Rickettsia spp. in Rhipicephalus sanguineus sensu lato ticks collected from stray dogs in Kerman city,Iran

Rickettsial diseases are recognized as one of the most important vector-borne infectious diseases for humans all over the world. Dogs and their ticks are considered the most important reservoirs for Rickettsia spp., especially in spotted fever group rickettsioses. The aim of the study was to investigate Rickettsia infections in ticks collected from stray dogs in southeastern Iran. In this study, 50 stray dogs in Kerman city were randomly selected, of 68% and 52% of which were above 8 months age and male, respectively. Ticks were collected from the dog skins. After identification of collected ticks, genomic DNA of all ticks was extracted. DNA samples were tested using real-time PCR for Rickettsia spp. infections. The species of Rickettsia in positive samples were determined using gltA gene amplification and sequencing. A total of 250 ticks were collected from 50 stray dogs and all of them belonged to Rhipicephalus sanguineus sensu lato. Totally, 10 pooled of 50 pooled ticks were positive for Rickettsia spp. in real-time PCR and the minimal Rickettsial infection rate was 4% in this study. The identified Rickettsia spp. included R. massiliae (n = 5), R. rhipicephali (n = 1), and R. sibirica (n = 1). In this study, molecular evidence of Rickettsia spp. infection was observed in collected ticks from stray dogs in southeast Iran. More sensitivity to human and animal health care systems in southeastern Iran is essential to the diagnosis of suspected clinical cases that are related to rickettsiosis.     

Two novel Rickettsia species of soft ticks in North Africa: ‘Candidatus Rickettsia africaseptentrionalis’ and ‘Candidatus Rickettsia mauretanica’

Rickettsia are obligate intracellular bacteria often reported from hard ticks but more rarely from soft ticks. In this study, we detected in Northern Africa two putatively novel Rickettsia species in soft tick species of the Ornithodoros erraticus complex: Ornithodoros occidentalis from Morocco, Ornithodoros erraticus from Algeria and Ornithodoros normandi from Tunisia. We characterized these two novel Rickettsia species on the basis of comparative DNA sequence analyses and phylogenetics of four genes (gltA, 16S rRNA, coxA and ompB). These Rickettsia, provisionally named ‘Candidatus Rickettsia africaseptentrionalis’ and ‘Candidatus Rickettsia mauretanica’, differed in nucleotide sequence from those of other Rickettsia species by 0.38–21.43 % depending on the gene examined. Phylogenetics further showed that the two novel Rickettsia species are closely related to each other and represent sister taxa to R. hoogstraalii, R. felis and R. asembonensis within the transitional Rickettsia group. While Ornithodoros host species of ‘Candidatus Rickettsia africaseptentrionalis’ and ‘Candidatus Rickettsia mauretanica’ are among the most common soft ticks to bite humans, their pathogenicity remains to be investigated.     

Genetic variability of Rickettsia spp. in Ixodes persulcatus/Ixodes trianguliceps sympatric areas from Western Siberia,Russia: Identification of a new Candidatus Rickettsia species

Rickettsia spp. are the causative agents of a number of diseases in humans. These bacteria are transmitted by arthropods, including ixodid ticks. DNA of several Rickettsia spp. was identified in Ixodes persulcatus ticks, however, the association of Ixodes trianguliceps ticks with Rickettsia spp. is unknown. In our study, blood samples of small mammals (n = 108), unfed adult I. persulcatus ticks (n = 136), and I. persulcatus (n = 12) and I. trianguliceps (n = 34) ticks feeding on voles were collected in two I. persulcatus/I. trianguliceps sympatric areas in Western Siberia. Using nested PCR, ticks and blood samples were studied for the presence of Rickettsia spp. Three distinct Rickettsia species were found in ticks, but no Rickettsia species were found in the blood of examined voles. Candidatus Rickettsia tarasevichiae DNA was detected in 89.7% of unfed I. persulcatus, 91.7% of engorged I. persulcatus and 14.7% of I. trianguliceps ticks. Rickettsia helvetica DNA was detected in 5.9% of I. trianguliceps ticks. In addition, a new Rickettsia genetic variant was found in 32.4% of I. trianguliceps ticks. Sequence analysis of the 16S rRNA, gltA, ompA, оmpB and sca4 genes was performed and, in accordance with genetic criteria, a new Rickettsia genetic variant was classified as a new Candidatus Rickettsia species. We propose to name this species Candidatus Rickettsia uralica, according to the territory where this species was initially identified. Candidatus Rickettsia uralica was found to belong to the spotted fever group. The data obtained in this study leads us to propose that Candidatus Rickettsia uralica is associated with I. trianguliceps ticks.     

