Explanatory models for tick-borne disease incidence (Astrakhan rickettsial fever and Crimean-Congo hemorrhagic fever)

Introduction. The study focuses on methods providing mathematical substantiation of discrepancies between actual incidence rates of Astrakhan rickettsial fever (ARF) and Crimean-Congo hemorrhagic fever (CCHF) and predicted rates due to the indirect impact of weather conditions during the current epidemic season.The purpose of the study was to develop explanatory models for ARF and CCHF incidence using satellite monitoring (remote sensing) data and to present the results of their practical evaluation in the Stavropol Territory and Astrakhan Region.Materials and methods. The materials included climate data provided by the Space Research Institute of the Russian Academy of Sciences as well as epidemiological data on CCHF and ARF incidence from 2005 to 2021. The explanatory models incorporated the Bayes theorem and Wald sequential analysis. All the calculations were completed using the Microsoft Excel 2010-based program developed by the authors.Results. It has been found that the greatest indirect effect on development of the CCHF epidemiological situation is produced by the normalized difference vegetation index and relative air humidity in June-July in the Stavropol Territory and by the maximum, minimum and average air temperature in October as well as the minimum air temperature in July in the Astrakhan Region. ARF incidence rates depend on the indirect effect of the annual average and average annual maximum temperature, maximum temperature and the normalized difference vegetation index in April-July. The match between explanatory model-based results and prediction model-based results ranged within 46.2-100%.Discussion. In addition to projecting incidence rates, which could be reached with the observed values of climatic factors in the current year, the explanatory models can be used for indirect verification of prediction models and for identification of factors causing differences in results. Conclusion. The practical evaluation of explanatory models confirms the prospects and benefits of the study that should be continued, involving other regions highly endemic for tick-borne infections.

Development and Validation of a Protein Array for Detection of Antibodies against the Tick-Borne Pathogen Borrelia miyamotoi

Current serological tests for the emerging tick-borne pathogen Borrelia miyamotoi lack diagnostic accuracy. To improve serodiagnosis, we investigated a protein array simultaneously screening for IgM and IgG reactivity against multiple recombinant B. miyamotoi antigens. The array included six B. miyamotoi antigens: glycerophosphodiester phosphodiesterase (GlpQ), multiple variable major proteins (Vmps), and flagellin. Sera included samples from cases of PCR-proven Borrelia miyamotoi disease (BMD), multiple potentially cross-reactive control groups (including patients with culture-proven Lyme borreliosis, confirmed Epstein-Barr virus, cytomegalovirus, or other spirochetal infections), and several healthy control groups from regions where Ixodes is endemic and regions where it is nonendemic. Based on receiver operating characteristic (ROC) analyses, the cutoff for reactivity per antigen was set at 5 μg/mL for IgM and IgG. The individual antigens demonstrated high sensitivity but relatively low specificity for both IgM and IgG. The best-performing single antigen (GlpQ) showed a sensitivity of 88.0% (95% confidence interval [CI], 78.9 to 93.5) and a specificity of 94.2% (95% CI, 92.7 to 95.6) for IgM/IgG. Applying the previous published diagnostic algorithm-defining seroreactivity as reactivity against GlpQ and any Vmp-revealed a significantly higher specificity of 98.5% (95% CI, 97.6 to 99.2) but a significantly lower sensitivity of 79.5% (95% CI, 69.3 to 87.0) for IgM/IgG compared to GlpQ alone. Therefore, we propose to define seroreactivity as reactivity against GlpQ and any Vmp or flagellin which resulted in a comparable sensitivity of 84.3% (95% CI, 74.7 to 90.8) and a significantly higher specificity of 97.9% (95% CI, 96.9 to 98.7) for IgM/IgG compared to GlpQ alone. In conclusion, we have developed and validated a novel serological tool to diagnose BMD that could be implemented in clinical practice and epidemiological studies. IMPORTANCE This paper describes the protein array as a novel serological test for the diagnosis of Borrelia miyamotoi disease (BMD), by reporting the methodology, the development of a diagnostic algorithm, and its extensive validation. With rising numbers of ticks and tick bites, tick-borne diseases, such as BMD, urgently deserve further societal and medical attention. B. miyamotoi is prevalent in Ixodes ticks across the northern hemisphere. Humans are exposed to, and infected by, B. miyamotoi and develop BMD in Asia, in North America, and to a lesser extent in Europe. However, the burden of infection and disease remains largely unknown, due to the noncharacteristic clinical presentation, together with the lack of awareness and availability of diagnostic tools. With this paper, we offer a novel diagnostic tool which will assist in assessing the burden of disease and could be implemented in clinical care.

Prevalence and clinical manifestation of Borrelia miyamotoi in Ixodes ticks and humans in the northern hemisphere: a systematic review and meta-analysis

BACKGROUND

Various studies have evaluated the infection of Ixodes ticks and humans with the relapsing fever spirochaete Borrelia miyamotoi. However, to our knowledge, the prevalence of infection and disease has not been assessed systematically. We aimed to examine the prevalence of B miyamotoi in Ixodes ticks and humans, and the disease it can cause, in the northern hemisphere.

METHODS

For this systematic review and meta-analysis, we searched PubMed and Web of Science up to March 1, 2021. Studies assessing Ixodes tick infection published since Jan 1, 2011 were eligible, whereas no time limitation was placed on reports of human infection and disease. We extracted B miyamotoi test positivity ratios and used a random-effects model to calculate estimated proportions of infected ticks, infected humans, and human disease with 95% CI. This study was registered with PROSPERO, CRD42021268996.

FINDINGS

We identified 730 studies through database searches and 316 additional studies that referenced two seminal articles on B miyamotoi. Of these 1046 studies, 157 were included in the review, reporting on 165 637 questing ticks, 45 608 unique individuals, and 504 well described cases of B miyamotoi disease in humans. In ticks, the highest prevalence of B miyamotoi was observed in Ixodes persulcatus (2·8%, 95% CI 2·4-3·1) and the lowest in Ixodes pacificus (0·7%, 0·6-0·8). The overall seroprevalence in humans was 4·4% (2·8-6·3), with significantly (p<0·0001) higher seroprevalences in the high-risk group (4·6%, 2·6-7·1), participants with confirmed or suspected Lyme borreliosis (4·8%, 1·8-8·8), and individuals suspected of having a different tick-borne disease (11·9%, 5·6-19·9) than in healthy controls (1·3%, 0·4-2·8). Participants suspected of having a different tick-borne disease tested positive for B miyamotoi by PCR significantly more often than did the high-risk group (p=0·025), with individuals in Asia more likely to test positive than those in the USA (odds ratio 14·63 [95% CI 2·80-76·41]).

INTERPRETATION

B miyamotoi disease should be considered an emerging infectious disease, especially in North America and Asia. Prospective studies and increased awareness are required to obtain further insights into the burden of disease.

FUNDING

ZonMW and the European Regional Development Fund (Interreg).

