Granulocytic Anaplasmosis Research Articles

Anaplasma phagocytophilum Ats-1 enhances exosome secretion through Syntenin-1

Anaplasma phagocytophilum is an intracellular obligate parasite that causes granulocytic anaplasmosis. Effector Ats-1 is an important virulence factor of A. phagocytophilum. Multiomics screening and validation has been used to determine that Ats-1 regulates host cell apoptosis and energy metabolism through the respiratory chain mPTP axis. In this study, a total of 19 potential binding proteins of Ats-1 in host cells were preliminarily screened using a yeast two-hybrid assay, and the interaction between syntenin-1 (SDCBP) and Ats-1 was identified through immunoprecipitation. Bioinformatics analysis showed that SDCBP interacted with SDC1, SDC2, and SDC4 and participated in the host exosome secretion pathway. Further studies confirmed that Ats-1 induced the expression of SDC1, SDC2, and SDC4 in HEK293T cells through SDCBP and increased the exosome secretion of these cells. This indicated that SDCBP played an important role in Ats-1 regulating the exosome secretion of the host cells. These findings expand our understanding of the intracellular regulatory mechanism of A. phagocytophilum, which may enhance its own infection and proliferation by regulating host exosome pathways.

Development of a Model for Preliminary Diagnosis of Human Granulocytic Anaplasmosis.

Background: Human granulocytic anaplasmosis (HGA) is a vector-borne natural focal disease that is not officially registered in Ukraine. The first 13 cases of HGA in adults in Ukraine were identified in 2007. The purpose of our study was to develop a predictive model of HGA based on clinical and laboratory characteristics to develop a three-level standard case definition of HGA. Materials and Methods: Researchers examined 498 patients with suspected tick-borne infections and carried out a retrospective clinical and epidemiological analysis of 60 cases recruited from Lviv regional infectious disease hospitals. Logistic regression was used to create a model of the probability of the diagnosis of HGA depending on the presence of certain clinical and laboratory factors that, when examined, together may help to confirm a case of HGA. For logistic regression, eight clinical and laboratory factors were selected: history of tick bite, hyperthermia, signs of pharyngitis, changes in chest X-ray picture (enhancement of the pulmonary pattern and enlargement of the lung root boundaries), increased bilirubin (˃21 μmol/L), increased alanine aminotransferase (ALT ˃36 U/L), erythema migrans, and detected Lyme disease. Results: In the presence of all eight factors, the probability of HGA is 95.7%. When the five main signs are absent-signs of pharyngitis, changes in chest X-ray picture, increased bilirubin and ALT, and a history of tick bite-the probability of HGA in the patient dramatically decreases to 6.8%, meaning that HGA might be excluded. Conclusions: Based on the analysis of epidemiological, clinical, and laboratory signs, criteria for establishing a suspected, probable, and confirmed diagnosis of HGA have been developed to improve diagnosis.

Anaplasma phagocytophilum Ecotype Analysis in Cattle from Great Britain.

Anaplasma phagocytophilum (A. phagocytophilum) is the aetiological agent of tick-borne fever in cattle and sheep, and granulocytic anaplasmosis in human and dogs. Livestock, companion animal and human infections with A. phagocytophilum have been reported globally. Across England and Wales, two isolates (called ecotypes) have been reported in ticks. This study examined A. phagocytophilum isolates present in livestock and wildlife in Great Britain (GB), with a particular focus on cattle. Clinical submissions (EDTA blood) from cattle (n = 21) and sheep (n = 3) were received by APHA for tick-borne disease testing and the animals were confirmed to be infected with A. phagocytophilum using a PCR targeting the Msp2 gene. Further submissions from roe deer (n = 2), red deer (n = 2) and Ixodes ricinus ticks (n = 22) were also shown to be infected with A. phagocytophilum. Subsequent analysis using a nested PCR targeting the groEL gene and sequencing confirmed the presence of ecotype I in cattle, sheep, red deer and Ixodes ricinus, and ecotype II in roe deer and I. ricinus removed from deer carcasses. Despite the presence of two ecotypes, widely distributed in ticks from England and Wales, only ecotype I was detected in cattle in this study.

