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The occurrence of sporadic rickettsial infections has been consistently undervalued and overlooked, primarily owing to a limited emphasis on routine examinations for rickettsioses in clinical practice. At present, the immunofluorescence assay is the prevailing diagnostic method for suspected rickettsioses that enables the detection of specific antibodies against rickettsia in human serum. Herein, we present an exceptional instance of rickettsial infection that was characterized by a rare manifestation of extensive pericardial effusion leading to dyspnea and cardiac tamponade. A diagnosis of chronic fibrosing pericarditis was established based on pericardium tissue obtained through pericardiotomy, and a conclusive metagenomic next‐generation sequencing test confirmed the presence of Rickettsia felis infection. The cat flea, scientifically known as Ctenocephalides felis, is the predominant carrier of R. felis. An escalating incidence of human R. felis infections has raised concerns, particularly in light of the burgeoning population of domesticated animals in many contemporary societies. [ABSTRACT FROM AUTHOR]

Rickettsia felis is a rickettsial pathogen primarily associated with the cat flea, Ctenocephalides felis. Although laboratory studies have confirmed that R. felis is maintained by transstadial and transovarial transmission in C. felis, distinct mechanisms of horizontal transmission of R. felis among cat fleas are undefined. Based on the inefficient vertical transmission of R. felis by cat fleas and the detection of R. felis in a variety of haematophagous arthropods, we hypothesize that R. felis is horizontally transmitted between cat fleas. Towards testing this hypothesis, flea transmission of R. felis via a bloodmeal was assessed weekly for 4 weeks. Rhodamine B was used to distinguish uninfected recipient and R. felis-infected donor fleas in a rickettsial horizontal transmission bioassay, and quantitative real-time PCR assay was used to measure transmission frequency; immunofluorescence assay also confirmed transmission. Female fleas acquired R. felis infection more readily than male fleas after feeding on a R. felis-infected bloodmeal for 24 h (69.3% and 43.3%, respectively) and both Rickettsia-uninfected recipient male and female fleas became infected with R. felis after cofeeding with R. felis-infected donor fleas (3.3-40.0%). Distinct bioassays were developed to further determine that R. felis was transmitted from R. felis-infected to uninfected fleas during cofeeding and copulation. Vertical transmission of R. felis by infected fleas was not demonstrated in this study. The demonstration of horizontal transmission of R. felis between cat fleas has broad implications for the ecology of R. felis rickettsiosis. [ABSTRACT FROM AUTHOR]

The genus Rickettsia encompasses several species grouped into two main clusters, Typhus and the Transitional groups. The latter group contains Rickettsia felis, an endosymbiont of several arthropods with an uncertain human pathogenicity and whose most efficient transmission mechanism described thus far is transovarial. The aim of this study was to evaluate whether this pathway exists using phylogenetic analysis and partial sequences of the 17kDa and gltA genes and comparing them with host phylogeny using the cytb region. This is the first study that evaluates the vertical transmission of R. felis. In general, both phylogenies of R. felis showed no polytomies, as suspected if this pathway was the only pathway occurring. When phylogenies of the invertebrates and the gltA of R. felis were compared for strong coevolutionary insight, intricate relationships were observed, suggesting that other transmission pathways must occur, such as horizontal transmission. Further studies are needed to determine which other transmission routes occur in hematophagous arthropods. [ABSTRACT FROM AUTHOR]

Mosquitoes are generally recognized as the most important vector of many zoonotic pathogens. In this study, seven mosquitoes species were identified (Anopheles pullus, Anopheles sinensis, Anopheles lesteri, Anopheles kleini, Ochlerotatus dorsalis, Aedes koreicus and Culex inatomii) in samples collected from Yingkou City, Liaoning Province, Northeastern China. A novel Rickettsia species was detected in Anopheles sinensis (two of 71, 2.82%) and Anopheles pullus (one of 106, 0.94%) mosquitoes. Genetic analysis indicated that the rrs and ompB genes have highest 99.60% and 97.88%–98.14% identities to Rickettsia felis, an emerging human pathogen of global concern mainly harboured by fleas, mosquitoes and booklice. The gltA sequences of these strains have 99.72% of nucleotide similarity with Rickettsia endosymbiont of Medetera jacula. The groEL sequences have 98.37% similarity to both Rickettsia tillamookensis and Rickettsia australis. The htrA sequences have 98.77% similarity to Rickettsia lusitaniae. In the phylogenetic tree based on concatenated nucleotide sequences of rrs, gltA, groEL, ompB and htrA genes, these strains are closely related to R. felis. Herein, we name it 'Candidatus Rickettsia yingkouensis'. Its human pathogenicity to humans and animals is still to be determined. [ABSTRACT FROM AUTHOR]

Cat fleas ( Ctenocephalides felis) are known as the primary vector and reservoir of Rickettsia felis, the causative agent of flea-borne spotted fever; however, field surveys regularly report molecular detection of this infectious agent from other blood-feeding arthropods. The presence of R. felis in additional arthropods may be the result of chance consumption of an infectious bloodmeal, but isolation of viable rickettsiae circulating in the blood of suspected vertebrate reservoirs has not been demonstrated. Successful transmission of pathogens between actively blood-feeding arthropods in the absence of a disseminated vertebrate infection has been verified, referred to as cofeeding transmission. Therefore, the principal route from systemically infected vertebrates to uninfected arthropods may not be applicable to the R. felis transmission cycle. Here, we show both intra- and interspecific transmission of R. felis between cofeeding arthropods on a vertebrate host. Analyses revealed that infected cat fleas transmitted R. felis to naïve cat fleas and rat fleas ( Xenopsylla cheopis) via fleabite on a nonrickettsemic vertebrate host. Also, cat fleas infected by cofeeding were infectious to newly emerged uninfected cat fleas in an artificial system. Furthermore, we utilized a stochastic model to demonstrate that cofeeding is sufficient to explain the enzootic spread of R. felis amongst populations of the biological vector. Our results implicate cat fleas in the spread of R. felis amongst different vectors, and the demonstration of cofeeding transmission of R. felis through a vertebrate host represents a novel transmission paradigm for insect-borne Rickettsia and furthers our understanding of this emerging rickettsiosis. [ABSTRACT FROM AUTHOR]