Differential Laboratory Diagnosis of Acute Fever in Guinea: Preparedness for the Threat of Hemorrhagic Fevers

Acute febrile illnesses occur frequently in Guinea. Acute fever itself is not a unique, hallmark indication (pathognomonic sign) of any one illness or disease. In the infectious disease context, fever's underlying cause can be a wide range of viral or bacterial pathogens, including the Ebola virus. In this study, molecular and serological methods were used to analyze samples from patients hospitalized with acute febrile illness in various regions of Guinea. This analysis was undertaken with the goal of accomplishing differential diagnosis (determination of causative pathogen) in such cases. As a result, a number of pathogens, both viral and bacterial, were identified in Guinea as causative agents behind acute febrile illness. In approximately 60% of the studied samples, however, a definitive determination could not be made.

Whole genome sequencing of Borrelia miyamotoi isolate Izh-4: reference for a complex bacterial genome

BACKGROUND

The genus Borrelia comprises spirochaetal bacteria maintained in natural transmission cycles by tick vectors and vertebrate reservoir hosts. The main groups are represented by a species complex including the causative agents of Lyme borreliosis and relapsing fever group Borrelia. Borrelia miyamotoi belongs to the relapsing fever group of spirochetes and forms distinct populations in North America, Asia, and Europe. As all Borrelia species B. miyamotoi possess an unusual and complex genome consisting of a linear chromosome and a number of linear and circular plasmids. The species is considered an emerging human pathogen and an increasing number of human cases are being described in the Northern hemisphere. The aim of this study was to produce a high quality reference genome that will facilitate future studies into genetic differences between different populations and the genome plasticity of B. miyamotoi.

RESULTS

We used multiple available sequencing methods, including Pacific Bioscience single-molecule real-time technology (SMRT) and Oxford Nanopore technology (ONT) supplemented with highly accurate Illumina sequences, to explore the suitability for whole genome assembly of the Russian B. miyamotoi isolate, Izh-4. Plasmids were typed according to their potential plasmid partitioning genes (PF32, 49, 50, 57/62). Comparing and combining results of both long-read (SMRT and ONT) and short-read methods (Illumina), we determined that the genome of the isolate Izh-4 consisted of one linear chromosome, 12 linear and two circular plasmids. Whilst the majority of plasmids had corresponding contigs in the Asian B. miyamotoi isolate FR64b, there were only four that matched plasmids of the North American isolate CT13-2396, indicating differences between B. miyamotoi populations. Several plasmids, e.g. lp41, lp29, lp23, and lp24, were found to carry variable major proteins. Amongst those were variable large proteins (Vlp) subtype Vlp-α, Vlp-γ, Vlp-δ and also Vlp-β. Phylogenetic analysis of common plasmids types showed the uniqueness in Russian/Asian isolates of B. miyamotoi compared to other isolates.

CONCLUSIONS

We here describe the genome of a Russian B. miyamotoi clinical isolate, providing a solid basis for future comparative genomics of B. miyamotoi isolates. This will be a great impetus for further basic, molecular and epidemiological research on this emerging tick-borne pathogen.

[Features of hemorrhagic fever with renal syndrome with diabetes mellitus]

AIM

Diabetes mellitus (DM) is known to be a risk factor in adverse outcomes and complications in many infectious diseases. In the combination of hemorrhagic fever with renal syndrome (HFRS) and DM there are mutually exclusive pathogenetic States - hyperosmolarity, characteristic of DM is layered on the reduction of osmotic blood pressure in HFRS. Under these conditions, the effect of one disease (DM) on the clinical manifestations of another (HFRS) is not obvious. The aim of the work is to find out the clinical features during hfps in patients with DM.

MATERIALS AND METHODS

The study is based on the results of the retrospective studies "case - control" - studied the information contained in medical records of patient (form 003/u), who suffered HFRS in 2006-2018. The Selection of cards produced randomly. In the end, there were formed two groups: the first - 981 patient who suffered HFRS and had no signs of diabetes; the second, 33 patients who suffered HFRS on the background of previously existing (28 people), or the first identified (5) diabetes.

RESULTS

With a combination of HFRS and DM, a mild course of the disease is 2.5 times more common, there are no severe forms. Among this group of patients, complications are almost 10 times less common, less likely to develop infectious - toxic shock, acute kidney damage (class F by RIFLE), pulmonary edema. The combination of DM and HFRS is manifested by less high and prolonged fever, less high levels of urea and creatinine in the blood.

CONCLUSION

HFRS in combination with DM is easier, apparently, high osmolarity of the blood is a stabilizing factor during the disease.

Borrelia miyamotoi infection leads to cross-reactive antibodies to the C6 peptide in mice and men

OBJECTIVES

Borrelia miyamotoi is a relapsing fever Borrelia, transmitted by hard (Ixodes) ticks, which are also the main vector for Borrelia burgdorferi. A widely used test for serodiagnosis of Lyme borreliosis is an enzyme immunoassay (EIA) based on the C6 peptide of the B. burgdorferi sl VlsE protein. We set out to study C6 reactivity upon infection with B. miyamotoi in a large well-characterized set of B. miyamotoi disease (BMD) patient sera and in experimental murine infection.

METHODS

We performed in silico analyses, comparing the C6-peptide to immunodominant B. miyamotoi variable large proteins (Vlps). Next, we determined C6 reactivity in sera from mice infected with B. miyamotoi and in a unique longitudinal set of 191 sera from 46 BMD patients.

RESULTS

In silico analyses revealed similarity of the C6 peptide to domains within B. miyamotoi Vlps. Cross-reactivity against the C6 peptide was confirmed in 21 out of 24 mice experimentally infected with B. miyamotoi. Moreover, 35 out of 46 BMD patients had a C6 EIA Lyme index higher than 1.1 (positive). Interestingly, 27 out of 37 patients with a C6 EIA Lyme index higher than 0.9 (equivocal) were negative when tested for specific B. burgdorferi sl antibodies using a commercially available immunoblot.

CONCLUSIONS

We show that infection with B. miyamotoi leads to cross-reactive antibodies to the C6 peptide. Since BMD and Lyme borreliosis are found in the same geographical locations, caution should be used when relying solely on C6 reactivity testing. We propose that a positive C6 EIA with negative immunoblot, especially in patients with fever several weeks after a tick bite, warrants further testing for B. miyamotoi.

[A comparative analysis of allele frequencies of rs1801133 and rs1801131 of MTHFR in patients with stroke and healthy people from the Moscow region]

AIM

To study genetic characteristics of the population of the Moscow region and analyze the association of rs1801133 and rs1801131 of MTHFR with the risk of ischemic stroke (IS).

MATERIAL AND METHODS

A sample of 170 and 115 patients with atherothrombotic and cardioembolic subtypes of IS and 360 residents of the Moscow region without IS were examined. MTHFR alleles were determined by a multiplex real-time polymerase chain reaction.

RESULTS AND CONCLUSION

No association between the frequencies of MTHFR alleles and the risk of ischemic stroke was found. The comparison of allele frequencies with those in Caucasian populations published in the dbSNP (NCBI) and 1000 Genomes Project databases revealed significant differences for rs1801133 from the EUR 1000 Genomes Project. The allele frequency data for MTHFR could increase the accuracy and reliability of the individual risk calculation for multifactorial diseases in the Russian population.

