Genetic features of the Puumala virus (Hantaviridae: Orthohantavirus) identified in the Moscow region

INTRODUCTION

Puumala virus (family Hantaviridae, genus Orthohantavirus) is distributed in most regions of the European part of Russia. However, information about its genetic variants circulating on the territory of the Central Federal District is extremely scarce.

MATERIALS AND METHODS

Rodents' tissue samples were tested after reverse transcription by PCR for the presence of hantaviral RNA. The amplified fragments of the L segment were sequenced by the Sanger method. For two samples, sequences of all three segments were obtained using the NGS method. Phylogenetic trees were built in the MEGA-X software.

RESULTS

Puumala virus was found in six samples. Based on the phylogenetic analysis of sequences of three segments, the obtained genetic variants belong to the sublineage previously designated as W-RUS.

CONCLUSION

A genetic variant of the Puumala virus, belonging to the subline W-RUS, circulates on the territory of the Volokolamsk district of Moscow region.

Detection of Filoviruses in Bats in Vietnam

A new filovirus named Měnglà virus was found in bats in southern China in 2015. This species has been assigned to the new genus Dianlovirus and has only been detected in China. In this article, we report the detection of filoviruses in bats captured in Vietnam. We studied 248 bats of 15 species caught in the provinces of Lai Chau and Son La in northern Vietnam and in the province of Dong Thap in the southern part of the country. Filovirus RNA was found in four Rousettus leschenaultii and one Rousettus amplexicaudatus from Lai Chau Province. Phylogenetic analysis of the polymerase gene fragment showed that three positive samples belong to Dianlovirus, and two samples form a separate clade closer to Orthomarburgvirus. An enzyme-linked immunosorbent assay showed that 9% of Rousettus, 13% of Eonycteris, and 10% of Cynopterus bats had antibodies to the glycoprotein of marburgviruses.

The First Case of Zika Virus Disease in Guinea: Description, Virus Isolation, Sequencing, and Seroprevalence in Local Population

The Zika virus (ZIKV) is a widespread mosquito-borne pathogen. Phylogenetically, two lineages of ZIKV are distinguished: African and Asian-American. The latter became the cause of the 2015-2016 pandemic, with severe consequences for newborns. In West African countries, the African lineage was found, but there is evidence of the emergence of the Asian-American lineage in Cape Verde and Angola. This highlights the need to not only monitor ZIKV but also sequence the isolates. In this article, we present a case report of Zika fever in a pregnant woman from Guinea identified in 2018. Viral RNA was detected through qRT-PCR in a serum sample. In addition, the seroconversion of anti-Zika IgM and IgG antibodies was detected in repeated blood samples. Subsequently, the virus was isolated from the C6/36 cell line. The detected ZIKV belonged to the African lineage, the Nigerian sublineage. The strains with the closest sequences were isolated from mosquitoes in Senegal in 2011 and 2015. In addition, we conducted the serological screening of 116 blood samples collected from patients presenting to the hospital of Faranah with fevers during the period 2018-2021. As a result, it was found that IgM-positive patients were identified each year and that the seroprevalence varied between 5.6% and 17.1%.

Tetrahydroquinazoline N-oxide derivatives inhibit reproduction of tick-borne and mosquito-borne flaviviruses

Tick-borne encephalitis virus (TBEV), yellow fever virus (YFV), and West Nile virus (WNV) are flaviviruses causing emerging arthropod-borne infections of a great public health concern. Clinically approved drugs are not available to complement or replace the existing vaccines, which do not provide sufficient coverage. Thus, the discovery and characterization of new antiflaviviral chemotypes would advance studies in this field. In this study, a series of tetrahydroquinazoline N-oxides was synthesized, and the antiviral activity of the compounds was assessed against TBEV, YFV, and WNV using the plaque reduction assay along with the cytotoxicity to the corresponding cell lines (porcine embryo kidney and Vero). Most of the studied compounds were active against TBEV (EC₅₀  2 to 33 μM) and WNV (EC₅₀  0.15 to 34 μM) and a few also demonstrated inhibitory activity against YFV (EC₅₀  0.18 to 41 μM). To investigate the potential mechanism of action of the synthesized compounds, time-of-addition (TOA) experiments and virus yield reduction assays were performed for TBEV. The TOA studies suggested that the antiviral activity of the compounds should affect the early stages of the viral replication cycle after cell entry. Compounds with tetrahydroquinazoline N-oxide scaffold show a broad spectrum of activity against flaviviruses and represent a promising chemotype for antiviral drug discovery.

