Primary and secondary infection with Ehrlichia chaffeensis in white-tailed deer (Odocoileus virginianus)

White-tailed deer (Odocoileus virginianus) are the principal reservoir host for Ehrlichia chaffeensis, causative agent of human monocytic ehrlichiosis (HME). Because white-tailed deer maintain a long-term infection with E. chaffeensis and because deer can be naturally exposed to multiple strains of E. chaffeensis, we evaluated the response to secondary infection of E. chaffeensis in deer. For primary infection, six white-tailed deer were injected with 5.4 x 10(6) DH82 cells infected with the Arkansas strain of E. chaffeensis (Ark) and two control deer were injected with noninfected DH82 cells. On post-infection day 54, three E. chaffeensis (Ark) infected deer and one naive deer were injected with 4.2 x 10(6) cells infected with strain WTD-6045B E. chaffeensis, which differs from the Arkansas strain by number of nucleotide repeats in the variable length PCR target (VLPT) gene; three other Arkansas strain infected deer were injected with noninfected DH82 cells. All animals were monitored for 31 additional days. All deer in the primary infection became positive by PCR amplification of the 16S rRNA or VLPT genes and/or cell culture by DPI-8. PCR amplification of the VLPT gene on whole blood, cell culture, and tissues detected primary and/or secondary strains in all deer exposed to both primary and secondary strains; in one deer, the primary strain was cultured from the lymph node. Our culture results demonstrated that both strains were present; however, PCR detection suggests that the secondary strain may have been circulating in blood at higher levels. In conclusion, this study provides evidence that primary infection of deer with E. chaffeensis does not protect against subsequent exposure and confirms that deer can be simultaneously coinfected with at least two different strains of E. chaffeensis.     

Co-infection of white-tailed deer with multiple strains of Ehrlichia chaffeensis

We investigated the effect of exposing deer to multiple strains of Ehrlichia chaffeensis that differed in number of tandem repeats in either the variable-length PCR target (VLPT) gene or 120 kDa antigen gene. We hypothesized that infection with one strain would provide immunity to infection with other strains of E. chaffeensis. All deer initially exposed to strain A (604-2) became PCR and culture positive by 10 days post-infection (DPI). Three deer infected with strain A and subsequently inoculated with strain B (623-4) became infected with strain B. Two deer infected with strain A and subsequently inoculated with strain C (125B) became infected with strain C. Of three deer, each infected with strain B and subsequently inoculated with strain C, one was PCR positive for strain C. Of three deer previously inoculated with both strains A and B, and subsequently inoculated with strain C, one showed delayed evidence of strain C. Western blot analysis demonstrated that deer sera reacted differently to antigens from each exposed strain. A complementary in vitro study demonstrated that exposure to two strains differing in VLPT repeats may lead to co-infection of DH82 cells. These results complement a previous study and further show that deer can become sequentially infected with up to three strains of E. chaffeensis. This suggests that competitive exclusion, a phenomenon described in related organisms such as Anaplasma marginale whereby infection with one strain precludes subsequent infection by a second, distinct strain of the same species, may not occur with E. chaffeensis.     

Ehrlichia chaffeensis infection in dogs in South Korea

Ehrlichia chaffeensis is one of the causative agents of canine ehrlichiosis and human monocytic ehrlichiosis (HME). Canine ehrlichiosis caused by E. chaffeensis was diagnosed in two dogs in South Korea based on clinical findings, and the diagnosis was confirmed by polymerase chain reaction (PCR) and DNA sequencing. A 5-year-old intact male American Pit bull terrier allowed outdoors was found to be concurrently infected with Babesia gibsoni and E. chaffeensis. The major clinical findings were lethargy and reddish urine, and laboratory analysis revealed severe hematuria and thrombocytopenia. In addition, a 3-year-old neutered male Shih-tzu was also found to be infected with E. chaffeensis. Although this dog was an indoor companion animal, he was frequently allowed outside for exercise. The clinical signs observed in this dog included generalized purpura with petechiae and ecchymoses due to thrombocytopenia. A 390-bp partial portion of E. chaffeensis 16S rRNA gene was amplified in both cases, and nucleotide sequence analysis revealed 99% homology of this fragment with other E. chaffeensis isolates. These findings demonstrate the presence of E. chaffeensis infection in dogs in South Korea, and this is the first report to confirm clinical cases of E. chaffeensis infection in dogs.     

