Search Results (436)

Brazilian spotted fever (BSF) is a tick-borne acute febrile disease that can be lethal to humans, caused by the bacterium Rickettsia rickettsii. In the State of São Paulo, transmission occurs mainly through two tick species: Amblyomma sculptum and Amblyomma aureolatum. We analyzed trends in BSF incidence and mortality in relation to the spatial distribution of these vector species in the State of São Paulo from 2007 to 2017 and evaluated clinical outcomes according to hospitalization location. In A. sculptum areas, incidence and mortality showed significant increasing trends between 2007 and 2015 (p-value < 0.05). In contrast, A. aureolatum areas exhibited a significant decrease in incidence (p-value < 0.05), while mortality remained stable throughout the study period. Lethality was substantially higher in cases associated with A. aureolatum than in those linked to A. sculptum (67.1% versus 55.0%, p-value = 0.037). Most patients received care in hospitals located near the probable site of infection. Incidence and mortality patterns differed sharply between vector-specific areas, with notably higher mortality in A. aureolatum-related cases. These findings highlight the importance of incorporating vector distribution into surveillance, prevention, and clinical management strategies to better address the distinct epidemiological contexts within the State of São Paulo. Full article

Endosymbiotic bacteria influence the ecology and evolution of insects through complex associations within host cells. To explore how these relationships vary among environments and taxa, we examined 1028 insect specimens from 14 orders across Korea for infections by three representative endosymbionts (Wolbachia, Rickettsia, and Spiroplasma). Overall, 33.8% of specimens were infected, with single infections predominating and co-infections remaining relatively less common. Weak-to-modest but statistically significant associations were detected between several symbiont pairs (Rickettsia–Spiroplasma, Wolbachia–Spiroplasma, and Wolbachia–Rickettsia). Infection rates exhibited no significant variation among host orders except for Spiroplasma, and Wolbachia infections were more frequently detected in terrestrial than in aquatic insects. These results indicate that endosymbiont infection patterns might be shaped by factors operating at multiple biological scales, including host taxonomy and habitat types. As this study relied on polymerase chain reaction detection, infection frequencies should be interpreted as comparative rather than absolute measures. This survey provides baseline data that might help characterize regional patterns of endosymbiont distributions and their variation across taxonomic and ecological contexts. Full article

Ticks are one of the most important vectors of zoonotic pathogens in Europe, including Rickettsia spp. In Romania, several pathogenic species belonging to the Spotted Fever Group (SFG) transmitted primarily through tick bites have been identified. The aim of the present study was to determine the prevalence of Rickettsia spp. infection in ticks collected from public shelter dogs in Tulcea County, Romania, as an indicator of pathogen circulation within shelter environments and their potential epidemiological relevance. A total of 730 ticks collected between March 2023 and September 2024 from 216 public shelter dogs, belonging to four species (Rhipicephalus sanguineus s.l., Ixodes ricinus, Dermacentor marginatus, and Dermacentor reticulatus), were morphologically identified and pooled by species, sex, and developmental stage resulting in 132 pools. DNA extracted from pools was tested by Real-Time PCR, targeting the gltA gene, specific for Rickettsia spp. Overall, 123/132 (93.2%) pools tested positive for Rickettsia spp. DNA, while the Minimum Infection Rate (MIR) at tick level was 16.8%. High pool positivity rates were consistently observed across all four species: 93.6% positive pools for Rhipicephalus sanguineus s.l. (MIR 15%), 88.2% for Ixodes ricinus (MIR 20.5%), 87.5% for Dermacentor marginatus (MIR 58.3%), and 100% for Dermacentor reticulatus (MIR 21.7%). These findings demonstrate a substantial circulation of Rickettsia spp. in dog-shelter associated ticks, highlighting the role of dogs as sentinel hosts. Continuous molecular surveillance and identifying circulating species is needed for a better determination of the zoonotic risk. Full article

