Evaluation of PCR-based assay for diagnosis of spotted fever group rickettsiosis in human serum samples

Detection of tick-borne bacterial DNA (Rickettsia sp.) in reptile ticks Amblyomma moreliae from New South Wales, Australia

Ticks are major arthropod vectors of disease, transmitting tick-borne pathogens during blood meal episodes. Rickettsia spp. and Borrelia spp. are two tick-borne pathogens of zoonotic concern previously identified in DNA isolates from the tick genera Amblyomma and Bothriocroton associated with reptilian hosts in Australia. Some reports suggest that these reptile ticks bite and attach to humans via accidental parasitism and transmit disease, with the tick Bothriocroton hydrosauri known to transmit Rickettsia honei or Flinders Island Spotted Fever Rickettsia to humans. This descriptive study aims to identify the ticks collected from wild reptiles submitted to veterinary clinics and captured by snake rescuers from New South Wales (NSW), Australia, and detect the presence of tick-borne bacterial DNA using quantitative polymerase chain reaction (qPCR) to detect Rickettsia spp. and Bartonella spp. and conventional nested-PCR to detect Borrelia spp. Morphological identification revealed ticks removed from one eastern blue-tongued lizard (Tiliqua scincoides scincoides) from North-Eastern NSW (Lismore), one eastern blue-tongued lizard from the Greater Sydney area (Canley Heights), one diamond python (Morelia spilota spilota) from the Greater Sydney area (Woronora Heights) and one red-bellied black snake (Pseudechis porphyriacus) from the Greater Sydney Area (Cronulla) in New South Wales were Amblyomma moreliae. No ticks were positive for Bartonella spp. and Borrelia spp. DNA using real-time PCR targeting ssrA gene and nested PCR targeting Borrelia-specific 16S rRNA gene, respectively. Real-time PCR targeting gltA, ompA, ompB and 17kDa gene of Rickettsia spp. revealed 14 out of 16 ticks were positive. The undescribed Rickettsia sp. DNA was identical to that previously recovered from reptile ticks in Australia and closely related to Rickettsia tamurae and Rickettsia monacensis, both of which are aetiologic pathogens of the Spotted Fever Group Rickettsiosis (SFGR). These results accentuate the ongoing need for increased study efforts to understand zoonotic potential of bacteria from reptile ticks and the tick-reptile-human relationship.

First Records of Possibly Human Pathogenic Rickettsia Species in Bat Ticks, Carios vespertilionis, in Sweden

The Soprano pipistrelle bat, Pipistrellus pygmaeus, is a common species in large parts of Sweden. Many of its natural habitats are near human habitations. This creates opportunities for ticks infesting these bats to encounter humans and possibly transmit zoonotic pathogens by tick bites. The bats are often infested with Carios vespertilionis, a tick species that, in addition to bats, has been recorded to bite humans on occasion. This study aimed to investigate if C. vespertilionis acts as a reservoir for Anaplasma phagocytophilum, Neoehrlichia mikurensis, Tick-borne encephalitis virus, and species of Babesia and Rickettsia and to improve currently used conventional PCR protocols for molecular species determination of Rickettsia spp. Ninety-two C. vespertilionis ticks were collected from underneath a bat-box harbouring P. pygmaeus. Pathogen-specific PCR assays showed that 58.4% were positive for Rickettsia spp. and negative for the other pathogens analysed. Phylogenetic analyses indicate that the species belong to R. parkeri, R. conorii, R. slovaca, R. sibirica subsp. mongolotimonae, R. rickettsii, and a hitherto uncultured Rickettsia sp. Several of these species are considered pathogenic to humans. Given the ecology and behaviour of C. vespertilionis, it may be a vector of these rickettsiae among bats and occasionally humans. To determine the Rickettsia species with certainty, and to determine if C. vespertilionis may be a reservoir and vector of the Rickettsia spp., further studies are needed.

Human Rickettsia felis infections in Mainland China

We identified four flea-borne spotted fever cases caused by Rickettsia felis in a retrospective survey of 182 patients with fever of unknown origin (FUO) in China between 2021 and 2022. The clinical signs and symptoms of the patients were similar to those of other rickettsioses, including fever, rash, and liver and kidney dysfunction. All four patients in the present study developed pneumonia or lung lesions after R. felis infection. The cases of R. felis infection, a neglected infectious disease, were sporadic in multiple provinces of the country. The high prevalence (2.14%, 4/187) of R. felis among patients with FUO highlights the risk posed by this pathogen to public health in China.

High Prevalence of Tick-Borne Zoonotic Rickettsia slovaca in Ticks from Wild Boars, Northeastern Italy

Simple Summary

Tick-borne rickettsioses are emerging diseases that have become widespread in many European countries, particularly in those facing the Mediterranean basin. Although Rickettsia conorii was traditionally thought to be the most threatening species, in recent decades, thanks to the improvements in biomolecular tools, other zoonotic species have been identified, such as Rickettsia slovaca, the etiological agent of scalp eschar and neck lymphadenopathy after tick bite (SENLAT), as well as other neglected species. These pathogens are present in Italy, but few data are available. This research aimed to improve the epidemiological knowledge of rickettsial infections in tick and wild boar populations in the Euganean Hills Regional Park, an enclosed area in northeastern Italy. Both tick and wild boar blood samples were tested using biomolecular methods to detect and identify Rickettsia species. Only ticks tested positive, and Rickettsia slovaca was the most frequently detected species, showing a high prevalence, followed by Rickettsia monacensis and Rickettsia helvetica. These data highlight a non-negligible presence of these pathogens in northern Italy and outline that rickettsial infections deserve further investigation.

Abstract

Tick-borne rickettsiae are emerging pathogens that are becoming widespread in Europe. Rickettsiae are endemic in Italy, but epidemiological data are currently scarce. This study aimed to improve our knowledge about rickettsial infections in tick and wild boar populations. Blood and ticks were collected from 102 wild boars in 2010 and 2018. Ticks were also collected from the vegetation in the area. All of the samples were examined using real-time PCR targeting the gltA gene to detect Rickettsia DNA. Positivity was confirmed by PCR amplifying the gltA and/or ompB genes. A total of 254 ticks and 89 blood samples were analyzed. Zoonotic rickettsiae were detected in the ticks but not in the blood samples. Rickettsia slovaca (R. slovaca) was the most prevalent in ticks and was found in 23.7% of Dermacentor marginatus (D. marginatus) and in 3.4% of Ixodes ricinus (I. ricinus). Other zoonotic species were identified, such as Rickettsia monacensis, which was detected in 12% of I. ricinus ticks, and Rickettsia helvetica which was found in 3.4% of questing I. ricinus ticks and in 1.1% of D. marginatus collected from wild boars. This study highlights a high prevalence of zoonotic rickettsiae, particularly that of R. slovaca, in northeastern Italy. As rickettsioses are underreported and underdiagnosed in human medicine, both clinicians and researchers should pay more attention to this topic.

Clinical Aspects and Detection of Emerging Rickettsial Pathogens: A "One Health" Approach Study in Serbia, 2020

Ticks carry numerous pathogens that, if transmitted, can cause disease in susceptible humans and animals. The present study describes our approach on how to investigate clinical presentations following tick bites in humans. To this aim, the occurrence of major tick-borne pathogens (TBPs) in human blood samples (n = 85) and the ticks collected (n = 93) from the same individuals were tested using an unbiased high-throughput pathogen detection microfluidic system. The clinical symptoms were characterized in enrolled patients. In patients with suspected TBP infection, serological assays were conducted to test for the presence of antibodies against specific TBPs. A field study based on One Health tenets was further designed to identify components of a potential chain of infection resulting in Rickettsia felis infection in one of the patients. Ticks species infesting humans were identified as Ixodes ricinus, Rhipicephalus sanguineus sensu lato (s.l.), Dermacentor reticulatus, and Haemaphysalis punctata. Five patients developed local skin lesions at the site of the tick bite including erythema migrans, local non-specific reactions, and cutaneous hypersensitivity reaction. Although Borrelia burgdorferi s.l., Babesia microti, Anaplasma phagocytophilum, and Candidatus Cryptoplasma sp. DNAs were detected in tick samples, different Rickettsia species were the most common TBPs identified in the ticks. The presence of TBPs such as Rickettsia helvetica, Rickettsia monacensis, Borrelia lusitaniae, Borrelia burgdorferi, Borrelia afzelii, A. phagocytophilum, and B. microti in ticks was further confirmed by DNA sequencing. Two of the patients with local skin lesions had IgG reactive against spotted fever group rickettsiae, while IgM specific to B. afzelii, Borrelia garinii, and Borrelia spielmanii were detected in the patient with erythema migrans. Although R. felis infection was detected in one human blood sample, none of the components of the potential chain of infection considered in this study tested positive to this pathogen either using direct pathogen detection in domestic dogs or xenodiagnosis in ticks collected from domestic cats. The combination of high-throughput screening of TBPs and One Health approaches might help characterize chains of infection leading to human infection by TBPs, as well as prevalence of emerging rickettsial pathogens in the Balkan region.