Borrelia miyamotoi Disease in an Immunocompetent Patient, Western Europe

Borrelia miyamotoi disease is a hard tick–borne relapsing fever illness that occurs across the temperate climate zone. Human B. miyamotoi disease in immunocompetent patients has been described in Russia, North America, and Japan. We describe a case of B. miyamotoi disease in an immunocompetent patient in western Europe.

[Follow-up of patients with Ixodes tick-borne borrelioses caused by Borrelia miyamotoi or Borrelia burgdorferi sensu lato]

Ixodes tick-borne borrelioses (ITBB) are caused by two different spirochetes: Borrelia from the group of Borrelia burgdorferi sensu lato, the agents of the classic Lyme borreliosis (LB), and Borrelia miyamotoi that belongs to the group of Borrelia causing tick-borne relapsing fevers. ITBB caused by B. miyamotoi (BM-ITBB) is a previously unknown infectious disease discovered in Russia. It is known that the LB sequelae may reduce the long-term life guality of convalescents.

AIM

To study the follow-up of those who have recovered from new BM-ITBB infection in comparison with persons who have had LB.

SUBJECTS AND METHODS

The investigation enrolled 41 patients with BM-ITBB and 41 patients with LB who were treated at the Republican Infectious Diseases Hospital of Udmurtia. Within a year after the disease, they were followed up through clinical and instrumental examination of cardiac performance, expanded biochemical analysis of blood and urine, which could; estimate kidney and liver functions, and psychological questioning.

RESULTS

Asthenic syndrome and complaints about and objective signs of cardiac dysfunctions persisted supraventricular extrasystoles, left ventricular diastolic dysfunction, and elevated and/or unstable systolic blood pressure were detected in 20-30% of the convalescents for a long time. Kidney dysfunctions were manifested in albuminuria and the decrease of glomerular filtration rate. A year following the disease, 10-20% patients had persistently elevated concentrations of alanine aminotransferase, aspartate aminotransferase, and C-reactive protein and had higher levels of total cholesterol and low-density lipoproteins. The pathological consequences of ITBB were polymorphic and varied in different patients; in general, only 68% of them showed health improvement.

CONCLUSION

We assume that a significant role in the pathogenesis of BM-ITBB and LB is played by vascular endothelial damage possibly associated with the inflammatory and autoimmune aspects of an immune response in Borrelia infection. The consequences of this damage may persist and even intensify during a year, which provokes chronic dysfunction of the heart, kidney, or liver in a number of convalescents.

Serodiagnosis of Borrelia miyamotoi disease by measuring antibodies against GlpQ and variable major proteins

OBJECTIVES

Borrelia miyamotoi disease (BMD) is an emerging tick-borne disease in the Northern hemisphere. Serodiagnosis by measuring antibodies against glycerophosphodiester-phosphodiesterase (GlpQ) has been performed experimentally but has not been extensively clinically validated. Because we had previously shown the differential expression of antigenic variable major proteins (Vmps) in B. miyamotoi, our aim was to study antibody responses against GlpQ and Vmps in PCR-proven BMD patients and controls.

METHODS

We assessed seroreactivity against GlpQ and four Vmps in a well-described, longitudinal cohort of sera from BMD patients (n=182), healthy blood donors (n=136) and controls (n=68). All samples were tested by ELISA and positive sera were tested by western blot, and antibody dynamics and diagnostic value were assessed.

RESULTS

IgM antibodies against GlpQ and Vmps peaked between 11 and 20 days, and IgG between 21 and 50 days, after disease onset. Various combinations of GlpQ and Vmps increased sensitivity and/or specificity compared to single antigens. Notably, the GlpQ or variable large protein (Vlp)-15/16 combination yielded a sensitivity of 94.7% (95% CI: 75.4-99.7) 11-20 days after disease onset and a specificity of 96.6% (92.7-98.4) for IgM. A specificity of 100% (97.8-100) for IgM, and 98.3% for IgG (95.2-100), was found when positivity was defined as reactivity to GlpQ and any Vmp, with maximum sensitivities of 79% (56.7-91.5) for IgM and 86.7% (62.1-97.6) for IgG.

CONCLUSIONS

We clearly demonstrate here the diagnostic potential of these seromarkers. Our findings will facilitate future epidemiological and clinical studies on BMD and lead to the development of a serologic test to be used in clinical practice.

[Complex assessment of the contribution of genetic factors to the risk of ischemic stroke]

AIM

To develop a method of the complex assessment of genetic risk for ischemic stroke (IS) and evaluate its effectiveness.

MATERIAL AND METHODS

Genotyping of 182 patients with atherothrombotic and cardioembolic subtypes of IS and 360 healthy individuals of 48 single nucleotide polymorphic loci (SNP) associated with the risk of II and its subtypes was performed.

RESULTS AND CONCLUSION

In each group of SNPs, composite indicators of genetic risk of IS in groups of patients and healthy controls were identified. Differences between the calculated values of the genetic risk in these groups were significant (p <0,05). The quality of the binary classification validated by ROC-analysis confirmed the predictive potential of the proposed method of risk calculation for determining the genetic predisposition to the development of IS.

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

Insufficient efficacy and safety of intravenous ribavirin in treatment of haemorrhagic fever with renal syndrome caused by Puumala virus

BACKGROUND

Intravenous ribavirin has been reported to be an effective treatment for haemorrhagic fever with renal syndrome (HFRS) caused by Hantaan virus in Asia. However, its therapeutic benefits for HFRS caused by Puumala virus (PUUV) in Europe are still unknown.

METHODS

A randomized, open-label study of efficacy and safety of intravenous ribavirin in the treatment of HFRS was conducted in the European part of Russia. Seventy-three patients with suspected HFRS within 4 d of the onset of the disease were randomized to receive either intravenous ribavirin (33 mg/kg, followed by 16 mg/kg given every 6 h for 4 d and by 8 mg/kg given every 8 h for 3 d) plus standard therapy (n = 37) or standard therapy alone (n = 36). The primary outcome was the average change from baseline in viral load over time estimated as area under the viral load curve minus baseline (AUCMB). Fifty-five patients with HFRS confirmed by nested reverse transcriptase - polymerase chain reaction (PCR) assay were included in the assessment of the efficacy. All patients entered into the clinical trial were included in the assessment of the safety.

RESULTS

PUUV was detected in all cases of confirmed HFRS. Viral load kinetics were similar in both treatment groups. Significantly more patients receiving ribavirin than standard therapy experienced low haemoglobin level (95% vs 36%), hyperbilirubinemia (81% vs 3%), sinus bradycardia (43% vs 14%), and rash (19% vs 0%).

CONCLUSIONS

Results of the study showed insufficient efficacy and safety of intravenous ribavirin in the treatment of HFRS caused by PUUV.

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.