Lipid mediators of cerebrospinal fluid in response to TBE and bacterial co-infections

Tick-borne diseases are caused by monoinfection or co-infection with different pathogens, including viruses, bacteria and protozoa. Tick-borne diseases are usually accompanied by oxidative stress which promotes the modifications of the host's lipid metabolism. The aim of the study was to compare total antioxidant status and the level of lipid mediators in the cerebrospinal fluid in response to tick-borne encephalitis (TBE) and bacterial co-infections that cause diseases such as that is Lyme borreliosis (LB) and human granulocytic anaplasmosis (HGA). In our study cerebrospinal fluid samples were obtained from 15 patients with TBE and 6 patients with TBE co-infection with LB and/or HGA at admission and after treatment. Control group consisted of 14 patients in whom meningitis was excluded. Total antioxidant status, levels of lipid peroxidation products, endocannabinoids and eicosanoids (determined by liquid and gas chromatography–mass spectrometry) were compared between the groups. It was found that in TBE patients, total antioxidant status was decreased and accompanied by increased levels of lipid peroxidation products (4-HNE, MDA, isoprostanes and neuroprostanes), major endocannabinoids (AEA and 2AG), and eicosanoids (both anti-inflammatory and pro-inflammatory), which generally declined after treatment. On the other hand, in co-infections, significant changes in the levels of some lipid mediators were observed even after the treatment. TBE alone or along with bacterial co-infections promote redox balance disturbances in the cerebrospinal fluid leading to oxidative stress and increased metabolism of phospholipids in the brain tissue reflected in the level of lipid peroxidation products and lipid mediators. Changes in the level of lipid mediators in patients with co-infections after treatment suggest further intensification of metabolic disturbances rather than their resolution.

Doxycycline hyclate in late-term pregnant mares: pharmacokinetics, diffusion to the fetoplacental unit and safety in the resulting foal

Doxycycline is a second-generation tetracycline with excellent tissue penetration, high-protein-binding, and 5-10-fold higher lipophilic character than tetracycline. It is used to treat difficult-to-identify and atypical pathogens in diseases such as granulocytic anaplasmosis, Potomac fever, Lyme disease, and placentitis caused by Leptospira and nocardioform Actinomycetes. Despite routine use of doxycycline in pregnant mares, there is no data on their pharmacokinetics during pregnancy, transplacental diffusion, or potential toxicity to the fetus and resulting foal. This study aimed to determine the pharmacokinetics of doxycycline in the late-pregnant mare, its diffusion to the fetoplacental unit and its safety in the neonate. The study hypothesizes that doxycycline crosses the equine fetoplacental unit after administration during late-term pregnancy and is safe for the resulting foal. In experiment 1, six mares received a dose of compounded doxycycline hyclate (10mg/kg, p.o.) at 300d of gestation. Doxycycline plasma concentrations were measured with LC-MS/MS at 0, 0.25, 0.5, 0.75, 1, 2, 3, 4, 6, 8, 10, 12, 24, and 48h after administration to confirm absorption and pharmacokinetics. The compounded doxycycline used herein was absorbed rapidly, and maximum plasma concentrations were achieved in 0.79h. Pharmacokinetic parameters of the doxycycline were similar to previous studies using commercial canine preparations. In experiment 2, transplacental diffusion and safety to the resulting foal were studied after administration of repeated doses ofdoxycycline to late-term pregnant mares. Seven mares received doxycycline (10mg/kg p.o. q12h) from 320d of gestation until foaling, and six gestationally-age-matched mares served as controls. Once impending signs of imminent parturition were detected coupled with mammary gland secretion pH ≤6.4, foaling was induced with oxytocin (10-units, intramuscularly) to ensure a controlled sampling of fetal fluids. Fetal fluids and foal synovial fluids were harvested at foaling to determine doxycycline concentrations with LC-MS/MS. After parturition, foals had daily clinical examinations, blood chemistry, and complete blood cell counts performed for seven days. Shapiro-Wilk was used to test normal distribution and data were analyzed with ANOVA and Tukey's as post hoc. Mares received doxycycline on average for 15±2d (range 9-23d). No adverse side effects were associated with doxycycline treatment, and complete blood cell count or blood chemistry pre- and post-partum remained within normal reference ranges. Gestation length for doxycycline-treated mares (335±2d) was similar to controls (339±4) (P=0.4). Concentrations of doxycycline were 9-fold higher in the allantoic fluid (73.5±13.9ng/mL) than amniotic fluid (8.3±3.3ng/mL) and 1.5-fold higher in the foal's plasma (35.5±4.3ng/mL than its synovial fluid (23.6±4.3ng/mL). In conclusion, doxycycline was well-absorbed and detectable in fetal fluids, foal plasma, and synovial fluid, and no adverse effects were observed in mares nor their foals.

