Seroepidemiological investigations in domestic ruminants from Egypt, Somalia and Jordan for the demonstration of complement fixing antibodies against Rickettsia and Chlamydia (author's transl)]

1450 random serum samples of domestic ruminants from Egypt, Somalia and Jordan were investigated for complement fixing antibodies against Rickettsia and Chlamydia. Between 1.5 and 3.4% of the samples from the animals investigated had antibodies against the RMSF-group of Rickettsia, with exception of the sera from Somalian cattle and sheep from Jordan. Antibodies against Rickettsia of the Typhus-group were found in 4 cattle and 1 goat from Jordan and 2 sheep from Egypt; by agglutination test with type-specific antigen they were identified as antibodies against R. typhi. Using 2 different antigens, antibodies against Coxiella burnetii were found in every population tested. The prevalence was 2.0 to 12.2%, with the exception of cattle in Somalia, where only 1 positive serum (0.2%) was found. 27% of the serum samples from Jordan and 22% from Egypt but none of the 802 samples from Somalia had antibodies against Chlamydia. The results are discussed under an epidemiological point of view.     

Seroprevalence of Rickettsia spp. infection among tick-bitten patients and blood donors in Sweden

Serum samples from 236 Swedish patients with symptoms of infectious disease appearing after a tick bite were analysed for the presence of antibodies to Rickettsia helvetica, the only rickettsial species so far isolated from ticks in Sweden. Of these subjects, 137 had tested seropositive for Borrelia burgdorferi. For control purposes, sera from 161 healthy blood donors were examined. A total of 10/397 samples (2.6%) showed IgG-antibodies to R. helvetica at or above a titre of 1/80 as cut-off. 6/137 (4.4%) belonged to the Borrelia positive group, 3/99 (3.0%) to the tick-bitten but Borrelia negative group and 1/161 (0.6%) to the control group. The difference between the tick-exposed groups and the control group was significant in Pearson's 2-sided chi(2) test. In 1 serum sample the presence of antibodies to R. helvetica was further confirmed by Western immunoblot. The study shows that infection with Rickettsia spp. as well as coinfection with Lyme borreliosis needs to be considered in the diagnosis of tick-transmitted infections in Sweden. Owing to a known occurrence of immunological cross-reactivites, however, the results must be cautiously interpreted with regard to species of Rickettsia involved.     

Seroprevalence and risk factors of Toxoplasma gondii infection in domestic sika deer (Cervus nippon) in northeastern China

Toxoplasmosis is a worldwide zoonosis caused by Toxoplasma gondii, which can infect warm-blooded animals and humans. A serological survey was undertaken to examine the seroprevalence and risk factors associated with T. gondii infection in sika deer in northeastern China. 114 (13.46%, 95% CI 11.16–15.76) out of 847 serum samples were positive to T. gondii by modi?ed agglutination test (MAT) at a 1:25 cut-off, with titers of 1:25 in 44, 1:50 in 32, 1:100 in 17, 1:500 in 11, 1:1500 or higher in 10. These samples were collected between November 2012 and October 2013 from Inner Mongolia, Jilin and Heilongjiang provinces in China. However, statistically signi?cant differences were not observed between T. gondii seroprevalence and genders or regions of sika deer in the logistic regression analysis (P > 0.05) and left out of the ?nal model. Seroprevalence of T. gondii infection in male sika deer was 14.07% (95% CI 11.14–17.01), slightly higher than that in the female (12.38%) (95% CI 8.69–16.06) and seroprevalence of T. gondii infection in Harbin, Changchun city, Jilin city and Chifeng city were 12.02% (95% CI 7.60–16.44), 15.51% (95% CI 11.52–19.50), 12.27% (95% CI 7.23–17.31) and 12.50% (95% CI 7.38–17.63), respectively. Seasons of sampling were considered as main risk factors associated with T. gondii infection, autumn (15.32%) were more than two times (OR = 1.98, 95% CI = 1.18–3.33, P = 0.01) at risk of acquiring T. gondii infection compared to winter (8.37%). Our results indicated a widespread exposure to T. gondii among sika deer in China. To our knowledge, this is the first report of T. gondii seroprevalence in sika deer in China.     