Diagnosis of rickettsial infections is challenging due to nonspecific clinical symptoms and limitations of current diagnostic methods. Molecular assays allow early detection but are limited by cost and technical demands, whereas conventional serological tests often exhibit cross-reactivity and low sensitivity during the early stages of infection. This study aimed to develop and evaluate a recombinant-antigen sandwich ELISA for improved antibody detection against Rickettsia spp. Three Rickettsia akari proteins, rGroEL, rDnaK, and rA8GP63 (uncharacterized protein), were produced and validated for immunogenicity. The assay was evaluated using 94 patient serum samples, including those with positive, negative, and unknown clinical course. The optimized ELISA demonstrated high reproducibility, with IgG sensitivity of 89.47–95.39% and specificity of 90%. IgM detection, also assessed, showed lower sensitivity (42.11–82.89%) but maintained strong specificity (83.33%). The diagnostic performance was comparable to that of a commercial indirect immunofluorescence assay, with no cross-reactivity detected in sera from patients with unrelated infections. rDnaK and rA8GP63 represent newly explored diagnostic candidates. These findings highlight the potential of this recombinant protein-based ELISA as an accessible, sensitive and specific diagnostic tool, with a meaningful clinical impact for improving the early and accurate detection of rickettsial infections. Full article

Ticks transmit diverse pathogens, posing significant public health threats in northeastern China; clarifying human-biting tick species and their carried pathogens is crucial for risk assessment and prevention. This study was designed as a pathogen detection and molecular epidemiological investigation. During the May-August period of each of 2023 and 2024, 232 ticks that had bitten humans were collected from a local sentinel hospital. Ticks were morphologically identified, followed by DNA extraction, semi-nested/nested PCR targeting specific genetic markers, and Sanger sequencing to detect bacterial pathogens. Four tick species were found, with Ixodes persulcatus dominant (87.9%), followed by Dermacentor silvarum (6.9%), Haemaphysalis concinna (3.5%), and Haemaphysalis japonica (1.7%). Seven bacterial pathogens were detected, including Candidatus Rickettsia tarasevichiae (35.3%) and Borreliella garinii (17.2%); 49.6% of ticks were pathogen-positive. The coinfection rate was 13.8%, most commonly Candidatus R. tarasevichiae plus B. garinii, and I. persulcatus carried all pathogens. These findings provide basic data on human-biting tick species and their bacterial pathogen spectrum in the region, serving as a reference for subsequent tick-borne disease research and targeted prevention. Full article

The gut microbiota of insects plays a fundamental role in modulating host physiology, including nutrition, development, and adaptability to environmental challenges. The rice water weevil, Lissorhoptrus oryzophilus Kuschel (Coleoptera: Curculionidae), is a major invasive pest of rice worldwide, yet the composition and functional profile of its gut microbial community remain poorly characterized. Here, we employed metagenome sequencing on the Illumina NovaSeq X Plus platform to explore the gut microbial diversity and predicted functions in adults of L. oryzophilus. Our results revealed a rich microbial community, comprising 26 phyla, 42 classes, 72 orders, 111 families, and 191 genera. The bacterial microbiota was overwhelmingly dominated by the phylum Proteobacteria (85.13% of total abundance). At the genus level, Pantoea (48.86%) was the most predominant taxon, followed by Wolbachia (14.57%) and Rickettsia (11.81%). KEGG analysis suggested that the gut microbiota is primarily associated with metabolic pathways such as membrane transport, carbohydrate and amino acid metabolism, cofactor and vitamin metabolism, energy metabolism, and signal transduction. eggNOG annotation further highlighted significant gene representation in amino acid and carbohydrate transport and metabolism, while CAZy annotation revealed glycosyl transferases (GTs) and glycoside hydrolases (GHs) as the dominant carbohydrate-active enzymes. This study provides the first comprehensive insight into the gut microbiome of L. oryzophilus adults, highlighting its potential role in the ecological success of this invasive pest. Our findings lay groundwork for future research aimed at developing novel microbial-based strategies for the sustainable management of L. oryzophilus. Full article