Borrelia miyamotoi sensu lato seroreactivity and seroprevalence in the northeastern United States

Serum from �%^4% of residents was positive for infection, compared with �%^9% for B. burgdorferi.

Borrelia miyamotoi sensu lato, a relapsing fever Borrelia sp., is transmitted by the same ticks that transmit B. burgdorferi (the Lyme disease pathogen) and occurs in all Lyme disease�?"endemic areas of the United States. To determine the seroprevalence of IgG against B. miyamotoi sensu lato in the northeastern United States and assess whether serum from B. miyamotoi sensu lato�?"infected persons is reactive to B. burgdorferi antigens, we tested archived serum samples from area residents during 1991�?"2012. Of 639 samples from healthy persons, 25 were positive for B. miyamotoi sensu lato and 60 for B. burgdorferi. Samples from �%^10% of B. miyamotoi sensu lato�?"seropositive persons without a recent history of Lyme disease were seropositive for B. burgdorferi. Our resultsA suggest thatA human B. miyamotoiA sensu latoA infection may be common in southern New England and that B. burgdorferi antibody testing is not an effective surrogate for detecting B. miyamotoi sensu lato infection.

[A method for determination of Neisseria meningitidis serogroup A, B, C and W by real-time PCR]

AIM

Development and testing of a real-time PCR method for detection of Neisseria meningitiis serogroup A, B, C and W DNA.

MATERIALS AND METHODS

Reference strains and 187 samples of cerebrospinal fluid (CSF) from meningocci meningitis patients were used in the study. Multiplex PCR was carried out in an instrument with 5 channels of fluorescent detection:

RESULTS

Analysis of specific serogroup loci of the genome and design of oligonucleotides for the detection of DNA of all the capsule meningococci and 4 serogroups in particular was carried out. PCR conditions were optimized; specificity was shown and analytical sensitivity was evaluated using reference strains. DNA of the following serogroups was detected during study of clinical CSF samples: A--in 103 samples (55%), B--in 45 (24%), C--in 30 (16%), W--in 5 (3%). Only DNA of meningococci capstle gene ctrA was found in 4 samples; presumably, they contained DNA of other serogroups. Multilocus sequence-typing and detection of antigenic determinants of PorA and FetA genes for 27 DNA samples of group A menincococci as well as DNA of 5 group W meningococci and 4 ungroupable was carried out.

CONCLUSION

The method proposed allows to carry out serogrouping of no less than 95% of strains or DNA samples isolated from CSF of meningococci infection patients. Combined with other recommended non-cultural methods of genotyping, it may be useful for complex characteristics of pathogenic meningococci.

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.

The incidence of West Nile disease in Russia in relation to climatic and environmental factors

Since 1999, human cases of West Nile fever/neuroinvasive disease (WND) have been reported annually in Russia. The highest incidence has been recorded in three provinces of southern European Russia (Volgograd, Astrakhan and Rostov Provinces), yet in 2010-2012 the distribution of human cases expanded northwards considerably. From year to year, the number of WND cases varied widely, with major WND outbreaks in 1999, 2007, 2010, and 2012. The present study was aimed at identifying the most important climatic and environmental factors potentially affecting WND incidence in the three above-mentioned provinces and at building simple prognostic models, using those factors, by the decision trees method. The effects of 96 variables, including mean monthly temperature, relative humidity, precipitation, Normalized Difference Vegetation Index, etc. were taken into account. The findings of this analysis show that an increase of human WND incidence, compared to the previous year, was mostly driven by higher temperatures in May and/or in June, as well as (to a lesser extent) by high August-September temperatures. Declining incidence was associated with cold winters (December and/or January, depending on the region and type of model). WND incidence also tended to decrease during year following major WND outbreaks. Combining this information, the future trend of WND may be, to some extent, predicted, in accordance with the climatic conditions observed before the summer peak of WND incidence.

[Real-time pcr procedure for determination of Streptococcus pneumoniae serotypes]

AIM

Development and application of real-time PCR (RT-PCR) procedure for determination of Streptococcus pneumoniae serotypes.

MATERIALS AND METHODS

S. pneumoniae cps-locus wzx, wzy, wzz, wcwV and galU genes were chosen as PCR targets to select serotype-specific oligonucleotide primers and fluorescent labeled probes. 89 samples of cerebrospinal fluid (CSF) obtained in 2007 - 2010 from patients with pneumococcal meningitis diagnosis undergoing therapy in the Infectious Clinical Hospital No. 2, Moscow, were studied with the aim of testing the possibility of practical use of RT-PCR.

RESULTS

Primers and probes were selected for the determination of 16 vaccine and/or frequently encountered serotypes distributed among 4 reaction mixtures also including a pair of primers and a probe for cpsA gene detection that is present in all the capsule pneumococci (internal control). The procedure was tested on a collection of 108 pneumococci strains gathered in Research Institute of Antimicrobial Therapy and serotyped earlier by specific PCR with electrophoretic detection and serologically by using Pneumotest-Latex kit. The sensitivity and specificity of the RT-PCR was 100%. RT-PCR procedure allowed to determine pneumococcus serotype in 79% of CSF clinical samples containing S. pneumoniae DNA. Serotype 3 and 23F were detected most frequently (13%, each).

CONCLUSION

RT-PCR application does not assume causative agent seeding stage, significantly reduces analysis execution time and increases sensitivity of the study. The developed procedure will allow to begin addressing the important problem--clarification of spectra and frequency of occurrence of pneumococci serotypes circulating on the territory of Russia.

[The application of decision trees for constructing an algorithm for the differential diagnosis of zoonotic infections]

AIM

To attempt to construct an algorithm using the routine epidemiological, clinical and laboratory data for the differential diagnosis of ixodid tick-borne borreliosis (ITBB) caused by Borrelia miyamotoi (BM-ITBB) and other zoonotic infections that are endemic in Russia.

SUBJECTS AND METHODS

The investigation enrolled the adult patients treated at the Republican Hospital for Infectious Diseases (Izhevsk) in 2010-2012 with diagnoses of BM-ITBB (n = 71), Lyme disease (n = 38), tick-borne encephalitis (TBE) (n = 25), and hemorrhagic fever with renal syndrome (n = 27). The Decision Tree procedure in IBM SPSS Statistics was used to analyze more than 65 variables characterizing a disease case.

RESULTS

The final decision tree had 7 dichotomous fissions in accordance with the values of several indices (presence of erythema migrans, tick bite, goat's milk consumption, sweating, vertigo, nausea, abdominal pain, as well as blood concentrations of platelets, alanine aminotransferase, and count, and urea) and formed 8 terminal nodes. The proposed algorithm provides correct classification in 95% of disease cases.

CONCLUSION

ITBB caused by B. miyamotoi can be successfully discriminated from other widespread zoonotic infections. Thus, practitioners have an additional opportunity to detect and diagnose the "new" infection BM-ITBB.

Humans infected with relapsing fever spirochete Borrelia miyamotoi, Russia

Disease may occur throughout the world because of the widespread prevalence of this pathogen in ixodid ticks.