Marburg virus in Egyptian Rousettus bats in Guinea: Investigation of Marburg virus outbreak origin in 2021

In 2021, a patient died from Marburg virus (MARV) disease in Guinea and it was the first confirmed case in West Africa. The origin of the outbreak has not been identified. It was revealed that the patient didn't travel anywhere before the illness. Prior to outbreak, MARV had been found in bats in the neighboring Sierra Leone, but never in Guinea. Therefore, the origin of infection is unclear: was it an autochthonous case with spillover from a local population of bats or an imported case with spillover from fruit bats foraging/migrating from Sierra Leone? In this paper, we studied Rousettus aegyptiacus in Guinea as the possible source of MARV infection caused the patient death in 2021 in Guinea. We caught bats in 32 sites of Guéckédou prefecture, including seven caves and 25 locations of the flight path. A total of 501 fruit bats (Pteropodidae) were captured, including 66 R. aegyptiacus. The PCR screening showed three positive MARV R. aegyptiacus, roosting in two caves discovered in Guéckédou prefecture. After Sanger sequencing and phylogenetic analyses it was shown that found MARV belongs to the Angola-like lineage but it is not identical to the isolate obtained during the outbreak of 2021.

The Baikal subtype of tick-borne encephalitis virus is evident of recombination between Siberian and Far-Eastern subtypes

Tick-borne encephalitis virus (TBEV) is a flavivirus which causes an acute or sometimes chronic infection that frequently has severe neurological consequences, and is a major public health threat in Eurasia. TBEV is genetically classified into three distinct subtypes; however, at least one group of isolates, the Baikal subtype, also referred to as “886-84-like”, challenges this classification. Baikal TBEV is a persistent group which has been repeatedly isolated from ticks and small mammals in the Buryat Republic, Irkutsk and Trans-Baikal regions of Russia for several decades. One case of meningoencephalitis with a lethal outcome caused by this subtype has been described in Mongolia in 2010. While recombination is frequent in Flaviviridae, its role in the evolution of TBEV has not been established. Here, we isolate and sequence four novel Baikal TBEV samples obtained in Eastern Siberia. Using a set of methods for inference of recombination events, including a newly developed phylogenetic method allowing for formal statistical testing for such events in the past, we find robust support for a difference in phylogenetic histories between genomic regions, indicating recombination at origin of the Baikal TBEV. This finding extends our understanding of the role of recombination in the evolution of this human pathogen.

[Characteristics of imported cases of Dengue fever and hemorrhagic Dengue fever in 2009-2019]

INTRODUCTION

In Russia, the approved morbidity statistics system is represented by the International Classification of Diseases of the 10th revision (ICD-10). This classification provides two forms of dengue fever (DF): dengue fever (A90) and hemorrhagic dengue (A91). Official statistics on the ratio of forms of DF is not published in open sources and this lack of information about the real ratio of the forms of DF makes it difficult to objectively assess the factors that determine the severity of this disease.

THE AIM

compare the clinical and epidemiological features of dengue fever and hemorrhagic dengue fever in patients hospitalized in 2009-2019 to the City Infectious Clinical Hospital No. 1, Moscow.

MATERIALS AND METHODS

A retrospective cohort study. We analyzed the patient database and reviewed 391 medical records of patients with diagnosed dengue fever. We compared gender, age characteristics, travel geography including information about previous visits of patients to endemic regions and dengue virus serotype. To determine the primary and re-infection rate, an analysis of IgG for the dengue virus was carried out on days 1-5 of the disease. To compare indicators, 95% confidence intervals for proportions, medians, and interquartile ranges were calculated. The significance of differences between independent samples for assessing qualitative characteristics was carried out using the criteria χ2, the odds ratio. To assess the quantitative characteristics, the Mann-Whitney test was used. Differences were considered statistically significant at p ≤ 0.05.