Phylogenetic identification of Anaplasma phagocytophilum in horses in Baghdad, Iraq

This study aimed to detect Anaplasma phagocytophilum in horses through hematological and molecular tests. The 16S rRNA gene of the Anaplasma phagocytophilum parasite was amplified by polymerase chain reaction (PCR), then sequenced, and subjected to phylogenetic analysis to explore "Equine Granulocytic Anaplasmosis" (EGA) infection in three important gathering race horses areas in Baghdad governorate, Iraq. Blood samples were obtained from 160 horses of varying ages, three breeds, and both sexes, between January and December 2021. Prevalence and risk variables for anaplasmosis were analyzed using statistical odds ratio and chi-square tests. Results demonstrated that clinical anaplasmosis symptoms comprised jaundice, weight loss, paleness of mucus membrane with petechial hemorrhage in the third elides, and edema in extremities; There was no tick infestation. The hematological test did not significantly reveal decreases in red and white blood cells and platelet count. Microscopically found 11 from 160 smears (6.88%) had morulae within granulocytes, PCR results of Anaplasma spp primers was 32 positive amplicons (20%), and molecular sequencing results of “16S ribosomal RNA genes” confirmed 21 horses (13.13%) infected by Anaplasma phagocytophilum for the first time in Iraq horses. The results of the phylogenetic analysis revealed compatibility values similarity 98.81-99.76% with worldwide isolates. Mares occurred not significantly riskier; also age and breed were not illustrated risks of any group. This study is the first molecular detection of Anaplasma phagocytophilum in racehorses reared in Baghdad in Iraq. The outcomes of this study provide genetic data for early identification of Anaplasma phagocytophilum infection, treatment, and management of the illness in Iraq horses, as well as monitoring its transmission to the human population.

Clinically differential diagnosis of human granulocytic anaplasmosis and severe fever with thrombocytopenia syndrome

This study analyzed HGA and SFTS in patients with suspected tick-borne infection by focusing on key differences that clinicians can easily recognize. A retrospective analysis was performed on confirmed patients with HGA or SFTS in 21 Korean hospitals from 2013 to 2020. A scoring system was developed by multivariate regression analysis and accuracy assessment of clinically easily discriminable parameters was performed. The multivariate logistic regression analysis revealed that sex (especially male sex) (odds ratio [OR] 11.45, P = 0.012), neutropenia (< 1500) (OR 41.64, P < 0.001), prolonged activated partial thromboplastin time (OR 80.133, P < 0.001), and normal C-reactive protein concentration (≤ 1.0 mg/dL; OR 166.855, P = 0.001) were significantly associated with SFTS but not with HGA. Each factor, such as meaningful variables, was given 1 point, and a receiver-operating characteristic curve with a cutoff value (> 1) in a 5-point scoring system (0–4 points) was analyzed to evaluate the accuracy of differentiation between HGA and SFTS. The system showed 94.5% sensitivity, 92.6% specificity, and an area under the receiver-operating characteristic curve of 0.971 (0.949–0.9). Where HGA and SFTS are endemic, the scoring system based on these four parameters such as sex, neutrophil count, activated partial thromboplastin time, and C-reactive protein concentration will facilitate the differential diagnosis of HGA and SFTS in the emergency room in patients with suspected tick-borne infectious diseases.

