Granulocytic Anaplasmosis Research Articles

Prevalence and genetic diversity of Anaplasma phagocytophilum in wild small mammals from western Yunnan province, China.

Anaplasma phagocytophilum (A. phagocytophilum) is an emerging zoonotic pathogen causing human granulocytic anaplasmosis, linked to small mammal reservoirs that harbor various zoonotic pathogens, underscoring their importance in public health and ecology. This study seeks to determine the prevalence of A. phagocytophilum in small mammals using PCR, then sequence and genotype positive samples, and assess infection risk factors. Small mammals were seasonally captured and a nested polymerase chain reaction (nested-PCR) was conducted targeting the 16S rRNA gene on spleen samples to detect A. phagocytophilum infection from three counties in western Yunnan province, China. Positive samples were sequenced and genotyped, revealing genetic diversity and regional clustering of the pathogen. A total of 1,605 small mammals belonging to 30 species, 18 genera, 6 families, 3 orders were captured seasonally and screened in this region, yielding a 0.93% infection rate with A. phagocytophilum (15/1605). Significant variations in infection rates were observed across different species, counties, and habitats. The 16Sr RNA genes of A. phagocytophilum were categorized into two distinct clades, indicating notable genetic diversity. The identification of genetic variants in spleen samples underscores the potential public health risk and the critical importance of the One Health approach in disease surveillance. Our findings emphasize the necessity for continuous monitoring and highlight the value of nested-PCR testing on spleen samples for accurate prevalence assessment.

Hemophagocytic Lymphohistiocytosis Secondary to Anaplasmosis With Lyme Coinfection

Abstract Human granulocytic anaplasmosis and Lyme disease are tick-borne infections transmitted by the same vector, Ixodes scapularis, commonly isolated in areas within the Midwest region of the United States. Although typically associated with mild symptoms, both can progress to severe disease. Treatment of choice for a majority of tick-borne illness is doxycycline; however, options are limited in the setting of tetracycline allergy. Here, we present a complex case of human granulocytic anaplasmosis–induced hemophagocytic lymphohistiocytosis complicated by coinfection with Lyme encephalitis in a patient with a documented tetracycline allergy.

Culture and other direct detection methods to diagnose human granulocytic anaplasmosis

Culture and other direct detection methods to diagnose human granulocytic anaplasmosis

Anaplasma phagocytophilum effector EgeA facilitates infection by hijacking TANGO1 and SCFD1 from ER–Golgi exit sites to pathogen-occupied inclusions

The obligatory intracellular bacterium Anaplasma phagocytophilum causes human granulocytic anaplasmosis, an emerging zoonosis. Anaplasma has limited biosynthetic and metabolic capacities, yet it effectively replicates inside of inclusions/vacuoles of eukaryotic host cells. Here, we describe a unique Type IV secretion system (T4SS) effector, ER-Golgi exit site protein of Anaplasma (EgeA). In cells infected by Anaplasma, secreted native EgeA, EgeA-GFP, and the C-terminal half of EgeA (EgeA-C)-GFP localized to Anaplasma-containing inclusions. In uninfected cells, EgeA-C-GFP localized to cis-Golgi, whereas the N-terminal half of EgeA-GFP localized to the ER. Pull-down assays identified EgeA-GFP binding to a transmembrane protein in the ER, Transport and Golgi organization protein 1 (TANGO1). By yeast two-hybrid analysis, EgeA-C directly bound Sec1 family domain-containing protein 1 (SCFD1), a host protein of the cis-Golgi network that binds TANGO1 at ER-Golgi exit sites (ERES). Both TANGO1 and SCFD1 localized to the Anaplasma inclusion surface. Furthermore, knockdown of Anaplasma EgeA or either host TANGO1 or SCFD1 significantly reduced Anaplasma infection. TANGO1 and SCFD1 prevent ER congestion and stress by facilitating transport of bulky or unfolded proteins at ERES. A bulky cargo collagen and the ER-resident chaperon BiP were transported into Anaplasma inclusions, and several ER stress marker genes were not up-regulated in Anaplasma-infected cells. Furthermore, EgeA transfection reduced collagen overexpression-induced BiP upregulation. These results suggest that by binding to the two ERES proteins, EgeA redirects the cargo-adapted ERES to pathogen-occupied inclusions and reduces ERES congestion, which facilitates Anaplasma nutrient acquisition and reduces ER stress for Anaplasma survival and proliferation.

