Prevalence and diversity of spotted fever group Rickettsia species in ixodid ticks from domestic dogs in Chad, Africa

African tick-bite fever: a new entity in the differential diagnosis of multiple eschars in travelers. Description of five cases imported from South Africa to Switzerland

Diversity of spotted fever group Rickettsia infection in hard ticks from Suifenhe, Chinese–Russian border

Spotted fever group (SFG) rickettsiae are recognized as important agents of human tick-borne diseases worldwide, such as Mediterranean spotted fever (Rickettsia conorii) and Rocky Mountain spotted fever (Rickettsia rickettsii). Recent studies in several animal models have provided evidence of non-endothelial parasitism by pathogenic SFG Rickettsia species, suggesting that the interaction of rickettsiae with cells other than the endothelium may play an important role in pathogenesis of rickettsial diseases. These studies raise the hypothesis that the role of macrophages in rickettsial pathogenesis may have been underappreciated. Herein, we evaluated the ability of two SFG rickettsial species, R. conorii (a recognized human pathogen) and Rickettsia montanensis (a non-virulent member of SFG) to proliferate in THP-1 macrophage-like cells, or within non-phagocytic cell lines. Our results demonstrate that R. conorii was able to survive and proliferate in both phagocytic and epithelial cells in vitro. In contrast, R. montanensis was able to grow in non-phagocytic cells, but was drastically compromised in the ability to proliferate within both undifferentiated and PMA-differentiated THP-1 cells. Interestingly, association assays revealed that R. montanensis was defective in binding to THP-1-derived macrophages; however, the invasion of the bacteria that are able to adhere did not appear to be affected. We have also demonstrated that R. montanensis which entered into THP-1-derived macrophages were rapidly destroyed and partially co-localized with LAMP-2 and cathepsin D, two markers of lysosomal compartments. In contrast, R. conorii was present as intact bacteria and free in the cytoplasm in both cell types. These findings suggest that a phenotypic difference between a non-pathogenic and a pathogenic SFG member lies in their respective ability to proliferate in macrophage-like cells, and may provide an explanation as to why certain SFG rickettsial species are not associated with disease in mammals.

Mapping the global distribution of spotted fever group rickettsiae: a systematic review with modelling analysis

Spotted fever group (SFG) rickettsiae are important causative agents of (re)emerging tick-borne infectious diseases in humans, and ticks play a key role in their maintenance and transmission. In this study, hard ticks were collected from five sampling sites in North China in 2017 and 2018. Of them, Haemaphysalis longicornis, Rhipicephalus microplus and Dermacentor nuttalli were collected from livestock (sheep and goats) and the vegetation, Hyalomma asiaticum from sheep, goats and camels, and Hyalomma marginatum from sheep and goats. The SFG rickettsiae were identified in these ticks by amplifying the partial rrs and complete 17-kDa genes, with an overall infection rate of 52.9%. In addition, the nearly full-length rrs and gltA and partial ompA genes were recovered to classify the species of SFG rickettsiae further. Phylogenetic analysis revealed the presence of three human pathogenic species in Hy. asiaticum, Hy. marginatum, Ha. longicornis and De. nuttalli, including two cultured ones (Rickettsia raoultii and Rickettsia aeschlimannii) and one uncultured (Candidatus R. jingxinensis). Furthermore, partial groEL gene was also obtained, and phylogenetic trees were also reconstructed to better understand the genetic relationship with known sequences in each SFG rickettsiae species detected in the current study. Notably, the R. aeschlimannii sequences described in this study were closely related to those from abroad rather than from another part of China, indicating their different origin. However, the R. raoultii and Ca. R. jingxinensis sequences presented close relationship with variants from other parts of China. In sum, our data revealed SFG rickettsiae species in northern China, highlighting the need for surveillance of their infection in local humans.