Rickettsia felis belongs to spotted fever group Rickettsia and is an emerging human pathogen most commonly transmitted by a range of fleas and ticks. While recent evidence has suggested mosquitoes are infected with R. felis, there is little information about the role of mosquitoes in the organism's transmission. In this study, around 100 mosquitoes were collected monthly between 2013 and 2014 from the same residential dwelling at Yangzhou, China. The collected mosquitoes were identified for their species and gender, followed by gltA-based PCR and hydroxymethylbilane synthase-based PCR to determine the prevalence of Rickettsia and blood meal. Three mosquito species (Culex pipiens: 76%, 996/1,304; C. tritaeniorhynchus: 17%, 216/1,304; Aedes albopictus: 7%, 92/1,304) were identified. For 1,088 female mosquitoes, 31% of them n=336 were positive for blood meal and 7% n=77 carried R. felis DNA. In a strong contrast, none of the 216 male mosquitoes were positive for blood meal but two males were positive for Rickettsia. Interestingly, 63% of R. felis-positive mosquitoes (50/79) were negative for blood meal, being significantly higher than 37% of mosquitoes and being positive for both R. felis and blood meal P=0.008. Furthermore, we compared the prevalence of Rickettsia and blood meal in the mosquitoes collected in the months with temperature below and above 23°C, the minimum temperature required for mosquito egg hatching. Mosquitoes captured in the months below 23°C showed significant higher positivity of R. felis(71/936, 7.6% vs. 8/368, 2.2%; P=0.002) and blood meal (294/936, 31.4% vs. 36/368, 9.8%; P<10−4) than in the months above 23°C. Collectively, the seasonal and gender differences of R. felis and blood meal in mosquitoes add to the existing evidence, supporting a potential vector role of mosquitoes in the transmission of R. felis. Studies with a R. felis infection model covering the full life cycle of mosquitoes is necessary to unambiguously prove the transstadial and transovarial transmission of R. felis in mosquitoes. [ABSTRACT FROM AUTHOR]

Rickettsia felis has been recently cultured in XTC2 cells. This allows production of enough bacteria to create a genomic bank and to sequence it. The chromosome of R. felis is longer than that of previously sequenced rickettsiae and it possess 2 plasmids. Microscopically, this bacterium exhibits two forms of pili: one resembles a conjugative pilus and another forms hair-like projections that may play a role in pathogenicity. R. felis also exhibits several copies of ankyrin-repeat genes and tetratricopeptide encoding gene that are specifically linked to pathogenic host-associated bacteria. It also contains toxin-antitoxin system encoding genes that are extremely rare in intracellular bacteria and may be linked to plasmid maintenance. [ABSTRACT FROM AUTHOR]

Rickettsia felis, a Gram‐negative bacterium that causes spotted fever, is of increasing interest as an emerging human pathogen. R. felis and several other Rickettsia strains are classed as National Institute of Allergy and Infectious Diseases priority pathogens. In recent years, R. felis has been shown to be adaptable to a wide range of hosts, and many fevers of unknown origin are now being attributed to this infectious agent. Here, the structure of acetoacetyl‐CoA reductase from R. felis is reported at a resolution of 2.0 Å. While R. felis acetoacetyl‐CoA reductase shares less than 50% sequence identity with its closest homologs, it adopts a fold common to other short‐chain dehydrogenase/reductase (SDR) family members, such as the fatty‐acid synthesis II enzyme FabG from the prominent pathogens Staphylococcus aureus and Bacillus anthracis. Continued characterization of the Rickettsia proteome may prove to be an effective means of finding new avenues of treatment through comparative structural studies. [ABSTRACT FROM AUTHOR]

Rickettsia felis is an obligate intracellular Gram‐negative bacterium which causes flea‐borne spotted fever in humans. In the past decades, R. felis has been detected worldwide in Ctenocephalides felis fleas and various other arthropods. However, due to its shared symptoms with other common vector‐borne diseases, human infection is prone to be underestimated or misdiagnosed, especially in the malaria‐endemic areas including sub‐Saharan Africa, where confirmatory laboratory diagnoses are not usually available. In this study, a 'One Health' approach was adopted to explore potential vector‐borne and zoonotic pathogens in the Democratic Republic of Sao Tome and Principe (DRSTP), an island nation in the Gulf of Guinea. By collaborating with local veterinarians, 1,187 fleas were collected from 95 domestic dogs across the country and later identified as Ct. felis using taxonomic keys. A cytochrome oxidase gene‐based phylogenetic analysis revealed that all collected fleas belonged to a single haplotype and were identical to isolates from Ivory Coast and Brazil that clustered into a clade of tropical distribution. Additional samples of 14 chigoe fleas (Tunga penetrans) were collected from the surrounding environment of the dogs' resting spots. Rickettsia felis infection in fleas was examined by molecular methods targeting the citrate synthase (gltA)‐ and outer membrane protein A (ompA)‐coding genes as well as the R. felis‐specific pRF plasmid. The bacterial DNA was detected in 21.01% (146/695) of cat fleas but none of the chigoe fleas. Microimmunofluorescence assay was then performed to assess pathogen exposure of the residents. Of 240 dried blood spots from participants with dog contacts, 8 (3.33%) exhibited R. felis antibodies. Our findings demonstrated the presence of R. felis in DRSTP. Further extensive epidemiological studies regarding its prevalence and its role in causing febrile illness while the nation is entering pre‐elimination stage of malaria will be carried out. [ABSTRACT FROM AUTHOR]

Fleas and ticks represent the two main groups of ectoparasites that infest companion animals. In particular, the flea Ctenocephalides felis felis and several members of the Rhipicephalus sanguineus complex are the main vectors of a wide range of pathogens on the American continent. They are competent vectors for several members of the genus Rickettsia, which encompass at least 15 pathogenic obligate intracellular bacteria that colonize the endothelial cells of vertebrates. In Mexico, 10 species of Rickettsia belonging to three groups have been detected in six species of ectoparasites from dogs in 9 of the 32 states of the country. However, in some larger regions of the country, active epidemiological surveillance has not been carried out. For this reason, the aim of this study was to identify the presence of members of the genus Rickettsia in fleas and ticks of dogs and cats in the state of Puebla, Mexico. A cross‐sectional study was carried out to collect ectoparasites of dogs and cats during August to November 2019. Samples were fixed in 70% ethanol and examined to identify the presence of Rickettsia DNA by the amplification and sequencing of specific fragments of the gltA and ompB genes using conventional PCR. The recovered sequences were compared with those deposited in GenBank, and phylogenetic analyses were carried out to identify the position of the pathogens detected with respect to the valid species previously reported worldwide. Additionally, ecological parameters of the ectoparasite infestations were also calculated. We recovered 196 ectoparasites belonging to two species, 33 C. felis felis and 163 R. sanguineus s.l. (Rhipicephalus linnaei), parasitizing 46 hosts (42 dogs and 4 cats) in 11 localities of the state of Puebla. We detected the presence of Rickettsia felis in three pools of C. felis felis, and five from R. sanguineus s.l. Our work provides the first record of R. felis in hard ticks of Mexico and Central America, with new collection localities for this pathogen in central Mexico. [ABSTRACT FROM AUTHOR]