Biochemical characterization of ClpB and DnaK from Anaplasma phagocytophilum.

Anaplasma phagocytophilum is an intracellular tick-transmitted bacterial pathogen that infects neutrophils in mammals and causes granulocytic anaplasmosis. In this study, we investigated the molecular chaperones ClpB and DnaK from A. phagocytophilum. In Escherichia coli, ClpB cooperates with DnaK and its co-chaperones DnaJ and GrpE in ATP-dependent reactivation of aggregated proteins. Since ClpB is not produced in metazoans, it is a promising target for developing antimicrobial therapies, which generates interest in studies on that chaperone's role in pathogenic bacteria. We found that ClpB and DnaK are transcriptionally upregulated in A. phagocytophilum 3-5 days after infection of human HL-60 and tick ISE6 cells, which suggests an essential role of the chaperones in supporting the pathogen's intracellular life cycle. Multiple sequence alignments show that A. phagocytophilum ClpB and DnaK contain all structural domains that were identified in their previously studied orthologs from other bacteria. Both A. phagocytophilum ClpB and DnaK display ATPase activity, which is consistent with their participation in the ATP-dependent protein disaggregation system. However, despite a significant sequence similarity between the chaperones from A. phagocytophilum and those from E. coli, the former were not as effective as their E. coli orthologs during reactivation of aggregated proteins in vitro and in supporting the survival of E. coli cells under heat stress. We conclude that the A. phagocytophilum chaperones might have evolved with distinct biochemical properties to maintain the integrity of pathogenic proteins under unique stress conditions of an intracellular environment of host cells.

Bacterial reprogramming of tick metabolism impacts vector fitness and susceptibility to infection.

Arthropod-borne pathogens are responsible for hundreds of millions of infections in humans each year. The blacklegged tick, Ixodes scapularis, is the predominant arthropod vector in the United States and is responsible for transmitting several human pathogens, including the Lyme disease spirochete Borrelia burgdorferi and the obligate intracellular rickettsial bacterium Anaplasma phagocytophilum, which causes human granulocytic anaplasmosis. However, tick metabolic response to microbes and whether metabolite allocation occurs upon infection remain unknown. Here we investigated metabolic reprogramming in the tick ectoparasite I. scapularis and determined that the rickettsial bacterium A. phagocytophilum and the spirochete B. burgdorferi induced glycolysis in tick cells. Surprisingly, the endosymbiont Rickettsia buchneri had a minimal effect on bioenergetics. An unbiased metabolomics approach following A. phagocytophilum infection of tick cells showed alterations in carbohydrate, lipid, nucleotide and protein metabolism, including elevated levels of the pleiotropic metabolite β-aminoisobutyric acid. We manipulated the expression of genes associated with β-aminoisobutyric acid metabolism in I. scapularis, resulting in feeding impairment, diminished survival and reduced bacterial acquisition post haematophagy. Collectively, we discovered that metabolic reprogramming affects interspecies relationships and fitness in the clinically relevant tick I. scapularis.