Identification and distribution of nine tick-borne spotted fever group Rickettsiae in the Country of Georgia

Rickettsial pathogens cause diseases that vary in severity and clinical presentation. Rickettsia species transmitted by ticks are mostly classified within the spotted fever group of rickettsiae (SFGR) and are often associated with febrile diseases. Preliminary studies have detected three human-pathogenic SFGR from ticks in Georgia: Rickettsia aeschlimannii, Rickettsia raoultii, and Rickettsia slovaca. To more broadly assess the presence of tick-borne rickettsiae from Georgia we examined 1594 ticks, representing 18 species from five genera (Ixodes, Hyalomma, Haemaphysalis, Dermacentor, and Rhipicephalus), collected from eight regions of Georgia. A total of 498 tick DNA samples extracted from single ticks or pooled ticks were assessed by molecular methods. Genus-specific Rick17b and species-specific qPCR assays were used to identify six rickettsiae: R. aeschlimannii, R. raoultii, R. slovaca, Rickettsia conorii subsp. conorii, Rickettsia massiliae, and Rickettsia monacensis. Tick samples that were positive for Rickettsia, but not identified by the species-specific assays, were further evaluated by multi-locus sequence typing (MLST) using sequences of four protein-coding genes (gltA, ompA,ompB, sca4). Three additional Rickettsia species were identified by MLST: Candidatus Rickettsia barbariae, Rickettsia helvetica, and Rickettsia hoogstraalii. Overall, nine species of Rickettsia (six human pathogens and three species with unknown pathogenicity) were detected from 12 tick species of five different genera. A distribution map for the tick-borne rickettsiae revealed six newly identified endemic regions in Georgia.     

Comprehensive screening of tick-borne microorganisms indicates that a great variety of pathogens are circulating between hard ticks (Ixodoidea: Ixodidae) and domestic ruminants in natural foci of Anatolia

Grazing domestic ruminants serve as important reservoirs and/or amplificatory hosts in the ecology of tick-borne pathogens (TBPs) and tick vectors in the natural foci; however, many enzootic life cycles including ruminants and ticks are still unknown. This study investigated a wide range of TBPs circulating among ticks and grazing ruminants in the natural foci of Anatolia, Turkey. Tick specimens (n = 1815) were collected from cattle, sheep, and goats in three ecologically distinct areas (wooded, transitional, and semi-arid zones) of Anatolia and identified by species: Dermacentor marginatus, Dermacentor reticulatus, Hyalomma anatolicum, Hyalomma excavatum, Hyalomma marginatum, Hyalomma scupense, Haemaphysalis inermis, Haemaphysalis parva, Haemaphysalis punctata, Haemaphysalis sulcata, Ixodes ricinus, Rhipicephalus bursa, and Rhipicephalus turanicus. PCR-sequencing analyses revealed TBPs of great diversity, with 32 different agents identified in the ticks: six Babesia spp. (Babesia occultans, Babesia crassa, Babesia microti, Babesia rossi, Babesia sp. tavsan1, and Babesia sp. Ucbas); four Theileria spp., including one putative novel species (Theileria annulata, Theileria orientalis, Theileria ovis, and Theileria sp.); one Hepatozoon sp.; four Anaplasma spp., including one novel genotype (Anaplasma phagocytophilum, Anaplasma marginale, Anaplasma ovis, and Anaplasma sp.); six unnamed Ehrlichia spp. genotypes; Neoehrlichia mikurensis; nine spotted fever group rickettsiae, including one putative novel species (Rickettsia aeschlimannii, Rickettsia slovaca, Rickettsia hoogstraalii, Rickettsia monacensis with strain IRS3, Rickettsia mongolitimonae, Rickettsia raoultii, Candidatus Rickettsia goldwasserii, Candidatus Rickettsia barbariae, and Rickettsia sp.); and Borrelia valaisiana. Detailed phylogenetic analyses showed that some of the detected pathogens represent more than one haplotype, potentially relating to the tick species or the host. Additionally, the presence of Neoehrlichia mikurensis, an emerging pathogen for humans, was reported for the first time in Turkey, expanding its geographical distribution. Consequently, this study describes some previously unknown tick-borne protozoan and bacterial species/genotypes and provides informative epidemiological data on TBPs, which are related to animal and human health, serving the one health concept.     