Serological and molecular evidence of Rickettsia helvetica in Denmark

Recent seroepidemiological studies and examinations of Ixodes ricinus ticks in Europe have demonstrated the presence of an emerging tick-borne infection with Rickettsia helvetica. We conducted a serosurvey in 168 Danish patients seropositive for borreliosis reflecting their exposure to I. ricinus ticks. A total of 21 patients (12.5%) had positive antibody titres to R. helvetica including 4 cases of seroconversion. None of the samples were positive for antibodies to Ehrlichia. We conclude that in humans exposed to I. ricinus ticks in Denmark the risk of acquiring rickettsial infection is for the first time demonstrated. In the same region of Denmark we collected 570 I. ricinus ticks from various sources, and examinations by PCR for Rickettsia were performed. Positive reactions were obtained in 23 ticks (4%), and R. helvetica was identified in all 13 of those for which sequencing was performed.     

Enzyme immunoassay of antibody to Rochalimaea quintana: diagnosis of trench fever and serologic cross-reactions among other rickettsiae.

Enzyme immunoassay (EIA) tests were used to diagnose trench fever and to determine cross-reactions of Rochalimaea quintana with other rickettsiae. The results were compared with those obtained by counterimmunoelectrophoresis (CIE). All sera from cases of primary or relapsed forms of trench fever were positive both in EIA, with serum antibody titers of 1:20-1:640, and in CIE, giving one to three precipitin lines. Sera from patients with other rickettsial infections were also tested for reactivity with R. quintana antigen: typhus group (Rickettsia prowazekii, Ricketsia mooseri), 15 sera; spotted fever group (Ricketsia ricketsii, Rickettsia akari), eight sera; and scrub typhus (Rickettsia tsutsugamushi), six sera. Strong reactions occurred with four sera from patients with scrub typhus, giving one or two lines in CIE and EIA titers of 1:40-1:160; these results were extended to guinea pig antisera to R. tsutsugamushi. About 50% of typhus group sera reacted with a single line in CIE and had antibody titers of 1:20-1:80 by EIA. The results show that EIA is accurate for the diagnosis of trench fever and, with the results obtained by CIE, suggest that R. quintana is antigenically related to R. tsutsugamushi and possibly to rickettsiae in the typhus group as well.     

Demonstration of intracellular microorganisms (Rickettsia spp., Chlamydia pneumoniae, Bartonella spp.) in pathological human aortic valves by PCR

OBJECTIVES: Rickettsiae, which causes vasculitis, has not been linked to atherosclerotic cardiovascular disease in contrast to Chlamydia pneumoniae whose association with coronary artery disease and with sclerotic heart valves in patients undergoing aortic valve replacement is well established, even if causality is yet to unproven. In the search for any of these infectious agents, 84 pathological and 15 normal aortic heart valves of patients undergoing forensic autopsy were analysed by PCR and DNA-sequencing. METHODS: Two to four pieces of all valves were examined by semi-nested PCR, with primers specific for 16S rDNA, citrate synthase (gltA) and 17 kDa outer membrane protein (OMP) genes. RESULTS: Genetic material from Rickettsia spp. and C. pneumoniae was found in 17 (20.2%) and 22 (26.2%), respectively, of the 84 pathological aortic valves. In 35 (41.7%) of these 84 valves either C. pneumoniae or Rickettsia spp. were detected by PCR and in six cases (7.1%) these two organisms co-existed. In one case with Lambl's excrescences, previously considered as aseptic, presence of rickettsia-like organisms also was demonstrated by light microscopy, immunohistochemistry and sequencing of the amplified PCR product showing 100% homology with the published sequence for R. helvetica. In three of the 15 control valves, genetic material from only C. pneumoniae was detected compared to Rickettsia spp. that was significantly detected only in the pathological valves (Fisher's Exact test, 1-sided p = 0.046). CONCLUSIONS: The findings suggest that Rickettsia spp. also have a role in the pathogenesis of aortic valve disease.     