The Eastern Uttar Pradesh region of India is known for its endemicity of acute encephalitis syndrome (AES). Decades of research have established that Orientia tsutsugamushi, a causative of scrub typhus, is a substantial contributor (>60%) for the AES cases besides other aetiology, but additional factors in the remaining proportion are still unidentified. Rickettsial infections are challenging to diagnose in clinical settings due to overlapping clinical symptoms, the absence of definitive indicators, a low index of suspicion, and the lack of low‐cost, rapid diagnostic tools. Hence, the present study was designed to determine the load of rickettsial infections among AES cases. Furthermore, we aim to find out the prevalent rickettsial species in AES cases as well as in the vector population at this location. The study included the whole blood/cerebrospinal fluid of AES patients and arthropod specimens from rodents. The molecular identification was performed using the 23S‐5S intergenic spacer region and ompB gene with genomic DNA obtained from studied specimens. We detected 5.34% (62/1160) of rickettsial infection in AES cases. Among these, phylogenetic analysis confirmed the presence of 54.8% Rickettsia conorii (n = 34) and 16.1% of Rickettsia felis (n = 10), while the rest proportion of the isolates was unidentified at the species level. Furthermore, R. felis was identified in one CSF sample from AES patients and three flea samples from Xenopsylla cheopis. Rickettsia spp. was also confirmed in one Ornithonyssus bacoti mite sample. The results of this investigation concluded the presence of spotted fever group Rickettsia spp. among AES identified cases as well as in the mite and flea vectors that infest rodents. [ABSTRACT FROM AUTHOR]

Fleas are acknowledged vectors and reservoirs of various bacteria that present a wide range of pathogenicity. In this study, fleas collected from wild rodents from the Negev desert in southern Israel were tested for Rickettsia DNA by targeting the 16S rRNA (rrs) gene. Thirty-eight Xenopsylla ramesis, 91 Synosternus cleopatrae and 15 Leptopsylla flea pools (a total of 568 fleas) were screened. Rickettsia DNA was detected in 100% of the X. ramesis and in one S. cleopatrae flea pools. None of L. algira flea pools was found positive. All positive flea pools were further characterized by sequencing of five additional genetic loci (gltA, ompB, ompA, htrA and fusA). The molecular identification of the positive samples showed all sequences to be closely related to the 'Rickettsia felis-like' organisms (99-100% similarities in the six loci). To further investigate the association between 'R. felis-like' and X. ramesis fleas, ten additional single X. ramesis adult fleas collected from the wild and five laboratory-maintained X. ramesis imago, five larva pools (2-18 larvae per pool) and two egg pools (18 eggs per pool) were tested for the presence of 'R. felis-like' DNA. All samples were found positive by a specific ompA PCR assay, confirming the close association of this Rickettsia species with X. ramesis in all its life stages. These results suggest a symbiotic association between 'Rickettsia felis-like' and X. ramesis fleas. [ABSTRACT FROM AUTHOR]

Flea-borne typhus (FBT), due to Rickettsia typhi and R. felis, is an infection causing fever, headache, rash, hepatitis, thrombocytopenia, and diverse organ manifestations. Cough occurs in about 30% of patients with FBT, and chest X-ray abnormalities are seen in 17%. Severe pulmonary manifestations have also been reported in FBT, including adult respiratory distress syndrome and pulmonary embolism. Because of these pulmonary manifestations, FBT can mimic Coronavirus Illness 2019 (COVID-19), a febrile illness with prominent respiratory involvement. Flea-borne typhus and COVID-19 may also have similar laboratory abnormalities, including elevated ferritin, C-reactive protein, and D-dimer. However, elevated transaminase levels, rash, and thrombocytopenia are more common in FBT. Herein, we present four cases of patients with FBT who were initially suspected to have COVID-19. These cases illustrate the problem of availability bias, in which the clinician thinks a particular common condition (COVID-19 in this case) is more prevalent than it actually is. [ABSTRACT FROM AUTHOR]

Murine typhus is a cause of fever of intermediate duration in the south of Spain, where antibodies against Rickettsia typhi and Rickettsia felis were observed in humans. This study presents the first report from the northeast of Spain. Human serum samples were tested by serological test. R. typhi and R. felis seroprevalences were 8.8% and 3.2%, respectively. [ABSTRACT FROM AUTHOR]

Los Angeles and Orange Counties are known endemic areas for murine typhus in California; however, no recent reports of flea-borne rickettsioses are known from adjacent San Bernardino County. Sixty-five opossums ( Didelphis virginiana) were trapped in the suburban residential and industrial zones of the southwestern part of San Bernardino County in 2007. Sixty out of 65 opossums were infested with fleas, primarily cat fleas, Ctenocephalides felis (Bouché, 1835). The flea minimum infection rate with Rickettsia felis was 13.3% in pooled samples and the prevalence was 23.7% in single fleas, with two gltA genotypes detected. In spite of historic records of murine typhus in this area, no evidence for circulation of R. typhi in fleas was found during the present study. Factors contributing to the absence of R. typhi in these cat fleas in contrast to its presence in cat fleas from Orange and Los Angeles Counties are unknown and need to be investigated further in San Bernardino County. [ABSTRACT FROM AUTHOR]

Human infection with Rickettsia felis has been reported in most parts of the world, and R. felis has recently been confirmed in cat fleas in Western Australia. The clinical presentations of R. typhi and R. felis are similar, and in the past, the incidence of R. felis infection may have been underestimated. We describe the first reported cases of probable human R. felis infection in Australia. Two adults and three children in Victoria contracted a rickettsial disease after exposure to fleas from kittens. Molecular testing of fleas demonstrated the presence of R. felis but not R. typhi. [ABSTRACT FROM AUTHOR]

Haemaphysalis sulcata ticks collected from sheep and goats in southern Croatia were found infected with rickettsiae. Molecular analysis of the complete gltA gene and portion of 17 kDa and ompB genes revealed the presence of Rickettsia felis-like bacteria in up to 26% of tested ticks. [ABSTRACT FROM AUTHOR]

Genome analysis of Rickettsia felis highlighted the presence of three patatin-like protein (PLP) genes (pat1, pat2A, and pat2B), whereas only one PLP gene (pat1) is found in the other sequenced rickettsial genomes. Here, we aligned the rickettsial PLPs with characterized patatins from plants and found that they possess all the conserved amino acid residues identified as important for phospholipase A2 activity. We also carried out a phylogenic analysis of the rickettsial PLPs together with bacterial and eukaryotic homologs. The phylogeny of the rickettsial Pat1 proteins is in conflict with the currently recognized Rickettsia phylogeny. Possible scenarios that might explain this incongruence are discussed and involve either gene conversion or gene duplication events. [ABSTRACT FROM AUTHOR]