Frankenbacteriosis targeting interactions between pathogen and symbiont to control infection in the tick vector

Tick microbiota can be targeted for the control of tick-borne diseases such as human granulocytic anaplasmosis (HGA) caused by model pathogen, Anaplasma phagocytophilum. Frankenbacteriosis is inspired by Frankenstein and defined here as paratransgenesis of tick symbiotic/commensal bacteria to mimic and compete with tick-borne pathogens. Interactions between A.phagocytophilum and symbiotic Sphingomonas identified by metaproteomics analysis in Ixodes scapularis midgut showed competition between both bacteria. Consequently, Sphingomonas was selected for frankenbacteriosis for the control of A.phagocytophilum infection and transmission. The results showed that Franken Sphingomonas producing A.phagocytophilum major surface protein 4 (MSP4) mimic pathogen and reduce infection in ticks by competition and interaction with cell receptor components of infection. Franken Sphingomonas-MSP4 transovarial and trans-stadial transmission suggests that tick larvae with genetically modified Franken Sphingomonas-MSP4 could be produced in the laboratory and released in the field to compete and replace the wildtype populations with associated reduction in pathogen infection/transmission and HGA disease risks.

Liver manifestations of tick-borne diseases.

Liver manifestations of tick-borne diseases.

A rare occurrence of Anaplasma-associated peritonitis.

Anaplasmosis or human granulocytic anaplasmosis is a tick-borne illness caused by the bacteria, Anaplasma phagocytophilum, resulting from an infected tick bite. Examination of a blood smear within the first week of exposure may show microcolonies of anaplasmae (morulae) in the cytoplasm of neutrophils that are highly suggestive of anaplasmosis but not definitive. We present the first case describing Anaplasma-related peritonitis and morulae in peritoneal fluid granulocytes in a peritoneal dialysis patient who developed anaplasmosis.

Etiological Structure, Clinical and Epidemiological Characteristics of Infections Transmitted by Ixodic Ticks in the Sverdlovsk Region at the Present Stage

Relevance. The Sverdlovsk region is a highly endemic territory for infections transmitted by ixodic ticks. The possibilities of laboratory diagnostics of tick–borne infections in the routine practice of a clinician in the region today are limited mainly by testing blood serum for antibodies to the tick-borne encephalitis virus (TBE virus) and Lyme disease (LD) pathogens – Borrelia burgdorferi sensu lato complex, therefore, among tick-borne infections in the region currently mainly TBE and LD are registered. In case of negative results for antibodies to the pathogens of the above infections, the diagnosis may remain unknown. Aims. To study the etiological structure of infections transmitted by ixodic ticks in the Sverdlovsk region at the present stage, as well as to characterize the epidemiological and clinical features of the course of tick-borne infections detected in conditions of a combination of natural foci. Materials and methods. The study included 227 patients undergoing inpatient or outpatient treatment during the epidemic season of tick activity in 2021 (June-August) at LLS MO "New Hospital" (Urban Center of Natural Focal Infections). The case histories (epidemiological, clinical and laboratory indicators) were studied from each patient, as well as the material (blood) was examined prospectively and retrospectively using molecular biological (PCR) and serological (ELISA, planar protein biochip) methods. Results and discussion. During the study, six diseases were identified among the examined patients: TBE, LD (erythematous and nonerythematous forms), Borrelia miyamotoi disease (BMD), human granulocytic anaplasmosis (HGA), human monocytic ehrlichiosis (HME), as well as "Viral fever transmitted by arthropods" (VFTA). Among the examined patients, the proportion of patients with monoinfection was 49,5%, with mixed infection – 50,5%. Additional studies conducted by us using specific PCR for the presence DNA rickettsia and the causative agent of Q-fever in the blood of patients gave negative results. The general epidemiological characteristics for the above identified infections were the vector-borne mechanism, the prevalence of diseases in groups of middle-aged and elderly people, the largest number of cases of infection with pathogens of any tick-borne infection occurred in Yekaterinburg and its surroundings, for all infections, the duration of tick bite in most cases did not exceed one day; there were differences by sex, incubation period. Clinical symptoms were similar, except for the erythematous form of LD (the presence of erythema migrans at the byte site of tick), because the vast majority of patients had a general infectious syndrome; general laboratory indicators varied. Confirmation of the diagnosis was based on the results of the complex application of molecular biological and serological research methods. Conclusions. The modern etiological structure of infections transmitted by ixodic ticks in the Sverdlovsk region is represented not only by TBE and LD, but also by new disease to our country, such as BMD, HGA, HME, while a high proportion of mixed infections in various combinations has been revealed.