Etiology of acute undifferentiated febrile syndrome (AUFS) is often unknown, leading to inaccurate diagnosis and treatment. Villeta town has been identified as an endemic area for spotted fever group (SFG) rickettsioses but little is known about possible amplifier hosts and other Rickettsia species different from Rickettsia rickettsii. Besides, few studies have approached other AUFS etiologies in the region. We investigated the role of dengue, leptospirosis, rickettsioses, human anaplasmosis, and Q fever as possible causes of AUFS in patients from Villeta. Sera specimens and ticks from animals as well as ticks from vegetation were studied for the presence of different Rickettsia spp. Among 104 sera from patients with AUFS, 16.4%, 24.0%, and 2.9% patients seroconverted to dengue, Leptospira, and SFG Rickettsia, respectively, with a case of probable coinfection or cross-reaction with Anaplasma phagocytophilum. None of the samples were reactive for Coxiella burnetii. Sera samples from 74 horses, 118 dogs, and 62 bovines were collected and showed 33.8%, 14.4%, and 50.0% of seroprevalence for SFG Rickettsia, respectively. A total of 1,287 ixodid ticks were collected from animals/vegetation and processed in pools for polymerase chain reaction. Among them, 1.7% was positive for Rickettsia genes, and Rickettsia amblyommii, R. rickettsii, and Rickettsia spp. were found. These results confirm the circulation of dengue, different SFG Rickettsia species and the relevance of other etiologies like leptospirosis and human anaplasmosis. Further studies must identify different epidemiological variables to establish proper surveillance and control programs.

Dermacentor nuttalli has been a focus of study because tick-borne pathogens have been widely identified in this tick from northern and southwestern China. The aim of this study was to characterize the life cycle of D. nuttalli under laboratory conditions and to detect spotted fever group (SFG) Rickettsia in the midgut and salivary glands of both field-collected and first laboratory generation adults. D. nuttalli ticks were collected in the field on the Qinghai-Tibetan Plateau from March to April 2021 and their life cycle was studied under laboratory conditions. Tick identify was molecularly confirmed, and SFG Rickettsia were detected in the midgut and salivary glands of males and females by PCR targeting different rickettsial genes. The results showed that the life cycle of D. nuttalli under laboratory conditions was completed in an average of 86.1 days. High positivity of Rickettsia spp. was detected in the midgut and salivary glands of both males (92.0%) and females (93.0%) of field-collected D. nuttalli ticks. However, a relatively lower positivity (4.0-6.0%) was detected in first laboratory generation adults. Furthermore, sequencing analysis showed that the Rickettsia sequences obtained in this study shared 98.6 to 100% nucleotide identity with Rickettsia slovaca and Rickettsia raoultii isolated from Dermacentor spp. in China. Phylogenetic analysis of Rickettsia spp. based on the gltA, ompA, ompB and sca4 genes revealed that the Rickettsia sequences obtained could be classified as belonging to R. slovaca and R. raoultii clades. This study described for the first time the life cycle of D. nuttalli from the Qinghai-Tibetan Plateau under laboratory conditions. Two species of SFG Rickettsia were detected in the midgut and salivary glands of males and females in both field-collected and first laboratory-generation adults of D. nuttalli. Our study provides new insights into pathogen detection in ticks in the Qinghai-Tibet Plateau, and the relationships among hosts, ticks, and pathogens.