Tick-borne diseases in North Carolina: is "Rickettsia amblyommii" a possible cause of rickettsiosis reported as Rocky Mountain spotted fever?

Cases of Rocky Mountain spotted fever (RMSF) in North Carolina have escalated markedly since 2000. In 2005, we identified a county in the Piedmont region with high case numbers of RMSF. We collected ticks and examined them for bacterial pathogens using molecular methods to determine if a novel tick vector or spotted fever group rickettsiae (SFGR) might be emerging. Amblyomma americanum, the lone star tick, comprised 99.6% of 6,502 specimens collected in suburban landscapes. In contrast, Dermacentor variabilis, the American dog tick, a principal vector of Rickettsia rickettsii, comprised < 1% of the ticks collected. Eleven of 25 lone star tick pools tested were infected with "Rickettsia amblyommii," an informally named SFGR. Sera from patients from the same county who were presumptively diagnosed by local physicians with a tick-borne illness were tested by an indirect immunofluorescence antibody (IFA) assay to confirm clinical diagnoses. Three of six patients classified as probable RMSF cases demonstrated a fourfold or greater rise in IgG class antibody titers between paired acute and convalescent sera to "R. amblyommii" antigens, but not to R. rickettsii antigens. White-tailed deer, Odocoileus virginianus, are preferred hosts of lone star ticks. Blood samples collected from hunter-killed deer from the same county were tested by IFA test for antibodies to Ehrlichia chaffeensis and "R. amblyommii." Twenty-eight (87%) of 32 deer were positive for antibodies to E. chaffeensis, but only 1 (3%) of the deer exhibited antibodies to "R. amblyommii," suggesting that deer are not the source of "R. amblyommii" infection for lone star ticks. We propose that some cases of rickettsiosis reported as RMSF may have been caused by "R. amblyommii" transmitted through the bite of A. americanum.     

First detection of spotted fever group Rickettsiae in ticks in Serbia

Ticks can transmit multiple pathogenic bacteria responsible for diseases in animals and humans such as Borrelia burgdorferi sensu lato, Anaplasma phagocytophilum, and spotted fever group Rickettsia sp. The current study aimed to investigate the presence of Rickettsiae in ticks collected from seven localities in Serbia. One hundred thirty-one (131) questing ticks belonging to 5 tick species (Dermacentor marginatus, Dermacentor reticulatus, Haemaphysalis punctata, Haemaphysalis Concinna, and Ixodes ricinus) were collected in 2007 and 2009. Ticks were tested by polymerase chain reaction, amplifying gltA, ompA, and 17-kd genes, and sequencing analysis, revealing the presence of Rickettsia helvetica and Rickettsia monacensis in I. ricinus ticks only (infection rates 7.7% and 15.4% for R. helvetica and R. monacensis, respectively). R. helvetica has been isolated from I. ricinus ticks and has been implicated in fatal perimyocarditis. R. monacensis was first identified in I. ricinus samples collected in Germany and has recently been implicated in human infection. The results of the current study make fundamental the need to evaluate the incidence of infection with R. helvetica and R. monacensis among the resident population.     