Molecular and Serological Detection of Anaplasma phagocytophilum in Dogs from Germany (2008–2020)

Anaplasma phagocytophilum is an obligate intracellular bacterium that causes granulocytic anaplasmosis in domestic animals, wildlife, and humans and is primarily transmitted by ticks of the Ixodes persulcatus complex. This retrospective study aims to determine the percentages of dogs that tested positive for A. phagocytophilum in Germany. It included the results of direct (polymerase chain reaction [PCR]) and indirect (immunofluorescence antibody test [IFAT], antibody-enzyme-linked immunosorbent assay [ELISA]) detection methods performed in the laboratory LABOKLIN on canine samples provided by German veterinarians from 2008 to 2020. Out of a total of 27,368 dogs tested by PCR, 1332 (4.9%) tested positive, while 24,720 (27.4%) of the 90,376 dogs tested by IFAT/ELISA had positive serology. High rates of positive PCR results were observed in months with known peaks in vector activity, showing that the dynamics of A. phagocytophilum infections in dogs in Germany are consistent with vector activity. In dogs with a positive PCR result, peaks in serology could be observed four weeks after initial testing. Male and senior dogs had higher rates of positive serology. A possible impact of environmental factors such as changes in climate should be investigated further. Overall, the upward trend in positive test results over the years indicates that canine granulocytic anaplasmosis will continue to become increasingly important for veterinary medicine.

Enhancement of Cell Adhesion by Anaplasma phagocytophilum Nucleolin-Interacting Protein AFAP.

Anaplasma phagocytophilum, the aetiologic agent of human granulocytic anaplasmosis (HGA), is an obligate intracellular Gram-negative bacterium. During infection, A. phagocytophilum enhances the adhesion of neutrophils to the infected endothelial cells. However, the bacterial factors contributing to this phenomenon remain unknown. In this study, we characterized a type IV secretion system substrate of A. phagocytophilum, AFAP (an actin filament-associated Anaplasma phagocytophilum protein) and found that it dynamically changed its pattern and subcellular location in cells and enhanced cell adhesion. Tandem affinity purification combined with mass spectrometry identified host nucleolin as an AFAP-interacting protein. Further study showed the disruption of nucleolin by RNA interference, and the treatment of a nucleolin-binding DNA aptamer AS1411 attenuated AFAP-mediated cell adhesion, indicating that AFAP enhanced cell adhesion in a nucleolin-dependent manner. The characterization of cell adhesion-enhancing AFAP and the identification of host nucleolin as its interaction partner may help understand the mechanism underlying A. phagocytophilum-promoting cell adhesion, facilitating the elucidation of HGA pathogenesis.

Presence of Anaplasma phagocytophilum Ecotype I in UK Ruminants and Associated Zoonotic Risk.