RESULTS

The proportion of patients with dengue fever was 14.9% of all hospitalized with febrile illnesses that developed after international travel. Hemorrhagic dengue fever (DHF) was diagnosed in 15.7% of patients with dengue fever. DHF developed significantly more often in women, as well as in those who had history of repeated visits to endemic regions. However, DHF was also diagnosed in 10.9% of first-time travelers to tropical countries. We did not find significant differences in the rates of DHF development depending on age and dengue virus serotype. In a number of patients who had not previously traveled to endemic regions, IgG to the dengue virus were detected, which may indicate a previous infection with related flaviviruses.

CONCLUSION

It has been established that in the regions most visited by Russians, there is a circulation of all serotypes of the dengue virus with an annual change in the predominant serotype.

Rhipicephalus microplus and its vector-borne haemoparasites in Guinea: further species expansion in West Africa

Rhipicephalus microplus is an ixodid tick with a pantropical distribution that represents a serious threat to livestock. West Africa was free of this tick until 2007, when its introduction into Benin was reported. Shortly thereafter, further invasion of this tick species into other West African countries was identified. In this paper, we describe the first detection of R. microplus in Guinea and list the vector-borne haemoparasites that were detected in the invading and indigenous Boophilus species. In 2018, we conducted a small-scale survey of ticks infesting cattle in three administrative regions of Guinea: N`Zerekore, Faranah, and Kankan. The tick species were identified by examining their morphological characteristics and by sequencing their COI gene and ITS-2 gene fragments. R. microplus was found in each studied region. In the ticks, we found the DNA of Babesia bigemina, Anaplasma marginale, Anaplasma platys, and Ehrlichia sp. The results of this study indicate that R. microplus was introduced into Guinea in association with cows from Mali and/or the Ivory Coast.

Geographical and Tick-Dependent Distribution of Flavi-Like Alongshan and Yanggou Tick Viruses in Russia

The genus Flavivirus includes related, unclassified segmented flavi-like viruses, two segments of which have homology with flavivirus RNA-dependent RNA polymerase NS5 and RNA helicase-protease NS3. This group includes such viruses as Jingmen tick virus, Alongshan virus, Yanggou tick virus and others. We detected the Yanggou tick virus in Dermacentor nuttalli and Dermacentor marginatus ticks in two neighbouring regions of Russia. The virus prevalence ranged from 0.5% to 8.0%. We detected RNA of the Alongshan virus in 44 individuals or pools of various tick species in eight regions of Russia. The virus prevalence ranged from 0.6% to 7.8%. We demonstrated the successful replication of the Yanggou tick virus and Alongshan virus in IRE/CTVM19 and HAE/CTVM8 tick cell lines without a cytopathic effect. According to the phylogenetic analysis, we divided the Alongshan virus into two groups: an Ixodes persulcatus group and an Ixodes ricinus group. In addition, the I. persulcatus group can be divided into European and Asian subgroups. We found amino acid signatures specific to the I. ricinus and I. persulcatus groups and also distinguished between the European and Asian subgroups of the I. persulcatus group.

Ngari virus (Orthobunyavirus, Peribunyaviridae) in ixodid ticks collected from cattle in Guinea