BACKGROUND: In total, 30 ixodid tick species were found on the Crimean Peninsula. Their epidemiological importance was directly correlated with the pathogenicity of the infectious agents that they may transmit. One such established etiological agent is Rickettsia conorii, a representative of the spotted fever group rickettsiae. Rhipicephalus sanguineus ticks serve as both a vector and reservoir for R. conorii. Studying the prevalence of pathogenic agents among the ixodid ticks is particularly crucial given Crimea’s status as a health resort and a center for resort-based medicine. AIM: This work aimed to assess the role of ixodid ticks in the circulation of R. conorii and other spotted fever group rickettsiae. METHODS: The ticks were collected from the vegetation, from April to September, for 7 years (2016–2022). For this, flagging and dragging methods, as well as the examination and combing of large and small livestock, horses, dogs, cats, and hedgehogs, were employed. During the outbreaks of Mediterranean spotted fever, ticks were collected from the foci of infection in humans and domestic animals. Genetic markers of rickettsiae were detected using real-time polymerase chain reaction followed by species identification. RESULTS: In total, nine ixodid tick species were identified from the collected specimens. Overall, the most abundant species were Haemaphysalis punctata (42.9%), Rhipicephalus sanguineus (20.8%), Hyalomma marginatum (15.5%), and Ixodes ricinus (12.8%). The collections were predominated by H. punctata in 2016 (75.5%), H. marginatum in 2017 and 2021 (58.2% and 24.6%, respectively), I. ricinus in 2018 (59.5%), and R. sanguineus in 2019 (47.9%). The DNA of eight spotted fever group rickettsiae species, including R. conorii, R. massiliae, R. sibirica subspp. mongolotimonae, R. slovaca, R. aeschlimannii, R. monacensis, R. helvetica, and R. raoultii were detected in the collected ticks. R. conorii was found in R. sanguineus and H. marginatum. For the first time on the Crimean Peninsula, R. massiliae was detected in R. sanguineus; R. slovaca in Dermacentor marginatus, H. marginatum, H. punctata, R. sanguineus, and I. ricinus; R. mongolotimonae in H. marginatum and R. sanguineus; and R. helvetica in I. ricinus. The greatest diversity of the spotted fever group rickettsiae was recorded in R. sanguineus and H. marginatum. CONCLUSION: This study established the role of ixodid ticks in the circulation of eight species of spotted fever group rickettsiae on the Crimean Peninsula. They included R. conorii, R. massiliae, R. slovaca, R. raoultii, R. aeschlimannii, R. mongolotimonae, R. monacensis, and R. helvetica. The DNA sequences of R. conorii, R. massiliae, R. slovaca, and R. raoultii were deposited in the GenBank database. These findings on the quantitative and species composition of the ixodid fauna, tick infection rates, and genetic diversity of the detected rickettsiae highlight the need to expand laboratory capabilities, apply a risk-oriented approach, and implement corrective measures to the epidemiological surveillance system of spotted fever group rickettsioses on the peninsula.

To the Editor: The first human case of African tick-bite fever was described in 1992 as occurring in Zimbabwe. The causative agent was identified as a new serotype of the spotted fever group (SFG) rickettsiae and named Rickettsia africae (1). These findings confirmed observations made by Pijper in the 1930s, which suggested that there were 2 different kinds of human SFG rickettsioses in sub-Saharan Africa: Mediterranean spotted fever caused by R. conorii and transmitted by Rhipicephalus species, ticks of dogs, and African tick-bite fever caused by R. africae and transmitted by Amblyomma species, ticks of cattle and wild ungulates. African tick-bite fever has subsequently been diagnosed in patients from several other sub-Saharan countries and also from the West Indies (2,3). In a recent analysis of the spectrum of diseases among returning travelers, tick-borne spotted fever was (after malaria) the