First molecular evidence of Anaplasma ovis and Rickettsia spp. in keds (Diptera: Hippoboscidae) of sheep and wild ruminants

To evaluate the presence of rickettsial agents in hippoboscid flies with molecular methods, 81 sheep keds (Melophagus ovinus) were collected from 23 sheep, 144 deer keds (Lipoptena cervi) were caught in the environment, and a further 463 and 59 individuals of the latter species were obtained from fresh carcasses of 29 red deer and 17 roe deer, respectively. DNA was extracted individually or in pools. Anaplasma ovis was demonstrated in all examined sheep keds, and from one pool of free-living deer keds. Rickettsia helvetica or other, unidentified rickettsiae were also present in one pool of sheep keds, and in four pools of deer keds from both red deer and roe deer. This is the first account of polymerase chain reaction positivity of hippoboscid flies for A. ovis and rickettsiae. These results raise the possibility that-apart from cattle and roe deer as already reported-sheep and red deer might also play a reservoir role in the epidemiology of rickettsioses.     

Prevalence of antibodies to spotted fever group rickettsiae in humans and domestic animals in a Brazilian spotted fever-endemic area in the state of São Paulo, Brazil: serologic evidence for infection by Rickettsia rickettsii and another spotted fever group Rickettsia

In serum samples obtained from all the healthy humans, horses, dogs, and donkeys present on three farms in the Pedreira Municipality, an endemic area for Brazilian spotted fever, an indirect immunofluorescence assay (IFA) detected antibodies against Rickettsia rickettsii in 17 (77.3%) horses, 5 (31.3%) dogs (titers ranging from 64 to 4,048), and none of 4 donkeys or 50 humans. Five canine and eight equine sera with high antibody titers to R. rickettsii were also tested by IFA against R. bellii, R. akari, and R. africae antigens. Sera from two horses and two dogs that showed similar high antibody titers against two rickettsial antigens were evaluated after cross-absorption. Sera from seven horses and two dogs contained antibodies specific for R. rickettsii, and one dog serum had antibodies against a Rickettsia species very closely related to R. africae. The latter may have been caused by infection with the recently identified COOPERI strain.     

The prevalence of antibodies to Rickettsia rickettsii in an area endemic for Rocky Mountain spotted fever

A study of Rickettsia rickettsii was conducted in Rowan, Cabarrus, and Granville counties, North Carolina in an attempt to define the prevalence of endemic infection in this area. Serum samples were obtained from 1,976 healthy persons and tested by indirect hemagglutination for detectable antibodies to R. rickettsii. Of this group, 568 (28.7%) had detectable antibody (greater than or equal to 1:8), 80 (4%) had titers greater than or equal to 1:64, and 1,408 (70%) had no detectable antibody (less than or equal 1:8). Indirect immunofluorescence testing for antibody was also performed for 315 (15%) of the serum samples, of which 301 (95%) had undetectable titers and 14 (5%) had detectable titers ranging from 1:8 to greater than or equal to 1:64. Serological reactivity by indirect hemagglutination was detected in persons in the absence of known Rocky Mountain spotted fever. The study failed to show a good correlation of either the height of the geometric mean titer or percentage of seropositive persons with the previously determined age-related rates of acquisition of the disease. These data suggest that the antibodies measured may not be specific for R. rickettsii or that the antibody levels wane with time or both. It is probable that unrecognized infection occurs, but the true incidence or prevalence cannot be determined by available serological tests.     