Tick-borne zoonotic pathogens in ticks feeding on the common nightingale including a novel strain of Rickettsia sp.

We examined 77 Ixodes ricinus ticks found on 33 out of 120 common nightingales (Luscinia megarhynchos) sampled in the Czech Republic in 2008 for the presence of Borrelia spirochetes, Anaplasma phagocytophilum, Rickettsia spp., and Babesia spp. We detected Borrelia garinii (in 4% of ticks), A. phagocytophilum (1%), Rickettsia helvetica (3%), a novel strain of Rickettsia sp. (sister taxon of R. bellii; 1%), and Babesia sp. EU1 (1%). Thus, we conclude that nightingales are unlikely to be important reservoir hosts for tick-borne pathogens.     

Occurrence and clinical manifestations of tick-borne rickettsioses in Western Siberia: First Russian cases of Rickettsia aeschlimannii and Rickettsia slovaca infections

Rickettsia sibirica subsp. sibirica is a main agent of tick-borne rickettsioses in Western Siberia, Russia. Recently, the first cases of Rickettsia raoultii infection in patients hospitalized in Novosibirsk Province were described. The aim of this study was to establish the etiologic agents of tick-borne rickettsioses in Western Siberia during three epidemiological seasons.Clinical samples from 1008 patients hospitalized after tick bites in April–September 2017–2019 were examined by nested PCR for the presence of Rickettsia spp. All positive specimens were genetically characterized by sequencing of the gltA gene; some specimens were also genotyped based on the 16S rRNA, ompA, and ompB genes. Rickettsia spp. DNA was detected in clinical samples from 56 (5.6%) patients. Five Rickettsia species were identified: R. sibirica (n = 28), R. raoultii (n = 15), Rickettsia aeschlimannii (n = 3), “Candidatus Rickettsia tarasevichiae” (n = 2), and Rickettsia slovaca (n = 1). In addition, new unclassified Rickettsia genovariants were found in specimens from seven patients. Patients with R. raoultii infection presented rash, eschar, and high serum aminotransferase levels less frequently compared to patients with R. sibirica infections, but more frequently showed neurological symptoms. Among other patients, only persons with an R. aeschlimannii infection had rash and/or eschar, which are typical for tick-borne rickettsioses. The current study showed that R. raoultii is a common agent of tick-borne rickettsioses in Novosibirsk Province. DNA from R. aeschlimannii and R. slovaca was found in clinical samples of patients in the Russian Federation for the first time.     