Impact of Different Anthropogenic Environments on Ticks and Tick-Associated Pathogens in Alsace, a French Region Highly Endemic for Tick-Borne Diseases

Ticks and tick-borne diseases have spread over the last decades. In parallel, the incidence in humans, accidental hosts for most of these zoonotic diseases, has increased. This epidemiological intensification can be associated with anthropogenic alterations of forest ecosystems and animal biodiversity, but also with socioeconomic changes. Their proliferation is largely due to human-induced effects on the factors that favor the circulation of these infectious agents. We selected different types of anthropogenic environments in Alsace, a region endemic for tick-borne diseases in France, to better understand the impact of human interventions on tick populations and tick-borne disease incidence. Ticks were collected in one golf course, three urban parks, one mid-mountain forest, and one alluvial forest that is currently part of a protected natural area. Ixodes ricinus was found primarily in humid vegetation, which is favorable for tick survival, such as grounds populated with trees and covered with leaf litter. We also observed that reforestation and high animal biodiversity in a protected area such as the alluvial forest led to a greater number of ticks, including both Ixodes ricinus and Dermacentor reticulatus, as well as to a higher prevalence of pathogens such as Borrelia burgdorferi sensu lato, Anaplasma phagocytophilum, Borrelia miyamotoi, and Rickettsia raoulti.

An Update on the Laboratory Diagnosis of Rickettsia spp. Infection

Rickettsia species causing human illness are present globally and can cause significant disease. Diagnosis and identification of this intracellular bacteria are challenging with many available diagnostic modalities suffering from several shortcomings. Detection of antibodies directed against Rickettsia spp. via serological methods remains widely used with a broad range of sensitivity and specificity values reported depending on the assay. Molecular methods, including polymerase chain reaction (PCR) testing, enables species-specific identification with a fast turnaround time; however, due to resource requirements, use in some endemic settings is limited. Reports on the use of next-generation sequencing (NGS) and metagenomics to diagnose Rickettsia spp. infection have been increasing. Despite offering several potential advantages in the diagnosis and surveillance of disease, genomic approaches are currently only limited to reference and research laboratories. Continued development of Rickettsia spp. diagnostics is required to improve disease detection and epidemiological surveillance, and to better understand transmission dynamics.

Atelerix algirus, the North African Hedgehog: Suitable Wild Host for Infected Ticks and Fleas and Reservoir of Vector-Borne Pathogens in Tunisia

Small wild mammals are an important element in the emergence and transmission of vector-borne pathogens (VBPs). Among these species, hedgehogs have been found to be a reservoir of VBPs and host of arthropod vectors. Surveillance of VBPs in wildlife and their arthropods are crucial in a one health context. We conducted an exploratory study to screen Atelerix algirus hedgehogs and their infesting ticks and fleas for VBPs using a high throughput microfluidic real-time PCR system. Tested biopsies from hedgehogs were found to be naturally infected by Theileria youngi, Hepatozoon sp., Ehrlichia ewingii, Coxiella burnetii, and Candidatus Ehrlichia shimanensis. Similarly, Haemaphysalis erinacei and Rhipicephalus sanguineus tick species were infected by Ehrlichia ewingii, Rickettsia spp., Rickettsia massiliae, Borrelia sp., Coxiella burnetii, Rickettsia lusitaniae and Anaplasma sp. Archaeopsylla erinacei fleas were infected by Rickettsia asembonensis, Coxiella burnetii, and Rickettsia massiliae. Co-infections by two and three pathogens were detected in hedgehogs and infesting ticks and fleas. The microfluidic real-time PCR system enabled us not only to detect new and unexpected pathogens, but also to identify co-infections in hedgehogs, ticks, and fleas. We suggest that hedgehogs may play a reservoir role for VBPs in Tunisia and contribute to maintaining enzootic pathogen cycles via arthropod vectors.

Current tools for the diagnosis and detection of spotted fever group Rickettsia

Spotted fever group (SFG) rickettsiae causes a number of diseases in humans worldwide, which can range from mild to highly lethal. Since the clinical presentations of rickettsioses caused by SFG rickettsiae are variable and may be similar to the diseases caused by other rickettsiae, such as Orientia tsutsugamushi (agent for scrub typhus), Coxiella burnetii (agent for Q fever) and the typhus group rickettsiae (agents for epidemic and murine typhus), the accurate diagnosis of infections caused by SFG Rickettsia remains challenging especially in resource-poor settings in developing countries. This review summarizes the various diagnostic and detection tools that are currently available for the confirmation of infections by SFG rickettsiae. The advantages and challenges pertaining to the different serological and molecular detections methods, as well as new assays in development, are discussed. The utility of the detection tools contributing to the surveillance of SFG rickettsiae in arthropods and animals are reviewed.

Development of a Multiplex Loop-Mediated Isothermal Amplification (LAMP) Method for Simultaneous Detection of Spotted Fever Group Rickettsiae and Malaria Parasites by Dipstick DNA Chromatography

Spotted fever group (SFG) rickettsiae causes febrile illness in humans worldwide. Since SFG rickettsiosis’s clinical presentation is nonspecific, it is frequently misdiagnosed as other febrile diseases, especially malaria, and complicates proper treatment. Aiming at rapid, simple, and simultaneous detection of SFG Rickettsia spp. and Plasmodium spp., we developed a novel multiple pathogen detection system by combining a loop-mediated isothermal amplification (LAMP) method and dipstick DNA chromatography technology. Two primer sets detecting SFG Rickettsia spp. and Plasmodium spp. were mixed, and amplified products were visualized by hybridizing to dipstick DNA chromatography. The multiplex LAMP with dipstick DNA chromatography distinguished amplified Rickettsia and Plasmodium targeted genes simultaneously. The determined sensitivity using synthetic nucleotides was 1000 copies per reaction for mixed Rickettsia and Plasmodium genes. When genomic DNA from in vitro cultured organisms was used, the sensitivity was 100 and 10 genome equivalents per reaction for Rickettsia monacensis and Plasmodium falciparum, respectively. Although further improvement will be required for more sensitive detection, our developed simultaneous diagnosis technique will contribute to the differential diagnosis of undifferentiated febrile illness caused by either SFG Rickettsia spp. or Plasmodium spp. in resource-limited endemic areas. Importantly, this scheme is potentially versatile for the simultaneous detection of diverse infectious diseases.

Molecular identification and characterization of Rickettsia spp. and other tick-borne pathogens in cattle and their ticks from Huambo, Angola

Ticks are one of the most common vectors of a broad variety of pathogenic agents that significantly affects cattle production causing reduced productivity and important economic losses, while simultaneously having an impact on human health due to the zoonotic risk. In much of the territory of Angola urban population has grown rapidly in recent decades, sharing today close contact with large farms that are generally owned by city residents, providing the ideal conditions for vector-borne pathogens (VBP) transmission between animals and humans. Here we studied the occurrence of Rickettsia, Anaplasma, Ehrlichia, Babesia and Theileria in domestic cattle (n = 98) from Huambo, Angola, and their ticks (n = 116) to obtain a more detailed knowledge into the spectrum of tick-borne agents circulating in this population. We morphologically identified Amblyomma variegatum, Rhipicephalus decoloratus and R. evertsi mimeticus ticks, further confirmed by molecular analysis of the 12S rDNA and 16S rDNA genes. Although none of the bovine blood showed to be positive for R. africae by the ompB, ompA and gltA assays, five ticks showed to be positive for R. africae by the ompB, ompA and the gltA PCRs. Two 18S rRNA sequences were retrieved from bovine blood and one sequence from A. variegatum tick, showing 100% identity with Theileria mutans. By using a PCR targeting the 16S rRNA gene of Anaplama spp. we have also obtained six bovine blood samples showing 99-100 % nucleotide sequence identity with A. capra, two showing 98 % nucleotide sequence identity with A. phagocytophilum and three showing 98-100 % nucleotide sequence identity with A. platys. None of the ticks were positive. The present study shows the presence of a wide range of vector-borne diseases in domestic cattle and their ticks in Huambo province, Angola. Given the lack of both animal and human health infrastructures in this rural region, swift diagnosis and treatment is hampered which could produce a more severe impact on health.