Ngari virus is a mosquito-borne virus belonging to the genus Orthobunyavirus (Peribunyaviridae family). This virus is pathogenic to humans and causes severe illness. Ngari virus is present in several African countries, including Madagascar. Here, we report the detection of Ngari virus in ixodid ticks collected from cows in Guinea. A tick survey was conducted in March-November of 2018 in six regions of Guinea. The sample comprised 710 pools, with a total of 2067 ticks belonging to five species collected from 197 cows. At the initial stage, we screened a subsample of tick pools of vector-borne viruses with a multiplex genus-specific primer panel. In the second stage of the study, we narrowed the search and screened all the samples by qPCR for the detection of Ngari virus. All positive samples were sequenced with primers flanking Ngari virus-specific fragments on the S and M segments. We found Ngari virus in 12 pools that were formed from engorged ticks collected from livestock in three villages of the Kindia and Kankan regions. Sequencing of the S and M segments confirmed that the detected viruses belong to Ngari virus, and the viruses were most similar to the strain Adrar, which was isolated in Mauritania. We detected viral RNA in ticks of the following species: Amblyomma variegatum, Rhipicephalus geigyi, and Rh. (Boophilus) spp. There is no evidence that ixodid ticks are competent vectors of the Ngari virus. Most likely, the ticks obtained the virus through blood from an infected host. The study of engorged ticks can be recommended as a simpler approach for the wide screening of the Ngari virus and subsequent testing of cattle and mosquitos in those locations where the PCR-positive ticks were collected.

[Visceral leishmaniasis: a challenging diagnosis in internal medicine]

Leishmaniasis is a vector-born parasitic disease characterized by predominant cutaneous or visceral involvement with fever, hepatosplenomegaly and anemia. Leishmaniasis has relatively high prevalence in tropical and subtropical areas. Several sporadic and mostly imported cases are detected in Russian Federation. Nevertheless, some local incidents are noted in southern areas (Crimea, Dagestan). Lack of epidemiological alertness hampers confirmation of diagnosis and may lead to incorrect treatment. The article summarizes current state of knowledge in epidemiology, diagnostic approach and treatment of leishmaniasis. Particular clinical case is discussed.

[Laboratory diagnostic of human babesiosis.]

Human babesiosis caused by parasitic protozoan Babesia spp. is sporadic zoonotic vector-borne infection. The course of babesiosis and prognosis depend on the type of pathogen and on the patient's immunological status. Significance this disease is a severe, often fatal course with immunocompromissed patients resembling complicated falciparum malaria. In Europe to date, more than 50 cases of confirmed human babesiosis have been reported in most cases caused by Babesia divergens. Possible there are unrecognized cases. Pathogen is an obligate intraerythrocyte parasite of vertebrate animals. The organism is transmitted from animal to man through bite of Ixodidae tick. Asexual reproduction of the parasite occurs in a vertebrate host. The pathogenesis of babesiosis is caused by the destruction of host cells. Intensive haemolysis of red blood cells leads to the development of haemolytic anemia, haematuria, jaundice, and polyorgan failure may develop. The clinical manifestations of the disease are nonspecific. Detection of intraerythrocyte parasites in blood smears stained Gimsa-Romanovsky confirms the proposed diagnosis. Blood smears and some laboratory signs from fatal cases were analyzed in the Reference-centre of E. I. Martsinovskiĭ Institute. Original microphotographs B. divergens are shown. The main morphological forms of the parasite are shown. In addition to the well-known tetrades of parasites «Maltese Cross», for the first time, the parasites dividing into 6 interconnected trophozoites - "sextet" - were found. Originally, the invasion of Babesia in a normoblast is shown. An unusually high multiple invasion (14 parasites) of erythrocytes is noted. Because the patients, initially, were incorrectly diagnosed with malaria, the differential diagnosis of Babesia with Plasmodium is described step-by-step. It is important, since the treatment with antimalarial drugs is ineffective. Deviation laboratory signs are discussed. Complex morphological characteristics allowed us to speciated the parasites as B. divergens. DNA was detected in the sample with specific primers Bab di hsp70F/Bab di hsp70R and the probe Bab di hsp70P. The sequence demonstrated 99-100% and 98% similarity to the 18S rRNA gene fragment of B. divergence and Babesia venatorum, respectively. Molecular biological and serological methods of laboratory diagnosis of babesiosis are considered.

Bombali Virus in Mops condylurus Bats, Guinea

In 2018, a previously unknown Ebola virus, Bombali virus, was discovered in Sierra Leone. We describe detection of Bombali virus in Guinea. We found viral RNA in internal organs of 3 Angolan free-tailed bats (Mops condylurus) trapped in the city of N’Zerekore and in a nearby village.