Attempted experimental infection of domestic goats with Ehrlichia chaffeensis

Although white-tailed deer (WTD; Odocoileus virginianus ) are considered the primary natural reservoir host for Ehrlichia chaffeensis, the causative agent of human monocytotropic ehrlichiosis, the potential role of other vertebrates as reservoir hosts has not been fully explored. Because domestic goats are naturally infected in areas where E. chaffeensis is endemic in deer, we evaluated the susceptibility of domestic goats to experimental infection with E. chaffeensis. A total of 12 goats were inoculated with E. chaffeensis (15B-WTD-GA or Ark strain)-infected DH82 cells by one of three routes: intravenously, subcutaneously, or intradermally. White-tailed deer simultaneously inoculated with the same dose, route, and inoculum served as positive controls; additional goats and WTD were included as negative controls. Evidence of E. chaffeensis infection was evaluated in all animals by indirect fluorescent antibody assay, PCR, and cell culture isolation techniques. All goats exposed to E. chaffeensis seroconverted by 14 days post-infection (DPI), and E. chaffeensis was isolated from one goat on 3 DPI; however, molecular or cell culture evidence of active infection was not detected in goats later than 3 DPI. White-tailed deer exhibited serologic and molecular evidence of E. chaffeensis infection throughout both trials, and E. chaffeensis was reisolated in cell culture from all infected WTD on numerous days post-infection. Our results suggest that despite the occurrence of natural infection in goats, this animal may not be susceptible to experimental infection and thus may not serve as a suitable model of E. chaffeensis reservoir host infection.     

用半套式PCR检测蜱和啮齿动物中查菲埃立克体

目的　了解福建西北部林区查菲埃立克体 (Ehrlichiachaffeensis)的存在情况。方法　用 16SrRNA基因特异引物进行半套式PCR ,检测从福建武夷山和宁化采集的蜱类及野生动物中的查菲埃立克体DNA ,然后对有代表性的标本的扩增产物进行克隆和序列测定 ,并与GenBank中注册的核苷酸序列进行同源性比较。结果　从该地区的越原血蜱 ,野鼠(褐家鼠、黄毛鼠、黄胸鼠、社鼠、小家鼠 )和野兔的脾脏和 /或血块中均扩增出了查菲埃立克体的特异片段。越原血蜱成蜱 2 40组 (6 16只 ) ,31组阳性 ,最小阳性率 5 0 %。野鼠脾脏标本 39份 ,2 2份阳性。野鼠和野兔血块标本共 35份 ,14份阳性。 390bp的PCR产物经克隆、测序后分析发现其DNA序列与美国查菲埃立克体分离株对应位置一致。结论　福建西北部林区可能存在人单核细胞埃立克体病的自然疫源地。     

Tissue diagnosis of Ehrlichia chaffeensis in patients with fatal ehrlichiosis by use of immunohistochemistry, in situ hybridization, and polymerase chain reaction.

In the United States, human ehrlichiosis is a complex of emerging tick-borne diseases caused by 3 distinct Ehrlichia species: Ehrlichia chaffeensis, Ehrlichia ewingii, and the human granulocytotropic ehrlichiosis agent. Ehrlichioses are characterized by a mild to severe illness, and approximately 4% of cases are fatal. Because these obligate intracellular bacteria are difficult to resolve with routine histologic techniques, their distribution in tissues has not been well described. To facilitate the visualization and detection of ehrlichiae, immunohistochemistry (IHC), in situ hybridization (ISH), and polymerase chain reaction (PCR) assays were developed by use of tissues from 4 fatal cases of E. chaffeensis infection. Evidence of E. chaffeensis via IHC, ISH, and PCR was documented in all 4 cases. Abundant immunostaining and in situ nucleic acid hybridization were observed in spleen and lymph node from all 4 patients. Significantly, in 2 of these patients, serologic evidence of infection was absent. Use of IHC, ISH, and PCR to visualize and detect Ehrlichia in tissues can facilitate diagnosis of ehrlichial infections.     

