Rickettsia felis in Fleas, Germany

Among 310 fleas collected from dogs and cats in Germany, Rickettsia felis was detected in all specimens (34) of Archaeopsylla erinacei (hedgehog flea) and in 9% (24/226) of Ctenocephalides felis felis (cat flea). R. helvetica was detected in 1 Ceratophyllus gallinae (hen flea).     

Rickettsia slovaca and R. raoultii in Tick-borne Rickettsioses

Tick-borne lymphadenopathy (TIBOLA), also called Dermacentor-borne necrosis erythema and lymphadenopathy (DEBONEL), is defined as the association of a tick bite, an inoculation eschar on the scalp, and cervical adenopathies. We identified the etiologic agent for 65% of 86 patients with TIBOLA/DEBONEL as either Rickettsia slovaca (49/86, 57%) or R. raoultii (7/86, 8%).     

Novel Rickettsia in Ticks, Tasmania, Australia

A novel rickettsia was detected in Ixodes tasmani ticks collected from Tasmanian devils. A total of 55% were positive for the citrate synthase gene by quantitative PCR. According to current criteria for rickettsia speciation, this new rickettsia qualifies as Candidatus Rickettsia tasmanensis, named after the location of its detection.     

Human Rickettsia heilongjiangensis Infection, Japan

A case of Rickettsia heilongjiangensis infection in Japan was identified in a 35-year-old man who had rash, fever, and eschars. Serum contained R. heilongjiangensis antibodies, and eschars contained R. heilongjiangensis DNA. R. heilongjiangensis was also isolated from ticks in the suspected geographic area of infection.     

Human Infections with Rickettsia raoultii,China

We used molecular methods to identify Rickettsia raoultii infections in 2 persons in China. These persons had localized rashes around sites of tick bites. R. raoultii DNA was detected in 4% of Dermacentor silvarum ticks collected in the same area of China and in 1 feeding tick detached from 1 patient.     

Human Infection with Rickettsia felis, Kenya

To determine the cause of acute febrile illnesses other than malaria in the North Eastern Province, Kenya, we investigated rickettsial infection among patients from Garissa Provincial Hospital for 23 months during 2006–2008. Nucleic acid preparations of serum from 6 (3.7%) of 163 patients were positive for rickettsial DNA as determined by a genus-specific quantitative real-time PCR and were subsequently confirmed by molecular sequencing to be positive for Rickettsia felis. The 6 febrile patients’ symptoms included headache; nausea; and muscle, back, and joint pain. None of the patients had a skin rash.     

Molecular Detection and Characterization of Rickettsia asembonensis in Human Blood,Zambia

Rickettsia asembonensis is a flea-related Rickettsia with unknown pathogenicity to humans. We detected R. asembonensis DNA in 2 of 1,153 human blood samples in Zambia. Our findings suggest the possibility of R. asembonensis infection in humans despite its unknown pathogenicity.     

Rickettsia helvetica in Patient with Meningitis,Sweden, 2006

Pathogenicity of Rickettsia helvetica is relatively unknown. We isolated a spotted fever group rickettsial organism from a patient with subacute meningitis. Nucleotide sequences of the 16S rRNA, ompB, and 17kDa genes identified the isolate as R. helvetica. This organism may be associated with serious infections such as central nervous system disorders.     

Rickettsia parkeri in Argentina

Clinical reports of an eschar-associated rickettsiosis in the Paraná River Delta of Argentina prompted an evaluation of Amblyomma triste ticks in this region. When evaluated by PCR, 17 (7.6%) of 223 questing adult A. triste ticks, collected from 2 sites in the lower Paraná River Delta, contained DNA of Rickettsia parkeri.     

Confirmation of Rickettsia conorii Subspecies indica Infection by Next-Generation Sequencing,Shandong, China

We describe 3 similar cases of rickettsial disease that occurred after tick bites in a mountainous rural area of Shandong Province, China. Next-generation sequencing indicated the etiologic agent of 1 patient was Rickettsia conorii subspecies indica. This agent may be more widely distributed across China than previously thought.     