First whole genome sequencing of Russian isolate of Capnocytophaga canimorsus, opportunistic pathogen causing lethal sepsis

Capnocytophaga canimorsus is a part of healthy oral flora of dogs and cats. However, when it is transmitted to human subjects via animal bites or scratches, it can cause severe complications like endocarditis or even lethal septic shock, especially in immunocompromised persons. In this study, we performed the first whole-genome sequencing on Illumina HiSeq platform of Russian isolate of C. canimorsus that have caused lethal sepsis in 51-old male from Moscow. We believe that the availability of genomic sequence and annotation for the given strain could be useful for future epidemiological surveillance studies in Russia and other countries.

Clinical presentation of Ixodes tick-borne borreliosis caused by Borrelia miyamotoi in the context of an immune response to the pathogen

Ixodes tick-borne borreliosis caused by Borrelia miyamotoi (ITBB-BM) is a previously unknown infectious disease discovered in Russia. Aim. The present study continues the investigation of the clinical features of ITBB-BM in the context of an immune system-pathogen interaction. Subjects and methods. The study enrolled 117 patients with ITBB-BM and a comparison group of 71 patients with Lyme disease (LD) that is ITBB with erythema migrans. All the patients were treated at the New Hospital, Yekateringburg. More than 100 clinical, epidemiological and laboratory parameters were obtained from each patient’s medical history and included in the general database. A subset of patients hospitalized in 2015 and 2016 underwent additional laboratory examinations. Namely, the levels of B. miyamotoi-specific IgM and IgG antibodies were measured by the protein microarray containing GlpQ protein and four variable major proteins (VMPs): Vlp15/16, Vlp18, Vsp1, and Vlp5. The blood concentration of Borrelia was estimated by quantitative real-time PCR. Results. In contrast to LD, first of all (p

Variable Major Proteins as Targets for Specific Antibodies against Borrelia miyamotoi

Borrelia miyamotoi is a relapsing fever spirochete in Ixodes ticks that has been recently identified as a human pathogen causing hard tick-borne relapsing fever (HTBRF) across the Northern Hemisphere. No validated serologic test exists, and current serologic assays have low sensitivity in early HTBRF. To examine the humoral immune response against B. miyamotoi, we infected C3H/HeN mice with B. miyamotoi strain LB-2001 expressing variable small protein 1 (Vsp1) and demonstrated that spirochetemia was cleared after 3 d, coinciding with anti-Vsp1 IgM production. Clearance was also observed after passive transfer of immune sera to infected SCID mice. Next, we showed that anti-Vsp1 IgG eliminates Vsp1-expressing B. miyamotoi, selecting for spirochetes expressing a variable large protein (VlpC2) resistant to anti-Vsp1. The viability of Asian isolate B. miyamotoi HT31, expressing Vlp15/16 and Vlp18, was also unaffected by anti-Vsp1. Finally, in nine HTBRF patients, we demonstrated IgM reactivity to Vsp1 in two and against Vlp15/16 in four ∼1 wk after these patients tested positive for B. miyamotoi by PCR. Our data show that B. miyamotoi is able to express various variable major proteins (VMPs) to evade humoral immunity and that VMPs are antigenic in humans. We propose that serologic tests based on VMPs are of additional value in diagnosing HTBRF.

[Relapsing (recurrent) disease caused by Borrelia miyamotoi]

AIM

To clarify the clinical, laboratory, and epidemiological characteristics of relapsing Ixodes tick-borne borreliosis (ITB) caused by Borrelia miyamotoi.

SUBJECTS AND METHODS

Retrospective clinical observation was made in 79 inpatients of the Republican Infectious Diseases Hospital (Udmurt Republic), who had been diagnosed with B. miyamotoi-caused disease verified by real-time polymerase chain reaction. The latter and enzyme immunoassay ruled out possible vector-borne coinfections (ITB caused by B. burgdorferi sensu lato; tick-borne encephalitis; anaplasmosis; and ehrlichiosis).