Evaluation of a prototype Ehrlichia chaffeensis surveillance system using white-tailed deer (Odocoileus virginianus) as natural sentinels

The natural history of Ehrlichia chaffeensis, the causative agent of human monocytotropic ehrlichiosis, includes the lone star tick (LST, Amblyomma americanum) as a vector and white-tailed deer (WTD; Odocoileus virginianus) as both a natural reservoir of E. chaffeensis and a major host of LST. The goal of the current study was to implement and evaluate a prototype surveillance system to delineate the geographic distribution of E. chaffeensis using WTD as natural sentinels. To accomplish this goal, serologic testing using the indirect immunofluorescent antibody (IFA) test was performed on WTD serum samples, and to confirm serologic results, polymerase chain reaction (PCR) assays and culture isolation were conducted. Considerations relevant to the applicability of a surveillance system utilizing WTD were analyzed (e.g., age and gender relationships to serologic status, adequacy of sample sizes needed to distinguish between uninfected and infected populations, presence of LST, and ability to detect stability and spread of E. chaffeensis in WTD populations). Of 3275 WTD serologically tested, 549 (47%) from 17 of 18 states had antibodies reactive to E. chaffeensis (IFA titer > or = 1:128). No difference between age groups or gender was noted with serologic testing, thus these variables would not be a concern for a surveillance system using WTD. Significantly more deer in younger age groups (< or = 1.5 yr) were PCR and culture positive, and 46% of 122 seropositive WTD populations were confirmed positive by PCR or culture isolation. A significant association between LST infestation and E. chaffeensis seroreactivity was noted. Furthermore, the surveillance system was able to detect stability of E. chaffeensis within WTD populations and also spread to new populations, both of which were associated with LST status. These data clearly demonstrate that WTD are useful as natural sentinels for this emerging human pathogen, and establish a prototypical framework for a WTD surveillance system.     

Lack of susceptibility of guinea pigs and gerbils to experimental infection with Ehrlichia chaffeensis

Guinea pigs and Mongolian gerbils were experimentally infected with Ehrlichia chaffeensis (St. Vincent strain, 10 passages in vitro). The infection was monitored by serial blood sampling for PCR and by xenodiagnosis with Amblyomma americanum larvae. Exposure to the pathogen was confirmed using serology. Neither guinea pigs nor gerbils were susceptible to infection with E. chaffeensis, and ticks fed upon these animals did not become infected with the pathogen.     

Diagnosis of human cytomegalovirus central nervous system disease in AIDS patients by DNA amplification from cerebrospinal fluid.

The utility of amplification of human cytomegalovirus (HCMV) DNA in cerebrospinal fluid (CSF) for the diagnosis of HCMV central nervous system (CNS) disease in AIDS patients was studied. CSF specimens from 30 patients with neurologic dysfunction were assayed by polymerase chain reaction (PCR), and the results were correlated with histopathologic findings, CSF culture, and clinical manifestations. PCR was positive in all 11 patients who had histopathologic evidence of HCMV CNS disease, including 4 who were CSF culture-negative. Three patients with HCMV polyradiculopathy had CSF positive by PCR. Nine patients negative for HCMV by neuropathologic study and an additional 7 patients with HCMV-unrelated clinical diagnosis were all CSF PCR-negative, despite concomitant systemic HCMV infection in 7. In addition, 24 asymptomatic human immunodeficiency virus-infected individuals were CSF PCR-negative. CSF PCR appears to be a sensitive and specific diagnostic method for detection of HCMV CNS disease in AIDS patients.     

Molecular survey of Anaplasma and Ehrlichia infections of feral raccoons (Procyon lotor) in Hokkaido, Japan

Infection by Anaplasma and Ehrlichia in feral raccoons (Procyon lotor) in Hokkaido, Japan, was examined by molecular methods. A polymerase chain reaction (PCR) screen for Anaplasmataceae, based on 16S rRNA, showed that 38 (5.4%) of 699 raccoons examined were positive. These 38 positive samples were examined for Anaplasma phagocytophilum, Anaplasma bovis, Ehrlichia chaffeensis, and Ehrlichia canis infection by species-specific nested PCR. Nested PCR results indicated that 36 of the 38 samples were positive for A. bovis. All 38 samples were PCR negative for A. phagocytophilum, E. chaffeensis, and E. canis. This is the first report of the detection of A. bovis in the peripheral blood of raccoons. A total of 124 raccoons were infested with ticks, including Ixodes ovatus, Ixodes persulcatus, and Haemaphysalis spp. The rate of A. bovis infection in raccoons infested with Haemaphysalis spp. (46.7%, 7/15) was significantly higher than that in raccoons without Haemaphysalis spp. infestation (3.7%, 4/109, p?相似文献   