Molecular detection of Rickettsia,Anaplasma, and Bartonella in ticks from free-ranging sheep in Gansu Province,China

Ticks pose a serious threat to public health as carriers and often vectors of zoonotic pathogens. There are few systematic studies on the prevalence and genetic diversity of tick-borne bacterial pathogens in Western China. In this study, 465 ticks were collected from free-ranging sheep in Gansu Province in China. Ticks were divided into 113 pools and tick DNA was extracted from these ticks. PCR assays were performed using specific primers to screen for tick-borne pathogens as well as sequence analysis based on the 16S rRNA (rrs), ompB, gltA, ompA genes for Rickettsia, rrs, groEL genes for Anaplasma, and ssrA and rpoB genes for Bartonella. The PCR results showed that the minimum infection rates with Rickettsia, Anaplasma, and Bartonella were 16.8% (78/465), 18.9% (88/465), and 0.9% (4/465), respectively. Sequence analysis based on the concatenated sequences of rrs-ompB-gltA-ompA indicated that the Rickettsia species identified in the ticks belonged to Rickettsia raoultii, Rickettsia slovaca, and Rickettsia sibirica, respectively; phylogenetic analysis based on the groEL gene showed that all Anaplasma strains identified were Anaplasma ovis; and phylogenetic analysis based on the ssrA and rpoB genes indicated that all Bartonella strains in the ticks belonged to Bartonella melophagi. The results of this study showed that ticks in Gansu Province harbored multiple pathogens that may cause rickettsial diseases and bartonellosis. These diseases were neglected in the area and physicians and public health workers need to pay attention to their diagnoses to prevent human infection.     

Ticks and tick-borne rickettsiae from dogs in El Salvador,with report of the human pathogen Rickettsia parkeri

Twelve tick species have been reported in El Salvador; however, information regarding ticks infesting domestic dogs is lacking, and pathogenic tick-borne Rickettsia species have never been reported in El Salvador. This work evaluated ticks infesting 230 dogs from ten municipalities in El Salvador from July 2019 to August 2020. A total of 1,264 ticks were collected and identified into five species: Rhipicephalus sanguineus sensu lato (s.l.), Rhipicephalus microplus, Amblyomma mixtum, Amblyomma ovale, and Amblyoma cf. parvum. The tick R. sanguineus s.l. was the most frequent species in all localities (81.3% of sampled dogs), followed by Amblyomma mixtum (13.0%), Amblyomma ovale (10.9%) and Amblyomma cf. parvum (10.4%). The overall mean intensity of tick infestation was 5.5 ticks/dog. The highest specific mean intensity value was for R. sanguineus s.l. (4.8 ticks/dog), varying from 1.6 to 2.7 ticks/dog for the three Amblyomma species. From a random sample of 288 tick specimens tested molecularly for the presence of rickettsial agents, three spotted fever group Rickettsia were detected: Rickettsia amblyommatis in 90% (36/40) A. mixtum, 46% (11/24) A. cf. parvum, 4% (7/186) R. sanguineus s.l., and 17% Amblyomma spp.; Rickettsia parkeri strain Atlantic rainforest in 4% (1/25) A. ovale; and an unnamed rickettsia agent, designated as ‘Rickettsia sp. ES-A.cf.parvum’, in 4% (1/24) A. cf. parvum. Our finding of R. parkeri strain Atlantic rainforest in A. ovale is highly relevant because this agent has been associated to spotted fever illness in other Latin American countries, where A. ovale is implicated as its main vector. These findings suggest that spotted fever cases caused by R. parkeri strain Atlantic rainforest could be occurring in El Salvador.     

Detection of Rickettsia spp. in ring-tailed coatis (Nasua nasua) and ticks of the Iguaçu National Park,Brazilian Atlantic Rainforest