ABSTRACT Consistent with the effects of HIV on cell-mediated immunity, an increased susceptibility to intracellular microorganisms has been observed. Rickettsiae are obligate intracellular microorganisms. The aim of this study was to examine Rickettsia typhi and Rickettsia felis infections in HIV+ population. Sera of 341 HIV+ patients were evaluated by indirect immunofluorescent assay. Age, sex, residential locality, risk behavior, stage according to criteria of the Center for Disease Control and Prevention, CD4+/CD8+ T cells, Hepatitis B antigen, and Hepatitis C serology were surveyed. Seroprevalences of R. typhi and R. felis infection were 7.6% and 4.4%, respectively. No associations were found between seropositivities and the assessed variables. Findings were similar to those obtained in healthy subjects from the same region. [ABSTRACT FROM AUTHOR]

Spotted fever group (SFG) rickettsiae are obligatory intracellular bacteria that cause disease in humans and other animals. Ixodid ticks are the principal vectors of SFG rickettsiae. The present study aimed to determine the prevalence and species identity of SFG rickettsiae in ticks and horses from urban and rural areas of western Cuba using PCR assays. Tick samples, collected from 79 horses, consisted of 14 Amblyomma mixtum adults, 111 Dermacentor nitens adults and 19 pools of D. nitens nymphs (2–5 individuals/pool). The PCR results revealed the presence of Rickettsia spp. in 64% of the A. mixtum adults, 16% of the D. nitens adults, and 11% of the pooled samples of D. nitens nymphs. In contrast, Rickettsia spp. was not detected in any of the 200 horse blood samples included in this study. DNA sequence data of the rickettsial 17 kDa antigen gene showed that Rickettsia amblyommatis was present in A. mixtum; and Rickettsia felis in D. nitens. This is the first report of R. felis in D. nitens in Cuba. The present study extends our knowledge of the potential vector spectrum and distribution of SFG rickettsiae pathogens in western Cuba. [ABSTRACT FROM AUTHOR]

The presence of Rickettsia felis was investigated in three species of pulicid fleas ( Ctenocephalides felis, Ctenocephalides canis and Pulex irritans) collected in 38 locales in Andalusia (Spain) over the period 1999–2004. Amplification of a fragment of OmpB gene was positive in 54.17 % of lots of Ct. felis. The identity of the PCR bands was confirmed as R. felis by sequence data obtained directly from the PCR amplicon. No rickettsia was found in Ct. canis nor P. irritans. [ABSTRACT FROM AUTHOR]

Rickettsia typhi and Rickettsia felis (Rickettsiales: Rickettsiaceae) are two rickettsiae principally transmitted by fleas, but the detection of either pathogen has rarely been attempted in Taiwan. Of 2048 small mammals trapped in eastern Taiwan, Apodemus agrarius Pallas (24.5%) and Mus caroli Bonhote (24.4%) (both: Rodentia: Muridae) were the most abundant, and M. caroli hosted the highest proportion of fleas (63.9% of 330 fleas). Two flea species were identified: Stivalius aporus Jordan and Rothschild (Siphonaptera: Stivaliidae), and Acropsylla episema Rothschild (Siphonaptera: Leptopsyllidae). Nested polymerase chain reaction targeting parts of the ompB and gltA genes showed six fleas to be positive for Rickettsia spp. (3.8% of 160 samples), which showed the greatest similarity to R. felis, Rickettsia japonica, Rickettsia conorii or Rickettsia sp. TwKM01. Rickettsia typhi was not detected in the fleas and Rickettsia co-infection did not occur. Both flea species were more abundant during months with lower temperatures and less rainfall, and flea abundance on M. caroli was not related to soil hardness, vegetative height, ground cover by litter or by understory layer, or the abundance of M. caroli. Our study reveals the potential circulation of R. felis and other rickettsiae in eastern Taiwan, necessitating further surveillance of rickettsial diseases in this region. This is especially important because many novel rickettsioses are emerging worldwide. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine the prevalence of Bartonella species and Rickettsia species DNA in the blood, oral cavity, skin and claw beds of feral cats without evidence of skin disease that were housed in Alabama ( n = 24), Florida ( n = 27) and Colorado ( n = 32). Samples were assessed by use of polymerase chain reaction assays. The Bartonella species IgG prevalence was also determined. While Bartonella species DNA was not amplified from any sample from Colorado cats, it was commonly amplified from blood (56.9%), skin (31.4%), claws (17.6%) and gingiva (17.6%) of the 51 cats housed in Alabama and Florida. All 10 flea groups assessed in this study were infected with a Bartonella species or R. felis. Bartonella species IgG titres did not accurately predict bacteraemia (positive predictive value = 57.1%; negative predictive value = 82.1%). Bartonella species DNA was amplified from blood of cats with and without C. felis. Rickettsia felis DNA was only detected in or on the skin of one cat and the gingiva of an additional cat. It was concluded that cats can be an occupational health risk for veterinarians, particularly in areas with high prevalence of Ctenocephalides felis. Further study is required to determine whether Bartonella species or Rickettsia species infections of cats are associated with dermatological disease. The combination of Bartonella species serological test results with Bartonella species PCR or culture is likely to give the most accurate information concerning the current infection status of individual cats. [ABSTRACT FROM AUTHOR]

Over one hundred cases of human rickettsiosis, many fatal, are reported annually across the US‐Mexico transboundary region, representing a likely undercount. Although cases are often attributed to Rickettsia rickettsii, the agent of Rocky Mountain spotted fever, multiple other Rickettsia pathogens are present in North America. We conducted multiple‐host surveillance of domestic, synanthropic, and sylvatic mammals and their ectoparasites to investigate the ecology of Rickettsia species in this region. A total of 499 mammals, including 83 dogs, 23 wild carnivores, five lagomorphs, and 388 rodents were sampled, and 413 fleas and 447 ticks belonging to 15 and 4 species, respectively, were collected during 2017 and 2018. We detected Rickettsia spp. DNA in one blood sample of coyote (Canis latrans), 11 ear tissues of rodents (10.6%), and 79 ectoparasites (9.5%). Of the 64 Rickettsia‐positive fleas, 54 were Echidnophaga gallinacea and 10 were Pulex simulans, while of the 15 ticks, 11 were Rhipicephalus sanguineus s.l. and four Ixodes pacificus. The DNA sequence alignment of gltA and ompB regions revealed one and ten genetic variants of Rickettsia spp., respectively. These variants were clustered in clades of zoonotic species (R. felis, R. massiliae, R. parkeri, R. rickettsii, and R. typhi) and organisms of unknown pathogenic significance (R. asembonensis and Candidatus Rickettsia tarasevichiae). The finding of a coyote infected with R. rickettsii and the multiple zoonotic SFG rickettsial agents in the study area suggest that: 1) wild canids could serve as an amplifying host for RMSF, an alternate host for Rh. sanguineus s.l. ticks, and a means to spread infection and ticks over large areas; and 2) at least some of the human rickettsiosis cases attributed to R. rickettsii could be caused by other Rickettsia species. This study strongly supports the importance of multiple‐host and vector eco‐epidemiological studies and the One Health approach to better understand disease in a RMSF‐epidemic region. [ABSTRACT FROM AUTHOR]