Anaplasma phagocytophilum is the causative agent of tick-borne fever in sheep, pasture fever in cattle, and granulocytic anaplasmosis in humans. The increasing prevalence and transboundary spread of A. phagocytophilum in livestock, ticks, and wildlife in the UK poses a potential zoonotic risk that has yet to be estimated. Several ecotypes of A. phagocytophilum show variable zoonotic potential. To evaluate the possible risk associated with the transmission of A. phagocytophilum from ruminants to humans, the ecotype was determined by sequencing the groEL gene from 71 positive blood and tissue samples from UK ruminants. Thirty-four groEL sequences were obtained, fourteen of which were identified in multiple samples. Of the 13 nucleotide polymorphisms identified through pairwise comparison, all corresponded to synonymous substitutions. The subsequent phylogenetic estimation of the relationship with other European/world isolates indicated that all the groEL sequences clustered with other ecotype I sequences. The presence of ecotype I closely reflects that observed in ruminants in continental Europe and suggests a lower risk of zoonotic transmission from this reservoir.

A Disease Outbreak in Beef Cattle Associated with Anaplasma and Mycoplasma Infections.

An outbreak of disease in a Swedish beef cattle herd initiated an in-depth study to investigate the presence of bacteria and viruses in the blood of clinically healthy (n = 10) and clinically diseased cattle (n = 20) using whole-genome shotgun sequencing (WGSS). The occurrence of infectious agents was also investigated in ticks found attached to healthy cattle (n = 61) and wild deer (n = 23), and in spleen samples from wild deer (n = 30) and wild boars (n = 10). Moreover, blood samples from 84 clinically healthy young stock were analysed for antibodies against Anaplasma phagocytophilum and Babesia divergens. The WGSS revealed the presence of at least three distinct Mycoplasma variants that were most closely related to Mycoplasma wenyonii. Two of these were very similar to a divergent M. wenyonii variant previously only detected in Mexico. These variants tended to be more common in the diseased cattle than in the healthy cattle but were not detected in the ticks or wild animals. The DNA of A. phagocytophilum was detected in similar proportions in diseased (33%) and healthy (40%) cattle, while 70% of the deer, 8% of ticks collected from the cattle and 19% of the ticks collected from deer were positive. Almost all the isolates from the cattle, deer and ticks belonged to Ecotype 1. Based on sequencing of the groEL-gene, most isolates of A. phagocytophilum from cattle were similar and belonged to a different cluster than the isolates from wild deer. Antibodies against A. phagocytophilum were detected in all the analysed samples. In conclusion, uncommon variants of Mycoplasma were detected, probably associated with the disease outbreak in combination with immune suppression due to granulocytic anaplasmosis. Moreover, A. phagocytophilum was found to be circulating within this cattle population, while circulation between cattle and deer occurred infrequently.

Revealing the Tick Microbiome: Insights into Midgut and Salivary Gland Microbiota of Female Ixodes ricinus Ticks.

The ectoparasite Ixodes ricinus is an important vector for many tick-borne diseases (TBD) in the northern hemisphere, such as Lyme borreliosis, rickettsiosis, human granulocytic anaplasmosis, or tick-borne encephalitis virus. As climate change will lead to rising temperatures in the next years, we expect an increase in tick activity, tick population, and thus in the spread of TBD. Consequently, it has never been more critical to understand relationships within the microbial communities in ticks that might contribute to the tick's fitness and the occurrence of TBD. Therefore, we analyzed the microbiota in different tick tissues such as midgut, salivary glands, and residual tick material, as well as the microbiota in complete Ixodes ricinus ticks using 16S rRNA gene amplicon sequencing. By using a newly developed DNA extraction protocol for tick tissue samples and a self-designed mock community, we were able to detect endosymbionts and pathogens that have been described in the literature previously. Further, this study displayed the usefulness of including a mock community during bioinformatic analysis to identify essential bacteria within the tick.

Using Serum Specimens for Real-Time PCR-Based Diagnosis of Human Granulocytic Anaplasmosis, Canada

Whole blood is the optimal specimen for anaplasmosis diagnosis but might not be available in all cases. We PCR tested serum samples collected in Canada for Anaplasma serology and found 84.8%-95.8% sensitivity and 2.8 average cycle threshold elevation. Serum can be acceptable for detecting Anaplasma spp. when whole blood is unavailable.