Wild animals are of considerable importance in the ecology of infectious agents, as they can function as hosts and even as possible vectors. In this study, DNA from Rickettsia spp. was detected on ticks and fragments of skin collected from wild coatis with synanthropic habits in the Iguaçu National Park (INP) in the state of Paraná in southern Brazil. Testing was carried out on a total of 566 ticks, comprising Amblyomma spp. larvae, nymphs of Haemaphysalis juxtakochi, Amblyomma brasiliense, Amblyomma coelebs, and adults of Amblyomma ovale. The samples were tested by polymerase chain reaction (PCR) by amplifying htrA, gltA, ompA, and ompB gene fragments to detect Rickettsia spp. A fragment of each positive sample was sequenced in both directions, submitted to Genbank for a homology search, and also used for phylogenetic analyses. Samples of A. coelebs (1.90%, 8/420), A. ovale (13%, 6/45), and ring-tailed coati skin (1%, 1/75) amplified Rickettsia spp. DNA. Through sequencing, Rickettsia bellii was observed in A. ovale, Rickettsia amblyommatis in A. coelebs, while Rickettsia rhipicephali was detected in the skin samples. Wild ring-tailed coatis with synanthropic habits in the INP and their ticks are infected by Rickettsia spp., and associations with new hosts have been described.     

Detection of Rickettsia spp. and Anaplasma phagocytophilum in Ixodes ricinus ticks in a region of Middle Germany (Thuringia)

Rickettsia spp. and Anaplasma spp. are regarded as potentially emerging tick-borne pathogens, but so far data on prevalence rates in questing ticks and reports on human diseases in several parts of Europe are rarely available.In this study, 430 nymphs and 570 adult Ixodes (I.) ricinus ticks were collected from a frequently visited forest region of Thuringia (Zeitzgrund, near Stadtroda) in 2006 (n=506) and 2007 (n=494). Individual ticks were investigated for a part of the citrate synthase gene (gltA) of Rickettsia spp. and the 16S rRNA gene of Anaplasma phagocytophilum. Positive amplicons were identified with restriction fragment length polymorphism (RFLP) and/or sequencing. Overall, 14.7% (147/1000) of investigated ticks were infected with Rickettsia spp. After sequencing of 64/147 positive amplicons R. helvetica (29/64) was detected predominantly. Prevalence varied in different developmental stages between 9.3% (40/430) in nymphs and 18.8% (107/570) in adults. A. phagocytophilum-specific DNA was detected in 5.4% (54/1000) of ticks with an infection rate of 4.7% (20/430) in nymphs and 6.0% (34/570) in adults. In 1% (10/1000) of ticks coinfections with Rickettsia spp. and A. phagocytophilum were found. Our study provides interesting insights into the circulation and cocirculation of different rickettsial species and A. phagocytophilum in the same biotope.     

Genetic characterization of Candidatus Rickettsia vini,a new rickettsia amplified in ticks from La Rioja,Spain

A total of 222 ticks removed from birds in La Rioja (Spain) were screened for spotted fever group rickettsia species using ompA PCR assays. Rickettsia monacensis (n = 1) and R. sibirica (n = 1) were detected. Apart from that, 27 out of 29 Ixodes spp. DNA extracts that tested positive for ompA did not match with any validated spotted fever group rickettsia. Multilocus sequence typing for 16S rRNA, gltA, ompB, sca4, and 17-kDa antigen genes was performed, and R. heilongjiangensis was found to be the nearest validly published spotted fever group rickettsia. Based on genetic criteria agreed by experts, this genotype can be classified as a new Candidatus Rickettsia sp. and was named Candidatus Rickettsia vini.     

The potential role of migratory birds in transmission cycles of Babesia spp., Anaplasma phagocytophilum,and Rickettsia spp.

Babesia spp., Anaplasma phagocytophilum, and Rickettsia spp. are potentially emerging tick-borne pathogens, whereas many issues about their ecology, e.g. reservoir host specificity, are still unclear. In spring 2007, we collected 191 feeding Ixodes ricinus ticks from 99 birds of 11 different species on a German bird conservation island in the Baltic Sea. Babesia spp. were detected in 4.7% (9/191), A. phagocytophilum was present in 2.6% (5/191), and Rickettsia spp. were identified in 7.3% (14/191) of the investigated ticks. Further characterization of Babesia spp. infections resulted in B. divergens and B. microti. Among the Rickettsia spp. infections, we identified at least 2 different species: R. monacensis and R. helvetica. Furthermore, 2 ticks harboured mixed infections. Our study provides first interesting insights into the role of migratory birds in the distribution of several emerging tick-borne pathogens.     