Results of Epizootiological Survey of the Territories of the Republic of Crimea and Sevastopol in 2015–2022

Introduction: Systematic studies of endemic zoonotic diseases on the Crimean Peninsula resumed in 2015 after a long break. Objective: To specify boundaries and determine epizootiological activity of the natural foci of infectious diseases in the Crimea and to update the list of possible reservoir hosts and vectors based on the results of field studies conducted in 2015–2022. Materials and methods: Counting and trapping of small mammals, ixodid ticks and mosquitoes, collecting of pellets of birds of prey, sampling of water and other zoological and entomological materials were carried out in the Crimea in the years 2015 to 2022. Results and discussion: According to the results of epidemiological and epizootiological monitoring of the Crimean Peninsula, the samples tested positive for tularemia were collected on the territory of 14 administrative entities, leptospirosis – 21, hantaviruses – 12, tick-borne encephalitis – 2, Crimean-Congo hemorrhagic fever – 7, Lyme borreliosis – 21, West Nile fever – 3, Q fever – 2, Marseilles fever – 6, monocytic ehrlichiosis – 1, and granulocytic anaplasmosis – 8 entities. A new hantavirus was identified in the Leninsky district. Positive findings of markers of the Crimean-Congo hemorrhagic fever virus were registered not only in the main vector, but also in other species of ixodid ticks. True boundaries of the natural foci of Lyme borreliosis in the Crimea were much wider and ran through both forest and steppe zones. A stable reproducing population of epidemiologically significant Ae. albopictus mosquitoes was found on the southern coast of Crimea. Conclusions: Based on the findings, we specified the boundaries and confirmed the activity of natural foci of infectious diseases during the study period, updated sources of infections, reservoir hosts and vectors, and compiled the “List of enzootic (endemic) territories of the Crimea, on which circulation of infectious agents common to humans and animals was found based on the results of field material studies in 2015–2022,” all facilitating managerial decisions on prevention of natural focal infections.

Equine Granulocytic Anaplasmosis: A Systematic Review and Meta-Analysis on Clinico-Pathological Findings, Diagnosis, and Therapeutic Management.

Equine granulocytic anaplasmosis (EGA) is a tick-borne disease affecting horses worldwide, caused by Anaplasma phagocytophilum. The disease ranges from non-specific clinical signs to fatal outcomes. This paper aimed to analyze EGA cases reported in peer-reviewed journals, particularly on clinico-pathological findings, diagnosis, and therapeutic management. Overall, 189 clinical cases from 31 publications were included in the study. Extensive symptomatology for the EGA cases was reported, of which mostly was fever (90.30%), followed by limb edema (48.51%), anorexia (41.79%), depression (32.84%), icterus (22.39%), ataxia (17.91), tachycardia (16.42%), and lethargy (15.67%). Laboratory tests revealed thrombocytopenia (90.32%), anemia (75%), decreased hematocrit (70.59%), leukopenia (55.88%), lymphopenia (58.14%), and neutropenia (41.67%) as the most common hematological abnormalities. For a subset of tested animals, hyperbilirubinemia (20/29), hyperfibrinogenemia (13/15), and hyponatremia (10/10) were also reported. The diagnosis was established by microscopic identification of morulae (in 153 cases), and/or PCR (120 cases), isolation (1 case), or serology (56 cases). For treatment, oxytetracycline was used in the majority (52.24%) of EGA cases, but recovery without antibiotherapy (10.34%) was also noted. In conclusion, the variety of clinical and pathological findings and the challenging therapeutic approaches reported suggest that EGA should be included in the differential diagnosis when fever occurs.

Global prevalence of Borrelia burgdorferi and Anaplasma phagocytophilum coinfection in Ixodes tick populations: protocol for a systematic review and meta-analysis

IntroductionIxodes ticks are pivotal in transmitting diseases like Lyme disease and human granulocytic anaplasmosis, caused by Borrelia burgdorferi and Anaplasma phagocytophilum, respectively. These pathogens not only affect humans through single...