New Real-Time PCRs to Differentiate Rickettsia spp. and Rickettsia conorii

Rickettsia species are an important cause of emerging infectious diseases in people and animals, and rickettsiosis is one of the oldest known vector-borne diseases. Laboratory diagnosis of Rickettsia is complex and time-consuming. This study was aimed at developing two quantitative real-time PCRs targeting ompB and ompA genes for the detection, respectively, of Rickettsia spp. and R. conorii DNA. Primers were designed following an analysis of Rickettsia gene sequences. The assays were optimized using SYBR Green and TaqMan methods and tested for sensitivity and specificity. This study allowed the development of powerful diagnostic methods, able to detect and quantify Rickettsia spp. DNA and differentiate R. conorii species.

Detection of tick-borne pathogens in Rhipicephalus sanguineus sensu lato and dogs from different districts of Portugal

Dogs are highly exposed to pathogens transmitted by ectoparasites. The Mediterranean climate of Southern Europe, together with the presence of stray and/or neglected pets in close proximity with humans, contribute for tick expansion and stand for increased risk to infections in humans due to the zoonotic potential of many of these agents. The aim of this study was to perform a molecular survey in dogs (suspected of tick-borne disease and/or infested with ticks), as well as in ticks collected from those animals, from 12 districts of Portugal to investigate the occurrence of Rickettsia spp. and other tick-borne pathogens (Babesia, Ehrlichia, Anaplasma and Hepatozoon). Additionally, a serological survey of spotted fever group Rickettsia in Portuguese dogs was performed using an in-house immunofluorescence assay (IFA). A total of 200 whole-blood samples and 221 Rhipicephalus sanguineus s. l. ticks were collected from dogs. A total of 14 (7 %) blood samples and 10 (4.5 %) ticks yielded presumptively positive 420-bp amplicons using the Rickettsia spp. partial ompB nested PCR. Screening of the ompB-positive samples using the gltA gene showed 8 positive ticks. All Rickettsia ompB and gltA sequences had the highest identity with R. massiliae. The Rickettsia-positive dogs were further tested for other tick-borne pathogens and were found to be infected with Babesia spp. (n = 5), but not with Ehrlichia, Anaplasma or Hepatozoon. Of the 149 dog serum specimens tested in the serological assay, 103 (69 %) were positive for IgG antibodies against spotted fever group Rickettsia. Antibodies were found in dogs from all the studied districts, in 55 (53 %) of the stray and in 48 (47 %) of the owned dogs. Our study detected and characterized for the first time R. massiliae in dogs from Portugal, broadening the geographical range of this canine pathogen and adding knowledge to the impact of this disease in dogs.

Duplex qPCR assay for detection and quantification of Anaplasma phagocytophilum and Rickettsia spp

Anaplasma phagocytophilum and Rickettsia spp. are vector-borne zoonotic bacteria, which are clinically important especially in immunocompromised patients. There are large gaps in the current knowledge of their geographic distribution and prevalence in both their vectors and hosts. Our aim was to develop reliable and easy detection method for both these pathogens. We made a new hydrolysis probe based duplex Real-Time PCR assay based on previous studies. We optimized the assays and tested them to provide reliable recommended procedures with a sensitivity to a minimum of 10 target DNA copies per sample. The assays were designed to be specific for A. phagocytophilum and in the same reaction detect multiple species of rickettsiae. We designed gBlock quantification standards that provide the option to identify differences in pathogen load among different samples in subsequent studies.

Upscaling the Surveillance of Tick-borne Pathogens in the French Caribbean Islands

Despite the high burden of vector-borne disease in (sub)tropical areas, few information are available regarding the diversity of tick and tick-borne pathogens circulating in the Caribbean. Management and control of vector-borne disease require actual epidemiological data to better assess and anticipate the risk of (re)emergence of tick-borne diseases in the region. To simplify and reduce the costs of such large-scale surveys, we implemented a high-throughput microfluidic real-time PCR system suitable for the screening of the main bacterial and parasitic genera involved in tick-borne disease and potentially circulating in the area. We used the new screening tool to perform an exploratory epidemiological study on 132 adult specimens of Amblyomma variegatum and 446 of Rhipicephalus microplus collected in Guadeloupe and Martinique. Not only the system was able to detect the main pathogens of the area-Ehrlichia ruminantium, Rickettsia africae, Anaplasma marginale, Babesia bigemina and Babesia bovis-but the system also provided evidence of unsuspected microorganisms in Caribbean ticks, belonging to the Anaplasma, Ehrlichia, Borrelia and Leishmania genera. Our study demonstrated how high-throughput microfluidic real-time PCR technology can assist large-scale epidemiological studies, providing a rapid overview of tick-borne pathogen and microorganism diversity, and opening up new research perspectives for the epidemiology of tick-borne pathogens.

First records of tick-borne pathogens in populations of the taiga tick Ixodes persulcatus in Sweden

Background

The common tick Ixodes ricinus and the taiga tick I. persulcatus are the main tick vectors of Borrelia spirochaetes, TBE virus (TBEV) and of several other zoonotic pathogens in the western and eastern areas, respectively of the Palaearctic region. Recently, populations of the taiga tick were, for the first time, detected in northern Sweden. This prompted us to investigate if they harbour human pathogens.

Methods

A total of 276 I. persulcatus ticks (136 males, 126 females and 14 nymphs) and one I. ricinus nymph was collected by the cloth-dragging method in northern Sweden in July–August 2015 and May–July 2016. In addition, 8 males and 10 females of I. persulcatus were collected from two dogs (16 and 2 ticks, respectively) in two of the localities. All ticks were microscopically and molecularly identified to developmental stage and species and screened for B. burgdorferi (sensu lato), B. miyamotoi, Anaplasma phagocytophilum, Rickettsia spp., Neoehrlichia mikurensis, Babesia spp. and TBEV using real-time PCR followed by species identification by sequencing the PCR-products of conventional PCR assays.

Results

Of the ticks collected by the cloth-dragging method, 55% (152/277) were positive for Borrelia. There was no significant difference between the proportions of Borrelia-infected nymphs (33%, 5/15) and Borrelia-infected adult ticks (56%, 147/262), and no significant difference between the proportions of Borrelia-infected males (54%, 74/136) and Borrelia-infected females (58%, 73/126). Three different Borrelia species were identified. Borrelia afzelii was the predominant species and detected in 46% of all Borrelia-infected ticks followed by B. garinii, 35%, B. valaisiana, 1%, and mixed infections of different Borrelia species, 1%; 17% of all Borrelia-infections were untypeable. One I. persulcatus female contained Rickettsia helvetica, and one nymph contained Rickettsia sp. Of the 277 ticks analysed, all were negative for A. phagocytophilum, Babesia spp., Borrelia miyamotoi, N. mikurensis and TBEV. The ticks collected from the two dogs were negative for all pathogens examined except for Borrelia spp., that was detected in 5 out of 16 ticks removed from one of the dogs.

Conclusions

To our knowledge, this is the first time that I. persulcatus from Sweden has been analysed for the presence of tick-borne pathogens. The examined tick populations had a low diversity of tick-borne pathogens but a high prevalence of B. burgdorferi (s.l.).