Borrelia miyamotoi is distantly related to B. burgdorferi and transmitted by the same hard-body tick species. We report 46 cases of B. miyamotoi infection in humans and compare the frequency and clinical manifestations of this infection with those caused by B. garinii and B. burgdorferi infection. All 46 patients lived in Russia and had influenza-like illness with fever as high as 39.5°C; relapsing febrile illness occurred in 5 (11%) and erythema migrans in 4 (9%). In Russia, the rate of B. miyamotoi infection in Ixodes persulcatus ticks was 1%–16%, similar to rates in I. ricinus ticks in western Europe and I. scapularis ticks in the United States. B. miyamotoi infection may cause relapsing fever and Lyme disease–like symptoms throughout the Holarctic region of the world because of the widespread prevalence of this pathogen in its ixodid tick vectors.

[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.

Genetic diversity and geographic distribution of hantaviruses in Russia

Haemorrhagic fever with renal syndrome (HFRS) is the most prevalent zoonotic disease in Russia. It is caused by several hantavirus species hosted by small rodents. We describe spatial and temporal patterns of HFRS incidence in the Russian Federation, and the geographic distribution of prevalent hantavirus species: Puumala (PUUV) and Dobrava (DOBV). Partial sequencing of nucleocapsid and glycoprotein genes of 117 PUUV strains and 78 DOBV strains revealed several distinct genetic subgroups. The RNA of Volga PUUV subgroup was detected in patients with HFRS and bank voles Myodes glareolus in the Volga Federal District, where the highest HFRS incidence rate has been registered yearly. The RNA of Siberian PUUV subgroup was found in M. glareolus in the trans-Ural Tyumen and Omsk Provinces, where human HFRS cases have been rare. During an HFRS outbreak in 2007 in the Central Federal District, when more than 1000 patients were affected, specific subgroups of DOBV were discovered in patients and rodents, mainly in the striped field mouse Apodemus agrarius. DOBV strains might have 8–9% of nucleotide difference although they were collected at places separated by 30–100 km. The RNA of a unique DOBV subgroup was discovered in the southern semi-desert Astrakhan Province, mainly in A. agrarius and tamarisk jird Meriones tamariscinus. No human HFRS cases were diagnosed in this province. Russian PUUV and DOBV strains have no close homologues among European strains. Our DOBV strains might be genetically grouped together with Central European DOBV strains isolated from A. agrarius, but not from Apodemus flavicollis. The Volga PUUV subgroup is to some extent similar to Baltic PUUV strain, and Finnish PUUV strains resemble the strains from the Siberian PUUV subgroup. Thus, PCRbased monitoring and typing provided the opportunity to delineate and expand the area of hantaviruses in Russia and to identify their new genetic variants.

[Genetic characteristics of Neisseria meningitidis strains obtained from healthy carriers during meningococcal infection outbreaks]

AIM

Genetic and antigenic characterization of Neisseria meningitidis strains isolated during meningococcal infection outbreaks from individuals in contact with patients with generalized form of meningococcal infection.

MATERIALS AND METHODS

Strains obtained in 2007 - 2009 in Moscow during examination of individuals that were in contact with patients during meningococcal infection outbreaks were analyzed. Multilocus sequence typing, genetic subtyping and typing of VR fragment (FetA) techniques were used.

RESULTS

Data regarding investigated strains were submitted to the database at http://pubmlst.org/neisseria/. Previously undescribed sequence types were found in 12 strains, sequence-type could not be determined in 2 strains, 2 strains lacked VR fragment (FetA). Serogroup A meningococci had "P1.5-2,10: F3-5" antigenic profile and belonged to ST-75 and ST-3349 sequence-type, these data does not support the emergence of epidemically significant strains in the territory under surveillance. All typed serogroup C strains and 1 serogroup B strain are of "ST-41/44 complex/Lineage 3" clonal complex. Subtypes of serogroup C meningococci strains match subtypes of strains that cause generalized forms of infection, while serogroup B strains isolated from the carriers and strains isolated from the patients had different antigenic profiles. Ungrouppable strains had notably higher level of genetic and antigenic diversity: only 6 of 16 strains (37.5%) could be sequence-typed using earlier data, all these strains are of clonal complex "ST-53 complex" that consists mostly of strains isolated from the carriers. CONCLUSION. Ratio of meningococci population circulating in Moscow and subpopulation capable of causing generalized form of meningococcal infection (GFMI) is different for meningococci of various serogroups. Ungrouppable strains isolated from the carriers are highly different from strains causing GFMI.

[Genotyping of West Nile fever virus strains circulating in southern Russia as an epidemiological investigation method: principles and results]

AIM

Characteristic of West Nile fever (WNF) virus strains circulating in southern Russia.

MATERIALS AND METHODS

WNF RNA was amplified directly from clinical samples, mosquitoes and bird tissues by PCR, nucleotides were sequenced directly and analyzed comparatively.

RESULTS

Related but different genovariants of WNF lineage 1a--"Volgograd" and "Astrakhan"--circulated during WNF outbreaks of 1999 and 2000-2003 in Volgograd and Astrakhan regions. In 2005 "Volgograd" WNF variant emerged in Astrakhan region and along with "Astrakhan" variant caused a new morbidity increase. In 2004 in sera of 2 WNF patients from Rostov region WNF lineage 2 RNA was detected, this was the first WNF clinical case caused by WNF lineage 2 outside of Africa. WNF outbreak in Volgograd region in 2007 was caused by this unique WNF lineage that may preliminary be called Russian. Finally, during a major WNF outbreak in 2010 in Volgograd and Rostov regions in clinical samples only russian genovariant WNF lineage 2 RNA was detected again.

CONCLUSION

After emergence of a certain WNF genovariant the virus is capable of persisting in natural foci in southern Russia. A near disappearance of one of the WNF clones by substitution or displacement with another maybe possible. Determination of genetic characteristics of WNF strains circulating in Russia is an important element of WNF epidemiological surveillance and control of this disease.

[Genetic characteristics of Haemophilus influenzae type b isolated from children with bacterial meningitis in Moscow in 2007-2009]

AIM

Genetic characterization of 37 strains and CSF samples containing DNA of Haemophilus influenzae type b isolated in Moscow during 2007-2009.

MATERIALS AND METHODS

Multilocus sequence-typing method was used and also variant of method for capsule type determination was approbated.

RESULTS

Ten sequence types, of which 7 were described in previous studies and 3 were revealed for the first time during this work, were detected in studied sample. ST-6 and ST-92 were the most frequently detected--9 strains (24%) of Hib belonging to each sequence type were revealed. All detected sequence types, except one, belong to clonal complex "ST-6" ("A1/A2"). Obtained data were compared with results of typing of Hib strains isolated in Moscow in 1999-2001. Genetic changes in studied population of Hib are characterized by decreased proportion of Hib belonging to ST-6 (from 54% to 24%) and increased number of sequence types belonging to clonal complex "ST-6" differing from ST-6 on more than one locus of allelic profile (from 2 types [2 strains, 5.4%] to 5 types [9 strains, 24%]).