We investigated tick infestations in stray dogs from Chișinău, the capital of the Republic of Moldova, focusing on tick species distribution, and pathogen infection rates. Ticks were collected from 232 stray dogs across six major urban parks in 2021–2022. A total of 443 ticks were collected, belonging to five species: Ixodes ricinus (43.8%), Dermacentor reticulatus (35.2%), Dermacentor marginatus (20.5%), Rhipicephalus sanguineus s.l. and Haemaphysalis punctata with only 1 specimen. Notably, 92.5% of ticks were adults, while only 7% were nymphs and <1% were larvae. On average, 44.4% of stray dogs were infested with ticks, with an overall mean intensity of ~4.3 ticks per infested dog. Tick burden varied by location: dogs in large, less-maintained parks carried the most ticks. Tick pathogen screening revealed 24.4% of ticks (108/443) carried at least one pathogen. The most frequently detected were Babesia spp. in 12.2% of ticks, Borrelia burgdorferi s.l. in 7.4%, Rickettsia spp. in 3.4%, Anaplasma spp. in 2.5%, and Ehrlichia spp. in 0.5%; 4 ticks harbored co-infections. We discuss implications for public health and animal welfare and recommend control measures such as integrated stray-dog management and vegetation maintenance in urban parks. Full article

Tetracyclines are among the oldest classes of antibiotics, with broad activity against Gram-positive and Gram-negative bacteria, as well as Chlamydia, Legionella, Rickettsia, and Mycoplasma species. Widely used in human and veterinary medicine, agriculture, and aquaculture, they represent approximately 10–12% of the global antimicrobial market. Extensive use has driven the emergence and spread of antimicrobial resistance, posing ecological and public health risks. However, the full extent of these risks remains unclear due to limited data on tetracycline consumption, environmental occurrence, and resistance patterns across sectors. Recent One Health-oriented strategies have promoted the rational use of tetracyclines in medicine, veterinary practice, and agriculture. To reduce environmental accumulation, various degradation and remediation techniques have been developed, though most remain restricted to laboratory or engineered settings. This narrative review provides a comprehensive overview of global tetracycline consumption; environmental occurrence; distribution and concentration levels; resistance mechanisms and prevalence; and mitigation strategies, including antimicrobial stewardship and degradation approaches. Understanding these aspects is essential for developing evidence-based interventions to minimize the environmental and public health impacts of tetracycline use. Full article

This review summarizes the interactions between three major bacterial groups, Rickettsia sp., Bartonella sp. and Yersinia pestis, the flea vectors and the diverse gut microbiota of fleas and highlights open questions. The focus is on the plague pathogen, Y. pestis, which adapted to transmission by fleas several thousand years ago. This caused one of the deadliest infectious diseases known to mankind, and the three pandemics resulted in an estimated 200 million deaths. In the vector, Y. pestis resists the adverse conditions, like other numerous bacterial species. Rickettsia sp. and Bartonella sp. as well as Y. pestis induce specific changes in the microbiota. The presence of bacteria in the ingested blood activates the production of antimicrobial proteins and reactive oxygen species, which normally have no effect on the development of Y. pestis. This bacterium infects mammals by different modes, first by an early-phase transmission and then by biofilm-mediated blockage of the foregut. Both interfere with blood ingestion and lead to reflux or regurgitation of intestinal contents containing Y. pestis into the bite site. Blockage of the gut leads to more attempts to ingest blood, increasing the risk of transmission. The lifespan of the fleas is also reduced. As Y. pestis is still endemic in wildlife in many regions of the world and human infections continue to occur in limited areas, studies of the interactions are needed to find new ways to control the disease. Full article