Diagnosis of spotted fever group Rickettsia infections: the Asian perspective

Spotted fever group rickettsiae (SFG) are a neglected group of bacteria, belonging to the genus Rickettsia, that represent a large number of new and emerging infectious diseases with a worldwide distribution. The diseases are zoonotic and are transmitted by arthropod vectors, mainly ticks, fleas and mites, to hosts such as wild animals. Domesticated animals and humans are accidental hosts. In Asia, local people in endemic areas as well as travellers to these regions are at high risk of infection. In this review we compare SFG molecular and serological diagnostic methods and discuss their limitations. While there is a large range of molecular diagnostics and serological assays, both approaches have limitations and a positive result is dependent on the timing of sample collection. There is an increasing need for less expensive and easy-to-use diagnostic tests. However, despite many tests being available, their lack of suitability for use in resource-limited regions is of concern, as many require technical expertise, expensive equipment and reagents. In addition, many existing diagnostic tests still require rigorous validation in the regions and populations where these tests may be used, in particular to establish coherent and worthwhile cut-offs. It is likely that the best strategy is to use a real-time quantitative polymerase chain reaction (qPCR) and immunofluorescence assay in tandem. If the specimen is collected early enough in the infection there will be no antibodies but there will be a greater chance of a PCR positive result. Conversely, when there are detectable antibodies it is less likely that there will be a positive PCR result. It is therefore extremely important that a complete medical history is provided especially the number of days of fever prior to sample collection. More effort is required to develop and validate SFG diagnostics and those of other rickettsial infections.

Prevalence and molecular characterization of Rickettsia spp. in questing ticks from north-western Spain

Tick-borne rickettsioses, most of them belonging to the spotted fever group (SFG), have been recognized as important emerging vector-borne zoonotic diseases. In order to determine the presence of Rickettsia spp. in questing ticks from north-western Spain, 1056 Ixodes ricinus, 19 Dermacentor marginatus, 17 Dermacentor reticulatus and one Ixodes acuminatus were processed. Rickettsia DNA was detected by PCR targeting rOmpA and rOmpB genes. A total of 219 (20.7%) I. ricinus, 19 (100%) D. marginatus and four D. reticulatus (23.5%) were positive. The prevalence was significantly higher in I. ricinus from coastal areas and in winter. Five species were identified: Rickettsia felis, Rickettsia monacensis, Rickettsia raoultii, Rickettsia slovaca and "Candidatus Rickettsia rioja". Our results reveal a significant presence of some pathogenic Rickettsia species in questing tick populations from this area which involves a noticeable risk of rickettsiosis. As R. raoultii, R. slovaca and "Ca. R. rioja" DNA were identified in I. ricinus, considered an unusual vector for these Rickettsia species, further studies are needed to unravel the role of that tick species in the maintenance and transmission of these three Rickettsia species in north-western Spain.

Detection of zoonotic agents and a new Rickettsia strain in ticks from donkeys from South Africa: Implications for travel medicine

BACKGROUND

In rural South Africa, people are in close contact with tick-infested donkeys. This study aimed to investigate the presence of spotted fever group Rickettsia, Anaplasma, Ehrlichia and Coxiella species in these arthropods.

METHOD

376 ticks (7 species) from donkeys from Limpopo Province (South Africa) were pooled and analyzed using PCR assays for the bacterium detection.

RESULTS

Rickettsia africae was amplified in 6 Amblyomma hebraeum, 1 Rhipicephalus appendiculatus and 5 Rhipicephalus evertsi evertsi pools. Rickettsia aeschlimannii was found in 1 Hyalomma rufipes, 1 Rh. appendiculatus and 2 Rh. e. evertsi pools. Three Rhipicephalus simus specimens were infected with a new Rickettsia strain that showed low identity with any validated Rickettsia species. Ehrlichia canis was detected in 2 Rh. e. evertsi pools and in one of them Anaplasma bovis was amplified. An Am. hebraeum pool showed infection with Anaplasma ovis and another with Coxiella burnetii.

CONCLUSION

South African donkeys are involved in the epidemiology of tick-borne pathogens and other associated agents such as C. burnetii with Health importance. A potential new Rickettsia species, with unknown pathogenic potential, has been detected in the anthropophilic Rh. simus.

Geographical distribution of Orientia tsutsugamushi strains in chiggers from three provinces in Korea

Chiggers were collected from the central and southern parts of South Korea between April and November, 2009 with the aim of investigating the seasonal and geographical distribution of Or. A total of 1136 chiggers were identified. They included eight species belonging to four genera, as follows: Leptotrombidium scutellare (27.2%, n = 309), L. pallidum (54.6%, n = 621), L. orientale (6.25%, n = 71), L. palpale (1.59%, n = 18), L. zetum (2.0%, n = 23), Euschoengastia koreaensis (1.5%, n = 17), Cheladonta ikaoensis (0.08%, n = 1) and Neotrombicula japonica (1.05%, n = 12). The density of L. pallidum was high from April to May, whereas L. scutallare was not found in spring, being observed from October. Serotype-specific nested PCR targeting the 56 kDa protein gene and sequencing analysis identified that the strains of 1136 O. tsutsugamushi in the chiggers as Boryong (6.8%), Kanda (0.4%), Oishi (0.3%), Jecheon (0.1%), Youngworl (0.1%) and Wonju (0.1%). Our findings indicate that L. pallidum and L. scutellare are dominant species in Korea and have geographical and seasonal variations.

Development of a tick-borne pathogen QPCR panel for detection of Anaplasma, Ehrlichia, Rickettsia, and Lyme disease Borrelia in animals

Anaplasma spp., Ehrlichia spp., Rickettsia spp., and Lyme disease associated Borrelia spp. are the most common tick-borne pathogens reported to infect human beings worldwide and other animals, such as dogs and horses. In the present study, we developed a broad-coverage SYBR Green QPCR panel consisting of four individual assays for the detection and partial differentiation of the aforementioned pathogens. All assays were optimized to the same thermocycling condition and had a detection limit of 10 copies per reaction. The assays remained sensitive when used to test canine and equine blood DNA samples spiked with known amounts of synthetic DNA (gBlock) control template. The assays were specific, as evidenced by lack of cross reaction to non-target gBlock or other pathogens commonly tested in veterinary diagnostic labs. With appropriate Ct cutoff values for positive samples and negative controls and the melting temperature (TM) ranges established in the present study, the QPCR panel is suitable for accurate, convenient and rapid screening and confirmation of tick-borne pathogens in animals.

Clinically-diagnosed Mediterranean Spotted Fever in Malta

BACKGROUND

Mediterranean Spotted Fever (MSF) is a tick-borne zoonosis caused by Rickettsia conorii which is endemic in Malta, an island in the South Mediterranean that is a popular tourist destination. Diagnosis is frequently based on clinical manifestations as laboratory results are often limited to a retrospective diagnosis. We describe the clinical presentation, diagnosis and treatment of children <16 years who presented with MSF from 2011 to 2016.

METHOD

The demographics, clinical findings, laboratory results, management and outcome of all children hospitalised with suspected MSF based on the presence of fever and an eschar, were retrieved from their case notes.

RESULTS

Over the five-year study period six children, aged between 17 months and 15 years, were diagnosed with MSF. All children had contact with ticks and the majority presented in summer. Laboratory results were non-specific and included elevated inflammatory markers, lymphocytosis/lymphopenia and hyponatraemia. Serological and molecular techniques were used for diagnosis. Response to clarithromycin or doxycycline was immediate.

CONCLUSION

MSF should be included in the differential diagnosis of fever, rash and an eschar in children who travel to Malta. Despite advances in molecular diagnostics, clinical diagnosis remains important in the management of children with suspected MSF.