CONCLUSION

In 2007-2009, number of Hib strains with sequence type ST-95 (7 strains, 19%), which is typical for strains circulating in Russia, is markedly increased. Capsule type I was detected in 32 (86.5%) of studied strains, whereas capsule type II--in 5 (13.5%) of studied strains. Capsule type II was detected only in Hib strains with ST-80 sequence type.

[Usage of real time polymerase chain reaction for diagnostics of different tick-borne infections]

AIM

To create and test the complex of polymerase chain reaction-based methods for detection of pathogens vectored by ticks in clinical and environmental samples.

MATERIALS AND METHODS

Real time PCR methods with hybridization-fluorescent detection were developed for detection of tick-borne encephalitis virus, Borrelia burgdorferi sensu lato, Anaplasma phagocytophillum, Erlichia muris/E. chaffeensis, and B. miyamotoi. First four methods were combined in one assay in multiprime format. Efficacy of the assay was assessed by testing of blood samples from patients with tickborreliosis (166 patients), tick-born encephalitis (22 patients) and mixed infection tick-borne encephalitis + borreliosis (21 patients) from Sverdlovsk region.

RESULTS

It was shown that using PCR-based assay for testing the blood samples obtained during admission, it was possible to determine the etiology of disease in 39% of patients, whereas on the basis of serological data diagnosis, as a rule, is made not earlier than on 2nd week of therapy. False-positive results of PCR diagnostics were not observed. Infections caused by Anaplasma or Erlichia were not observed. It was shown that > 50% of cases of tick borreliosis without erythema were caused by B. miyamotoi, whereas B. burgdorferi sensu lato predominated as a causative agent of erythemic form of borreliosis.

CONCLUSION

Proposed complex of methods is useful for rapid diagnostics of tick-borne infections including previously unknown infection caused by B. miyamotoi.

[Genetic characteristic of Haemophilus influenzae type B strains isolated in Russian regions]

AIM

Genotyping of Hib strains isolated in regions of Russia as well as characterization of genetic relations of typed strains with strains isolated in other areas.

MATERIALS AND METHODS

Genetic characterization of 31 strains of Hib isolated in Russian regions during 2005-2008 was performed by multilocus sequence typing.

RESULTS

Studied strains belonged to 11 variants of sequence types, 6 of which were described in previous studies, whereas other 5 were isolated for the first time during this study. The most common isolated strains were ST-92 (13 strains or 42%) and ST-6 (6 strains or 19%). Typed strains were distributed to two clonal complexes. Clonal complex "A1/A2" ("ST-6") incorporates all typed strains except ST-93 strain belonging to clonal complex "B1b" ("ST-93"). The majority of studied strains (19 or 61%) had difference from "central" sequence type of clonal complex, A1/A2 ("ST-6") on not more than one allele.

CONCLUSION

Clonal structure of isolated strains is analogous to the one observed in Moscow and foreign strains.

[Relapsing borrelioses fevers: forgotten and new ones]

Relapsing fever borrelioses are widely spread in the endemic regions of Eurasia, Africa, and America as before and account for significant morbidity and mortality; however, these infections have been recently underestimated. The pathogens of the fevers are the Borrelia species transmitted by ticks of the Ornithodoros genus; they genetically differ from the pathogens of Lyme borreliosis--Borrelia burgdorferi sensu lato transmitted by Ixodes ticks. The species Borrelia miyamotoi belongs to the genetic species of Borrelia, the causative agents of relapsing fevers. The authors found Borrelia of this species in the Ixodes ticks of Russia and first showed that B. miyamotoi were able to induce multiple cases in man, which had been earlier diagnosed as erythema-free Ixodes tick-borne borreliosis. The review considers the pathogenesis, clinical picture, diagnosis, and treatment of "old" relapsing fever borrelioses versus the available data on the "new" infection caused by B. miyamotoi. This must assist Russian physicians and scientists both to treat "old" and new tick-borne relapsing borrelioses and to schedule studies of the "new" B. myamotoi infection.

[Monitoring for Neisseria meningitidis species using sequencing of variable fragments of surface proteins FetA and PorA genes]

AIM

To perform advanced antigenic characterization of meningococci belonging to serogroups A and B and circulating in Moscow according to modern nomenclature of Neisseria meningitidis strains.

MATERIALS AND METHODS

Method of typing of "VR" fragment of FetA protein together with methods of genetic subtyping and multilocus sequence typing was used.

RESULTS

Detailed information about studied strains was inputed in Internet database--http://pubmlst.org/neisseria/. Typing of serogroup B strains did not allow to define dominating variant of "VR, fragment of FetA protein which is in accordance with subtyping data obtained previously. Serogroup A strains were notable for less variability of "VR" fragment variants: 6 variants were detected. For the majority of serogroup A strains, it was possible to trace connection between belonging of the strain to particular genetic subgroup and its revealed antigenic profile. For strains from genetic subgroup VI, antigenic profile P1.5-2, 10; F1-5 detected in 14(18%) strains was typical, whereas antigenic profile P1.5-2, 10; F3-5 was typical for genetic subgroup X and was detected in 50 (63%) strains. Antigenic profile P1.5-2, 10-67; F3-5 was detected in 5 (6%) strains, and other 10 antigenic profiles were revealed in one strain each.

CONCLUSION

Prevalence of strains with antigenic profile P1.5-2, 10; F3-5 is explained by change of predominant genetic subgroup from subgroup VI to subgroup X in Moscow population serogroup A meningococci observed after 2003.

[Prospects for treating mosquito-borne flavivirus encephalitides]

The Japanese encephalitis virus and West Nile virus belong to the family Flaviviridae, genus Flavivirus; they have a similar transmission cycle, with birds serving as the natural vertebrate host and mosquitoes, primarily, Culex species, both serving as the enzootic vectors and infecting humans. These arboviruses have caused more human cases of severe neuroinvasive disease worldwide during the past decade than other mosquito-borne flaviviruses. The current data and concepts on the clinical manifestations, pathogenesis, diagnosis, and treatment of infections caused by West Nile virus and Japanese encephalitis virus, are considered. The need for developing innovative approaches to etiotropic therapy for West Nile fever and Japanese encephalitis is emphasized; these approaches should be based on the comprehensive insight and extensive studies of the pathogenesis of flaviviral infections.

Epidemiology of West Nile infection in Volgograd, Russia, in relation to climate change and mosquito (Diptera: Culicidae) bionomics

In 1999, there was the large outbreak of West Nile fever (WNF) in Southern Russia (>500 cases in the Volgograd Province). In 2000-2004, the WNF incidence rate decreased steadily to zero, but a new outbreak occurred in 2007 (64 cases). The analysis of historical climate data for Volgograd from 1900 to present showed that the years 1999 and 2007 were the hottest ones due to a very mild "winter" (Dec.-Mar.) and a hot "summer" (June-Sep.). There are up to 15 potential WNF vectors in Volgograd, but only Culex pipiens and Culex modestus are abundant in late summer, both in urban and rural settings. Only these species are naturally attracted to and feed on both humans and birds. The RNA of pathogenic WN virus genovariant was found by reverse transcriptase polymerase chain reaction only in Culex mosquitoes at the infection rate of about 0.04%. So these species may be considered as potential WNF "bridge vectors" between birds and humans as well as main vectors in sylvatic avain cycle. Their abundance in an epidemic season was higher in the years with a mild winter and a hot summer, so this phenomenon may serve as a connecting link between a climate and WNF epidemiology. These findings give some hints on the predisposing factors for WNF epidemic as well as the possibility to predict WNF outbreaks in the temperate climate zones.