Tick-borne bacteria in free-living jaguars (Panthera onca) in Pantanal, Brazil

Tick-borne bacteria were investigated in 10 free-living jaguars and their ticks in the Pantanal biome, Brazil. Jaguar sera were tested by indirect fluorescent antibody assays using Rickettsia rickettsii, Rickettsia parkeri, Rickettsia amblyommii, Rickettsia rhipicephali, Rickettsia felis, Rickettsia bellii, Ehrlichia canis, and Coxiella burnetii as crude antigens. All 10 jaguar sera reacted (titer ≥ 64) to at least one Rickettsia species; 4 and 3 sera reacted with E. canis and C. burnetii, respectively. One jaguar presented antibody titer to R. parkeri at least fourfold higher than those to any of the other five Rickettsia antigens, suggesting that this animal was infected by R. parkeri. Ticks collected from jaguars included the species Amblyomma cajennense, Amblyomma triste, and Rhipicephalus (Boophilus) microplus. No Rickettsia DNA was detected in jaguar blood samples, but an A. triste specimen collected on a jaguar was shown by PCR to be infected by R. parkeri. The blood of two jaguars and samples of A. triste, A. cajennense, and Amblyomma sp. yielded Ehrlichia DNA by PCR targeting the ehrlichial genes 16S rRNA and dsb. Partial DNA sequences obtained from PCR products resulted in a new ehrlichial strain, here designated as Ehrlichia sp. strain Jaguar. A partial DNA sequence of the 16S rRNA gene of this novel strain showed to be closest (99.0%) to uncultured strains of Ehrlichia sp. from Japan and Russia and 98.7% identical to different strains of Ehrlichia ruminantium. The ehrlichial dsb partial sequence of strain jaguar showed to be at most 80.7% identical to any Ehrlichia species or genotype available in GenBank. Through phylogenetic analysis, Ehrlichia sp. strain jaguar grouped in a cluster, albeit distantly, with different genotypes of E. ruminantium. Results highlight risks for human and animal health, considering that cattle ranching and ecotourism are major economic activities in the Pantanal region of Brazil.     

Detection and identification of Rickettsia species in the northeast of Italy

This study was carried out using Ixodes ricinus ticks collected during 2005 and 2006 from the Friuli Venezia Giulia (FVG) region in the northeastern part of Italy and an area along the Slovenian side of the western border of Italy. The results indicate that Rickettsia spp. is widely distributed throughout these areas, with the greatest prevalence in the central part of the FVG region. The prevalence of Rickettsia spp. was 4.5% during 2005 and 6.1% during 2006. By sequencing the 16S rRNA gene, we show for the first time the presence of Rickettsia helvetica in I. ricinus ticks in the FVG region and the presence of R. monacensis in ticks in both areas. Furthermore, we detected a sequence with a high homology with that of R. limoniae in a tick obtained from the alpine zone.     

Diagnosis of human ehrlichiosis with the indirect fluorescent antibody test: kinetics and specificity

Human ehrlichiosis, an acute febrile illness caused by Ehrlichia canis or a closely related rickettsial organism, was first identified in 1986. From 1986 through 1988, sera from 85 patients demonstrated a fourfold rise or fall in antibody titer to E. canis. Seven (22%) of 32 patients initially tested during the first week after onset of illness. 17 (68%) of 25 tested during the second week, and all 18 tested during the third week had titers that exceeded the minimum positive titer of greater than or equal to 80. Of the 85 confirmed ehrlichiosis patients, 31 (36.5%) also had indirect fluorescent antibody titers considered diagnostic of infection with Rickettsia rickettsii, Rickettsia typhi, or Coxiella burnetti, but in most these diagnoses were not supported by epidemiologic, clinical, or serologic evidence. These results emphasize that patients suspected of having a tick-borne infection should be tested for antibodies to E. canis as well as for those to other rickettsiae.     

Correlation of rickettsial titers, circulating endotoxin, and clinical features in Rocky Mountain spotted fever

Blood rickettsial titers, skin biopsy results, and circulating endotoxin measurements were correlated with the clinical course of disease in patients with Rocky Mountain spotted fever (RMSF). Nine of 11 patients with documented RMSF had Rickettsia rickettsii isolated from plasma samples. Of the eight patients in whom rickettsial titers were measured, seven had 10(0.7) to 10(1.2) median tissue culture infective doses (TCID50) per milliliter; all seven had mild to moderately severe disease. One patient with fulminant, fatal untreated RMSF had 10(3) TCID50/mL of postmortem plasma. Two patients from whom rickettsiae were not isolated had positive direct immunofluorescent stains of skin biopsy material for R rickettsii. Circulating endotoxin was present in two patients, one with documented rickettsemia and one with a positive skin biopsy alone. Only low levels of circulating rickettsiae are present in patients with moderately severe disease. Measurement of plasma endotoxin is not useful in the early diagnosis of RMSF.     