Ticks use multiple sensory organs to facilitate host detection, including Haller’s organs (HOs) that allow ticks to sense infrared (IR) radiation from potential hosts. Additionally, ticks have primitive eyes to sense light sources. The possibility exists that these senses may detect stimuli that attract ticks to road edge habitat, where IR radiation tends to be elevated. We investigated the role of the HOs and eyes in the attraction of adult American dog ticks, Dermacentor variabilis, towards road edge habitat(s). Adult D. variabilis were collected from multiple study sites and separated into three groups: (1) Haller’s organs removed; (2) eyes painted with black nail polish; and (3) unmodified ticks (control). All tick groups were marked with a unique fluorescent paint color and released 7.5 m from the road edge at two study sites. Tick movements were tracked at night using ultraviolet lights, tick position(s) were recorded using flags, and measurements were recorded to track tick movement in relation to the release point and road edge. Surface temperatures were recorded at the road edge and in the field to detect a potential thermal stimulus. Mixed-effects models were applied to investigate the significance of tick proximity to the road edge between the groups and sites. Our results demonstrated that the control unmodified group was significantly closer to the road edge than the modified groups lacking Haller’s organ or eyes (p ≤ 0.0001, p = 0.0049), leading to the conclusion that unmodified ticks move towards road edges. Modifying ticks, either by removing the HO or eyes of adult D. variabilis decreased tick movement toward road edges. Full article

Semiaphis heraclei Takahashi (Hemiptera: Aphididae) serves as a vital resource for natural enemies from functional plant Cnidium monnieri (L.) Cusson (Apiaceae), playing a crucial role in ecological dynamics. Endosymbionts influence the performance of their hosts. Here, we determined the communities of facultative endosymbionts in aphids from Lonicera japonica Thunb. (Caprifoliaceae), Apium graveolens L. (Apiaceae), and C. monnieri and assessed the performance of four aphid clones. The infection rates of Serratia symbiotica Moran (Gammaproteobacteria: Enterobacteriaceae) and Regiella insecticola Moran (Enterobacteriales: Enterobacteriaceae) reached 100%. Notably, the infection rates of Spiroplasma and Rickettsia varied across host plants. Fitness assessment revealed that aphids performed better on their natal hosts, exhibiting shorter nymphal development times and higher fecundity. S. symbiotica had contrasting effects on aphids based on their origin. It prolonged the development duration and decreased the intrinsic rate of increase (r_m), net reproductive rate (R₀), and finite rate of increase (λ) in aphids collected from plant A. graveolens. However, for aphids collected from plant C. monnieri, it shortened the doubling time (DT) and improved r_m, R₀, and λ, while prolonging the mean generation time. Our studies are the first to investigate the infection status and role of facultative endosymbionts in aphid S. heraclei, extending the documented effects of plant diversity to fluctuations in the infection rate, with potentially far-reaching consequences for related endosymbionts’ ecosystem processes. Full article

The Xinjiang Uygur Autonomous Region, situated in northwest China, boasts a unique geographical position and a consequent variety of environmental characteristics. T. truncatus is prevalent throughout this region as the primary pest affecting various crops. In this study, we analyzed the microbial community structures of endosymbiotic bacteria in T. truncatus collected from 17 regions and three host plants in Xinjiang using 16S rRNA sequencing. Through composition analysis of the endosymbiotic bacteria in T. truncatus from Xinjiang, it was found that the dominant bacterial phyla were Pseudomonadota and Bacillota. At the genus level, in addition to Wolbachia, Cardinium, and Spiroplasma (common symbiotic bacteria in T. truncatus), the infection rate of Rickettsia in T. truncatus in Xinjiang was found to be 92.8%. The diversity of the endosymbiotic bacteria community in T. truncatus is shaped by both host plant species and geographical region. Specifically, the endosymbiotic bacterial diversity in T. truncatus populations on corn was significantly higher than that observed in populations on cotton and soybean (p < 0.05). Furthermore, we discovered the diversity of endosymbiotic bacteria in T. truncatus was significantly higher in southern Xinjiang than in northern Xinjiang (p < 0.05). Full article