second most frequent cause of systemic febrile illness among those returning from sub-Saharan Africa. It occurred more frequently than typhoid fever and dengue fever (4). The following case description reports an infection with R. africae in a man in France who recently returned from Ethiopia. On November 4, 2005, a 62-year-old French man sought care at the Medical Center of the Institut Pasteur in Paris for fever, along with chills, headache, neck and shoulder pain, and fatigue over the previous 4 days. At the onset of these symptoms he had noticed dark nodular lesions on his neck and his left groin followed 2 days later by a slightly painful eruption on his arms and his trunk. He had spent a month in southwest Ethiopia, north of Kelem near the Sudanese border, and returned to France on October 26, 2005. While in Ethiopia, he had assisted with a production of a documentary film about an Ethiopian tribe and had been in contact with cattle in the villages. He had not noticed any tick bites. On physical examination he had a fever of 38°C, a nodular lesion with a central dark crust on his neck, a second lesion on his left inguinal fold (Figure, panel A), and a vesicular eruption on his arms and his trunk (Figure, panel B). Leukocyte count was 3,200, including 1,869 neutrophils and 867 lymphocytes. The platelet level was 174,000/mm3. The C-reactive protein level was 28.3 mg/L. The aspartate aminotransferase level was slightly elevated. The patient was treated with doxycycline 200 mg/day for 1 week for suspected African tick-bite fever. Follow-up showed a quick recovery from his symptoms except for fatigue that persisted for ≈1 month. Figure Inoculation eschar on left inguinal fold (A) and vesicular skin lesion (B) in a traveler recently returned to France from Ethiopia. A commercial immunofluorescence assay for R. conorii and R. typhi immunoglobulin G performed both on an initial blood sample and a second sample taken 1 week later were negative. A blood sample and a biopsy specimen of the inguinal eschar were sent to the National Reference Center of Rickettsiae in Marseille, France. Although cellular culture of both specimens and molecular testing of the blood sample were negative, PCR for the sequences of citrate synthase (GenBank accession no. {type:entrez-nucleotide,attrs:{text:RAU59733,term_id:1389980}}RAU59733, 93.1% homology) and rickettsial OmpA (GenBank accession no. {type:entrez-nucleotide,attrs:{text:RAU83436,term_id:62861416}}RAU83436, 99.3% homology) applied on the skin biopsy detected R. africae and confirmed the diagnosis of African tick-bite fever. From 1969 to 1971, SFG rickettsiae were isolated from Amblyomma spp. ticks collected in Ethiopia. They were regarded as R. conorii or as closely related bacteria (5). Later, more specific tests using western immunoblots with monoclonal antibodies showed that these rickettsiae differed from R. conorii (6). In 1992 SFG rickettsiae isolated from Amblyomma ticks collected in Zimbabwe and from the blood of a patient in Zimbabwe were compared to R. conorii, to other pathogenic SFG rickettsiae, and to a SFG rickettsia isolated from an Amblyomma spp. tick in Ethiopia 20 years before. The SFG rickettsia isolates from Ethiopia were identical to isolates obtained in Zimbabwe from the Amblyomma ticks and the patient’s blood and were different from R. conorii and other pathogenic SFG rickettsiae. This new serotype of SFG rickettsiae was named R. africae (1,7). A recent study confirmed the presence of R. africae in ticks collected in Ethiopia, as well as R. aeschlimanii (8). Thus, evidence of R. africae in Ethiopia has been known for a long time. The geographic distribution of African tick-bite fever is related to the presence of Amblyomma spp. ticks, vectors and reservoirs of R. africae. Consequently African tick-bite fever should also be considered as a possible diagnosis in patients with febrile illness returning from countries where R. africae has been detected in Amblyomma ticks, even if a human infection has not yet been reported (9,10).