Serologic survey of cattle in the northeastern and north central United States,Virginia, Alaska,and Hawaii for antibodies to Cache Valley and antigenically related viruses (Bunyamwera serogroup virus)

Bovine sera from northeastern states (Connecticut, Delaware, Maine, Maryland, Massachusetts, New York, Pennsylvania, Vermont, and West Virginia), north central states (Indiana, Illinois, Iowa, Kentucky, Michigan, Minnesota, North Dakota, Ohio, South Dakota, and Wisconsin), Virginia, Alaska, and Hawaii were examined for the presence of neutralizing antibodies to Cache Valley (CV), Lokern (LK), Main Drain (MD), Northway (NW), and Tensaw (TS) viruses. Microneutralization tests were performed using Vero cells. Ninety percent inhibition of the virus at a 1:10 serum dilution was considered positive for the presence of specific antibody. Sera having antibody to more than one virus were titrated from 1:10 to 1:640. The results indicated that 4-28% of the cattle per region had specific antibodies to CV virus. Neutralizing antibodies to NW, LK, and TS viruses were also detected, indicating possible exposure to these Bunyamwera serogroup viruses along with CV virus. Antibody titers measured against NW virus were very similar to those against CV virus. Antibodies to MD virus were present in low levels in bovine sera from Illinois, Maryland, and Ohio. Cattle from Alaska had only antibodies to NW virus. Antibodies to Bunyamwera serogroup viruses were not observed in sera from Hawaii.     

Japanese encephalitis virus infection in cattle: a serological survey in Saitama and Kagoshima Prefectures

Serum samples were collected from a total of 1,306 and 536 cattle raised in Saitama and Kagoshima Prefectures, respectively, during a period from 1982 to 1984. Their antibody titers against Japanese encephalitis virus (JEV) were determined by the hemagglutination-inhibition test. Antibody prevalences were 65.5% (856/1306) and 68.8% (369/536) in Saitama and Kagoshima Prefectures, respectively. In both prefectures, there was a rapid increase in positive rate and mean titer in summer. Afterwards, there was a gradual decrease in both rate and titer in Saitama Prefecture in winter. In Kagoshima Prefecture, however, the rate and titer did not so markedly decrease in winter, but remained high in December. The rate of positive reactors to JEV in Kagoshima Prefecture increased gradually from 29.4% (1 year old) to 74.5% (4 years old) with advance in age. This rate in each age group remained almost at the same level ranging from 64.0% to 82.8% in Saitama Prefecture.     