We evaluated the presence of Rickettsia infection among fleas collected on domestic dogs in two Guarani Indian communities in the suburban area of São Paulo Municipality, Brazil. A total of 114 Ctenocephalides felis felis and 47 Ctenocephalides canis were collected from 40 dogs. A total of 41 C. felis felis (36.0%) and 9 C. canis (19.1%) fleas yielded expected bands by PCR, which were all shown by DNA sequencing to be indentical to the corresponding sequence of a fragment of the Rickettsia felis gltA gene deposited in GenBank. The overall prevalence of R. felis was 31.0% (49/161). [ABSTRACT FROM AUTHOR]

Soft ticks are neglected competent vectors of a wide range of pathogenic microorganisms, among which bacteria of the genera Rickettsia and Borrelia stand out. In Mexico, previous studies have shown the presence of a member of the Ornithodoros talaje complex in the Virginia opossum (Didelphis virginiana Didelphimorphia: Didelphidae Kerr) from southeastern Mexico. However, its specific identification has not been achieved. Two D. virginiana were treated in a private clinic during the period of April–May 2022. Tick larvae were manually removed, DNA extraction was performed, and some genes from various bacterial and parasitic pathogens were amplified and sequenced. A total of 96 larvae were recovered, which were morphologically identified as Ornithodoros puertoricensis (Ixodida: Argasidae Fox); the 16 S sequences showed a similarity of 96.79%–99.51% with sequences of O. puertoricensis from Panama and Colombia. The presence of Rickettsia felis (Rickettsiales: Rickettsiaceae Bouyer et al.) was detected in 15 specimens from one host. The soft tick O. puertoricensis is recorded for the first time as an ectoparasite of the Virginia opossum in America and represents the second report for this soft tick in Mexico since 1963. This represents the most northern record of this tick species in its geographic distribution and brings a new soft tick‐Rickettsia association. [ABSTRACT FROM AUTHOR]

Until the year 2000, only three Rickettsia species were known in South America: (i) Rickettsia rickettsii, transmitted by the ticks Amblyomma cajennense, and Amblyomma aureolatum, reported in Colombia, Argentina, and Brazil, where it is the etiological agent of Rocky Mountain spotted fever; (ii) Rickettsia prowazekii, transmitted by body lice and causing epidemic typhus in highland areas, mainly in Peru; (iii) Rickettsia typhi, transmitted by fleas and causing endemic typhus in many countries. During this new century, at least seven other rickettsiae were reported in South America: Rickettsia felis infecting fleas and the tick-associated agents Rickettsia parkeri, Rickettsia massiliae, Candidatus“Rickettsia amblyommii,” Rickettsia bellii, Rickettsia rhipicephali, and Candidatus“Rickettsia andeanae.” Among these other rickettsiae, only R. felis, R. parkeri, and R. massiliae are currently recognized as human pathogens. R. rickettsii is a rare agent in nature, infecting ≤1% individuals in a few tick populations. Contrastingly, R. parkeri, Candidatus“R. amblyommii ,” R. rhipicephali, and R. bellii are usually found infecting 10 to 100% individuals in different tick populations. Despite rickettsiae being transmitted transovarially through tick generations, low infection rates for R. rickettsii are possibly related to pathogenic effect of R. rickettsii for ticks, as shown for A. aureolatum under laboratory conditions. This scenario implies that R. rickettsii needs amplifier vertebrate hosts for its perpetuation in nature, in order to create new lines of infected ticks (horizontal transmission). In Brazil, capybaras and opossums are the most probable amplifier hosts for R. rickettsii, among A. cajennense ticks, and small rodents for A. aureolatum. [ABSTRACT FROM AUTHOR]

The first description of Mediterranean spotted fever (MSF) was made by Conor and Brush in 1910 in Tunisia, where, at the same time, Nicolle described the role of lice in transmission of epidemic typhus. However, along this century, there have been few and fragmentary reports about ecology and epidemiology of rickettsioses in North Africa. This region was always considered, for these diseases, like other Mediterranean regions. The most human tick-borne rickettsiosis known to occur in North Africa is MSF caused by R. conorii and transmitted by the brown dog tick, Rhipicephalus sanguineus. Recent studies showed that other arthropode-transmitted rickettsiae are prevalent in North Africa: R. aeschlimannii, R. massiliae, and R. felis. Moreover, R. felis and R. aeschlimannii human infection were respectively confirmed, by serology in Tunisia, and by PCR in Morocco. The seroprevalence of R. conorii among healthy population was ranging from 5% to 8% in most of the countries. Epidemiological and clinical features are frequently resumed in an eruptive fever with eschar occurring in hot season in rural areas. Typhus group rickettsioses, caused by R. typhi and R. prowazekii are less frequently reported than in the 1970s. Seroprevalence of R. typhi among blood donors was from 0.5% to 4%. In Algeria about 2% of febrile patients had R. prowazekii antibodies. Moreover, reemerging threat of epidemic typhus should be considered, after the two cases recently diagnosed in the highlands of Algeria. Murine typhus, considered as “benign” typhus, is underestimated. When R. typhi was inserted in serologic tests, murine typhus became more frequently confirmed. In a recent study in Central Tunisia, we confirmed an emergence of murine typhus mistaken for R. conorii or viral infection. In addition to typhus surveillance, future studies have to determine which spotted fever group rickettsiae are prevalent in vectors and in human pathology. [ABSTRACT FROM AUTHOR]

Although rickettsioses are among the oldest known vector-borne zoonoses, several species or subspecies of rickettsias have been identified in recent years as emerging pathogens throughout the world including in sub-Saharan Africa. To date, six tick-borne spotted fever group pathogenic rickettsias are known to occur in sub-Saharan Africa, including Rickettsia conorii conorii, the agent of Mediterranean spotted fever; R. conorii caspia, the agent of Astrakhan fever; R. africae, the agent of African tick-bite fever; R. aeschlimannii; R. sibirica mongolitimonae; and R. massiliae. On the other hand, fleas have long been known as vectors of the ubiquitous murine typhus, a typhus group rickettsiosis induced by R. typhi. However, a new spotted fever rickettsia, R. felis, has also been found to be associated with fleas, to be a human pathogen, and to be present in sub-Saharan Africa. Finally, R. prowazekii the agent of louse-borne epidemic typhus continues to strikes tens to hundreds of thousands of persons who live in Sub-Saharan with civil war, famine and poor conditions. We present an overview of these rickettsioses occurring in sub-Saharan Africa, focusing on the epidemiological aspects of emerging diseases. [ABSTRACT FROM AUTHOR]