Diagnostic Assay for Rickettsia japonica

We developed a specific and rapid detection system for Rickettsia japonica and R. heilongjiangensis, the causative agents of spotted fever, using a TaqMan minor groove binder probe for a particular open reading frame (ORF) identified by the R. japonica genome project. The target ORF was present only in R. japonica–related strains.     

Common Epidemiology of Rickettsia felis Infection and Malaria,Africa

This study aimed to compare the epidemiology of Rickettsia felis infection and malaria in France, North Africa, and sub-Saharan Africa and to identify a common vector. Blood specimens from 3,122 febrile patients and from 500 nonfebrile persons were analyzed for R. felis and Plasmodium spp. We observed a significant linear trend (p<0.0001) of increasing risk for R. felis infection. The risks were lowest in France, Tunisia, and Algeria (1%), and highest in rural Senegal (15%). Co-infections with R. felis and Plasmodium spp. and occurrences of R. felis relapses or reinfections were identified. This study demonstrates a correlation between malaria and R. felis infection regarding geographic distribution, seasonality, asymptomatic infections, and a potential vector. R. felis infection should be suspected in these geographical areas where malaria is endemic. Doxycycline chemoprophylaxis against malaria in travelers to sub-Saharan Africa also protects against rickettsioses; thus, empirical treatment strategies for febrile illness for travelers and residents in sub-Saharan Africa may require reevaluation.     

Prevalence of antibodies to Rickettsia conorii Coxiella burnetii and Rickettsia typhi in Salamanca province (Spain). Serosurvey in the human population

The Salamanca Province of Spain is an endemic zone for Mediterranean spotted fever. In this area, only one case of Q fever has been reported and typhus group rickettsial diseases have never been diagnosed. To obtain a panoramic view of the presence of antibodies to the most ubiquitous rickettsial agents, 400 sera specimens from a statistically representative sample of the human population of Salamanca City and its surrounding province were subjected to indirect microimmunofluorescent test for antibodies against Rickettsia conorii, Coxiella burnetii, phase II, and Rickettsia typhi antigens. Titers 1:40 to R. conorii were found in 73.5% of the sera. Positivity was more common in subjects who reported closer contact with the natural environment and/or with domestic animals. Seropositivity to C. burnetii, phase II, was detected in 50.2% of sera. These positive cases were related to rural environmental factors and to prevoius contact with animals. The frequency of antibodies increased with age showing a progressive exposure to the rickettsial antigen. The prevalence of antibodies to R. conorii and C. burnetii in the human population of Salamanca Province is higher than that reported from any other geographic zone. The study of antibodies to R. typhi showed that 12.5% of the sera had titers 1:40. According to our results, seropositivity to this rickettsial antigen cannot be related to any particular group of population nor interpreted totally as cross reactivity with R. conorii. Our data show a wide distribution of R. conorii and C. burnetii antigens in Salamanca Province, and also indicate the presence of R. typhi antigens in this area.     

Rickettsia parkeri in Amblyomma americanum Ticks, Tennessee and Georgia, USA

To determine the geographic distribution of the newly recognized human pathogen Rickettsia parkeri, we looked for this organism in ticks from Tennessee and Georgia, USA. Using PCR and sequence analysis, we identified R. parkeri in 2 Amblyomma americanum ticks. This rickettsiosis may be underdiagnosed in the eastern United States.     

Spotted-fever group Rickettsia in Dermacentor variabilis, Maryland

Three-hundred ninety-two adult Dermacentor variabilis were collected from six Maryland counties during the spring, summer, and fall of 2002. Infection prevalence for spotted fever group Rickettsia was 3.8%, as determined by polymerase chain reaction. Single strand conformational polymorphism (SSCP) analysis followed by sequencing indicated that all infections represented a single rickettsial taxon, Rickettsia montanensis.     

Rickettsia slovaca Infection in Humans,Portugal

Fifteen years after the initial detection of Rickettsia slovaca in ticks in Portugal, 3 autochthonous cases of R. slovaca infection were diagnosed in humans. All patients had an eschar on the scalp and lymphadenopathy; 2 patients had facial edema. R. slovaca infection was confirmed by serologic testing, culture, and PCR.     

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.     

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.     

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.