Importance of Common Wall Lizards in the Transmission Dynamics of Tick-Borne Pathogens in the Northern Apennine Mountains, Italy

During the investigations on ticks and tick-borne pathogens (TBP) range expansion in the Northern Apennines, we captured 107 Podarcis muralis lizards. Sixty-eight animals were infested by immature Ixodes ricinus, Haemaphysalis sulcata and H. punctata. Borrelia burgdorferi s.l. was detected in 3.7% of I. ricinus larvae and 8.0% of nymphs. Together with the species-specific B. lusitaniae, we identified B. garinii, B. afzelii and B. valaisiana. Rickettsia spp. (18.1% larvae, 12.0% nymphs), namely R. monacensis, R. helvetica and R. hoogstraalii, were also found in I. ricinus. R. hoogstraalii was detected in H. sulcata nymphs as well, while the two H. punctata did not harbour any bacteria. One out of 16 lizard tail tissues was positive to R. helvetica. Our results support the hypothesis that lizards are involved in the epidemiological cycles of TBP. The heterogeneity of B. burgdorferi genospecies mirrors previous findings in questing ticks in the area, and their finding in attached I. ricinus larvae suggests that lizards may contribute to the maintenance of different genospecies. The rickettsiae are new findings in the study area, and R. helvetica infection in a tail tissue indicates a systemic infection. R. hoogstraalii is reported for the first time in I. ricinus ticks. Lizards seem to favour the bacterial exchange among different tick species, with possible public health consequences.

First isolation of Rickettsia monacensis from a patient in South Korea

A Rickettsia sp. was isolated from the blood of a patient with an acute febrile illness using the shell vial technique; the isolate was named CN45Kr and was identified by molecular assay as Rickettsia monacensis, which was first recognized as a pathogen in Spain. Sequencing analysis showed that the gltA sequence of the isolate was identical to that of Rickettsia sp. IRS3. The ompA-5mp fragment sequence showed 100% identity to those of R. monacensis and Rickettsia sp. In56 and ompA-3pA In56 and 100% identity to that of Rickettsia sp. IRS3. The ompB sequence was found to have 99.9% similarity to that of R. monacensis IrR/Munich. This study confirms the pathogenicity of this agent and provides additional information about its geographic distribution.

African tick bite fever in returning Swedish travellers. Report of two cases and aspects of diagnostics

Introduction: African tick-bite fever, caused by Rickettsia africae, is endemic in rural areas of sub-Saharan Africa and a possible cause of fever in returning Swedish travellers. Two patients are presented, and the advantages and disadvantages of different diagnostic methods are discussed. Patients and methods: Two middle-aged men fell ill with fever after returning home from South Africa. Both had single eschars and one also presented with a lymph node swelling. Samples were taken for serology, general bacterial culture from the wound (Patient 1) using a swab and additionally for Patient 2 PCR of a skin biopsy from the eschar. Results and discussion: Both patients seroconverted one month after onset. Real-time PCR of the biopsy was positive, where sequencing of the gltA gene was 99-100% consistent with R. africae. A drop of fluid from the biopsy contained a sufficient number of bacteria to also allow for isolation of rickettsiae in Vero cell culture. Direct molecular detection by PCR from a swab used for bacteria culture from the eschar from Patient 1 also yielded a positive result. In conclusion, the findings highlight the usefulness of swabs for early non-invasive diagnosis of African tick-bite fever in febrile travellers.

Serological and molecular detection of spotted fever group Rickettsia in a group of pet dogs from Luanda, Angola

Background

Infections with tick-borne rickettsiae can cause diseases well known in humans but still not so well characterized in dogs. Susceptibility to infection depends on the virulence of Rickettsia spp. and only a few of them have been described to cause disease in dogs. The aim of this study was to investigate the exposure to Rickettsia spp. among a group of pet dogs from Luanda, Angola.

Results

Out of 103 dogs included in the study, 62 (60.2%) were infested with ticks. Plasma specimens tested for serology by an immunofluorescence assay (IFA) revealed that six (5.8%) dogs had detectable immunoglobulin G (IgG) antibodies to spotted fever group Rickettsia (SFGR), with endpoint titers of 64 for two dogs, 128 for three dogs and 1024 for one dog. From the seropositive group of dogs, five (83%) of them were males, with their age ranging from 1 to 8 years old. Among the seropositive dogs, four (66.7%) were parasitized with ticks and no breed (or cross) was found to be associated with specific antibodies. Rickettsia spp. DNA was detected by nested-polymerase chain reaction (PCR) in two (1.9%) dogs that were found to be seronegative.

Conclusions

Seroprevalence and molecular detection of Rickettsia spp. infection in this group of pet dogs from Luanda is low compared with other studies performed in the same type of hosts in other areas. Although many dogs were parasitized with ticks, a low prevalence of Rickettsia spp. could be related with the hypothesis of a low rickettsial prevalence in the infesting ticks. This study provides evidence that dogs in Luanda are exposed to Rickettsia spp., but further studies are needed to better characterize the bacterial infections in dogs and in their ectoparasites.

Severe interstitial pneumonia due to murine typhus in a patient returning from Bali

Murine typhus has been increasingly reported as a cause of fever in returning travelers from Southeast Asia. We report a case of a previously healthy traveler returning from Bali with an non-specific febrile illness which quickly progressed to a severe form of interstitial pneumonia. After a careful epidemiological evaluation and laboratory analysis, murine typhus was diagnosed.

Molecular detection of Rickettsia species in ticks collected from the southwestern provinces of the Republic of Korea

Background

Rickettsiae constitute a group of arthropod-borne, Gram-negative, obligate intracellular bacteria that are the causative agents of diseases ranging from mild to life threatening that impact on medical and veterinary health worldwide.

Methods

A total of 6,484 ticks were collected by tick drag from June-October 2013 in the southwestern provinces of the Republic of Korea (ROK) (Jeollanam, n = 3,995; Jeollabuk, n = 680; Chungcheongnam, n = 1,478; and Chungcheongbuk, n = 331). Ticks were sorted into 311 pools according to species, collection site, and stage of development. DNA preparations of tick pools were assayed for rickettsiae by 17 kDa antigen gene and ompA nested PCR (nPCR) assays and the resulting amplicons sequenced to determine the identity and prevalence of spotted fever group rickettsiae (SFGR).

Results

Haemaphysalis longicornis (4,471; 52 adults, 123 nymphs and 4,296 larvae) were the most commonly collected ticks, followed by Haemaphysalis flava (1,582; 28 adults, 263 nymphs and 1,291 larvae), and Ixodes nipponensis (431; 25 adults, 5 nymphs and 401 larvae). The minimum field infection rate/100 ticks (assuming 1 positive tick/pool) was 0.93% for the 17 kDa antigen gene and 0.82% for the ompA nPCR assays. The partial 17 kDa antigen and ompA gene sequences from positive pools of H. longicornis were similar to: Rickettsia sp. HI550 (99.4–100%), Rickettsia sp. FUJ98 (99.3–100%), Rickettsia sp. HIR/D91 (99.3–100%), and R. japonica (99.7%). One sequence of the partial 17 kDa antigen gene for H. flava was similar to Rickettsia sp. 17kd-005 (99.7%), while seven sequences of the 17 kDa antigen gene obtained from I. nipponensis ticks were similar to R. monacensis IrR/Munich (98.7–100%) and Rickettsia sp. IRS3 (98.9%).

Conclusions

SFG rickettsiae were detected in three species of ixodid ticks collected in the southwestern provinces of the ROK during 2013. A number of rickettsiae have been recently reported from ticks in Korea, some of which were identified as medically important. Results from this study and previous reports demonstrate the need to conduct longitudinal investigations to identify tick-borne rickettsiae and better understand their geographical distributions and potential impact on medical and veterinary health, in addition to risk communication and development of rickettsial disease prevention strategies.

Anaplasma, Ehrlichia and rickettsial pathogens in ixodid ticks infesting cattle and sheep in western Oromia, Ethiopia

Although ticks are widely distributed in all agro-ecological zones of Ethiopia, information on tick-borne pathogens is scarce. This study was conducted to determine the presence of Anaplasma spp., Ehrlichia spp., and Rickettsia spp. in Rhipicephalus evertsi and Rhipicephalus (Boophilus) decoloratus collected from cattle and sheep at Bako, western Oromia, Ethiopia, using polymerase chain reaction and sequencing. Anaplasma ovis and Anaplasma spp., Ehrlichia ruminantium and Ehrlichia spp. were detected in Rh. decoloratus, whereas only A. ovis was detected in Rh. evertsi. Both tick species were found to harbor DNA belonging to Rickettsia spp., and Rickettsia africae. Our findings highlight the risk of infection of animals and humans with these zoonotic tick-borne bacteria in Ethiopia.