In Bhutan, information on rickettsiae is limited to a few epidemiological studies. There is no information on ticks and tick-associated rickettsiae. Ticks were collected opportunistically from domestic animals residing in eight districts where a seroprevalence study had been carried out previously. Morphological identification of the ticks was performed in the United States National Tick Collection and testing for rickettsiae was carried out in the Australian Rickettsial Reference Laboratory. Samples positive for rickettsiae by qPCR were subjected to conventional PCR followed by DNA sequencing and phylogenetic analysis. A total of 200 ticks were sampled from 155 domestic animals including cattle, dogs, goats, horses, yaks, sheep and cats. The ticks belonged to twelve different species, the commonest being Rhipicephalus microplus, followed by Rhipicephalus haemaphysaloides, Haemaphysalis sp. near ramachandrai, Haemaphysalis tibetensis, Haemaphysalis bispinosa, Haemaphysalis sp., Haemaphysalis sp. near davisi, Rhipicephalus sanguineus, Haemaphysalis shimoga, Haemaphysalis hystricis, Ixodes ovatus, and Amblyomma testudinarium. Rickettsial DNA sequence analysis showed that the rickettsiae infesting ticks in Bhutanese domestic animals aligned with R. gravesii, R. canadensis, R. honei, R. africae, R. felis, R. akari, R. australis, R. japonica, R. africae, R. heilongjiangensis, R. conorii, R. peacockii, R. honei, R. massiliae and R. rhipicephali. However, these may not be conclusive due to low bootstrap values in the phylogenetic tree. Bhutan will benefit from larger studies on ticks and tick-borne infections, burden and damage assessment to livestock and human health, public health interventions and clinical guidelines to reduce morbidity and mortality in human and animal health. Full article

Rickettsia rickettsii is the most virulent agent of the genus Rickettsia that causes one of the most relevant vector-borne diseases in the Americas (RRSF). RRSF manifests with many non-specific acute clinical symptoms complicating its diagnosis and can lead to death if not treated appropriately. RRSF has been reported in Canada, the United States of America, Mexico, Costa Rica, Panama, Colombia, Brazil, and Argentina. In addition to R. rickettsii, mild and severe spotted fever group rickettsioses (SFGR) have been reported in the Americas; however, the true prevalence of these diseases is unknown. In Panama, RRSF have been reported in four of 14 provinces during two outbreak periods: five cases including two fatalities were identified in 1950–1951, and 23 cases including 17 fatalities between 2004 and 2025. This paper presents the clinical characterization of a fatal case of RRSF in Coclé province and a severe case of SFGR in a mountainous area of the Gnäbe Buglé Indigenous Comarca (GBIC). Laboratory confirmation was performed by molecular analysis of tissues obtained from necropsies in the case of RRSF and by immunofluorescence assay (IFA) in the case of SFGR. Furthermore, this paper identifies existing gaps in the initial clinical suspicion and pertinent to SFGR in Panama, which may be applicable to other countries in the region. In the last 21 years, cases have occurred upon contact with ticks in rural areas (13), urban and suburban locations (7), rural woodlands (2), and forests (1). Provinces with more cases are Panamá (7 of 23, 6 died), Coclé (5 of 23, 5 died), Colón (3 of 23, 1 died), Panamá Oeste (1 of 23, 1 died), and GBIC (7 of 23, 4 died), including a cluster of seven cases in 2019. Therefore, Coclé province is considered one of the endemic areas for RRSF in Panama, while the latest cases from the GBIC since 2019 indicate that mountainous areas are an eco-epidemiological scenario to include in the transmission of these diseases. Although this disease has a low prevalence, patients who present symptoms commonly associated with more common diseases such as dengue, other arboviruses, malaria, and leptospirosis, among others, should be included in the diagnostic suspicion. Without diagnostic suspicion and adequate treatment, the patient can die. Full article

The increasing prevalence of Lyme disease, tick-borne encephalitis (TBE), and other tick-borne infections such as Babesia, Ehrlichia, Rickettsia, and Anaplasma is a growing public health concern. Existing tick bite prevention strategies are insufficient; therefore, vaccines represent a promising preventive measure. At the moment, only a vaccine for tick-borne encephalitis is available on the market. A vaccine for Lyme disease, however, is at an advanced stage of clinical trials. In this article, we focus on describing the progress in the invention of vaccines for tick-borne diseases. This article analyzes their development and effectiveness. Full article