Search Results (1,013)

Background: Anaplasmosis is an emerging tick-borne infection that typically presents as a non-specific febrile illness, with variable degrees of cytopenias and liver tests abnormalities. Severe complications remain atypical and uncommon. Case Report: We report a case of acute pulmonary embolism (PE) occurring during confirmed anaplasmosis in a 73-year-old male with no traditional thromboembolic risk factors. The patient presented with fever, constitutional symptoms, thrombocytopenia, leukopenia, and abnormal liver tests, raising suspicion for a tick-borne illness. Despite early clinical improvement on doxycycline, persistent tachycardia triggered further evaluation and uncovered an acute PE. Comprehensive workup at admission and repeated 14 months later excluded inherited and acquired thrombophilias, malignancies, autoimmune diseases, and alternative infectious etiologies. The patient was treated with doxycycline 100 mg orally twice daily for 10 days and anticoagulation with unfractionated heparin followed by 6 months of apixaban for a first episode of provoked PE. He attained complete clinical recovery without recurrence of thrombosis at the two-year follow-up. Discussion: Infectious diseases are increasingly recognized as contributors to thrombosis through inflammation-mediated hypercoagulability and endothelial dysfunction. Pulmonary involvement in anaplasmosis typically manifests as pneumonitis, pneumonia or acute respiratory distress syndrome, but thrombotic complications such as PE are exceedingly rare. This case highlights a rare but clinically significant vascular complication of anaplasmosis and underscores the importance of considering thromboembolic events in patients with persistent or unexplained tachycardia. Conclusions: As the incidence of anaplasmosis continues to rise, greater awareness of its potential cardiovascular manifestations is essential. Early recognition and prompt treatment with doxycycline remain critical, while further studies are needed to better define the thrombotic risk associated with this infection. Full article

Ticks are haematophagous ectoparasites and vectors of a diverse range of pathogens, exerting substantial impacts on wildlife, domestic animals and public health. In Australia, despite the country’s rich and unique biodiversity, a comprehensive understanding of ticks and tick-borne pathogens associated with wildlife remains limited. Environmental change, urban expansion and climate variability are increasingly disrupting wildlife habitats, potentially intensifying interactions between wildlife hosts, ticks and humans. A broad evidence synthesis of studies published between January 1940 and March 2024 was conducted, retrieving 133 eligible records from Web of Science, CABI Abstracts and PubMed databases. Fifty tick species parasitising 160 wildlife species were identified, predominantly from the genera Ixodes, Amblyomma and Haemaphysalis. The most commonly reported hosts included marsupials, particularly bandicoots, wallabies and possums, with notable tick species being Ixodes tasmani, Ixodes holocyclus and Amblyomma triguttatum. Microorganism records were relatively limited and mostly represented molecular detections or reported associations, including Babesia, Borrelia, Coxiella, Rickettsia and Theileria species, rather than confirmed vector competence, reservoir status or pathogenicity. Key limitations included geographic sampling biases towards eastern Australia, limited molecular identification of ticks and infrequent pathogen screening, particularly regarding the ecology, epidemiology and molecular diversity of host–vector–microorganism interactions. Improved surveillance, expanded molecular characterisation, and integrated One Health investigations are required to better understand the ecological and public health significance of these host–vector–microorganism interactions. Full article

Spotted fever group (SFG) rickettsioses are emerging zoonotic diseases of increasing relevance in Latin America, yet the specific species involved in human infections remain poorly defined in many endemic regions. This study aimed to determine the most probable antigen among SFG-seroreactive febrile patients from Villeta, Colombia. A panel of 25 convalescent-phase serum samples previously identified as positive for SFG Rickettsia spp. antibodies was analyzed by indirect immunofluorescence assay using antigens of Rickettsia rickettsii, R. amblyommatis and R. parkeri. Antibody titers were compared to identify differential seroreactivity patterns. Overall, 44% (11/25) of the samples showed differential antibody titers against one of the tested antigens. Among these, nine (36%) exhibited higher titers to R. parkeri and two (8%) to R. amblyommatis, while none showed exclusive reactivity to R. rickettsii. The remaining 56% (14/25) presented similar titers across antigens, consistent with indeterminate or cross-reactive SFG responses. Antibody titers ranged from 1:128 to 1:4096, with R. parkeri showing the strongest reactivity. These findings suggest R. parkeri or a highly related Rickettsia species as the predominant probable antigen in Villeta, highlighting its potential role in mild rickettsial infections and emphasizing the need for eco-epidemiological studies to identify local vectors and reservoirs. Full article