Anaplasma phagocytophilum in urban and peri-urban passerine birds in Ile-de-France

Wild animals in general, birds in particular, play a key role in transporting ticks and propagating tick-borne pathogens. Several studies have confirmed the infection of birds with Anaplasma phagocytophilum, with overall prevalence varying widely from country to country and/or study to study. This zoonotic bacterium, transmitted mainly by ticks of the genus Ixodes, is responsible for granulocytic anaplasmosis in humans (HGA) and domestic animals (cats, dogs, horses). The disease is also called tick-borne fever (TBF) in ruminants. Extremely rare in the USA, TBF is very common in Europe, where it causes economic losses in livestock. Conversely, HGA is well established in the USA whereas only a few less severe cases have been observed in Europe. Current typing techniques support the existence of multiple variants with differences in virulence/pathogenicity and tropism for certain tick and host species. However, epidemiological cycles remain difficult to characterize in Europe. Several studies describe a cycle apparently involving only birds in Europe, but no such study has been conducted in mainland France. Our objectives were to search for A. phagocytophilum in passerine birds in the Ile-de-France region and to explore their diversity using groEL and ankA gene typing and multilocus sequence typing (MLST). Various tissues (spleen, liver, and skin) were collected from cadavers of 680 passerines between March and December 2021. The presence of A. phagocytophilum was detected by qPCR Taqman targeting the msp2 gene. Three blackbirds (Turdus merula) were found positive, representing detection rates of 0.4 % in all birds tested and 3.3 % in blackbirds. The higher frequency of detection in blackbirds could be at least partially explained by their lifestyle, as they feed on the ground. Analysis of the results of groEL and ankA typing and MLST from positive blackbirds support the hypothesis that the avian A. phagocytophilum strains in Ile-de-France are distinct from those found in mammals, and that they form their own cluster in Europe.

Tick-borne infections in the Leningrad oblast: incidence and seroprevalence

The study’s objective was to reveal trends in infections transmitted by ixodes ticks epidemic processes and the level of seroprevalence of the population to the tick-borne encephalitis virus, Borrelia burgdorferi sensu lato, Coxiella burnetii, Anaplasma phagocytophilum and Ehrlichia chaffeensis/ E. muris in the Leningrad Oblast.Materials and methods. A retrospective epidemiological analysis of the tick-bite incidence rate, the ixodic tick-borne borreliosis, tick-borne encephalitis, Q fever, human granulocytic anaplasmosis and human monocytic ehrlichiosis incidence rates, as well as vaccination against tick-borne encephalitis of the population of the Leningrad Oblast in 20112020. The official data of the tick-bite incidence rate, infections transmitted by ixodes ticks incidence rates and vaccination of the population was taken from the forms of federal statistical observation No. 2 and No. 5. Blood was sampled in 2019-2020 from randomly selected donors. Blood serum samples were examined by enzyme-linked immunosorbent assay for the presence of IgG antibodies to the pathogens of the studied infections using commercial test systems according to the manufacturer’s instructions.Results. In the Leningrad Oblast, in 2011-2020, there was a downward trend in the tick-bite incidence rate, as well as in the incidence rates of infections transmitted by ixodic ticks. The long-term average tick bite incidence rate was 369.0. The long-term average incidence rate of ixodic tick–borne borreliosis was 4.1; tick–borne encephalitis was 1.4; Q fever was 0.02. During the analyzed period, no cases of human granulocytic anaplasmosis and human monocytic ehrlichiosis were reported. The seroprevalence to tick-borne encephalitis virus was 1.7%; to B. burgdorferi s. l. – 3.7%; to C. burnetii – 1.8%; to A. phagocytophilum – 1.0%; to E. chaffeensis/ E.muris – 3.2%.Conclusion. The results obtained indicate the existence of active natural foci of infections transmitted by ixodes ticks, fairly frequent contact of the residents with these foci, and possible significant hypodiagnosis of these infections in the Leningrad Oblast.

Assessment of the Current State of the Hissar High-Mountain Natural Plague Focus in the Republic of Tajikistan