[Detection of a new natural virus focus Dobrava in the Astrakhan Region]

A natural focus of Dobrava hantavirus was first revealed in an arid zone of the Astrakhan Region, by using molecular genetic methods. A polymerase chain reaction was employed to examine 389 lung tissue suspension samples taken from 9 species. Hantavirus RNA was found in 35 samples from 22 field mice (Apodemus agrarius), 8 tamarisk gerbils (Meriones temariscinus), 4 common voles (Microtus arvalis), and 1 house mouse (Mus musculus). Sequencing determined the taxonomic affiliation of 18 new isolates to the Dobrava species and 1 isolate to the Puumala species although the new Dobrava isolated greatly differed from all known strains of this virus in the nucleotide sequence of the genomic M and S segments. Hantavirus-infected rodents were found in 3 of 4 districts of the Astrakhan Region, located in the steppe and semidesert zones and at the intrazonal stations of the Volga-Akhtuba flood-lands. The high (up to 12%) hantavirus infection rates were ascertained in a tamarisk gerbil, the typical inhabitant of desert and semidesert ecosystems.

[Application of molecular genetic methods during Legionnaires' disease outbreak in town Verkhnyaya Pyshma]

The aim of the study was to perform molecular genetic analysis based on multi-locus sequence typing in order to identify source of Legionnaires' disease outbreak in town Verkhnyaya Pyshma in July 2007 and genetic profile of the causative agent. Sequence-based typing protocol recommended by European Working Group on Legionella infection (EWGLI) was used. It was not possible to obtain satisfactory results of Fla gene sequencing for all samples. Obtained allelic profiles of other genes were typical for L. pneumophila. Allelic profiles of L. pneumophila isolated from patients were identical and matched with L. pneumophila DNA detected in water from hot water supply of domestic building, but differed from cooling tower's isolates and isolates from showerhead in apartment of one patient. Identity of 5 genes of L. pneumophila isolated from autopsy samples and from hot water of central hot water supply of domestic building confirms aspiration route of infection through hot water contaminated by the microorganism. L. pneumophila detected in water from cooling tower, showerhead in apartment of one patient, and from drainage canal of hot water supply station belonged to other allelic variants and, therefore, are not related with the outbreak.

[Genetic subgroups of Neisseria meningitidis serogroup A isolated from patients with disseminated forms of meningococcal infection in Moscow, 1969-2006]

Results of microbiological monitoring for serogroup A Neisseria meningitidis circulated in Moscow from 2002 to 2006 are presented. Using multilocus sequence-typing, molecular and epidemiologic characteristics of 32 cultures isolated from cerebro-spinal fluid of patients with generalized forms of meningococcal infection. Typed isolates belonged to 4 sequence types: CT-3349 (detected in 24 cultures), CT-2 (detected in 5 cultures), CT-75 (detected in 2 cultures), and CT-5803 (detected in 1 culture). All sequence types (except CT-5803) were detected in Moscow in previous years. Using Internet database (http://pubmlst.org/neisseria) they were genetically characterized and compared with data on serogroup A meningococci circulated in Moscow before 2002., meningococci belonging to epidemically dangerous genetic subgroup III were not detected between characterized strains. Typed isolates were distributed between subgroups VI and X, which are typical for the area under surveillance. Genetic changes in Moscow population of Neisseria meningitidis serogroup A, which manifested by shift of dominating genetic subgroup after 2002-2003, were analyzed.

[A complex of blood-sucking mosquitoes (Diptera, Culicidae) in the focus of West Nile fever in the Volgograd Region. III. Species feeding on birds and man and the rhythms of their nocturnal activity]

The rate and nocturnal rhythm of mosquito attacks of birds and human beings were studied in the open biotopes of Volgograd and its vicinity in 2004. Thirteen and 11 species of the subfamily Culicinae were collected under the Berezantsev bell and from the traps containing a chicken (a hen), respectively; of them 9 species were common. The mosquitoes of an Anopheles maculipennis complex were caught in a small portion to the traps of both types. Most species of Aedes were highly anthropophilic, showed the minimum activity at night and their abundance considerably decreased by the early transmission period. Among the species that were active during the transmission period, Ae. vexans, Coq. richiardii, and Cx. modestus more intensively attacked a human being than birds and Cx. pipiens was frequently attracted into the hen traps. The attraction of each species of the caught varied during the transmission period. The maximum attacks of Cx. modestus and Cx. pipiens on man and birds coincide and those of Coq. Richiardii and Cx. pipiens on man was observed earlier than on birds. A possible role of mosquitoes of different species in the epizootic and epidemiological processes is discussed.

[ELISA and PCR test systems used to detect Crimean-Congo hemorrhagic fever virus]

Studying the sensitivity and specificity of enzyme-linked immunosorbent assay (ELISA) for the indication of Crimean-Congo hemorrhagic fever (CCHF) virus antigens and those of reverse transcription and polymerase chain reaction (RT-PCR) for the detection of CCHF virus RNA, and those of a intercerebral infection method in newborn albino mice systems for the determination of viral infectious activity established that the sensitivity of ELISA was 1-2 orders of magnitude less than that of RP-PCR. The latter proved to be better in studying the sera sampled from patients with CCHF. The results of studying the samples of H. marginatum ticks, the CCHF virus vectors by ELISA and RT-PCR were similar.

[The evaluation of viral load in patients with hemorrhagic fever with renal syndrome (HFRS) by real-time polymerase chain reaction]

The system for real-time polymerase chain reaction was developed for detection of Puumala virus RNAand quantitative analysis of viral RNAload in clinical samples. Dynamics of viral load in blood samples from 12 patients with HFRS (from day 4 to day 17 of the disease) was studied. At day 4 viral RNA load varied from 4 x 10(4) to 1 x 10(6) copies/ml. During the period of observation viral load decreased by 10 - 200 times and was not detected in majority of patients to day 11 - 15 of the disease. The hantavirus persisted in blood of four patients to day 17 of the disease with viral load varied from 2.7 x 10(3) to 2 x 10(4) copies/ml. Developed method was characterized by highest sensitivity (100%) for HFRS detection from day 4 to day 8 of the disease.