In Cambodia, livestock production plays an important role in the national economy and food security, yet tick-borne diseases remain an underrecognized constraint on animal health and productivity. Domestic animals may also serve as reservoirs of zoonotic pathogens in this predominantly rural setting. To address the lack of baseline molecular data on tick-borne pathogens in Cambodia, we conducted a cross-sectional study of ticks collected from November 2022 to April 2023 across 24 provinces. Ticks were collected from various hosts and environments, including cats, cattle, dogs, goats, pangolins, pythons, wild pigs, and bat cave floors, representing urban, rural, farm, wildlife rescue center, and forest fringe habitats. A total of 1526 ticks belonging to nine species were pooled into 352 samples and screened using conventional PCR (cPCR) targeting Anaplasma, Ehrlichia, Babesia, and Coxiella. Additionally, a subset of Rhipicephalus microplus ticks was analyzed using metatranscriptomic next-generation sequencing (NGS). Rhipicephalus microplus ticks collected from cattle tested positive for Anaplasma marginale (1.1% of pools) and Ehrlichia minasensis (0.9% of pools), whereas Rhipicephalus linnaei ticks collected from dogs were positive for Anaplasma platys (0.3% of pools) and Babesia canis (2.0% of pools). A high prevalence of Coxiella-like endosymbionts (15.6% of pools) was found in R. microplus from both cattle and goats. Metatranscriptomic analysis also identified six tick-associated viruses in R. microplus from cattle; with Guangdong tick manly virus being the most dominant (32.5% of samples); followed by Zhangzhou Totiv tick virus 1 (15.0%), Jingmen tick virus (5.0%), and Mogiana tick virus; Rhipicephalus-associated rhabdo-like virus; and Rhipicephalus-associated flavi-like virus; each at 2.5%. These findings provide the first molecular evidence of numerous bacterial, protozoal, and viral pathogens circulating in R. microplus and R. linnaei in Cambodia. The study highlights the need for integrated One Health surveillance to better understand, prevent, and control tick-borne diseases in the region. Full article

Background: Crimean–Congo hemorrhagic fever virus (CCHFV) is an important tick-borne zoonosis and an emerging public health threat across Africa. Although evidence of viral circulation is mounting, information remains fragmented, limiting a comprehensive understanding of transmission ecology, regional hotspot heterogeneity, and preparedness needs across the continent. Methods: This narrative review critically synthesized published literature on CCHFV in Africa, identified through PubMed, Scopus, and Google Scholar and supplemented by citation tracking and authoritative public health reports. Evidence from epidemiological, ecological, molecular, surveillance, and One Health studies was integrated to examine transmission dynamics, geographic hotspot distribution, viral diversity, risk factors, diagnostic and surveillance challenges, and preparedness strategies. Results: Available evidence shows marked geographic heterogeneity in CCHFV transmission across Africa, with hotspot regions shaped by ecological suitability, Hyalomma tick distribution, livestock–human interactions, and health system capacity. Livestock consistently show higher exposure than humans, underscoring their role as key indicators of viral circulation. Diagnostic limitations, passive surveillance, ecological variability, and serological cross-reactivity contribute to substantial under recognition of disease burden, while molecular studies reveal considerable viral diversity and ongoing evolution across African regions. Conclusions: CCHFV remains underdiagnosed and underreported in many African settings because of limited surveillance and diagnostic capacity. Strengthening integrated One Health surveillance, expanding laboratory and genomic capacity, utilizing livestock as sentinel populations, and improving cross-sectoral collaboration are critical for enhancing early detection, outbreak preparedness, and effective public health response across the continent. Full article