Diversity and geographic distribution of rickettsial agents identified in brown dog ticks from across the United States

Rhipicephalus sanguineus sensu lato, or brown dog ticks, transmit a variety of pathogens of veterinary and public health importance globally. Pathogens vectored by brown dog ticks and identified in the United States include Babesia vogeli, Ehrlichia canis, and several spotted fever group Rickettsia spp. (SFGR). Due to the challenge of collecting canine blood samples nationwide to screen for exposure to these pathogens, we took an indirect approach and tested brown dog ticks for molecular evidence of infection. Brown dog ticks (616 adults and 65 nymphs) collected from dogs and cats across the nation were tested by separate PCR assays detecting Babesia spp., E. canis, and SFGR. While no Babesia sp. was found, we identified rickettsial agents in 3.5% (24/681; 95% CI 2.4–5.2%) of the ticks. Pathogens and related organisms detected in ticks included E. canis (n = 1), Rickettsia amblyommatis (n = 3), Rickettsia massiliae (n = 11), Rickettsia monacensis (n = 3), Rickettsia montanensis (n = 5), and an undefined Rickettsia species (n = 1). These data demonstrate a wider geographic distribution of R. massiliae than previously known, and to the authors’ knowledge, reports R. monacensis in brown dog ticks for the first time. Due to the close association that brown dog ticks have with domestic dogs and humans, more research is needed to understand the full array of organisms, some of which are zoonotic, potentially transmitted by this widespread tick complex.     

Molecular characterization of tick-borne bacteria and protozoans in yaks (Bos grunniens), Tibetan sheep (Ovis aries) and Bactrian camels (Camelus bactrianus) in the Qinghai-Tibetan Plateau Area,China

Due to the specific plateau climate, a variety of unique animals live in the Qinghai-Tibetan Plateau Area (QTPA) including yaks (Bos grunniens), Tibetan sheep (Ovis aries) and Bactrian camels (Camelus bactrianus). However, information on tick-borne diseases (TBDs) in the QTPA and on the molecular characteristics of tick-borne pathogens (TBPs) in the area is limited. Therefore, the aim of this study was to investigate Anaplasma spp., Babesia spp., Theileria spp., Borrelia burgdorferi sensu lato and Rickettsia spp. infecting yaks, Tibetan sheep and camels in this area. A total of 276 animals were screened. Overall, 84.5% (164/194) of yaks, 58% (23/40) of Tibetan sheep, and 38% (16/42) of camels tested positive for at least one pathogen. Theileria spp., Anaplasma ovis and spotted fever group (SFG) Rickettsia spp. were detected as TBPs in the current study with overall infection rates of 10.9% (30/276), 8.3% (23/276) and 62.9% (171/276), respectively. Further study revealed that 1.5% (3/194) of the yaks were infected with Theileria sp. OT3, 1.5% (3/194) with T. luwenshuni, 6.2% (12/194) with T. uilenbergi, 1.1% (2/194) with T. ovis and 82% (159/194) with SFG Rickettsia spp. It was also shown that 58% (23/40) of the Tibetan sheep were infected with A. ovis and 15% (6/40) with T. ovis. Among the camels, 10% (4/42) were infected with T. equi, while 29% (12/42) were positive for Rickettsia spp. Sequence analysis revealed that the Rickettsia spp. infecting yaks and camels were Rickettsia raoultii and Rickettsia slovaca. To the best of our knowledge, this study reports the first detection and characterization of these pathogens in yaks, Tibetan sheep and camels in the country, except for T. luwenshuni infections in yaks.     