Experimental and field studies on the suitability of raccoons (Procyon lotor) as hosts for tick-borne pathogens

We investigated the experimental susceptibility and natural exposure of raccoons (Procyon lotor) to five tick-borne pathogens of human and veterinary importance, Ehrlichia canis, E. chaffeensis, E. ewingii, Anaplasma phagocytophilum (ApVariant 1 and Ap-ha HGE-1 strains), and Borrelia lonestari. Infections were assessed by polymerase chain reaction (PCR), indirect fluorescent antibody (IFA) testing, and/or culture isolation methods for at least 30 days postinoculation (DPI). Two E. chaffeensis-inoculated raccoons seroconverted and were transiently PCR positive. One raccoon was culture positive. Laboratory raised Amblyomma americanum nymphs fed on a third infected raccoon failed to become infected. Two A. phagocytophilum (HGE-1)-inoculated raccoons became PCR positive and seroconverted. Both remained positive for at least 74 DPI. In contrast, raccoons inoculated with A. phagocytophilum (Ap-Variant 1) were only transiently PCR positive and only seroconverted with low titers. No evidence of infection was observed for E. ewingii- and B. lonestari-inoculated raccoons. Only one E. canis-inoculated raccoon was PCR positive 3 DPI. Serologic testing of wild raccoons from five populations (3 infested with ticks) in Georgia and Florida showed antibodies reactive with E. chaffeensis in the 3 tick-infested populations (range of 30%-46%), E. canis in the same three populations (8%-23%), A. phagocytophilum in a single raccoon from Florida (12%), and Borrelia spp. in all 5 populations (8%-53%). All raccoons were PCR negative for tick-borne pathogens. These data suggest that raccoons are likely not important reservoirs of E. canis, E. ewingii, or B. lonestari. However, raccoons are experimentally susceptible and naturally exposed to E. chaffeensis, and these data support the previous finding that raccoons may be involved in the natural history of A. phagocytophilum.     

东北林区啮齿动物的查菲埃立克体核酸检测

目的 调查东北林区啮齿动物的查菲埃立克体感染水平。方法 采用巢式PCR检测吉林省集安和辽宁省宽甸林区野鼠脾脏样本的查菲埃立克体16S rRNA DNA;对阳性扩增产物作DNA序列测定,并对测定的序列进行同源性比较和聚类分析。结果 检测两地野鼠132只,阳性19只,阳性率14.39%。其中,集安野鼠阳性率 7.58%(5/66),宽甸野鼠阳性率 21.21%(14/66), 宽甸野鼠阳性率明显高于集安(χ²=3.9348, P=0.0473)。不同鼠种查菲埃立克体阳性率无明显差异。扩增阳性DNA片段测序后与GenBank中注册的埃立克体16S rRNA基因对应序列进行同源性比较, JA-m51(集安株)、KD-m18(宽甸株)二者基因序列相差4个核苷酸,而JA-m51与查菲埃立克体美国株及我国云南株核苷酸序列完全一致,进化树分析显示JA-m51、KD-m18与查菲埃立克体同属一个分支。结论 辽宁省、吉林省林区野鼠查菲埃立克体感染较普遍,该地区存在单核细胞埃立克体病的自然疫源地。     

Distribution of Enterococci in Hong Kong

Objectives: To study the distribution of hospital isolates of enterococci from urines, bile, blood and body fluids and to evaluate different methods for the identification of enterococci.Methods: Enterococci isolated from urine, bile, blood and body fluids collected during 1997 and 1998 were identified by polymerase chain reaction (PCR), API 20 Strep and conventional biochemical tests.Results: A total of 498 non-duplicate enterococci were studied: 398 and 43 isolates from urine and bile, respectively, 49 from blood, two from cerebrospinal fluid and six from body fluids. Both API 20 Strep and PCR gave the same identification results for 240 Enterococcus faecalis isolates, 45 E. faecium isolates and one isolate each of E. gallinarum and E. Casseliflavus. These isolates were re-defined by conventional biochemical tests. PCR could correctly identify 303 (98%) isolates while API 20 Strep could only correctly identify 287 (93%) isolates (99% of E. faecalis and 57–87% of the other Enterococcus sp.). Thus, PCR was used in the identification of the remaining isolates and the identity of isolates other than E. faecalis was subsequently confirmed by biochemical tests.Conclusions: The majority of enterococci isolated wasE. faecalis (81%) while only 15% were E. faecium and 4% the other enterococcal species. PCR could correctly identify E. faecalis while the identity of other enterococcal species had to be confirmed by biochemical tests.     