Rocky Mountain spotted fever (RMSF), caused by Rickettsia rickettsii, is a potentially severe tick-borne disease affecting both dogs and humans. While commercial in-clinic diagnostic tests have improved the detection of several common canine tick-borne diseases, RMSF is not routinely included in many point-of-care screening panels. In addition, infected dogs may present with subtle or nonspecific clinical signs, making diagnosis challenging. This retrospective observational study evaluated the occurrence of PCR-confirmed Rickettsia rickettsii infection in dogs presented to a veterinary lameness and performance referral center. From March 2022 through February 2024, a convenience sample of 51 dogs underwent RMSF testing as part of their diagnostic evaluation. Blood samples were analyzed using a commercial vector-borne disease PCR panel. Overall, 13 of 51 dogs (25.5%) were PCR-positive for Rickettsia rickettsii. Thirty-six dogs originated from North Carolina and South Carolina, of which 13 (36.1%) were PCR-positive. These findings suggest that RMSF should be considered among the differential diagnoses in dogs presenting with unexplained lameness, reduced athletic performance, or other nonspecific clinical concerns in regions where tick-borne diseases are common. The identification of PCR-confirmed Rickettsia rickettsii infection in this referral population highlights the potential value of expanded vector-borne disease testing. Full article

Crimean-Congo hemorrhagic fever (CCHF) is a tick-borne zoonotic disease of significant public health concern, particularly in endemic regions. However, data on the distribution and circulation of Crimean-Congo hemorrhagic fever virus (CCHFV) in animal populations remain limited, despite their importance for assessing virus circulation and infection patterns. A cross-sectional seroepidemiological study was conducted in North Macedonia (N. Macedonia) to determine the seroprevalence rates of CCHFV in small ruminants and to identify areas at increased risk of virus circulation. A total of 1992 sera samples from sheep and goats were tested for Crimean-Congo hemorrhagic fever virus (CCHFV) antibody using a commercial enzyme-linked immunosorbent assay (ELISA). Data on species, age, animal origin, and risk factors (questionnaire) were collected and analyzed. Overall, true seroprevalence, calculated by adjusting the apparent seroprevalence according to the diagnostic performance of the ELISA assay in order to estimate the actual prevalence in the studied population, was 25.02% (493/1992; 95% CI 23.11–26.94). Sheep showed higher seroprevalence rates, 27.34% (397/1452; 95% CI 25.11–29.69), compared to goats, 17.78% (96/540; 95% CI 14.78–21.23). Seroprevalence rates varied markedly across regions, ranging from 2.41% to 49.80%, with the highest values observed in the Eastern and Vardar regions. Seroprevalence rates increased with age, reaching the highest values in animals aged ≥ 5 years, 27.27% (81/297; 95% CI 22.52–32.60). Small ruminants, particularly sheep, may serve as useful indicators for defining the high-risk areas for CCHFV transmission, providing valuable support for a One Health approach. Full article

Canine monocytic ehrlichiosis, caused by Ehrlichia canis, is an important tick-borne disease of dogs in tropical and subtropical regions. This cross-sectional study investigated the occurrence, associated risk factors, and molecular confirmation of E. canis infection among clinically suspected dogs in Andhra Pradesh, India, and evaluated the diagnostic performance of blood smear microscopy relative to PCR. Peripheral blood samples were collected from 442 clinically suspected dogs presented to 90 veterinary dispensaries across the state. Dogs were selected based on clinical features suggestive of ehrlichiosis, including inappetence, pale mucous membranes, tick infestation, fever, lymphadenopathy, weakness, and hemorrhagic signs. Samples were examined by Giemsa-stained blood smear microscopy and subsequently tested by PCR. Representative virB9 gene amplicons were sequenced and compared with reference sequences available in GenBank. Microscopy detected E. canis in 37/442 dogs (8.37%), whereas PCR detected infection in 51/442 dogs (11.54%). Logistic regression analysis indicated that female dogs, mongrels, kennel dogs, and dogs with tick infestation had significantly higher odds of infection, while dogs with a history of tick-control measures had lower odds. Sequence comparison and phylogenetic placement based on the partial virB9 fragment supported molecular confirmation of the detected E. canis isolates and showed similarity with previously reported Indian and international isolates. These findings provide regional evidence on the occurrence and epidemiology of canine ehrlichiosis in clinically suspected dogs and support PCR as a more reliable confirmatory method than microscopy. Full article