RESULTS

The recurrent course of the disease was observed in 8 (10%) of the 79 patients. The relapsing fever curve was noted in 6 of the 8 patients; 4 patients had 2 episodes of fever and 2 patients had 3 episodes; the wave-like continuous type of fever cannot enable one to estimate the specific number of episodes in 2 more cases. Relapses occurred in all the 8 patients before antibiotic treatment. Febrile syndrome (weakness, headache, chill, fever, sweating, dizziness, nausea, vomiting, myalgia, and arthralgia) was leading in patients with relapses. These patients were less frequently observed to have signs of organ dysfunctions than those with one episode of fever. The values of clinical and biochemical blood tests and urinalyses were normal and near-normal in the majority of patients on hospital admission.

CONCLUSION

Relapsing B. miyamotoi infection cases detected in the directed study proved to be unrecognized by practical health authorities during the first and sometimes second episodes of fever. This indicates that the prevalence of this disease is essentially underestimated and there is a need to increase physicians' alertness and awareness and to introduce adequate diagnostic methods.

[The blood coagulation system and microcirculatory disorders in ixodid tick-borne borreliosis caused by Borrelia miyamotoi]

AIM

To study blood coagulation and microcirculatory disorders as a possible cause of transient dysfunctions of organs (the kidney, liver, heart, lung, etc.) in patients with ixodid tick-borne borreliosis caused by Borrelia miyamotoi (Bmt). SUBJECTS AND METHODS; Twenty-four patients with Lyme disease (LD) and 28 Bmt patients treated at Izhevsk City Hospital (Udmurtia) were examined in the study. Platelet counts and the presence of D-dimers were determined; activated partial thromboplastin time, prothrombin time, thrombin time, fibrinogen and antithrombin III levels, and Factor XIIa-dependent fibrin clot lysis time were measured. Slit lamp microscopy of the conjunctiva was. also carried out. Results. Platelet counts'were less than 150,000 per pL of blood in 43% of the Bmt patients. All the Bmt patients had at least one abnormal coagulation parameter of the eight ones that were tested; 64% of them had marked coagulation disorders with three or more abnormal laboratory findings. In contrast, all the eight parameters were normal in 71% of the LD patients. The other seven LD patients had only one or two abnormal coagulation parameters (p < 0.001 in comparison with Bmt patients). Microscopic examination of eye capillary blood flow revealed pathological findings that included aggregates of erythrocytes and obstructed and/or sinuous capillaries in 22 (79%) of the Bmt patients, but none of the LD patients. A total of 14 Bmt patients had both coagulation and microcirculatory abnormalities. Eleven of them also had transient signs of organ dysfunction.

CONCLUSION

As far as Borrelia secrete no known toxins, we hypothesized that uncovered disorders of blood coagulation and microcirculation in Bmt patients may contribute to organ dysfunction.

[Detection of West Nile virus RNA and specific antibodies in blood donors of Volgograd region]

AIM

Study infection level by West Nile virus (WNV) of donors living on the territory of West Nile fever (WNF) foci with long-term activity, and evaluate the possibility of non-transmissible transfer of the causative agent during use of donor blood.

MATERIALS AND METHODS

Blood sera (432) collected in August and September 2012 in Volgograd and Volzhsky cities were studied by PCR and EIA.

RESULTS

Antibodies to WNV were detected in 16.2% (70/432); 8.8% (38/432) donors had IgG; 0.93% (4/432)--IgM and 6.5% (28/432)--IgG and IgM antibodies simultaneously. WNV RNA was detected in one of the samples in the last group. Thus, 5 donors (1.1%, 5/432) were at the early stages after infection.

CONCLUSION

The data obtained give evidence on the necessity to execute control of donor blood by PCR and EIA in WNF foci with long-term activity.