内蒙古中西部草原蜱媒病原体多样性及基因型分析

目的了解内蒙古中西部草原蜱类的群落结构、携带病原体多样性及基因型。方法于2016-2019年春夏季,在内蒙古中西部草原,采用动物体表搜集法采集蜱标本,进行蜱种鉴定。解剖摘取蜱的唾液腺并提取基因组DNA,以斑点热立克次体柠檬酸合成酶A (gltA)、疏螺旋体以鞭毛蛋白B (flaB)、埃立克体属以外膜蛋白质1 (omp1)、无形体属主要表面蛋白2 (msp2)为靶基因进行PCR扩增初筛。立克次体gltA初筛阳性样品经限制性片段长度多态性(RFLP)分类,再根据蜱种和地区每类选20~30个代表性样品进行gltA、立克次体外膜蛋白A (rOmpA)基因测序。扩增序列测序后用BLAST、 Clustal W和MEGA 7.0软件进行同源性分析,以邻接法构建系统进化树。结果共采集成蜱3 822只,经形态学特征和特异性18S r RNA基因分型法鉴定,隶属于2属3种,分别为草原革蜱、亚东璃眼蜱和边缘璃眼蜱,其中草原革蜱占55.7%(2 129/3 822)、亚东璃眼蜱占30.0%(1 147/3 822),为该地区的优势蜱种。PCR检测结果显示,立克次体gltA基因阳性蜱1 899只,阳性率为49.7%(1 899/3 822), gltA基因阳性样品根据RFLP结果分为两类,两类样品的gltA基因序列均为581 bp,与R. raoultii (DQ365804)或R. aeschlimanni (KT873466)的同源性为100%;两类样品的rOmpA基因均长367 bp,与R. raoultii (AH015610)或R. aeschlimanni (U83466)的同源性为100%,与gltA基因的结果相符。3 822只蜱中,R. raoultii和R. aeschlimanni的阳性率分别为37.2%(1 422/3 822)和12.5%(477/3 822),其中草原革蜱中分别为58.5%(1 245/2 129)和11.1%(477/2 129);亚东璃眼蜱中分别为15.4%(177/1 147)和0;边缘璃眼蜱中分别为0和44.0%(240/546)。疏螺旋体flaB基因阳性蜱28只,阳性率为0.7%(28/3 822),其中草原革蜱中为0.8%(16/2 129),亚东璃眼蜱为1.0%(12/1 147)。共获得疏螺旋体flaB基因序列10条,与莱姆病主要病原体B. garinii (AB035602)和B. afzelii PKo (NC008277)的同源性分别为90.6%~100%和95.6%~100%。亚东璃眼蜱中B. garinii和B. afzelii的阳性率分别为0.9%(10/1 147)和0.2%(2/1 147),草原革蜱中均为0.4%(8/2 129)。3 822只蜱中omp1基因阳性1只,TA克隆后获得8个氨基酸序列相同的克隆和3个氨基酸序列存在差异的克隆,11个克隆的氨基酸序列与E. muris的同源性最高,但仅为65%~69%。3 822只蜱中均未检出无形体属菌群。系统进化树分析结果显示,3种蜱感染的立克次体均与R. raoultii和R. aeschlimanni聚在一簇。在获得的10条疏螺旋体菌群flaB基因序列中,源于草原革蜱和亚东璃眼蜱的1条序列与B. garinii聚在一簇,草原革蜱的另1条序列与B. afzelii聚在一簇,其余8条序列与B. garinii和B. afzelii的flaB基因序列处在不同的分支。草原革蜱感染的埃立克体属菌与目前已知的埃立克体属菌群关系较远,形成独自的聚类。结论内蒙古中西部草原存在草原革蜱、亚东璃眼蜱和边缘璃眼蜱,蜱类中广泛存在斑点热立克次体和莱姆病螺旋体的感染,是R. raoultii、R. aeschlimanni、 B. garinii和B. afzelii潜在的自然疫源地。有必要加强该地区蜱媒传染病的预防控制工作。     

First detection of Rickettsia helvetica in Ixodes ricinus ticks in Austria

A total of 853 Ixodes ricinus ticks collected from the nine federal states of Austria were examined by molecular methods for possible infections with Rickettsia spp. It was shown that roughly one-third of the ticks were infected with Rickettsia spp. Moreover, Rickettsia helvetica was detected in Austria for the first time.     

Serologic evidence for Rickettsia typhi and an ehrlichial agent in Norway rats from Baltimore, Maryland, USA

We screened serum from 90 Norway rats trapped in East Baltimore, Maryland, USA, from April to November 2005 for antibodies against Rickettsia typhi and Ehrlichia chaffeensis. Six rats had positive titers of > or = 1:64 against R. typhi and did not react with R. akari. In addition, four rats had cross-reactive antibodies with titers of > or = 1:64 against Ehrlichia chaffeensis. Sera from these rats also cross-reacted with Anaplasma phagocytophilum or Ehrlichia muris. Our data indicate that the agent of murine typhus and ehrlichial agents are circulating in the Norway rat population in Baltimore.