Mechanisms of arboviral neuroinvasion are still incompletely resolved, despite longstanding emphasis on the blood-brain barrier (BBB) as the principal interface for central nervous system (CNS) entry. While BBB-centered models have been highly informative, they may underrepresent the contribution of other CNS border structures, particularly the choroid plexus and the blood-cerebrospinal fluid barrier (BCSFB). Here, we re-examine the BCSFB as a relevant but unevenly supported neuroinvasion interface in arboviral encephalitis. The strongest direct evidence is currently available for Zika virus (ZIKV), for which experimental studies support infection of choroid plexus-associated cells and CNS access through the blood-CSF axis. Semliki Forest virus (SFV) provides additional direct, although still limited, support for this concept. In contrast, for West Nile virus (WNV), Japanese encephalitis virus (JEV), and tick-borne encephalitis virus (TBEV), evidence for choroid plexus involvement remains indirect or insufficiently resolved, even though neuroinvasion itself is well established. We therefore argue not for replacement of BBB-centered models, but for broader integration of the BCSFB into current frameworks of arboviral CNS invasion. This evidence-based perspective supports a hierarchical, virus-dependent view of choroid plexus involvement and highlights the need for mechanistic studies that directly test when and how this interface contributes to encephalitic disease. Full article

Ticks are important arthropod vectors that transmit various pathogens to humans, livestock, and wildlife, thereby contributing significantly to the global burden of vector-borne diseases. The tick microbiome, consisting of bacteria, viruses, protozoa, and other microorganisms, plays a crucial role in pathogen transmission dynamics and the emergence of new zoonotic diseases. This review examines the characteristics of tick vectors, the composition and dynamics of tick-associated microbiomes, and their implications for zoonotic disease transmission. We analyze current knowledge of tick-borne pathogens, including Borrelia burgdorferi sensu lato, Rickettsia species, Anaplasma species, and Coxiella species, and highlight the potential for microbiome constituents to serve as reservoirs for emerging pathogens. The complex interactions between tick hosts, their microbiomes, and vertebrate hosts create opportunities for pathogen evolution and interspecies transmission. Recent advances in molecular techniques have revealed previously unknown microbial diversity within tick populations, suggesting that many potential zoonotic pathogens remain undiscovered. We discuss future research directions, including field screening methodologies for pathogen detection, microbiome-based risk assessment approaches, and the development of novel prevention strategies, including tick vaccines. Full article

Babesia microti is the primary agent of human babesiosis, an emerging tick-borne disease with limited treatment options and growing evidence of drug resistance. Deubiquitinases (DUBs) play critical roles in protein homeostasis and host–pathogen interactions, yet none have been characterized in B. microti. Here, we report the first molecular cloning, expression, and functional characterization of an OTU-like cysteine protease from B. microti (bm-OTU). The recombinant bm-OTU protein (~22 kDa) was expressed in E. coli, purified to high homogeneity, and exhibited ~93% solubility under native conditions. In vitro fluorogenic assays confirmed its deubiquitinase activity. Expression of bm-OTU in HEK293T cells was associated with reduced ubiquitination in cells and increased apoptosis in this overexpression model, as demonstrated by flow cytometry and Western blot analyses. Furthermore, transcriptomic analysis revealed that bm-OTU modulates host immune pathways, notably suppressing the expression of interferon-stimulated genes (APOBEC3G, G1P2) while upregulating the pro-apoptotic gene BAK and the inflammasome sensor AIM2. These findings establish bm-OTU as a functional deubiquitinase and a potential virulence factor that may contribute to immune evasion and pathogenesis in babesiosis and may represent a potential target, pending further validation. Full article