Identification of Ehrlichia chaffeensis,Anaplasma phagocytophilum,and A. bovis in Haemaphysalis longicornis and Ixodes persulcatus ticks from Korea

A total of 1,467 tick (1,463 of Haemaphysalis longicornis, three of Ixodes persulcatus and one of I. turdus) collected from nine provinces of Korea were examined by TaqMan real-time PCR for the presence of Ehrlichia and Anaplasma species. One set of primers and a probe were designed for detection of all of the Ehrlichia and Anaplasma species. Template DNAs (total 803) were prepared either from pools of larvae, nymphs, adult males and females, or from the salivary gland and midgut of adult ticks. Only DNAs positive in TaqMan PCR were examined for A. phagocytophilum with nested PCR and for E. chaffeensis with PCR. Four A. phagocytophilum 16S rRNA gene PCR products were sequenced for comparison with sequences previously reported. Amplification of a 16S rRNA gene fragment of Ehrlichia and Anaplasma species was observed in 364 tick DNAs (45.3% of the total). Of these 364 positive ticks, species-specific PCRs confirmed that 35 H. longicornis and one I. persulcatus were positive for A. phagocytophilum and one I. persulcatus was positive in E. chaffeensis. Except for one (AB-GGHL, GenBank accession number [GAN] AF470698), three of the four 16S rRNA gene fragment sequences of the A. phagocytophilum-positive samples were similar or identical to the sequences of variants of A. phagocytophilum deposited in GenBank. The 16S rRNA gene fragment sequence of AB-GGHL was similar to that of Anaplasma (Ehrlichia) bovis 16S rRNA (GAN U03775). The identities of the Anaplasmataceae genus and species DNA in the 327 ticks that could not be confirmed infected with either E. chaffeensis, A. phagocytophilum, or A. bovis are not known. This study is the first to demonstrate the presence of E. chaffeensis, A. phagocytophilum and A. bovis in Korean ticks.     

Comparison of three PCR methods for detection of Helicobacter pylori DNA and detection of cagA gene in gastric biopsy specimens

AIM:To comparatively evaluate PCR and other diagnosticmethods (the rapid urease test and/or culture) in order todetermine which of the three PCR methods (ureA,glmMand 26-kDa,SSA gene) was most appropriate in the diagnosisof Helicobacterpylori(Hpylori) infection and also to evaluatethe detection of a putative virulence marker of H pylori,thecage,gene,by PCR in biopsy specimens.METHODS:One hundred and eighty-nine biopsy specimenswere collected from 63 patients (three biopsies each)undergoing upper gastroduodenal endoscopy for variousdyspeptic symptoms.The PCR methods used to detectH pylori DNA directly from biopsies were the glmM,26-kDa,ureA and then cagA was used to compare the culturetechnique and CLO for urease with the culture techniquebeing used as the gold standard.RESULTS:Thirty-five percent of the biopsies were positivefor H pylori DNA using the 3 PCR methods,while 68% ofthese were positive for the cagA gene.Twenty-four percentof the biopsies were negative for H pylori DNA in all PCRmethods screened.The remaining 41% were either positivefor ureA gene only,glmM only,26-kDa only,or ureA glmM,ureA 26-kDa,glmM 26-kDa.Out of the 35% positivebiopsies,41% and 82% were positive by culture and CLOrespectively,while all negative biopsies were also negativeby culture and cagA.Cag A infection was also predominantlyfound in H pylori DNA of the biopsies irrespective of theclinical diagnosis.CONCLUSION:This method is useful for correctly identifyinginfections caused by H pylori and can be easily applied inour laboratory for diagnostic purposes.     