The review is devoted to discussing the results of survey in the Hissar high-mountain natural plague focus on the territory of the Republic of Tajikistan in 2015–2023. Regular examination of the focus was carried out in 1970–1991. According to its results, the main carrier of the plague pathogen was the juniper vole, in the population of which a strain of the non-main subspecies central asiatica (0.PE4) of Hissar biovar (0.PE4h) was steadily circulating, the strain considered avirulent for humans. During that period, 853 strains were isolated in the focus, of which 799 (93.7%) were from the juniper vole and its fleas. Secondary carriers – the silver vole, the pygmy wood mouse, and the gray hamster – were rarely involved in epizootics. The red marmot, which has epidemiological significance due to its hunting by the local population, occupies a special position in the focus. Socio-political phenomena at the end of the 20th – early 21st century caused a long break in the work of the Tajik Plague Control Station. In 2008, the Station was transformed into the Republican Center for Combating Quarantine Diseases under the Ministry of Health and Social Protection of the Population of the Republic of Tajikistan. In 2015, studies were resumed, but carried out on a small scale. In 2021–2023, epizootiological monitoring in the Hissar focus was performed jointly with Russian specialists with the testing of field material samples for plague and other natural-focal infections. Currently, against the background of low numbers and population density of small mammals and their blood-sucking ectoparasites – potential carriers and vectors of zoonoses – the circulation of agents of plague, tularemia, pseudotuberculosis, tick-borne viral encephalitis, Ixodidae tick-borne borreliosis, human granulocytic anaplasmosis, human monocytic ehrlichiosis has not been registered. Markers (DNA) of causative agents of leptospirosis and intestinal yersiniosis have been identified. Joint Tajik-Russian cooperation on issues of ensuring the epidemiological well-being of the population of the Republic of Tajikistan must be continued.

Ceramide-1-phosphate is a regulator of Golgi structure and is co-opted by the obligate intracellular bacterial pathogen Anaplasma phagocytophilum.

Many intracellular pathogens structurally disrupt the Golgi apparatus as an evolutionarily conserved promicrobial strategy. Yet, the host factors and signaling processes involved are often poorly understood, particularly for Anaplasma phagocytophilum, the agent of human granulocytic anaplasmosis. We found that A. phagocytophilum elevated cellular levels of the bioactive sphingolipid, ceramide-1-phosphate (C1P), to promote Golgi fragmentation that enables bacterial proliferation, conversion from its non-infectious to infectious form, and productive infection. A. phagocytophilum poorly infected mice deficient in ceramide kinase, the Golgi-localized enzyme responsible for C1P biosynthesis. C1P regulated Golgi morphology via activation of a PKCα/Cdc42/JNK signaling axis that culminates in phosphorylation of Golgi structural proteins, GRASP55 and GRASP65. siRNA-mediated depletion of Cdc42 blocked A. phagocytophilum from altering Golgi morphology, which impaired anterograde trafficking of trans-Golgi vesicles into and maturation of the pathogen-occupied vacuole. Cells overexpressing phosphorylation-resistant versions of GRASP55 and GRASP65 presented with suppressed C1P- and A. phagocytophilum-induced Golgi fragmentation and poorly supported infection by the bacterium. By studying A. phagocytophilum, we identify C1P as a regulator of Golgi structure and a host factor that is relevant to disease progression associated with Golgi fragmentation.IMPORTANCECeramide-1-phosphate (C1P), a bioactive sphingolipid that regulates diverse processes vital to mammalian physiology, is linked to disease states such as cancer, inflammation, and wound healing. By studying the obligate intracellular bacterium Anaplasma phagocytophilum, we discovered that C1P is a major regulator of Golgi morphology. A. phagocytophilum elevated C1P levels to induce signaling events that promote Golgi fragmentation and increase vesicular traffic into the pathogen-occupied vacuole that the bacterium parasitizes. As several intracellular microbial pathogens destabilize the Golgi to drive their infection cycles and changes in Golgi morphology is also linked to cancer and neurodegenerative disorder progression, this study identifies C1P as a potential broad-spectrum therapeutic target for infectious and non-infectious diseases.

Epidemiological, clinical, and laboratory characteristics of human granulocytic anaplasmosis in North India.