To the Editor: In Greece, 6 spotted fever group (SFG) Rickettsia species have been detected in ticks: Rickettsia conorii, R. massiliae, R. aeschlimannii, R. sibirica mongolitimonae, R. slovaca, and R. rhipicephali (1). SFG species present characteristic clinical signs, including high fever, headache, and maculopapular rash; an inoculation eschar at the tick bite site is characteristic of some, but not all, SFG rickettsioses. Symptoms during the early stages of illness are nonspecific, and diagnosis is a challenge for physicians who are not familiar with rickettsial diseases. So far, 2 SFG Rickettsia species have been implicated in human disease in Greece: Mediterranean spotted fever caused by R. conorii (2), and lymphagitis-associated rickettsiosis (LAR) caused by R. sibirica mongolitimonae (3). We report a rickettsiosis case in a man on the island of Crete, Greece caused by a third Rickettsia species belonging to the SFG, R. aeschlimannii. During June 2010, a 70-year-old man residing in an agricultural area of eastern Crete was admitted to the emergency unit of General Hospital of Agios Nikolaos for evaluation of a reddish, painless papule on the anterior surface of his left arm. The papule was 2 cm in diameter, and was surrounded by a less reddened infiltrated area 8 cm in diameter (Figure). The area was without tenderness or pruritus. At the center of the papule, which was cyanotic, the presence of a tick was recorded, and the tick was removed carefully in its entirety. The patient was afebrile and reported no other symptoms. The papule had developed within few hours, although 5 days previously, the patient had noticed a dark colored nodule on his left arm but paid no attention to it. The patient reported that rabbits were bred and goats and sheep grazed at close proximity to his residence. Figure Papule on the anterior surface of the left arm of a 70-year-old man, Crete, Greece. The papule was surrounded by an infiltrated area without tenderness or pruritus. A tick was found in the center of the papule and carefully removed in its entirety. Serum and whole blood samples were drawn, and a local skin biopsy was performed from the center of the skin lesion. Laboratory tests revealed a high level of C-reactive protein, microscopic hematuria, and a leukocyte count of 6.01 × 109 cells/L. Hepatic enzymes alanine transaminase and aspartate aminotransferase were within normal ranges. The patient was treated with doxycycline, 100 mg twice daily for 7 days; he did not develop further symptoms, and the skin lesion healed without ulceration. All samples were sent to the Laboratory of Clinical Bacteriology, Parasitology, Zoonoses and Geographic Medicine at the University of Crete for further testing. The tick was identified as Rhipicephalus turanicus by using standard taxonomic keys (4). IgG and IgM titers reactive to SFG rickettsiae antigens were determined by an immunofluorescence antibody assay as described by the manufacturer (bioMerieux, Marcy l’Etoile, France). Twenty days after initial assessment and treatment, convalescent-phase blood samples were drawn for serum and whole blood analysis. Titers against R. conorii were detected in both the initial samples (IgM 1/100, IgG 1/60) and the convalescent-phase samples (IgM 1/100, IgG 1/120). DNA was extracted from the blood samples, the skin biopsy, and the tick by using a QIAamp Tissue Kit (QIAGEN, Courtaboeuf, France ) and used as a template in previously described PCR assays by using primers RpCS 877p-RpCS 1258n and Rr19070p-Rr190602n, targeting a 381-bp portion of the gltA and a 532-bp portion of the ompA genes of Rickettsia spp. (5). The whole blood drawn in the hospital, the skin biopsy, and the tick were positive for both genes. However, the convalescent-phase blood sample was negative. PCR products were purified by using the QIAquick Spin PCR Purification Kit (QIAGEN) and sequenced (Bioanalytica–Genotype, Athens, Greece) according to the manufacturer’s instructions. Sequences obtained shared 100% similarity to the corresponding fragment of the genome of R. eschlimannii (gltA: {type:entrez-nucleotide,attrs:{text:JF803904,term_id:353260511,term_text:JF803904}}JF803904; ompA: {type:entrez-nucleotide,attrs:{text:JF803906,term_id:353260495,term_text:JF803906}}JF803906). All samples were cultured in human embryonic lung fibroblasts as described (6). After 4 weeks, no bacteria were isolated. We report a human case of R. eschlimannii infection in Crete, Greece. Our finding was confirmed by molecular methods. However, we were not able to cultivate R. aeschlimannii from samples collected. This result suggests that living microorganisms may have died before testing or that only DNA, but no living organism, was present in the samples. R. aeschlimannii was first isolated from Hyalomma marginatum ticks from Morocco (7). In Europe, R. aeschlimannii has also been found in ticks from Germany, Russia, Italy, France, Croatia, Portugal, and Spain (8). In Greece, R. aeschlimannii has been detected in H. anatolicum excavatum ticks collected from sheep (1). The tick removed from this patient was Rh. turanicus, a species that has been reported in Spain to be infected with R. aeschlimannii (9). The first human case of R. aeschlimannii infection was identified in a patient who had fever, rash, and an eschar after travel in Morocco (10). R. aeschlimannii infections in humans have been previously confirmed in South Africa, in Algeria, and in Tunisia (8). To our knowledge, human cases of R. aeschlimannii infection have not been reported in Europe. Our results emphasize that ticks should be considered as potential vectors for rickettsial infections in humans. We recommend that when one species or serotype of tick-transmitted Rickettsia is identified in an area, physicians be informed through established clinical or public health channels of the potential pathogen, its manifestations, and recommended treatments for humans.