Our aim was to determine the presence of Rickettsia spp. in 66 fleas from Uruguay. Rickettsial DNA was amplified using gltA and ompB PCR primers. Rickettsia spp. were found in 41% of the fleas (25 Ctenocephalides felis and 2 Ctenocephlides canis). Sequences resulted in the identification of Rickettsia felis and four genotypes closely related to this species ( Rickettsia sp. TwKM03, California 2, Hf187, and RF2125). The presence of R. felis in fleas from Uruguay in was demonstrated. This is the second species of Rickettsia identified in Uruguay in the past 2 years using molecular approaches, and it is helping to clarify the etiology of rickettsial diseases in the region. [ABSTRACT FROM AUTHOR]

Rickettsiae survival implicates adaptation to different environmental conditions. We hypothesized that multiple copies of genes in bacteria with reduced genomes might account for such a process. Transcription of spoT and sca paralogs was thus analyzed in R. conoril and R. fells. [ABSTRACT FROM AUTHOR]

Ticks are pivotal in transmitting a variety of pathogens that affect both humans and animals. These pathogens often occur in guilds, groups of species that exploit similar resources in similar ways. Although the composition of tick‐borne pathogen (TBP) guilds is well‐documented, the interactions among pathogens within these guilds remain poorly understood. We hypothesized that abiotic and biotic factors significantly influence the patterns of occurrence and interactions among pathogens within these guilds. To investigate this, we analyzed microfluidic‐based high‐throughput data on microorganisms from 166 Hyalomma excavatum ticks (94 male and 72 female) collected across different seasons from cattle in the central Algerian steppe using network analysis to uncover complex pathogen–pathogen interaction patterns. We found that female ticks had a higher infection rate (63.9%) with common pathogens such as Rickettsia slovaca (26.4%), unclassified Apicomplexa (22.2%), and Borrelia afzelii (19.4%). Male ticks showed a 56.4% infection rate, with Rickettsia (31.1%) and R. slovaca (16%) being the most prevalent. Notable pathogen–pathogen interactions within guilds were identified, with positive associations such as between R. slovaca and Rickettsia conorii in males, and B. afzelii and Borrelia spielmanii in females, indicating cooperative interactions. Conversely, negative associations, such as between Anaplasma phagocytophilum and Francisella tularensis, suggested competitive exclusion. The observed variation in interaction patterns under different conditions indicates that ecological determinants, both biotic and abiotic, influence pathogen association dynamics within guilds. These findings have significant implications for understanding disease transmission and developing control strategies. [ABSTRACT FROM AUTHOR]

The genus Rickettsia is the causative agent of several rickettsial diseases that are primarily transmitted by hard ticks. The occurrence of Rickettsia in chigger mites, which are vectors of scrub typhus in the western Pacific region, has been infrequently investigated. We identified Rickettsia spp. in chiggers collected from small mammals in six counties of Taiwan. Moreover, by capitalising on parallel Rickettsia detections on small mammals and their infested ticks and fleas, we were able to identify Rickettsia spp. that suggested more intimate associations with chigger mites. Rickettsia detection rates in 318 pools of chiggers were 21.7% and 22.3% when based on the ompB and gltA gene, respectively. Overall, we identified six (based on the ompB gene) and eight (gltA gene) Rickettsia species. Approximately half of the sequenced species were most similar to Rickettsia sp. clone MB74‐1 (ompB gene) and Rickettsia sp. TwKM02 (gltA gene). Furthermore, both species were either infrequently or never identified in small mammals, ticks and fleas, which suggests that chigger mites might be the primary host of both rickettsiae. Whether both species are pathogenic to humans remains to be studied. They may also be microbial endosymbionts of chigger mites, with their potential effects on the pathogenicity of the aetiologic agent of scrub typhus deserving further investigations. [ABSTRACT FROM AUTHOR]

Fleas ( Insecta: Siphonaptera) are obligate bloodsucking insects, which parasitize birds and mammals, and are distributed throughout the world. Several species have been implicated in pathogen transmission. This study aimed to monitor red foxes and the fleas isolated from them in the Palermo and Ragusa provinces of Sicily, Italy, as these organisms are potential reservoirs and vectors of pathogens. Thirteen foxes ( Vulpes vulpes) and 110 fleas were analysed by polymerase chain reaction ( PCR) to detect DNA of the pathogens Ehrlichia canis, Babesia microti, Rickettsia spp., Anaplasma phagocytophilum, Anaplasma platys, Anaplasma marginale and Anaplasma ovis. In the foxes, A. ovis was detected in only one animal, whereas the prevalence of the E. canis pathogen was 31%. B. microti and Rickettsia spp. were not detected. Of all of the collected fleas, 75 belonged to the species Xenopsylla cheopis, 32 belonged to Ctenocephalides canis, two belonged to Ctenocephalides felis and one belonged to Cediopsylla inaequalis. In the fleas, the following pathogens were found: A. ovis (prevalence 25%), A. marginale (1%), A. phagocytophilum (1%), Rickettsia felis (2%) and E. canis (3%). X. cheopis was the flea species most frequently infected with Anaplasma, in particular A. ovis (33%), A. marginale (1%) and A. phagocytophilum (1%). Both C. felis exemplars were positive for R. felis. E. canis was found in the lone C. inaequalis and also in 3% of the X. cheopis specimens. No fleas were positive for B. microti or A. platys. As foxes often live in proximity to domestic areas, they may constitute potential reservoirs for human and animal parasites. Further studies should be performed on fleas to determine their vectorial capacity. [ABSTRACT FROM AUTHOR]

Although Mediterranean spotted or “boutonneuse” fever (MSF) has been documented in central Tunisia, other spotted fever group rickettsioses (SFGR) and typhus group rickettsioses (TGR) have received little attention in our region. We sought to determine the role of rickettsioses, Q fever, ehrlichioses, and bartonelloses among patients with acute fever. The results of this study of 47 persons with acute fever of undetermined origin are reported in this paper. We concluded that SFGR, murine typhus, and acute Q fever are common causes of acute isolate fever in summer in central Tunisia and should be investigated systematically in patients with acute fever of unknown origin. [ABSTRACT FROM AUTHOR]

In this study we describe molecular mechanisms of resistance to several classes of antibiotics within drug targets by in silico genome comparisons for bacteria of the genus Rickettsia. Apart from the mutations in the rpoB gene in naturally rifampin-resistant Rickettsia species previously reported by our team, we found that typhus group (TG) rickettsiae had a triple amino acid difference in the highly conserved region of the L22 ribosomal protein as compared to the spotted fever group rickettsiae (SFG), which could explain the natural resistance of SFG rickettsia to erythromycin. We found also that the genome of R. conorii contains an aminoglycoside 3'-phosphotransferase. Finally, either folA gene (encoding dihydrofolate reductase) and/or folP gene (encoding dihydropteroate synthase) was missing in the genome of rickettsial strains explaining the natural resistance to cotrimoxazole. Finally, multiple genes encoding for pump efflux were found especially in the genome of R. conorii that could be involved in resistance to antibiotics. Five specific ORFs related to antibiotic resistance have been identified in the genome of R. felis including a streptomycin resistance protein homologue, a class C beta-lactamase, a class D beta-lactamase, a penicillin acylase homologue, and an ABC-type multidrug transporter system. For the first time, using this approach, an experimental beta-lactamase activity has been shown for this bacterium. We believe that whole genome sequence analysis may help to predict several phenotypic characters, in particular resistance to antibiotics for obligate intracellular bacteria. [ABSTRACT FROM AUTHOR]