Tick-borne encephalitis (TBE) is an emerging vector-borne disease in Europe, but its epidemiology remains poorly defined in Serbia. In orthoflavivirus-endemic settings, diagnostic challenges may contribute to underrecognition of TBE, particularly among patients with suspected West Nile virus (WNV) infection. We conducted a multicenter retrospective study including patients hospitalized between 2018 and 2023 with suspected WNV neuroinvasive disease or viral encephalitis of unknown etiology. Serum samples were tested for TBEV-neutralizing antibodies using a microneutralization assay. Among 79 patients, TBEV-neutralizing antibodies were detected in four (5.1%). Most reactive cases occurred in patients initially classified as having suspected WNV-associated meningoencephalitis, while TBE had not been considered in the differential diagnosis at admission. These findings suggest that TBE may be underrecognized in Serbia and highlight the importance of confirmatory testing in orthoflavivirus-endemic settings. Strengthening clinical awareness and surveillance will be essential to better define the burden of TBE and inform prevention strategies. Full article

In this study, we combined computational predictions with experimental validation as a hybrid strategy to explore whether the E protein of tick-borne encephalitis virus (TBEV) possesses autoimmune potential. Using in silico homology searches, we identified two viral epitopes (evglekl and vtgtqgt) within the TBEV E protein that share sequence identity with fragments of the human proteins DNAH7 and CSMD2. Antibodies against these epitopes were detected in the plasma of a subset of patients after natural TBEV infection. Notably, no such antibodies were found in recipients of the Tick-E-Vac vaccine, indicating that the current vaccine does not induce cross-reactive humoral responses to these epitopes. Further computational analysis predicted that these epitopes could be presented by HLA class II molecules (alleles DRB1*09:01 and DRB1*07:01), which are known to be associated with autoimmune pathologies. Molecular dynamics simulations confirmed stable binding of the peptides within the HLA grooves, with favorable binding energies. These findings suggest a possible involvement of T-helper cells in the autoreactive process. Natural TBEV infection can give rise to antibodies against epitopes homologous to human proteins, particularly in genetically predisposed hosts. While such homology alone does not predict the onset of autoimmune disease, it represents a risk factor. Full article

Babesiosis is a zoonosis caused by protozoan parasites of the genus Babesia. It has a worldwide distribution and affects many kinds of mammals, principally domestic animals and humans. Because there are no safe and effective vaccines available, the treatment and control for babesiosis continues to involve the use of chemotherapeutics. For years, only a few drugs have been used for clinical treatment, namely atovaquone plus azithromycin or clindamycin plus quinine for human, and imidocarb dipropionate and diminazene aceturate for domestic animals. Although screening and developing alternative drugs are continuously pursued, only a few drugs have been prospected to have clinical applications. Of these, tafenoquine has shown wide and potent antibabesial activity, offering a new option to control babesiosis. This article aims to present the current clinical therapeutic strategies for babesiosis and their limitations, as well as the prospect of tafenoquine as a promising drug to treat babesiosis. Full article

Tick-borne encephalitis virus (TBEV) is a major arthropod-borne flavivirus responsible for severe neurological disease in humans across Europe and Asia. It is maintained in nature through complex interactions within ticks and between tick vectors, vertebrate hosts and environmental factors. This review summarizes current knowledge on TBEV–tick interactions, focusing on virus acquisition, dissemination, vector competence, and long-term persistence within tick vectors. TBEV is acquired by ticks during blood feeding on viremic hosts or through co-feeding transmission under experimental conditions. Transovarial transmission has also been reported, as indicated by the detection of infected larvae in nature, although its efficiency appears to be low and variable. Following ingestion, TBEV infects and replicates in the tick midgut before dissemination via the hemolymph to secondary tissues, including the salivary glands and reproductive organs, which are essential for viral persistence and transmission. Vector competence and capacity vary between tick species and are shaped by intrinsic and extrinsic factors. Although transstadial transmission and transovarial transmission contribute to long-term virus maintenance, their efficiency is generally low and variable. In vitro models, including tick cell lines, have provided valuable insights into virus–tick interactions. Nevertheless, important knowledge gaps remain, particularly in understanding early events at the tick–host interface and mechanisms underlying viral dissemination and persistence within ticks. Full article