculiarities of behaviour of taiga (Ixodes persulcatus) and sheep (Ixodes ricinus) ticks (Acarina: Ixodidae) determined by different methods.

A comparison of the behavioural peculiarities of Ixodes persulcatus Schulze, 1930 (north-western population, Russia) and Ixodes ricinus (L., 1758) from western Russia and Denmark was determined by using two methods. Method 1 involved a sojourn of ticks on vertical plastic sticks and showed that the questing behaviour of I. ricinus nymphs was dependent on temperature and relative humidity (RH). A significantly greater number of nymphs quested at 22 degrees C and 100% RH than at 18 degrees C. When the humidity was reduced to 30% all of the nymphs departed. In the second method, the activity of ticks on an inclined "ticksdrome" was estimated. The activity of I. ricinus adults from the Danish population was 1.2 times greater than that of ticks from Russia. Females of the species studied and specimens from all study areas were more active than all other stages of development. The locomotor activity of both adult and immature I. ricinus that were infected with Borrelia burgdorferi sensu lato was suppressed when compared with uninfected specimens. The locomotor activity of I. persulcatus females infected by borreliae with exoskeleton anomalies was 1.3 times greater (P<0.05) than that of infected ticks without anomalies. Our data showed that infected females with exoskeleton anomalies could crawl faster on a human and reach uncovered parts of the body that are vulnerable for attachment and feeding. A study of locomotor activity and questing behaviour may be useful for comparing the risk for different tick species and populations to transmit tick-borne pathogens.

Abiotic parameters and diel and seasonal activity of Borrelia-infected and uninfected Ixodes persulcatus (Acarina: Ixodidae).

During the 1997 season of Ixodes persulcatus Schulze tick activity, 579 specimens were collected by flagging in the vicinity of St. Petersburg (Morskaja, Lisy Nos). Collections were made from April to July, and at each collection time the following measurements were recorded: light intensity (in lux); temperature of soil 1-1.5 cm below leaf litter, at the soil surface, and in the air 1.5 m above the soil surface; and relative humidity. The gradient between soil at a depth of 1-1.5 cm and soil surface temperatures appeared to be the main physical parameter that initiated tick migration out of the leaf litter. At soil temperature intervals of 5-10 degrees C and 21-26 degrees C, ticks were found only when the soil temperature 1-1.5 cm below the soil surface was colder than at its surface. When temperature ranged from 11 to 20 degrees C, 24% of the ticks were collected when the surface temperature was colder than that below the soil surface. Sixty percent of the ticks, especially nymphs, were collected when the soil surface and subsoil temperature difference ranged from 0 to 2.0 degrees C. The gradient between soil temperature and relative humidity appeared to increase the importance of the gradient between the soil and surface temperature at which time the maximum number of ticks were caught. Borrelia burgdorferi sensu lato infected ticks were collected only after 1100 hours. Prior to and just after 1100 h the mean difference between soil temperatures was 4.7 degrees C, whereas the mean difference between soil and surface temperatures was 6.4 degrees C at this time. The most important factors that influenced the appearance of Borrelia-infected ticks were the temperature gradients that existed between the surface and soil temperatures and the soil and air relative humidity. Greater numbers of infected nymphs were collected when temperature intervals ranged from 10 to 14 degrees C and lower numbers were collected between 15 and 20 degrees C. No Borrelia-infected nymphs were captured when the temperature interval ranged from 21 to 26 degrees C. Infected adults appeared to be more tolerant of higher temperatures than Borrelia-infected nymphs. A significant relationship was found between the activity of Borrelia-infected I. persulcatus and the temperature of the air, soil below the surface, at the soil surface, and relative humidity.

Sexual transmission of Borrelia garinii by male Ixodes persulcatus ticks (Acari, Ixodidae).

We investigated the transmission of Borrelia garinii and Borrelia afzelii between male and female Ixodes persulcatus ticks. For this purpose the infection rate of partners from tick couples was determined by polymerase chain reaction and reverse line blot. In couples, where the male tick was infected with B. garinii, four out of nine female partners carried B. garinii. In eight couples, male ticks had a dual infection of B. afzelii and B. garinii and three female partners were infected by Borrelia spirochetes. Two female ticks carried B. garinii, and one female tick had a dual infection. No evidence for transmission of B. afzelii from male to female ticks was found among seven couples. In 45 couples where the female tick was infected, not one male tick carried spirochetes. The difference in the B. garinii infection rate between male and female ticks among these couples is highly significant. Our data suggest that transmission of B. garinii from male ticks to female ticks does occur. Sexual transmission of this pathogen may play an important role in the maintenance of B. garinii in I. persulcatus.

[Current problems in medical entomology]. / Aktual'nye problemy meditsinskoi éntomologii.

The major problems facing medical entomology as a science and practical health care facilities in the Russian Federations allows to outline the tasks to be solved in order of their priority and significance. These include the study and monitoring of tick-borne infections, resurrecting malaria, gnat-induced diseases, acariases, allergosis and pediculosis. It is emphasized that medical entomology as a science cannot develop since the man-made changes of the environment and the predicted global warming of the Earth climate are not taken into account. The present status of medical entomological service is considered to be poor. Governmental support is required.

[The biodiversity dynamics of the causative agents of diseases transmitted by ticks in the genus Ixodes: an analysis of multiyear data]. / Dinamika bioraznoobraziia vozbuditelei boleznei, perenosimykh kleshchami roda Ixodes: analiz mnogoletnykh dannykh.

Fauna of pathogen's met in the organism of the primary tick-borne disease vectors--Ixodes persulcatus Schulze and Ixodes ricinus (L.) was observed. Prevalence of Borrelia mono- and poly-infection in the I. persulcatus ticks within a season of the vector activity was analyzed and increase of the number of the dual infected specimens during the season was demonstrated. The first determination of Ehrlichia infected I. ricinus and I. persulcatus collected in the Baltic region of Russia was stated. The triple infection of Ixodes ticks in was proved: infection by the two species of Borrelia and Ehrlichia; infection by the three species of Borrelia and infection by the tick-borne encephalitis virus and two species of Borrelia. The first determination of the tick-borne encephalitis virus in I. ricinus in the recreational zone of Kaliningrad Province (Courland [correction of Curonian] Spit) was described. Dipetalonema sp. was detected in the St. Petersburg population of I. persulcatus. The prevalence of poly-infection among I. persulcatus ticks was stated.