Arthropod‐borne diseases are widespread worldwide and are a complex interaction between animals, humans and ectoparasites. The understanding of the diversity and epidemiology of organisms transmitted by arthropod vectors, and the role of hosts and vectors in transmission of infections remain limited in Lao PDR. What knowledge does exist is primarily focused on more rural regions of the country. This study screened ectoparasites from domestic dogs in Vientiane city for the presence of bacterial pathogens of zoonotic importance. A total of 3,511 arthropod vectors were collected from 112 dogs. Vectors collected were Rhipicephalus sanguineus ticks, Ctenocephalides felis felis and Ctenocephalides felis orientis fleas and Heterodoxus spiniger lice. A sub‐sample of vectors from each dog was analysed by PCR to identify the potential bacteria. From 129 vector pools, Rickettsia spp. was detected in 6.7% (7/105) pools of ticks, 86.4% (19/22) pools of fleas and both pools of lice. Sequencing analysis confirmed Rickettsia felis in 13 flea pools and one louse pool and Rickettsia asembonensis in six flea pools. Anaplasmataceae was identified in 14.3% (15/105) tick pools and 100% (22/22) flea pools. Sequencing revealed the presence of Anaplasma platys in ticks and Wolbachia pipientis in fleas. Leptospira spp. was detected in one tick and one louse pool, and Brucella spp. was detected in 12.4% (13/105) tick pools. All samples were negative for Bartonella spp., Coxiella burnetii and Borrelia burgdorferi. This is the first study providing evidence of R. asembonensis in fleas in Laos. Results from this study show arthropods are potential vectors to transmit zoonotic infection in Vientiane city, suggesting humans are at risk of zoonotic infections in the city. [ABSTRACT FROM AUTHOR]

Tick-borne diseases affecting domestic animals and humans have increased globally in recent years. Pakistan, in particular, faces a significant economic threat from ticks, where two specific species, Rhipicephalus microplus and Hyalomma anatolicum, act as vectors for various pathogens such as piroplasma, Anaplasma, Ehrlichia, and Rickettsia that pose a significant burden on livestock production in the country. To better understand the risk that tick-borne pathogens (TBPs) pose to livestock in Pakistan, we conducted a cross-sectional study of the occurrence, diversity, and coinfection of these pathogens in small and large ruminants owned by small farms as well as in ticks collected from these animals. We collected blood samples from 224 cattle, 224 buffalo, 69 goats, and 56 sheep, gathered from 112 farms located in seven districts of Punjab, one of Pakistan's largest province. In addition, we collected a total of 476 ticks attached to these animals. Based on the identification of tick species through morphology and sequence analysis of the 16S rRNA and cytochrome c oxidase subunit 1 (cox1) gene, we confirmed that the most commonly collected tick species were Rh. microplus (38.65% of all individuals), H. anatolicum (31.93%), and Rh. decoloratus (8.40%). Notable pathogens detected in the collected ticks included Theileria annulata (18.4% prevalence), Anaplasma ovis (15.79%), A. centrale (13.16%), and Rickettsia slovaca (13.16%). In blood samples, the most frequently detected pathogens were T. annulata (n = 8), Babesia bovis (n = 7), A. centrale (n = 6), and B. bigemina (n = 5). In some cases, both cattle and buffaloes were found to be coinfected with B. bovis, T. annulata, and A. centrale. These findings provide valuable insights into the circulation of TBPs in livestock and highlight the need for further research on the epidemiological risk that these pathogens pose to ruminants in Pakistan. [ABSTRACT FROM AUTHOR]

Rickettsioses are emerging zoonotic diseases reported worldwide. In spite of the serological evidence of spotted fever group rickettsioses in febrile patients in Malaysia, limited studies have been conducted to identify the animal reservoirs and vectors of rickettsioses. This study investigated the presence of rickettsiae in the tissue homogenates of 95 wild rats and 589 animal ectoparasites. Using PCR assays targeting the citrate synthase gene (gltA), rickettsial DNA was detected in the tissue homogenates of 13 (13.7%) wild rats. Sequence analysis of the gltA amplicons showed 98.6–100% similarity with those of Rickettsia honei/R. conorii/R. raoultii (Rickettsiales:Rickettsiaceae). Sequence analysis of outer membrane protein A gene (ompA) identified Rickettsia sp. TCM1 strain from two rats. No rickettsia was detected from Laelaps mites, Rhipicephalus sanguineus and Haemaphysalis bispinosa ticks, and Felicola subrostratus lice in this study. R. felis was identified from 32.2% of 177 Ctenocephalides felis fleas. Sequence analysis of the gltA amplicons revealed two genotypes of R. felis(Rf31 and RF2125) in the fleas. As wild rats and cat fleas play an important role in the enzoonotic maintenance of rickettsiae, control of rodent and flea populations may be able to reduce transmission of rickettsioses in the local setting. [ABSTRACT FROM AUTHOR]

Fleas are insects with a worldwide distribution that have been implicated in the transmission of several pathogens. The present study aimed to investigate the presence of Rickettsia spp. (Rickettsiales: Rickettsiaceae) and Bartonella spp. (Rhizobiales: Bartonellaceae) in fleas from free‐ranging crab‐eating foxes Cerdocyon thous (Linnaeus, 1766) (Carnivora: Canidae) from Rio Grande do Sul, southern Brazil. Fleas were collected manually from animals and used for the molecular detection of Rickettsia spp. and Bartonella spp. Twenty‐nine C. thous were sampled in six municipalities. Four foxes were parasitized by 10 fleas, all of which were identified as Ctenocephalides felis (Bouché, 1935) (Siphonaptera: Pulicidae). DNA from Rickettsia felis Bouyer et al., 2001 and Rickettsia asembonensis Maina et al., 2016 were found in three and eight fleas, respectively. In four fleas, DNA of Bartonella sp. was identified. Phylogenetic analysis grouped Bartonella sp. together with other genotypes previously reported in C. felis worldwide. The scenario described in the present study highlights a Neotropical canid parasitized by the invasive cosmopolitan cat flea, which in turn, is carrying potentially invasive vector‐borne microorganisms. These findings suggest that C. felis is adapted to wild hosts in wilderness areas in southern Brazil, hypothetically exposing the Neotropical fauna to unknown ecological and health disturbances. [ABSTRACT FROM AUTHOR]