Comparative evaluation of two Rickettsia typhi-specific quantitative real-time PCRs for research and diagnostic purposes

Rickettsioses are caused by intracellular bacteria of the family of Rickettsiaceae. Rickettsia (R.) typhi is the causative agent of endemic typhus. The disease occurs worldwide and is one of the most prevalent rickettsioses. Rickettsial diseases, however, are generally underdiagnosed which is mainly due to the lack of sensitive and specific methods. In addition, methods for quantitative detection of the bacteria for research purposes are rare. We established two qPCRs for the detection of R. typhi by amplification of the outer membrane protein B (ompB) and parvulin-type PPIase (prsA) genes. Both qPCRs are specific and exclusively recognize R. typhi but no other rickettsiae including the closest relative, R. prowazekii. The prsA-based qPCR revealed to be much more sensitive than the amplification of ompB and provided highly reproducible results in the detection of R. typhi in organs of infected mice. Furthermore, as a nested PCR the prsA qPCR was applicable for the detection of R. typhi in human blood samples. Collectively, the prsA-based qPCR represents a reliable method for the quantitative detection of R. typhi for research purposes and is a promising candidate for differential diagnosis.

Molecular analysis of Crimean-Congo hemorrhagic fever virus and Rickettsia in Hyalomma marginatum ticks removed from patients (Spain) and birds (Spain and Morocco), 2009-2015

Crimean-Congo hemorrhagic fever virus (CCHFV) was detected in Spain in 2010. The presence of CCHFV in Hyalomma marginatum ticks from migratory birds passing through Morocco during the spring migration strengthened the hypothesis of the arrival of infected ticks transported by birds to the Iberian Peninsula. Furthermore, Hyalomma species are vectors of bacterial infections such as spotted fever rickettsioses. CCHFV and Rickettsia were screened in Hyalomma ticks from Spain attached to patients (n=12) and birds (n=149). In addition, Rickettsia was investigated in 52 Hyalomma ticks from Morocco (previously reported as CCHFV-infected). No sample collected in Spain showed an infection with CCHFV. Two ticks removed from patients (16.7%), as well as 47 (31.5%) and 4 (7.7%) from birds, collected in Spain and Morocco respectively, were infected with Rickettsia aeschlimannii. Rickettsia sibirica subsp. mongolitimonae was also found in 2 ticks from birds collected in Spain (1.3%). The risk of CCHFV-infected ticks attached to migratory birds to reach the North of Spain is low. This study corroborates the presence of R. aeschlimannii in Spain and Morocco, and supports that H. marginatum can be a potential vector of R. sibirica subsp. mongolitimonae in the Iberian Peninsula.

Strategies for detecting rickettsiae and diagnosing rickettsial diseases

Rickettsial diseases and scrub typhus constitute a group of the oldest known vector-borne diseases. The cosmopolitan distribution of the vectors that transmit rickettsiae and orientiae leads to a worldwide prevalence of these diseases. Despite their significant historical status, detection and diagnosis of these diseases are still evolving today. Serological methods remain among the most prevalent techniques used for the detection/diagnosis of rickettsial diseases and scrub typhus. Molecular techniques have been instrumental in increasing the sensitivity/specificity of diagnosis, identifying new Rickettsia and Orientia species and have enhanced epidemiological capabilities when used in combination with serological methods. In this review, we discuss these techniques and their associated pros and cons.

Investigation of Rickettsia, Coxiella burnetii and Bartonella in ticks from animals in South Africa

Ticks are involved in the epidemiology of several human pathogens including spotted fever group (SFG) Rickettsia spp., Coxiella burnetii and Bartonella spp. Human diseases caused by these microorganisms have been reported from South Africa. The presence of SFG Rickettsia spp., C. burnetii and Bartonella spp. was investigated in 205 ticks collected from domestic and wild animals from Western Cape and Limpopo provinces (South Africa). Rickettsia massiliae was detected in 10 Amblyomma sylvaticum and 1 Rhipicephalus simus whereas Rickettsia africae was amplified in 7 Amblyomma hebraeum. Neither C. burnetii nor Bartonella spp. was found in the examined ticks. This study demonstrates the presence of the tick borne pathogen R. massiliae in South Africa (Western Cape and Limpopo provinces), and corroborates the presence of the African tick-bite fever agent (R. africae) in this country (Limpopo province).

Tick-borne Rickettsiales: Molecular tools for the study of an emergent group of pathogens

The use of molecular techniques in recent years has enhanced the sensitivity and specificity of the diagnosis of Rickettsiales, a bacterial order which includes significant emerging and re-emerging pathogens of humans and animals. Molecular detection enables the accurate identification at the species level, providing additional information on the epidemiology and course of the clinical cases. Moreover, PCR and enzyme restriction analysis of the vector blood meal can be employed to study the tick feeding source and possibly identify pathogen's reservoir. Here, we review the molecular tools available for the identification and characterization of tick-borne bacteria from the genera Rickettsia, Ehrlichia and Anaplasma and for the study of ticks feeding behavior. We summarize the significant criteria for taxonomic identification of Rickettsiales species and propose a procedure algorithm for the classification of bacterial isolates as members of this order.

Spotted fever group rickettsiae detected in immature stages of ticks parasitizing on Iberian endemic lizard Lacerta schreiberi Bedriaga, 1878

Spotted fever rickettsioses are tick-borne diseases of growing public health concern. The prevalence of rickettsia-infected ticks and their ability to parasitize humans significantly influence the risk of human infection. Altogether 466 Ixodes ricinus ticks (428 nymphs and 38 larvae) collected from 73 Lacerta schreiberi lizards were examined by PCR targeting the citrate synthetase gene gltA for the presence of Rickettsia spp. Rickettsial DNA was detected in 47% of nymphs and 31.6% of larvae. They were subsequently subjected to a second PCR reaction using primers derived from the outer membrane protein rOmpA encoding gene (ompA) to detect spotted fever group rickettsiae (SFG). This analysis shows that 41.4% of nymphs and 7.9% of larvae collected from the lizards contain DNA of SFG rickettsiae. Sequencing of 43 randomly selected samples revealed two different haplotypes, both closely related to R. monacensis (39 and 4 samples, respectively). The remaining ompA negative Rickettsia spp. samples were determined to be R. helvetica based on sequencing of ompB and gltA fragments. Our results indicate that the role of Iberian endemic lizard L. schreiberi and its ectoparasites in the ecology and epidemiology of zoonotic SFG rickettsioses may be appreciable.

Detection of spotted fever group Rickettsiae in ticks from Zhejiang Province, China

Tick species distribution and prevalence of spotted fever group Rickettsiae (SFGR) in ticks were investigated in Zhejiang Province, China in 2010 and 2011. PCR was used to detect SFGR and positive amplicons were sequenced, compared to published sequences and phylogenic analysis was performed using MEGA 4.0. A total of 292 adult ticks of ten species were captured and 7.5 % (22/292) of the ticks were PCR-positive for SFG Rickettsia. The PCR-positive rates were 5.5 % (6/110) for Haemaphysalis longicornis, 3.6 % (1/28) for Amblyomma testudinarium and 16 % (15/94) for Ixodes sinensis, respectively. Phylogenetic analyses of gltA genes detected in ticks indicated that there are two dominating groups of SFGR. Sequences of group one were closely related to Rickettsia monacensis, whereas sequences of group two were closest related to Rickettsia heilongjiangensis and Rickettsia japonica, which are human pathogens. Our findings underline the importance of these ticks in public health surveillance in Zhejiang Province, China.

Investigation of tick-borne bacteria (Rickettsia spp., Anaplasma spp., Ehrlichia spp. and Borrelia spp.) in ticks collected from Andean tapirs, cattle and vegetation from a protected area in Ecuador

Background

Ixodid ticks play an important role in the transmission and ecology of infectious diseases. Information about the circulation of tick-borne bacteria in ticks is lacking in Ecuador. Our aims were to investigate the tick species that parasitize Andean tapirs and cattle, and those present in the vegetation from the buffer zone of the Antisana Ecological Reserve and Cayambe-Coca National Park (Ecuador), and to investigate the presence of tick-borne bacteria.