Spotted fever group rickettsioses (SFGR) are infections caused by established and emerging human pathogens worldwide. These rickettsial agents are transmitted to humans via arthropods and may result in mild to severe and potentially fatal diseases. Spotted fever group rickettsioses are characterized by similar clinical features, including fever, rash, headache and myalgias, with the development of an inoculation eschar in many, but not all cases. Endemic rickettsial infections do occur but are infrequent in Canada, in contrast to the United States, where these infections are far more prevalent. Travel-associated rickettsioses, however, are being diagnosed with increasing frequency in Canadian travellers returning from international trips abroad, in particular in travellers returning from Africa. The diagnosis of rickettsial infections can be challenging owing to the non-specific nature of the clinical symptoms and the requirement for specialized testing. Serology cannot distinguish between the approximately 20 spotted fever group rickettsial species currently known or suspected to be capable of causing human infection. Molecular testing is required to determine the rickettsial species responsible for infection, but requires greater effort on the part of the clinician to collect appropriate samples, including cutaneous skin swabs from under the eschar or skin punch biopsies of the eschar or rash. Infections with spotted fever group rickettsiae likely occur more commonly than currently recognized and should be considered in patients with appropriate symptoms and exposure histories.

Molecular identification of tick (Acari: Ixodidae) and tick-borne pathogens from Przewalski's gazelle (Procapra przewalskii) and Tibetan sheep (Ovis aries) in Qinghai Lake National Nature Reserve, China

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.

BackgroundThe importance of tick-borne diseases is increasing all over the world, including Turkey. The tick-borne disease outbreaks reported in recent years and the abundance of tick species and the existence of suitable habitats increase the importance of studies related to the epidemiology of ticks and tick-borne pathogens in Turkey. The aim of this study was to investigate the presence of and to determine the infection rates of some tick-borne pathogens, including Babesia spp., Borrelia burgdorferi sensu lato and spotted fever group rickettsiae in the ticks removed from humans in different parts of Ankara.Methodology/Principal FindingsA total of 169 ticks belonging to the genus Haemaphysalis, Hyalomma, Ixodes and Rhipicephalus were collected by removing from humans in different parts of Ankara. Ticks were molecularly screened for Babesia spp., Borrelia burgdorferi sensu lato and spotted fever group rickettsiae by PCR and sequencing analysis. We detected 4 Babesia spp.; B. crassa, B. major, B. occultans and B. rossi, one Borrelia spp.; B. burgdorferi sensu stricto and 3 spotted fever group rickettsiae; R. aeschlimannii, R. slovaca and R. hoogstraalii in the tick specimens analyzed. This is the report showing the presence of B. rossi in a region that is out of Africa and in the host species Ha. parva. In addition, B. crassa, for which limited information is available on its distribution and vector species, and B. occultans, for which no conclusive information is available on its presence in Turkey, were identified in Ha. parva and H. marginatum, respectively. Two human pathogenic rickettsia species (R. aeschlimannii and R. slovaca) were detected with a high prevalence in ticks. Additionally, B. burgdorferi sensu stricto was detected in unusual tick species (H. marginatum, H. excavatum, Hyalomma spp. (nymph) and Ha. parva).Conclusions/SignificanceThis study investigates both the distribution of several tick-borne pathogens affecting humans and animals, and the presence of new tick-borne pathogens in Turkey. More epidemiological studies are warranted for B. rossi, which is very pathogenic for dogs, because the presented results suggest that B. rossi might have a wide distribution in Turkey. Furthermore, we recommend that tick-borne pathogens, especially R. aeschlimannii, R. slovaca, and B. burgdorferi sensu stricto, should be taken into consideration in patients who had a tick bite in Turkey.

In this study, we aimed to identify and genetically characterize spotted fever group (SFG) rickettsiae in ticks, domestic one-humped camels, and horses from farms and Bedouin communities in southern Israel. A total of 618 ixodid ticks (Hyalomma dromedarii, Hyalomma turanicum, Hyalomma excavatum, and Hyalomma impeltatum) collected from camels and horses, as well as 152 blood samples from 148 camels and four horses were included in the study. Initial screening for rickettsiae was carried out by targeting the gltA gene. Positive samples were further analyzed for rickettsial ompA, 17kDa, ompB, and 16S rRNA genes. Rickettsia aeschlimannii DNA was detected in the blood of three camels and 14 ticks (H. dromedarii, H. turanicum, and H. excavatum). Rickettsia africae was found in six ticks (H. turanicum, H. impeltatum, H. dromedarii, and H. excavatum). In addition, Rickettsia sibirica mongolitimonae was detected in one H. turanicum tick. These findings represent the first autochthonous detection of R. africae in Israel. Previous detections of R. africae in Asia were reported from the Sinai Peninsula (Egypt) and Istanbul, only. Furthermore, we report for the first time the finding of R. aeschlimannii in H. turanicum and H. excavatum ticks, as well as the first identification of R. sibirica mongolitimonae in H. turanicum ticks. The tick species identified to harbor R. africae and other SFG rickettsiae have been reported to occasionally feed on people, and, therefore, physicians should be aware of the possible exposure of local communities and travelers, especially those in contact with camels, to these tick-borne rickettsial pathogens.