High seroprevalence of Borrelia miyamotoi antibodies in forestry workers and individuals suspected of human granulocytic anaplasmosis in the Netherlands

Substantial exposure to Borrelia miyamotoi occurs through bites from Ixodes ricinus ticks in the Netherlands, which also transmit Borrelia burgdorferi sensu lato and Anaplasma phagocytophilum. Direct evidence for B. miyamotoi infection in European populations is scarce. A flu-like illness with high fever, resembling human granulocytic anaplasmosis, has been attributed to B. miyamotoi infections in relatively small groups. Borrelia miyamotoi infections associated with chronic meningoencephalitis have also been described in case reports. Assuming that an IgG antibody response against B. miyamotoi antigens reflects (endured) infection, the seroprevalence in different risk groups was examined. Sera from nine out of ten confirmed B. miyamotoi infections from Russia were found to be positive with the recombinant antigen used, and no significant cross-reactivity was observed in secondary syphilis patients. The seroprevalence in blood donors was set at 2.0% (95% CI 0.4-5.7%). Elevated seroprevalences in individuals with serologically confirmed, 7.4% (2.0-17.9%), or unconfirmed, 8.6% (1.8-23%), Lyme neuroborreliosis were not significantly different from those in blood donors. The prevalence of anti-B. miyamotoi antibodies among forestry workers was 10% (5.3-16.8%) and in patients with serologically unconfirmed but suspected human granulocytic anaplasmosis was 14.6% (9.0-21.8%); these were significantly higher compared with the seroprevalence in blood donors. Our findings indicate that infections with B. miyamotoi occur in tick-exposed individuals in the Netherlands. In addition, B. miyamotoi infections should be considered in patients reporting tick bites and febrile illness with unresolved aetiology in the Netherlands, and other countries where I. ricinus ticks are endemic.

[South African tick bite fever in a group of Russian tourists]

The paper describes a clinical case of South African tick bite fever in a group of Russian tourists. The group of 5 people who had been ill with this disease after a tourist trip to the South African Republic (the Kruger National Park in the north-eastern province of Mpumalanga) were followed up. During their trip, all of them were bitten by different insects many times. The disease exhibited different clinical presentations; however, all the patients were noted to have a fever with slight intoxication and a maculopapular rash at different sites of the body; 3 had lymphadenopathy and one had a primary effect at the site of tick sticking. The diagnosis was verified by indirect immunofluorescence for the detection of high titers to Rickettsia conorii. The course of the disease was favorable in all the patients treated with antibiotics (doxycycline or ceftriaxone).

[Clinical presentation of "new" tick-borne borreliosis caused by Borrelia miyamotoi]

AIM

The objective of this study was to confirm the role of B. miyamotoi in the etiology of ITBB-WOEM in Udmurtia and to investigate in detail the clinical presentation of this "new" disease.

MATERIALS AND METHODS

50 adult patients with ITBB-WOEM treated in Republic Hospital for Infectious Diseases, Udmurtia, in 2010-2011 had PCR-confirmed infection by B. miyamotoi. The laboratory evidence of co-infection by other pathogens, including tick-borne encephalitis virus, B. burgdorferi sensu lato, A. phagocytophilum, E. chaffeensis, and E. muris, were absent.

RESULTS

All patients had a tick bite from 10 to 18 days before the acute disease onset. The main clinical signs were high fever, fatigue, headache, chill, and sweat. Clinical, biochemical, and instrumental investigations also showed the signs of functional impairment of various organs: the liver (in about half of the patients), kidney (in 10 patients), heart (6 patients), etc. In contrast, acute ITBB with erythema migrans was usually a localized infection without a pronounced intoxication syndrome and impairments of the organs.

CONCLUSION

ITBB-WOEM caused by B. miyamotoi is a systemic disease that is clinically closer to relapsing fevers transmitted by argasid ticks than to Lyme borreliosis. The number of B. miyamotoi infections in Russia may be comparable with that of Lyme disease cases, so the investigations of epidemiology, clinical presentation and therapy of this "new" disease are urgently requested.