Methods

Tick species were identified based on morphologic and genetic criteria. Detection of tick-borne bacteria belonging to Rickettsia, Anaplasma, Ehrlichia and Borrelia genera was performed by PCRs.

Results

Our ticks included 91 Amblyomma multipunctum, 4 Amblyomma spp., 60 Rhipicephalus microplus, 5 Ixodes spp. and 1 Ixodes boliviensis. A potential Candidatus Rickettsia species closest to Rickettsia monacensis and Rickettsia tamurae (designated Rickettsia sp. 12G1) was detected in 3 R. microplus (3/57, 5.3%). In addition, Anaplasma spp., assigned at least to Anaplasma phagocytophilum (or closely related genotypes) and Anaplasma marginale, were found in 2 A. multipunctum (2/87, 2.3%) and 13 R. microplus (13/57, 22.8%).

Conclusions

This is the first description of Rickettsia sp. in ticks from Ecuador, and the analyses of sequences suggest the presence of a potential novel Rickettsia species. Ecuadorian ticks from Andear tapirs, cattle and vegetation belonging to Amblyomma and Rhipicephalus genera were infected with Anaplasmataceae. Ehrlichia spp. and Borrelia burgdorferi sensu lato were not found in any ticks.

'Candidatus Rickettsia asemboensis' and Wolbachia spp. in Ctenocephalides felis and Pulex irritans fleas removed from dogs in Ecuador

Background

Flea-borne infections are distributed worldwide. Up to date there are no reports about microorganisms associated to fleas in Ecuador.

Methods

Seventy-one Pulex irritans and 8 Ctenocephalides felis fleas were removed from dogs in two Ecuadorian areas (Pastaza and Chimborazo Provinces) in December 2012. DNA extracts were tested by polymerase chain reaction (PCR) assays targeting universal 16S rRNA, as well as screened for the presence of Rickettsia spp. (gltA, htrA, ompB, sca4 and ompA genes) and Bartonella spp. (rpoB, gltA and ITS genes).

Results

Our results showed the presence of ‘Candidatus Rickettsia asemboensis’ (highly similar to R. felis) in C. felis and Wolbachia spp. endosimbionts in P. irritans collected from animals in Ecuador. No fleas were found to be positive for any Bartonella species or Yersinia pestis.

Conclusions

Clinicians should be aware of the potential risk of this new Candidatus Rickettsia sp. and keep in mind other flea-borne infections since these flea species frequently bite humans.

Syndromic classification of rickettsioses: an approach for clinical practice

Rickettsioses share common clinical manifestations, such as fever, malaise, exanthema, the presence or absence of an inoculation eschar, and lymphadenopathy. Some of these manifestations can be suggestive of certain species of Rickettsia infection. Nevertheless none of these manifestations are pathognomonic, and direct diagnostic methods to confirm the involved species are always required. A syndrome is a set of signs and symptoms that characterizes a disease with many etiologies or causes. This situation is applicable to rickettsioses, where different species can cause similar clinical presentations. We propose a syndromic classification for these diseases: exanthematic rickettsiosis syndrome with a low probability of inoculation eschar and rickettsiosis syndrome with a probability of inoculation eschar and their variants. In doing so, we take into account the clinical manifestations, the geographic origin, and the possible vector involved, in order to provide a guide for physicians of the most probable etiological agent.

Spotted fever Rickettsia species in Hyalomma and Ixodes ticks infesting migratory birds in the European Mediterranean area

Background

A few billion birds migrate annually between their breeding grounds in Europe and their wintering grounds in Africa. Many bird species are tick-infested, and as a result of their innate migratory behavior, they contribute significantly to the geographic distribution of pathogens, including spotted fever rickettsiae. The aim of the present study was to characterize, in samples from two consecutive years, the potential role of migrant birds captured in Europe as disseminators of Rickettsia-infected ticks.

Methods

Ticks were collected from a total of 14,789 birds during their seasonal migration northwards in spring 2009 and 2010 at bird observatories on two Mediterranean islands: Capri and Antikythira. All ticks were subjected to RNA extraction followed by cDNA synthesis and individually assayed with a real-time PCR targeting the citrate synthase (gltA) gene. For species identification of Rickettsia, multiple genes were sequenced.

Results

Three hundred and ninety-eight (2.7%) of all captured birds were tick-infested; some birds carried more than one tick. A total number of 734 ticks were analysed of which 353 ± 1 (48%) were Rickettsia-positive; 96% were infected with Rickettsia aeschlimannii and 4% with Rickettsia africae or unidentified Rickettsia species. The predominant tick taxon, Hyalomma marginatum sensu lato constituted 90% (n = 658) of the ticks collected. The remaining ticks were Ixodes frontalis, Amblyomma sp., Haemaphysalis sp., Rhipicephalus sp. and unidentified ixodids. Most ticks were nymphs (66%) followed by larvae (27%) and adult female ticks (0.5%). The majority (65%) of ticks was engorged and nearly all ticks contained visible blood.

Conclusions

Migratory birds appear to have a great impact on the dissemination of Rickettsia-infected ticks, some of which may originate from distant locations. The potential ecological, medical and veterinary implications of such Rickettsia infections need further examination.

Spotted fever group rickettsiae in multiple hard tick species from Fairfax County, Virginia

Spotted fever group rickettsiosis (SFGR) is a potentially fatal disease that has displayed increasing incidence in the United States in recent years. The most well-known and severe type of this disease is Rocky Mountain spotted fever, but there are other mild forms that occur. Recently, human infection with Rickettsia parkeri has been reported and linked with the tick Amblyomma maculatum. In 2010, a population of R. parkeri-infected A. maculatum was discovered in Fairfax County, Virginia, leading to increased surveillance of tick species. In this study, we report the presence of R. parkeri in Rhipicephalus sanguineus, Haemaphysalis leporispalustris, and Dermacentor variabilis in Fairfax County. R. parkeri was discovered in two Rh. sanguineus, one H. leporispalustris, and 17 D. variabilis. These findings suggest that spillover infections of R. parkeri may be occurring in tick species not typically associated with this pathogen; however, vector competence studies need to be conducted to determine if these tick species can serve as potential vectors for human SFGR.

Molecular Detection of Various Rickettsiae in Mites (Acari: Trombiculidae) in Southern Jeolla Province, Korea

This study revealed the presence of various rickettsial agents in mites from wild rodents collected in Southern Jeolla Province, Korea, by nested polymerase chain reaction (PCR) and sequence analysis of a partial citrate synthase and rickettsia outer membrane protein B genes. Rickettsial agents closely related to the Rickettsia species TwKM02, R. australis, and the Rickettsia species Cf15 were successfully identified in this study, for the first time in Korea, and R. japonica, R. akari, R. conorii, R. felis, and R. typhi were also detected, as previously described. The data presented in this paper extend knowledge on the geographic distribution of SFG rickettsiae in eastern Asia and it may necessary to consider the role of mites in rickettsial transmission.

Detection of Rickettsia monacensis from Ixodes nipponensis collected from rodents in Gyeonggi and Gangwon Provinces, Republic of Korea

A total of 1,305 ticks were collected from wild rodents captured monthly, except July and August, during 2008 at three US-ROK operated military training sites and three US military installations in Gyeonggi and Gangwon Provinces, the Republic of Korea (ROK). Ixodes nipponensis was the most frequently collected tick (n = 1,299, 99.5 %), followed by Ixodes pomerantzevi (n = 6, 0.5 %). The ticks were pooled (1-15/sample) and tested by nested polymerase chain reaction (nPCR) for spotted fever group (SFG) rickettsiae with primer sets targeting the outer membrane protein B (ompB), citrate synthase (gltA), and 17-kDa antigen gene loci. A total of 115/197 (58.4 %) pools were positive by nPCR for the outer membrane protein ompB. Nucleotide sequence analysis of 105/115 (91.3 %) ompB targeted nPCR positive products showed a high degree of similarity to Rickettsia monacensis (99.3-100 %, n = 87) and R. japonica (99.5-100 %, n = 18). From the 87 positive samples demonstrating a high degree of similarity to R. monacensis, 15 were selected and analyzed by nPCR for gltA and the 17-kDa genes. A total of 12/15 pooled samples were positive for by nPCR for gltA, with amplicons demonstrating a high degree of similarity to R. monacensis (99.3-99.7 %). A total of 13/15 pooled samples were positive by nPCR for the 17-kDa gene, with amplicons demonstrating a high degree of similarity to R. monacensis (99.4-100 %). These findings demonstrate that R. monacensis is distributed throughout Gyeonggi and Gangwon Provinces in the ROK. Furthermore, data suggest a relative high prevalence of R. monacensis in the tick, I. nipponensis.