Human granulocytic anaplasmosis (HGA) is an emerging, rickettsial tick-borne disease caused by Anaplasma phagocytophilum. Sero-epidemiological data demonstrate that this pathogen has a worldwide distribution. The diagnosis of HGA requires a high index of clinical suspicion, even in endemic areas. In recent years, HGA has increasingly been reported from Asia and described in China, Japan, and Korea. We serologically and molecularly screened 467 patients with clinical suspicion of Anaplasmosis. The present study describes the epidemiology, clinical, and laboratory details of 6 confirmed and 43 probable cases of human granulocytic anaplasmosis. One of the HGA patients developed secondary invasive opportunistic Aspergillus fumigatus and Acinetobacter baumanii infection during the illness, which resulted in a fatal infection. The HGA patients without severe complications had excellent treatment responses to doxycycline. The emergence of this newly recognized tick-borne zoonotic HGA in North India is a significant concern for public health and is likely underdiagnosed, underreported, and untreated. Hence, it is also essential to establish a well-coordinated system for actively conducting tick surveillance, especially in the forested areas of the country.IMPORTANCEThe results of the present study show the clinical and laboratory evidence of autochthonous cases of Anaplasma phagocytophilum in North India. The results suggest the possibility of underdiagnosis of HGA in this geographical area. One of the HGA patients developed secondary invasive opportunistic Aspergillus fumigatus and Acinetobacter baumanii infection during the illness, which resulted in a fatal infection.

Epizootological situation and epidemiological risks for natural focal infections in the territory of new subjects of the Russian Federation (Donetsk People's Republic, Lugansk People's Republic, Zaporozhye and Kherson regions)

An epizootological inspection of the liberated territories of the Donetsk and Lugansk People's Republics, Zaporozhye and Kherson regions was carried out. It was established that the faunal complex of small mammals, hare-like and ectoparasites, as well as their number, make it possible to ensure the circulation of natural focal infections identified by the results of laboratory studies: tularemia, Crimean hemorrhagic fever (CHF), West Nile fever (WNF), ixodic tick-borne borreliosis (ITB), rickettsiosis, human granulocytic anaplasmosis (HGA), leptospirosis, hemorrhagic fever with renal syndrome (HFRS), Q fever, intestinal yersiniosis, Batai, Inco, Sindbis, Tyaginya fevers. For the first time, the PCR method in field material from the Zaporozhye region (Berdyansk and Melitopol regions) detected the Crimean-Congo hemorrhagic fever virus, on the territory of the Donetsk and Lugansk People's Republics in the populations of small mammals (rodents and insectivores), the circulation of viruses Inco, Sindbis, Tyagin, Batai was established. In the territories of Kherson and Zaporozhye regions, the presence of combined and conjugated natural foci of ixodic tick-borne borreliosis, rickettsiosis and human granulocytic anaplasmosis is determined. According to the results of molecular genetic analysis, it was shown that the causative agents of natural focal infections (Crimean hemorrhagic fever, West Nile fever, ixodic tick-borne borreliosis, rickettsiosis) identified in 2023 are genetically close to strains circulating in the regions of the south European part of Russia.

Tick-borne diseases in the North Sea region–A comprehensive overview and recommendations for diagnostics and treatment

As part of the NorthTick project, co-funded by the European Union through the European Regional Development Fund and the North Sea Region Programme, specialists in the field of tick-borne diseases from seven North Sea countries co-operated with patient organisations and governmental health care institutions to provide this comprehensive overview of diagnostics and treatment recommendations in the region for Lyme borreliosis, Borrelia miyamotoi infection, tick-borne encephalitis, human granulocytic anaplasmosis, rickettsiosis, neoehrlichiosis and babesiosis. The main conclusion is that the recommendations in these northern countries are essentially the same, with very few differences. This overview presents the current diagnostics and provides useful clinical guidance.