[Interaction of the Siberian and Far Eastern subtypes of tick-borne encephalitis virus in mammals with mixed infection. I. Factors influencing the type of interaction]

Polytypic strains containing the fragments of genes of Siberian and Far Eastern tick-borne encephalitis (TBE) virus subtypes were isolated from the brain of fatal TBE patients, the blood of TBE patients, and Ixodes persulcatus ticks in the foci of concomitant circulation of the two subtypes. The interaction of the Siberian and Far Eastern TBE virus subtypes was studied in the neural phase of the infection of albino mice and Syrian hamsters in order to understand conditions for formation of these strains and their role in the etiology of acute TBE. Their viral progeny was genotyped by reverse transcription-polymerase chain reaction and fluorescence hybridization assay with genotype-specific probes. Mixed infection showed an effect of synergism, independent reproduction of the two subtypes in the brain and spleen, competitive exclusion of one subtype from the viral population. The type of the Interaction depended on the species of animals, the properties of partner strains, and the target organ.

[Detection of tick-borne encephalitis virus in Ixodes ticks collected in a natural focus of Gornyi Altai]

Enzyme immunoassay of tick-borne encephalitis virus (TBE) in the samples of Ixodes ticks collected in the outskirts of the settlement of Manzherok, Maiminsk District, Republic of Altai, revealed TBE antigen in 16.9 +/- 1.9% of the talga ticks. Real-time reverse transcription-polymerase chain reaction (RT-PCR) with specific fluorescent probes and phylogenetic analysis of the nucleotide sequences of RT-RCR products corresponding to 5'-terminal fragment of the E gene of TBE, all the virus strains isolated from the ticks collected in Gomyi Altai were referred to as the Siberian genetic type that was dominant in virus-carrying ticks in the majority of endemic areas of Russia and near abroad. Viral load assays using the real-time RT-PCR with the probes indicated the threshold cycles Ct = 25.34-28.98, which, with regard to the efficiency of RNA identification and reverse transcription, was equal to about 10(4)-10(5) viral RNA copies per tick.

Omsk haemorrhagic fever

Omsk haemorrhagic fever is an acute viral disease prevalent in some regions of western Siberia in Russia. The symptoms of this disease include fever, headache, nausea, severe muscle pain, cough, and moderately severe haemorrhagic manifestations. A third of patients develop pneumonia, nephrosis, meningitis, or a combination of these complications. The only treatments available are for control of symptoms. No specific vaccine has been developed, although the vaccine against tick-borne encephalitis might provide a degree of protection against Omsk haemorrhagic fever virus. The virus is transmitted mainly by Dermacentor reticulatus ticks, but people are mainly infected after contact with infected muskrats (Ondatra zibethicus). Muskrats are very sensitive to Omsk haemorrhagic fever virus. The introduction of this species to Siberia in the 1930s probably led to viral emergence in this area, which had previously seemed free from the disease. Omsk haemorrhagic fever is, therefore, an example of a human disease that emerged owing to human-mediated disturbance of an ecological niche. We review the biological properties of the virus, and the epidemiological and clinical characteristics of Omsk haemorrhagic fever.

[Polymorphism of mitochondrial DNA and infection with symbiotic cytoplasmic bacterium Wolbachia pipientis in mosquitoes of the Culex pipiens complex from Russia]

A total of 208 mosquitoes of the Culex pipiens complex from 15 basement and terrestrial populations collected in different regions of the European part of Russia and Siberia were examined by genetic methods. Among these, two major mitotypes, M and P, were identified. These mitotypes differed by six substitutions in the 246-bp mitochondrial DNA cytochrome oxidase I gene fragment examined. Urban basement mosquito ecotype C. pipiens (form molestus) were characterized by the presence of mitotype M and infection with the endosymbiotic bacteria of the genus Wolbachia. Mosquitoes of the C. pipiens complex inhabiting opened biotopes harbored mitotype P, or its variety, mitotype P1, and were not infected with Wolbachia. Thus, in natural conditions marked linkage disequilibrium between cytoplasmic elements, mitochondrial DNA and Wolbachia, can be observed. Similarity of mitotypes in form molestus mosquito from different geographical localities favors the hypothesis on the common ancestry of urban mosquitoes.