Global status of Anaplasma phagocytophilum infections in human population: A 50-year (1970-2020) meta-analysis.

Anaplasma phagocytophilum causes human granulocytic anaplasmosis; a febrile tick-borne bacterial zoonosis of increasing public health importance in many parts of the world which is life threatening in undiagnosed, misdiagnosed and untreated cases. In this study we determined and reported the global status of the pathogen in man. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines was used to perform a systematic review and meta-analysis of data published in six electronic databases between 1970 and 2020. We pooled data using the random-effects model, performed sensitivity analysis by the single study deletion method and assess across study bias by the funnel plot and its statistical significance by the Egger's regression test. A total of 7018 cases of A. phagocytophilum were reported from 48,619 individuals examined across 22 countries in three continents. Overall pooled estimate was 8.13% (95% CI: 5.70 - 11.47) with a range of 4.64 (95% CI: 1.78 - 11.54) to 12.18% (95% CI: 7.66 - 18.83) across sub-groups. Regional prevalence was highest in North America 11.07% (95% CI: 3.13 - 32.38), while that in relation to study population was highest among occupationally exposed population 11.41% (95% CI: 5.69 - 21.56). The study revealed a significant variation in the prevalence of A. phagocytophilum across Asia, Europe and North America, with the highest prevalence in North America and among occupationally exposed population. To curtail the menace of this growing public health crisis, we recommend integrated control programmes involving tick control, the use of appropriate clothing by occupationally exposed population and health education.

Human granulocytic anaplasmosis complicated by hemophagocytic syndrome and coinfection.

KEY POINTS A 74-year-old man with end-stage renal disease was admitted to hospital in the spring after an episode of syncope that occurred during a hemodialysis session 1 day after he returned from his cottage in eastern Ontario. Within 24 hours of admission, he developed a fever (38.6°C) and

Seroplrevalence of &lt;i&gt;Anaplasma phagocytophilum&lt;/i&gt; and &lt;i&gt;Ehrlichia&lt;/i&gt; sp. among people affected by tick bites

Background. In spring and summer, the population of the Baikal region regularly comes into contact with the pathogens transmitted through the bites of ixodid ticks. In the Center for Diagnosis and Prevention of Tick-Borne Infections (Irkutsk, Russian Federation), we annually detect anaplasmas of the Anaplasma phagocytophilum species, as well as Ehrlichia chaffeensis/E. muris in both ixodid ticks and blood samples from people who have been bitten by ticks. At the same time, there are no data in open sources on the incidence of human granulocytic anaplasmosis and human monocytic ehrlichiosis in the Baikal region. Currently, there is very little information on the studies of intensity of the immune response to anaplasmas and ehrlichia in people living in the surveyed area, although this information is critical for assessing the frequency of contacts and the risk of infection of people in a territory endemic for tick-borne infections. The aim. To update information on the presence and prevalence of specific immunoglobulins M and G to A. phagocytophilum and Ehrlichia sp. among the population of the Irkutsk Region affected by tick bites. Materials and methods. In total, 204 samples of blood serum from the residents of the Irkutsk Region who were registered to be bitten by ticks were analyzed for the presence of IgM and IgG to human monocytic ehrlichiosis and human granulocytic anaplasmosis agents. Results. IgG to A. phagocytophilum were found in 9 samples, IgG to E. chaffeensis/E. muris – in 1 sample; no IgM to both pathogens were found in any sample. Conclusions. The results obtained indicate regular infection of the population with anaplasmas and ehrlichia which is a testifies to the existence of active natural foci of human monocytic ehrlichiosis and human granulocytic anaplasmosis in the Baikal region. To clarify the real epidemic role of these infections, a detailed study of the immune status is required both among healthy individuals and among patients with symptoms of an infectious disease.