Rab27a via Its effector JFC1 Localizes to Anaplasma Inclusions and Promotes Anaplasma Proliferation in Leukocytes

Anaplasma phagocytophilum is an obligatory intracellular bacterium that causes tick-borne zoonosis called human granulocytic anaplasmosis. Mechanisms by which Anaplasma replicates inside of the membrane-bound compartment called “inclusion” in neutrophils is incompletely understood. A small GTPase Rab27a is found in the secretory granules and multivesicular endosomes. In this study we found Rab27a-containing granules were localized to Anaplasma inclusions in guanine nucleotide-dependent manner, and constitutively active Rab27a enhanced Anaplasma infection and dominant-negative Rab27a inhibited Anaplasma infection. Rab27a effector, JFC1 is known to mediate docking/fusion of Rab27a-bearing granules for exocytosis in leukocytes. shRNA stable knockdown of Rab27a or JFC1 inhibited Anaplasma infection in HL-60 cells. Similar to Rab27a, JFC1 were localized to Anaplasma inclusions by immunostaining, and fluorescent probe transfection in live cells. The JFC1 C2A domain that binds 3'-phosphoinositides, was sufficient and required for JFC1 and Rab27a localization to Anaplasma inclusions which were enriched with phosphatidylinositol 3-phosphate. Nexinhib20, the small molecule inhibitor specific to Rab27a and JFC1 binding, inhibited Anaplasma infection. Taken together, these results imply elevated phosphatidylinositol 3-phosphate in the inclusion membrane recruits JFC1 to mediate Rab27a-bearing granules/vesicles to dock/fuse with Anaplasma inclusions, the lumen of which is topologically equivalent to the exterior of the cell to benefit Anaplasma proliferation.

1779. Trends in Anaplasmosis Over the Past Decade: A Review of Clinical Features, Laboratory Data and Outcomes

Abstract Background Human granulocytic anaplasmosis (HGA) is an emerging tick-borne illness endemic to the northeastern and midwestern United States. Risk factors for the severity of infection, predictors for hospitalization, temporal trends, co-infections, and outcomes are poorly studied. Methods We conducted a retrospective review of HGA at Mayo Clinic, Rochester, between 2011-2021. Cases were identified by positive Anaplasma PCR at our reference laboratory. Variables included patients’ characteristics, symptoms, risk factors for tick-borne illness, laboratory parameters, co-infections, treatment, and clinical outcomes. Results We identified 471 cases with a positive Anaplasma PCR, and 146 cases were included in this interim analysis. Table 1 shows a summary of the baseline characteristics. An increasing annual trend in diagnosis of HGA was noted from 2014 to 2016 with lower rates observed during COVID-19 pandemic (2020 to 2022) (Figure 1). Of the 146 patients, 19 (13%) were immunocompromised secondary to hematologic malignancies, solid organ malignancies, and pharmacological immunosuppression. Frequently reported symptoms included fever (79.5%), malaise (68.5%), chills (51.4%), and myalgia (50%). Tick exposure was documented in 79.2 % of cases. Forty-seven (33%) patients were hospitalized; older patients were more likely to be hospitalized (Table 2). The most common complications among the hospitalized patients included respiratory failure (50%), encephalopathy (44.4%) and renal failure (37.5%). One patient required ICU admission. Twenty-five patients (17.5%) and one patient (0.7%) were co-infected with Lyme and Ehrlichiosis, respectively. Higher rates of leukopenia and thrombocytopenia were associated with mono-infection with Anaplasma (p < 0.001). Follow up data was available for 136 patients; all of them had favorable response to doxycycline.Table 1:Summary of baseline characteristics, labs and treatment.Table 2:Predictors of HospitalizationFigure 1:Annual Trends in Anaplasmosis from 2011-2021. Conclusion Our study demonstrated comprehensive clinical characteristics of patients with HGA. Interestingly, tick exposure history was common, yet most patients did not have other tick-borne co-infections. Furthermore, only a minority of patients developed severe diseases and required hospitalization. The recent decline in cases during the early part of the COVID-19 pandemic is worth further investigation. Disclosures All Authors: No reported disclosures

Strains of Anaplasma phagocytophilum from horses in Ohio are related to isolates from humans in the northeastern USA.