Identification of Rickettsia spp., Anaplasma spp., and an Ehrlichia canis-like agent in Rhipicephalus microplus from Southwest and South-Central China

Rhipicephalus microplus is considered to be the most important tick infesting cattle, buffalo, horse, goats as well as other animals. They transmit diseases between domestic animals and act as vectors of a variety of zoonotic pathogens. Although pathogens harbored by R. microplus have been extensively studied, the Rickettsiales pathogens vectored by R. microplus in some areas of China remained largely unexplored. From August to October 2020, a total of 291 R. microplus ticks were collected from goats and cattle in three Southern China provinces, Guangxi (n = 138), Sichuan (n = 120) and Hubei (n = 33) provinces. Phylogenetic analysis based on COI gene sequences shows that these ticks are divided into three distinct clades, indicating the remarkable genetic diversity of R. microplus ticks in China. These samples were subsequently screened for the presence of Rickettsia, Anaplasma and Ehrlichia using conventional PCR and sequencing. Subsequently, five bacterial species were identified. Out of the 120 tick DNA samples from Sichuan province, 35.83% (43/120) were positive for Rickettsia sp. belonging to spotted fever group (SFG), 12.50% (15/120) were positive for Anaplasma marginale and 0.83% (1/120) was identified as A. platys. From the 138 DNA samples from Guangxi province, an Ehrlichia canis-like and Rickettsia sp. were detected, with a positive rate of 11.59% (16/138) and 2.17% (3/138), respectively. A. capra DNA was detected in 4 out of 33 (12.12%) samples from Hubei province. Notably, the 16S, gltA and groEL sequences of the E. canis-like are closely related to the E. canis strain previously identified from China, and form a distinct cluster in the phylogenetic trees. Collectively, our results expand the knowledge on tick-borne Rickettsiales pathogens in China. Because the state of engorgement of ticks was not recorded, it is not clear at this stage whether these pathogens are infecting the ticks or are simply present in the blood meal. Given the public health significance of SFG Rickettsia, A. capra, A. platys and E. canis, a thorough investigation of the diversity and presence of pathogens in R. microplus in areas with tick-associated diseases are needed.     

Rickettsia spp. in ticks from a tropical dry forest reserve on Mexico's Pacific Coast

The present study analyzes the diversity of bacteria of the genus Rickettsia in ticks collected from wild mammals and vegetation at the Chamela Biological Station (EBCh), Jalisco, Mexico, a core area in the Chamela-Cuixmala Biosphere Reserve, which is characterized by the presence of tropical dry forest, one of the most threatened ecosystems in the world. Ticks were collected during April and November 2018 and 2019, determined to species, and subsequently processed for rickettsiae. Genomic DNA was extracted from each of 349 ticks (198 from mammals, 151 from vegetation) and screened for Rickettsia by targeting the gltA and ompA genes. Overall, 75 ticks (21.5%) were positive for rickettsiae (46 from mammals, 29 from vegetation). Through BLASTn and maximum likelihood analysis, four Rickettsia taxa were identified. Only Rickettsia amblyommatis had been previously recorded in the vicinity of the EBCh, and we confirm its presence in this reserve, associated with Amblyomma mixtum, Amblyomma cf. oblongoguttatum and Amblyomma parvum. Additionally, we record for the first time at EBCh the taxa Rickettsia parkeri strain Atlantic rainforest, which is known to cause spotted fever illness in humans, detected in Amblyomma ovale; Rickettsia bellii in A. parvum and Ornithodoros talaje; and an undescribed Rickettsia sp. in Ixodes sinaloa.     

Prevalence of Coxiella burnetii and Rickettsia spp. in ticks and rodents in southern Germany