Infection rates of Amblyomma americanum and Dermacentor variabilis by Ehrlichia chaffeensis and Ehrlichia ewingii in southwest Missouri

Both Ehrlichia chaffeensis and Ehrlichia ewingii are causative agents of human ehrlichiosis. Both pathogens are transmitted to humans through the bite of an infected lone star tick (Amblyomma americanum). Since Missouri has a high incidence of human monocytic ehrlichiosis, we investigated the prevalence of E. chaffeensis- and E. ewingii-infected A. americanum and Dermacentor variabilis (American dog tick) ticks to help assess the relative risk for humans exposed to these vectors. We used a nested polymerase chain reaction assay for the detection of ehrlichial DNA in the collected ticks. Infection rates for both ehrlichial species were calculated from the assay results for each of the tick species. E. chaffeensis was found to be present in 9.8% of adult A. americanum ticks (57 of 579) and 6.7% of D. variabilis ticks (eight of 120). E. ewingii DNA was present at an infection rate of 5.4% in adult A. americanum (31 of 579) and 3.3% of D. variabilis ticks (four of 120). A minimum infection rate for nymph pools of A. americanum was 1.7% for E. chaffeensis and 0.6% for E. ewingii.     

The distribution and duration of hantaan virus in the body fluids of patients with hemorrhagic fever with renal syndrome

The distribution and duration of Hantaan virus (HTNV) in the body fluids of patients were studied by immunofluorescence, reverse passive hemagglutination, and cell culture assays. Virus antigen of hemorrhagic fever with renal syndrome in peripheral blood mononuclear cells (PBMCs) was usually present before day 11 of the disease, especially from days 4-7. Virus isolates were more readily recovered from plasma early in the course of the illness and less frequently after day 7. The use of PBMCs rather than plasma enabled isolates to be recovered at a rate nearly twice that permitted by plasma and allowed the isolation peak of HTNV (days 4-7 after onset of disease) to extend an additional 2 or 3 d, thus prolonging the period of detectable viremia until days 8-11. PBMCs were especially useful in isolating viruses from patients with hemorrhagic fever with renal syndrome in whom antibody titers were generally high during the acute phase of the disease. HTNV was isolated from the cerebrospinal fluid of patients, but was difficult to recover from other body fluids.     

Comparison of three PCR methods for detection of Helicobacter pylori DNA and detection of cagA gene in gastric biopsy specimens

AIM: To comparatively evaluate PCR and other diagnostic methods (the rapid urease test and / or culture) in order to determine which of the three PCR methods (ureA, glmM and 26-kDa, SSA gene) was most appropriate in the diagnosis of Helicobacter pylori (H pylori ) infection and also to evaluate the detection of a putative virulence marker of H pylori, the cagA gene, by PCR in biopsy specimens. METHODS: One hundred and eighty-nine biopsy specimens were collected from 63 patients (three biopsies each) undergoing upper gastroduodenal endoscopy for various dyspeptic symptoms. The PCR methods used to detect H pylori DNA directly from biopsies were the glmM, 26-kDa, ureA and then cagA was used to compare the culture technique and CLO for urease with the culture technique being used as the gold standard. RESULTS: Thirty-five percent of the biopsies were positive for H pylori DNA using the 3 PCR methods, while 68% of these were positive for the cagA gene. Twenty-four percent of the biopsies were negative for H pylori DNA in all PCR methods screened. The remaining 41% were either positive for ureA gene only, glmM only, 26-kDa only, or ureA + glmM, ureA + 26-kDa, glmM + 26-kDa. Out of the 35% positive biopsies, 41% and 82% were positive by culture and CLO respectively, while all negative biopsies were also negative by culture and cagA. Cag A+ infection was also predominantly found in H pylori DNA of the biopsies irrespective of the clinical diagnosis. CONCLUSION: This method is useful for correctly identifying infections caused by H pylori and can be easily applied in our laboratory for diagnostic purposes.     

山东省首例实验室诊断人单核细胞埃立克体病调查

目的 报告山东省首例人单核细胞埃立克体病的发现、诊治经过及其实验室检测.方法 对该疑似病例开展流行病学调查并填写个案调查表,采集其血标本,套式-PCR技术检测血液中嗜吞噬细胞无形体和查菲埃立克体特异性16S rRNA基因.结果 患者为不明原因发热,伴WBC和PLT减少.嗜吞噬细胞无形体特异性核酸检测阴性,查菲埃立克体特异性核酸检测阳性.PCR扩增阳性产物进行测序并与GenBank中注册的已知序列进行比较分析,显示与查菲埃立克体的同源性＞99％.结论 山东省存在查菲埃立克体感染病例,进一步开展自然疫源地调查十分必要.