Monitoring Causative Agents of Tick-Borne Infections in Primorsky Krai (2014–2018)

The two ixodid tick species Dermacentor reticulatus (Fabricius) and Dermacentor silvarum Olenev occur at the northern distribution limit of the genus Dermacentor in Eurasia, within the belt of 34−60 • N latitude. Whilst the distribution area of D. reticulatus extends from the Atlantic coast of Portugal to Western Siberia, that of D. silvarum extends from Western Siberia to the Pacific coast. In Western Siberia, the distribution areas of the two Dermacentor species overlap. Although the two tick species are important vectors of disease, detailed information concerning the entire distribution area, climate adaptation, and proven vector competence is still missing. A dataset was compiled, resulting in 2188 georeferenced D. reticulatus and 522 D. silvarum locations. Up-to-date maps depicting the geographical distribution and climate adaptation of the two Dermacentor species are presented. To investigate the climate adaptation of the two tick species, the georeferenced locations were superimposed on a high-resolution map of the Köppen-Geiger climate classification. The frequency distribution of D. reticulatus under different climates shows two major peaks related to the following climates: warm temperate with precipitation all year round (57%) and boreal with precipitation all year round (40%). The frequency distribution of D. silvarum shows also two major peaks related to boreal climates with precipitation all year round (30%) and boreal winter dry climates (60%). Dermacentor silvarum seems to be rather flexible concerning summer temperatures, which can range from cool to hot. In climates with cool summers D. reticulatus does not occur, it prefers warm and to a lesser extent hot summers. Lists are given in this paper for cases of proven vector competence for various agents of both Dermacentor species. For the first time, the entire distribution areas of D. reticulatus and D. silvarum were mapped using georeferenced data. Their climate adaptations were quantified by Köppen profiles.

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“…( 2018 ) 2 l Russia Leonova et al. ( 2018 ) 4 m Russia Pukhovskaya et al. ( 2018 ) 4 h Russia Seryodkin et al.…”

Section: Methodsmentioning

confidence: 99%

Vectors of disease at the northern distribution limit of the genus Dermacentor in Eurasia: D. reticulatus and D. silvarum

et al. 2020

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“…Циркуляция возбудителя возвратной клещевой лихорадки B. miyamotoi была зарегистрирована в природных биотопах Республики Удмуртия (у 6,3% клещей рода Ixodes), в Рязанской и Свердловской областях (2,9%), Республике Алтай (7,5%), в Иркутской (10,4%) и Новосибирской (2,8%) областях, Красноярском крае (5%), Хабаровском крае (3,24%), Амурской области (3,65%) и Приморском крае (8,5%). Установлено, что эндемичные районы для B. miyamotoi частично совпадают с таковыми для возбудителей ИКБ (B. burgdorferi sensu lato), при этом выявлены случаи микстинфицирования иксодовых клещей двумя видами спирохет [13][14][15][16][17].…”

Section: обсуждение основного результата исследованияunclassified

Distribution of the causative agent of relapsing tick-borne fever <i>Borrelia miyamotoi</i> in natural focus in the Tomsk region

Воронкова

Lukashova

Karpova

et al. 2022

Epidemiology and Infectious Diseases

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Background: Knowledge about the infectious potential of the causative agent of recurrent tick-borne fever Borrelia miyamotoi and the role of this pathogen in the etiological structure formation of transmissible natural focal infections in a number of regions remains incomplete. Among them is the Tomsk region where in 2021 the incidence of ixodic tick-borne borreliosis was 15.7 per 100 thousand population, which is 3.6 times higher than the all-Russian indicator. Aims: to summarize and analyze epidemiological data, as well as the results of our own clinical observations and laboratory studies conducted in 2015-2021 confirming the distribution of the causative agent of relapsing tick-borne fever B. miyamotoi in the Tomsk region. Materials and methods: Epidemiological data on the manifestation of natural foci of tick-borne infections were analyzed in the Tomsk region for the period 2015-2021. A clinical case of febrile infection caused by B. miyamotoi infection is described as an example of underdiagnosis of relapsing tick-borne fever. Verification of the etiological variant of borreliosis was carried out using real-time PCR. DNA extraction and detection of B. miyamotoi genetic markers were performed using RealBest series kits (Vector-Best, Novosibirsk), followed by nucleic acid sequencing of B. miyamotoi 23SrRNA, glpQ, and recA gene sequences. Ixodid ticks (I. persulcatus, I. pavlovskyi, D. reticulatus) collected in the Tomsk region were studied for infestation with B. miyamotoi. Detection of genetic markers of pathogenic borrelia was carried out in nucleic acid samples isolated from tick homogenates using kits of the RealBest series (Vector-Best, Novosibirsk). Results: In 2016, the first clinical case of borreliosis caused by B. miyamotoi confirmed by molecular genetic methods in the Tomsk region was identified. During the period 2015-2021, the infection rate of B. miyamotoi ticks of the genus Ixodes in the Tomsk region was up to 7%; ticks of the genus Dermacentor up to 3%. Conclusion. The results of this study demonstrated the distribution the causative agent of relapsing tick-borne fever B. miyamotoi in the natural foci of the Tomsk region, which requires further monitoring of the epizootic situation and study of the role of this pathogen in the formation of the etiological structure of transmission natural focal infections.

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Comparative Analysis of Methods Efficiency of Virification of the Tick-Borne Encephalite Virus

Леонова¹

2019

RCLD

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Based on experimental studies with 10-fold dilutions of two the strains TBEV of the Far Eastern subtype, different in molecular-genetic characteristic complex data of simultaneously taking into account three indicators of their verification (virus titer, ELISA and PCR-RT) were obtained. The efficiency of detecting a genetic marker in PCR compared with ELISA for a weakly pathogenic strain with defects in the genetic structure was higher by a factor of 10, and for a highly pathogenic strain by a factor of 5,000. At the same time, positive results in both reactions with respect to two strains were detected with a virus titer of not less than 1-1.5 log TCID50, i.e. this level of virus in the sample is defined as epidemically significant. An algorithm for conducting research on the verification of TBEV is proposed: 1) Ticks collected from vegetation can be examined by ELISA or by PCR. All positive results can be summarized and considered viral ticks; 2) All samples with positive results only in PCR or ELISA must be investigated in two reactions in order to obtain confirmation of the possible infectivity of the pathogen; 3) To obtain a fast complex result of infection of the removed ticks from patients or blood after a tick bite, studies should be carried out simultaneously in two reactions simultaneously in ELISA and PCR; 4) Isolation virus should be carried out in biological samples (ticks collected from vegetation, ticks removed from patients, the blood of patients with suspected TBE, mammals) only with the same results in PCR and ELISA. Thus, such an approach to verifying TBEV in a tick or in the blood of patients will improve the reliability of laboratory diagnostics, identifying not only markers of TBEV, but also determining the infectivity of the pathogen, which may be the basis for the appointment of early intensive antiviral therapy.

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Monitoring Causative Agents of Tick-Borne Infections in Primorsky Krai (2014–2018)

Cited by 7 publications

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Vectors of disease at the northern distribution limit of the genus Dermacentor in Eurasia: D. reticulatus and D. silvarum

Vectors of disease at the northern distribution limit of the genus Dermacentor in Eurasia: D. reticulatus and D. silvarum

Distribution of the causative agent of relapsing tick-borne fever <i>Borrelia miyamotoi</i> in natural focus in the Tomsk region

Comparative Analysis of Methods Efficiency of Virification of the Tick-Borne Encephalite Virus

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