Bell's palsy and sudden deafness associated with Rickettsia spp. infection in Sweden. A retrospective and prospective serological survey including PCR findings

BACKGROUND AND PURPOSE

Sixty patients with facial palsy and 67 with sudden deafness were retrospectively or prospectively examined for serological evidence of rickettsial infection; in six cases where cerebrospinal fluid was available, patients were also examined for presence of rickettsial DNA.

METHODS

Rickettsial antibodies were detected in single or paired serum samples using immunofluorescence with Rickettsia helvetica as the antigen and in four cases also using western blot. Using PCR and subsequent direct cycle sequencing, the nucleotide sequences of the amplicons (17 kDa protein gene) in cerebrospinal fluid were analysed.

RESULTS

Five out of 60 (8.3%) patients with facial palsy and eight of 67 (11.9%) with hearing loss showed confirmative serological evidence of infection with Rickettsia spp. An additional three and four patients in the facial palsy and hearing loss groups, respectively, showed evidence of having a recent or current infection or serological findings suggestive of infection. In four cases, the specificity of the reaction was confirmed by western blot. An additional 70 patients were seroreactive with IgG or IgM antibodies higher than or equal to the cut-off of 1:64, whereas 37 patients were seronegative. Only two of 127 patients had detectable antibodies to Borrelia spp. In three of six patients, rickettsial DNA was detected in the cerebrospinal fluid, where the obtained sequences (17 kDa) shared 100% similarity with the corresponding gene sequence of Rickettsia felis.

CONCLUSIONS

These results highlight the importance of considering Rickettsia spp. as a cause of neuritis, and perhaps as a primary cause of neuritis unrelated to neuroborreliosis.

Simple method to differentiate among Rickettsia species

In this work we present a new option to identify 11 rickettsial species that cause human rickettsioses, with some advantages over the previous methods described. Using rickettsial isolates from 11 Rickettsia species as a sample, we used the polymerase chain reaction to amplify a 990- to 1,000-bp DNA fragment from the ompB gene, common for the 11 Rickettsia species analyzed in this study, which were digested with AluI restriction enzyme to obtain different digestion patterns. This restriction pattern can be visualized using a polyacrylamide gel electrophoresis technique. Using this method we could differentiate between the 11 Rickettsia species analyzed regardless of the group to which the Rickettsia belonged. We developed a simple method to identify 11 Rickettsia species which cause human rickettsioses using polymerase chain reaction and restriction fragment length polymorphism techniques with the advantage that it only needs one amplicon and only one restriction enzyme to obtain the restriction pattern. The identification of the species infecting vectors, reservoirs, and humans is essential to establish the ecological and behavioral ecosystem involved in its maintenance and transmission in nature in the specific region where the pathogen is circulating. This method is very helpful to identify Rickettsia species in a short time.

Detection of Rickettsia massiliae in Rhipicephalus sanguineus from the eastern United States

We report the first evidence of Rickettsia massiliae in the brown dog tick, Rhipicephalus sanguineus, from the East Coast of the United States. As part of routine pathogen surveillance, DNA samples from ixodid ticks were tested for spotted fever group rickettsiae by nested PCR. A R. massiliae-positive tick was collected off a beagle mix recently rescued from North Carolina. Infection was confirmed by partial sequence analysis of the htrA, gltA, ompB, ompA, and sca4 genes, which had 100% identity to a R. massiliae isolate from Arizona.

Usefulness of rickettsial PCR assays for the molecular diagnosis of human rickettsioses

BACKGROUND

The effectiveness of PCR methods to amplify rickettsiae from clinical samples has still not been evaluated. Our aim was to determine the sensitivity and usefulness for Rickettsia species identification by PCR methods, targeting 16S rDNA, htrA, gltA, ompA, and ompB genes for molecular diagnosis of rickettsioses.

METHODS

A total of 72 clinical samples (EDTA-blood, skin biopsies and ticks) taken from 52 patients in the early phase of the illness with PCR-confirmed rickettsioses were included. Single [16S rDNA, gltA (5' end), and htrA genes] and sequential (nested or semi-nested) PCR assays [ompB, gltA (central region) and ompA genes] were performed.

RESULTS

For single-stage PCR assays, the greatest sensitivity (33.3%) was obtained using the gltA (5' end), while for sequential assays, the most sensitive results were obtained using the ompB assay (83.3%). The highest sensitivity (100%) was achieved using the three sequential PCRs. The ompA PCR method was the most reliable for identifying Rickettsia species, according to clinical features.

CONCLUSIONS

PCR-based amplification methods are useful rickettsial diagnostic tools in the early phase of the illness. The three sequential PCR assays here investigated (ompB, gltA and ompA) appear to be useful tools for molecular diagnosis of rickettsioses. ompB PCR assay is effective for primary screening, since it detects a high percentage of positive samples. ompA assay is the most useful method to identify a Rickettsia species in human pathology. Nevertheless, epidemiology, clinical symptoms and the vector involved in the infection have to be taken into account for the diagnosis of rickettsioses.

Molecular detection and analysis of spotted fever group Rickettsia in patients with fever and rash at a tertiary care centre in Tamil Nadu, India

BACKGROUND

Detection of specific targets by PCR is used to confirm a diagnosis of spotted fever, but serological tests are still widely used. In this prospective study, nested PCR was performed on skin biopsy specimens to confirm the diagnosis of spotted fever.

METHODS

In 58 clinically suspected cases of spotted fever, nested PCR, to detect gltA, 17 kDa lipoprotein antigen gene (17 kDa), ompA and ompB, from skin biopsy of the rash was performed. Sequencing was carried on amplicons representing the four targets to confirm specificity of amplification. This was followed by phylogenetic analysis using MEGA version 4.0 software.

RESULTS

The gltA, 17 kDa, ompA, and ompB genes were detected from skin biopsy specimens in 38, 23, 27, and 22 individuals. Sequence analysis revealed that the gltA, 17 kDa, ompA, and ompB sequences belonged to spotted fever group (SFG) rickettsia. Of the six partial ompA gene sequences, only one was dissimilar to the previously reported 'Candidatus Rickettsia kellyi'.

CONCLUSION

Further evidence indicates that SFG rickettsiae resembling 'Candidatus Rickettsia kellyi' cause fever and rash in southern India. More detailed phylogenetic analysis following isolation of rickettsia in culture is required for providing irrefutable proof for the occurrence of novel spotted fever rickettsiae in this region.

Study on ticks and tick-borne zoonoses in public parks in Italy

A survey on tick density and on tick-borne zoonoses was carried out in four public parks in the outskirts of Imola (northern Italy) from June to October 2006. All stages of Ixodes ricinus and only larvae of Riphicephalus sanguineus were recovered by dragging, performed on 100-m transects. Almost all ticks (99%) were harvested in one park. I. ricinus density (nymphs/100 m(2) ) ranged from 0 in park L to 6.3 in park F. Nymphs and adults of I. ricinus were subjected to PCR for Anaplasma phagocytophilum, Bartonella spp., Borrelia burgdorferi s. l. and Rickettsia spp. The observed prevalences were 38.3% for Bartonella henselae, 5.2% for Bartonella clarridgeiae, 10.4% for B. burgdorferi s. l., 2.6% for Rickettsia helvetica and 13% for Rickettsia monacensis, respectively. No DNA of A. phagocytophilum was found. Acarological risks (AR) were calculated as probabilities of collecting at least one infected nymph per transect. The AR values calculated for the various zoonotic agents were 11.4% for R. helvetica, 27.7% for B. clarridgeiae, 49.7% for B. burgdorferi s. l., 57.2% for R. monacensis and 90.4% for B. henselae, respectively. In this study, B. clarridgeiae was for the first time identified in I. ricinus ticks.