Coxiella burnetii, the causative agent of Q fever, and Rickettsia spp. are bacterial pathogens that can be transmitted by ticks of the genus Dermacentor (i.e., Dermacentor marginatus and D. reticulatus). In Germany, the occurrence of these ticks is currently limited to few areas. However, due to increasing temperatures, these vectors will likely extend their distribution in the future, and C. burnetii and Rickettsia spp. might spread with them. To assess the prospective risk of human infections by these agents, it is important to know their current distribution. We collected 666 adult Dermacentor spp. and 119 rodents, mainly Microtus arvalis, in 3 Q fever endemic areas in southern Germany. Ticks and rodent organ pools were screened by PCR for C. burnetii and Rickettsia spp. No evidence of C. burnetii infections could be found in ticks or rodents, suggesting that these animals do not play an essential role in the epidemiology of Q fever in Germany. Rickettsia raoultii and R. slovaca could be detected in 30.3% and 0.75% of all examined ticks, respectively. In contrast, no rickettsia infections could be found in any rodent samples. Both rickettsia species can cause tick-borne lymphadenopathy (TIBOLA), a usually mild human disease. Because of the possible transmission of these rickettsiae to humans, TIBOLA should be considered in the differential diagnosis of tick-borne diseases. Our data show that a spread of these rickettsiae is possible in Germany and that more studies on the distribution of these agents are necessary.     

A 15-year monitoring of Rickettsiales (Anaplasma phagocytophilum and Rickettsia spp.) in questing ticks in the city of Hanover,Germany

Rickettsiales (Anaplasma phagocytophilum and Rickettsia spp.) are regarded as potentially emerging tick-borne pathogens and may change in abundance in response to global climate change. However, continuous monitoring on their prevalence in questing ticks is only available for the northern German city of Hanover. In the presented follow-up of this long-term study, 2100 questing ticks of the Ixodes ricinus/Ixodes inopinatus-complex collected from April to October 2020 at ten different recreation sites in Hanover were individually analysed for Rickettsia and A. phagocytophilum infection by quantitative real-time PCR. Together with previous results from years 2005, 2010 and 2015, the current study allows to assess potential changes in tick infection rates with Rickettsiales over a 15-year monitoring period. In 2020, 3.0% (63/2100) of ticks were infected with A. phagocytophilum, 36.0% (756/2100) with Rickettsia spp. and 1.2% (26/2100) with both pathogens. Regarding the different developmental tick stages, nymphs showed a significantly lower A. phagocytophilum prevalence of 0.5% (5/1050) than adult ticks (5.5% [58/1050]) as well as compared to females (5.4% [38/700]) and males (5.7% [20/350]). For Rickettsia spp., nymphs also showed a lower prevalence of 33.2% (349/1050) with a significant difference to adult ticks (38.8% [407/1050]) and female ticks (40.7% [285/700]), while males had a Rickettsia infection rate of 34.9% (122/350). Comparison with previous years indicated a stable A. phagocytophilum prevalence over the 15-year monitoring period. In contrast, fluctuating Rickettsia prevalences were observed, with a peak in 2015 in all developmental stages, but similar infection rates in 2005 and 2020. Therefore, epidemiological changes in response to climate change are not (yet) evident. Nevertheless, the long-term monitoring study will be continued in the future, as climatic impacts on tick and reservoir host populations may have a delayed effect on pathogen prevalence and, consequently, transmission to humans and domestic animals.     

Spotted fever group rickettsiae identified in Dermacentor marginatus and Ixodes ricinus ticks in Algeria

Our study was carried out using Ixodes ricinus ticks collected from cattle from Tizi-Ouzou and Dermacentor marginatus ticks collected from the vegetation of the Blida region, a tourist site, both regions situated in northern Algeria. The results of real-time quantitative PCR (qPCR) specific for a partial sequence of the citrate synthase gene (gltA) indicate that Rickettsia spp. were present in 11/23 (48%) and 4/9 (44%) of the examined ticks from Tizi-Ouzou and Blida, respectively. The sequences of Rickettsia helvetica and Ri. monacensis were found in I. ricinus ticks using gltA primers. In addition, Ri. slovaca was detected based on the sequences of the gltA and the outer membrane protein (OmpA) genes in D. marginatus ticks. DNA sequencing to identify the species revealed for the first time the presence of Ri. helvetica in I. ricinus ticks and Ri. slovaca in D. marginatus ticks from Algeria and confirmed the presence of Ri. monacensis.