The tick-borne obligatory intracellular bacterium Anaplasma phagocytophilum infects granulocytes of humans as well as domesticated and wild animals, causing a febrile disease collectively called granulocytic anaplasmosis. The host species specificity and zoonotic potential of A. phagocytophilum strains remain unclear. In the USA, human granulocytic anaplasmosis (HGA) is primarily reported in Wisconsin and Minnesota, the northeastern coastal states, and northern California. In horses, A. phagocytophilum causes equine granulocytic anaplasmosis (EGA). Although EGA has been reported in the same US regions as HGA, horses with a definitive diagnosis of EGA have not been reported in Ohio, where the incidence of HGA is low. In this study, samples from archived blood smears or whole blood from three horses from three different counties in Ohio that presented in 2018, 2020, and 2021 with clinical signs and laboratory findings consistent with EGA were evaluated by PCR and sequencing. Sequences of ankA (encoding ankyrin A) of the three A. phagocytophilum strains were identical and related to strains isolated from humans in the northeastern USA yet distinct from those in California or Europe based on phylogenetic analysis. Each Ohio strain contains unique A. phagocytophilum p44 genes encoding the immunodominant major outer membrane proteins, underscoring the antigenic diversity of A. phagocytophilum strains that cause EGA in Ohio. From 2018 to 2023, 14 additional cases of EGA were identified by serodiagnosis in Ohio and nearby locations in Pennsylvania, pointing to a heretofore unrecognized prevalence of EGA and the risk of transmission of anaplasmosis to humans and animals in this region.IMPORTANCEThe tick-borne obligatory intracellular bacterium Anaplasma phagocytophilum infects humans as well as domesticated and wild animals, causing a febrile disease collectively called granulocytic anaplasmosis. The epidemiology and the host species specificity and zoonotic potential of A. phagocytophilum strains remain unclear. In this study, ankA (encoding ankyrin A) and p44 gene sequences of A. phagocytophilum were determined in clinical specimens from horses in Ohio and compared with those found in A. phagocytophilum strains from various hosts and geographic regions. With increasing numbers of seropositive horses, the study points out the unrecognized prevalence and uncharacterized strains of A. phagocytophilum infection in horses and the importance of A. phagocytophilum molecular testing for the prevention of equine and human granulocytic anaplasmosis.

Granulocytic anaplasmosis in cats from central Europe and molecular characterization of feline Anaplasma phagocytophilum strains by ankA gene, groEL gene and multilocus sequence typing

BackgroundAnaplasma phagocytophilum is a Gram-negative obligate intracellular bacterium that replicates in neutrophil granulocytes. It is transmitted by ticks of the Ixodes ricinus complex and causes febrile illness called granulocytic anaplasmosis primarily in humans, horses, dogs, sheep, cattle and goats. In comparison, clinically apparent disease has been described rarely in cats especially compared to dogs and horses. It is currently unknown whether cats are less susceptible to A. phagocytophilum or whether granulocytic anaplasmosis might be underdiagnosed in cats.MethodsTo address this question, we examined clinical signs and laboratory findings in seven A. phagocytophilum infected cats from Germany and Switzerland. We then genetically characterized feline A. phagocytophilum strains and compared them to those from other hosts showing clinically apparent disease. For this purpose, ankA-based, groEL-based and multilocus sequence typing (MLST) were applied. Furthermore, the concordance between these typing methods was assessed.ResultsFever, lethargy and anorexia were the most common clinical signs in cats suffering from granulocytic anaplasmosis. The most frequent laboratory finding was thrombocytopenia. All three typing methods consistently indicated that the A. phagocytophilum strains found infecting cats are the same as those that cause disease in humans, dogs and horses. In general, the three typing methods applied exhibited high concordance.ConclusionsThe genetic characterization of the feline A. phagocytophilum strains indicates that strain divergence is not the explanation for the fact that granulocytic anaplasmosis is much less frequently diagnosed in cats than in dogs and horses. Otherwise, it may be possible that cats are less susceptible to the same strains than dogs and horse are. However, due to the unspecific clinical signs, it should be considered that granulocytic anaplasmosis may be under-diagnosed in cats.Graphical