[Mosquito complex (Diptera, Culicidae) in a West Nile fever focus in the Volgograd Region. II. Host-feeding patterns of mosquitoes in different habitats]

Host preference of the mosquitoes collected in the urban and rural habitats of Volgograd and its suburbs was studied by the precipitation reaction test. Human and avian blood was detected in Cx. pipiens, Cx. modestus, Ae. vexans, Ae. behningi, Ae. caspius, Ae. sticticus, and females of the Anopheles maculipennis. The proportion of the mosquitoes fed on birds was similar in the urban and rural biotopes whereas that of the mosquitoes feeding on humans was significantly higher in Volgograd than in its environs. The increase in the number of human blood-fed mosquitoes in the city resulted mainly from the females collected in its multi-storied buildings.

[Mosquito complex (Diptera, Culicidae) in a West Nile fever focus in the Volgograd region. I. Species diversity and relative abundance in different habitats]

Potential West Nile virus (WNV) vectors were assessed during 2003 and 2004 at the indoor and outdoor collection sites of Volgograd and surrounding rural areas. A total of 26 387 female mosquitoes comprising 16 species in 5 genera of the subfamily Culicinae and 4 species of the subfamily Anophelinae were collected. The seasonal abundance and the dominance structure greatly differed in the multi-storied buildings, farms, and open habitats whereas the similarity of species diversity remained high throughout the season. In the porches of buildings, Aedes vexans (58%) and Cx. pipiens (37%) prevailed in early July (the beginning of a transmission period), Cx. pipiens (92%) was an absolute dominant species in August. The autogenous form of Cx. pipiens was most common in the flooded-basement houses of the city's outskirts. The number of anautogenous females in the indoor collections increased by August. Only the anautogenous form of Cx. pipiens was sampled in the open rural and urban areas. The findings suggest that the attraction of potential vectors, including anautogenous Cx. pipiens, from the outdoor biotopes to the porches of apartment houses is one of the main reasons for the spread of the disease in the urban population.

[Genetic relationships of Moscow and foreign strains of Haemophilus influenzae, serotype B]

46 Haemophilus influenzae strains of serotype b, isolated on the territory of Moscow and compared with foreign strains, were characterized by the method of multilocus sequencing-typing. Among the strains circulating in Moscow 10 variants of sequence-types were observed; of these, only one variant (CT-6) had been described earlier. The analysis of the data revealed that the strains under study were distributed in two clonal complexes; the overwhelming majority of the strains belonged to sequence-type 6. The distribution of Moscow strains in clonal complexes repeated the clonal organization detected in foreign strains. The conclusion was made that lower morbidity rate in Hib meningitis in Moscow (in comparison with that in the countries of Europe and America before the introduction of prophylactic vaccination) was not due to the peculiar genetic features of the circulating strains.

Evaluation of potential West Nile virus vectors in Volgograd region, Russia, 2003 (Diptera: Culicidae): species composition, bloodmeal host utilization, and virus infection rates of mosquitoes

Potential West Nile virus (family Flaviviridae, genus Flavivirus, WNV) vectors were assessed during 2003 at indoor and outdoor collection sites in urban Volgograd, Russia, and in three nearby towns and surrounding rural areas. In total, 9,182 female mosquitoes comprising 13 species in six genera were collected. Relative abundance and bloodmeal host utilization differed temporarily and spatially. During June and July in Volgograd, Aedes vexans (Meigen) (85.4%) and Culex p. pipiens L. (7.6%) were the two most abundant species collected indoors, whereas during August, Cx. p. pipiens was the dominant species, accounting for 87.9% of specimens collected. Two WNV-positive mosquito pools were detected in August: one pool was composed of Cx. p. pipiens and the other pool of Culex modestus Ficalbi. Anopheles messeae Falleroni, Aedes caspius (Pallas), Ae. vexans, Cx. modestus, and Cx. p. pipiens used both humans and birds as bloodmeal sources. In urban areas, 20.4% of the Cx. p. pipiens fed on humans, 58.1% fed on chickens, and six specimens were positive for both chicken and human blood. Culex p. pipiens collected from flooded basements were predominantly autogenous (91.7%), whereas adult females resting in buildings with dry basements were composed of 67.5% anautogenous and 32.5% autogenous specimens. Our data suggest that the primary WNV vectors in the Volgograd region were Cx. p. pipiens and Cx. modestus and that intense transmission of WNV to humans in urban areas during the epidemic of 1999 may have been facilitated by the abundance and concentration of anautogenous Cx. p. pipiens in multistory buildings. The role of autogenous Cx. p. pipiens in urban transmission remains unresolved.

[Analysis of the Moscow population of Neisseria meningitidis strains by the method of multilocus sequencing-typing]

The analysis of meningococcal strains of different serogroups, isolated from the liquor of patients in Moscow, which was carried out with the method of multilocus sequencing-typing (MLST), was presented. At the periods of epidemic morbidity rises in Moscow the prevalence of group A meningococcal strains, belonging to subgroups III with sequence-types 5 (in the 1970s) and 7 (in 1996), was noted, and at a period between epidemics strains of genetic subgroups VI and X were isolated. Meningococcal strains, groups B and C, isolated in 1995 - 2002, had, as a rule, unique sequence-types, differing both one from another and from N. meningitidis sequence-types detected in other countries. Among group B meningococci the prevalence of strains belonging to clonal complex ST-18 was noted, while for group C meningococcci strains belonging to clonal complex ST-41/44 were most typical. Such genetic variability of circulating meningococci was regarded as characteristic of the period between epidemics, observed in Moscow since the end of the 1980s.

Economic evaluation of Haemophilus influenzae type b vaccination in Moscow, Russian Federation

OBJECTIVE

To estimate the cost-effectiveness of providing Haemophilus influenzae type b (Hib) vaccine to children in Moscow in routine immunization services.

METHODS

The incidence of Hib meningitis among children aged <5 years in Moscow was obtained from a prospective surveillance study undertaken during October 1999-September 2001, with treatment cost data collected for all cases. Sequelae in surviving children were assessed in December 2002. The costs of Hib vaccination in Moscow were estimated assuming a vaccine price of US dollar 5 per dose and the same four-dose schedule and 97% coverage as for diphtheria-tetanus-pertussis vaccine. The most uncertain variables were varied in a sensitivity analysis.

RESULTS

The annual incidence of Hib meningitis was 5.7 per 100,000 children <5 years. The average treatment cost for an acute Hib meningitis case was US dollar 1296. For a patient with sequelae, the average additional lifetime discounted treatment cost was US dollar 15,820. The total annual cost of Hib vaccination of infants in Moscow was estimated as US dollar 1.5 million per year. In the base case analysis, the cost-effectiveness ratios amount to US dollar 77,503 per Hib meningitis case averted and US dollar 10,842 per discounted disability adjusted life year averted. The break-even vaccine price, where the annual vaccination costs equal annual treatment costs averted, is only US dollar 0.04 per dose in the base case scenario. If discounted indirect costs are included, the break-even vaccine price is US dollar 0.5 per dose.

CONCLUSION

In Moscow, the incidence of Hib meningitis is low and the costs of hospitalization and subsequent medical treatment are relatively inexpensive. Given these factors, Hib vaccine at US dollar 5 per dose would not be a cost-effective option in Moscow at the present time.