Fleas (Siphonaptera) are ubiquitous blood‐sucking parasites that transmit a range of vector‐borne pathogens. The present study examined rodents (n = 29) and domestic dogs (n = 7) living in the vicinity of the Volcanoes National Park, Rwanda, for fleas, identified flea species from these hosts, and detected Bartonella (Rhizobiales: Bartonellaceae) and Rickettsia (Rickettsiales: Rickettsiaceae) DNA. The most frequently encountered flea on rodents was Xenopsylla brasiliensis (Siphonaptera: Pulicidae). In addition, Ctenophthalmus (Ethioctenophthalmus) calceatus cabirus (Siphonaptera: Hystrichopsyllidae) and Ctenocephalides felis strongylus (Siphonaptera: Pulicidae) were determined using morphology and sequencing of the cytochrome c oxidase subunit I and cytochrome c oxidase subunit II genes (cox1 and cox2, respectively). Bartonella tribocorum DNA was detected in X. brasiliensis and Rickettsia asembonensis DNA (a Rickettsia felis‐like organism) was detected in C. felisstrongylus. The present work complements studies that clarify the distributions of flea‐borne pathogens and potential role of fleas in disease transmission in sub‐Saharan Africa. In the context of high‐density housing in central sub‐Saharan Africa, the detection of B. tribocorum and R. asembonensis highlights the need for surveillance in both rural and urban areas to identify likely reservoirs. The present study identified flea species on owned dogs and wild rodents in Rwanda.Bartonella tribocorum DNA was detected in Xenopsylla brasiliensis found on rodents.Rickettsia asembonensis DNA was detected in Ctenocephalides felis strongylus found on dogs. [ABSTRACT FROM AUTHOR]

Objectives To define the prevalence of Bartonella spp., Rickettsia felis, Mycoplasma haemofelis, ‘ Candidatus Mycoplasma haemominutum’ (Mhm) and ‘ Candidatus Mycoplasma turicensis’ (Mtc) in cats and their fleas in eastern Australia. Design and procedure Conventional PCR assays that detect Bartonella spp., M. haemofelis, Mhm, Mtc, Rickettsia spp., Ehrlichia spp., Anaplasma spp. and Neorickettsia spp. were performed on DNA extracted from blood and fleas collected from 111 cats. Cat sera were assayed by ELISA for IgG of Bartonella spp. Results DNA of M. haemofelis, Mtc and Mhm was amplified from 1 (0.9%), 1 (0.9%) and 17 cats (15.3%), respectively. Only DNA of Mhm was amplified from the 62 of 111 pooled flea samples (flea sets; 55.9%). Overall, the prevalence rates for Bartonella spp. DNA in the cats and the flea sets was 16.2% (18 cats) and 28.8% (32 flea sets), respectively. Bartonella spp. IgG was detected in 42 cats (37.8%), of which 11 (26.2%) were positive for Bartonella spp. DNA in their blood. R. felis DNA was amplified from 22 flea sets (19.8%), but not from cats. Overall, DNA of one or more of the organisms was amplified from 27% (30) of cats and 67.6% (75) of the flea sets. Conclusions This is the first Australian study to determine the prevalence of R. felis and B. clarridgeiae in both fleas and the cats from which they were collected. Flea-associated infectious agents are common in cats and fleas in eastern Australia and support the recommendation that stringent flea control be maintained on cats. [ABSTRACT FROM AUTHOR]

The presumptive cases of Mediterranean spotted fever have been identified in 1993 and since that time, its frequency has steadily increased. The prospective study, in summer 2004, was conducted in order to present the descriptive clinic and epidemiology, to identify more severe forms, the presence of the multiple eschars, and different rickettsial strains caused the disease in our region. In Oran, the cases were diagnosed clinically. In Marseille, serum specimens were tested by IFA using the panel of eight rickettsial antigen; Western blot and cross-adsorption studies were also performed in order to confirm the diagnosis. Ninety-three patients clinically diagnosed were recorded from July 3 to October 28, 2004. Eighty percent were male, the mean age was 44.3 years, 90% were exposed to dog and 32% reported tick bites. Clinical signs were as follow: presence of underlying disease (44%), sudden onset (78%), fever (100%), loss of weight (63%), conjunctivitis (43%), and a tache noire was noticed in 70%. Interestingly, two patients had two and three eschars, respectively. The rash was maculopapular (palm and sole) and purpuric in nine cases. Doxycycline was the most antibiotic (91%) with favourable outcome in 91% of the cases. Malignant form with death is reported for three patients (3.2%). Among the 93 patients, 104 serum from 65 patients were tested (serums of others patients were lost or ticket not found on tube. Sixty-three patients out of 65 had a positive serology by IFA with cross-reactive antibodies especially between R. conorii, R. felis and/or R. typhi. Two others negative serology were: one precocious serum and second from the patient, which presented symptoms of MSF and tested two serums, Western blot and cross-adsorption. [ABSTRACT FROM AUTHOR]

In Europe, rickettsioses are long-known infectious diseases. Until recently, it was thought that Mediterranean spotted fever due to Rickettsia conorii was the only tick-borne rickettsiosis in Europe. In the last decade new Rickettsia spp. have been implicated in human pathology ( R. slovaca, R. sibirica mongolotimonae, R. helvetica). Furthermore, cases of infection due to flea-borne rickettsioses ( R. typhi, R. felis) have been described. Finally, although no outbreak of epidemic typhus has been reported yet in central and southern Europe, we should be aware of the possibility of reemergence of this disease in Europe. Other rickettsioses exist that have not yet been implicated in human pathology. We should consider that climate changes and other factors could contribute to the emergence and reemergence of other new diseases. [ABSTRACT FROM AUTHOR]

A series of sudden unexpected cardiac deaths among Swedish elite orienteerers in the 1980s have resulted from the combination of infectious diseases and physical exercise. Studies in the late 1990s have pointed to Chlamydia and Barontella, which both had a high seroprevalence among Swedish elite orienteerers. We conducted a case–control study aimed to elucidate the serologic prevalence of rickettsial diseases among Danish elite orienteerers. Ticks are known as vectors for some rickettsial diseases. None of the orienteerers had a positive antibody titer against any of the tested Rickettsia despite a very high frequency of tick bites in this group. [ABSTRACT FROM AUTHOR]

Our aim was to determine the presence of Rickettsia spp. and Bartonella spp. in Ctenocephalides felis and Ctenocephalides canis from La Rioja (Spain). A total of 88 specimens were tested by polymerase chain reaction (PCR) using gltA and ompB genes as targets for Rickettsia spp., and 16S rRNA and ribC genes for Bartonella spp. Rickettsia felis-like (28.4%), Bartonella clarridgeiae (6.8%), and Bartonella henselae (3.4%) were detected in Ctenocephalides spp. Other Bartonella sp. different from B. clarridgeiae and B. henselae could also be present in fleas from La Rioja. [ABSTRACT FROM AUTHOR]