Rickettsial Seroepidemiology among farm workers, Tianjin, People's Republic of China

High seroprevalence rates for Anaplasma phagocytophilum (8.8%), Coxiella burnetii (6.4%), Bartonella henselae (9.6%), and Rickettsia typhi (4.1%) in 365 farm workers near Tianjin, People's Republic of China, suggest that human infections with these zoonotic bacteria are frequent and largely unrecognized. Demographic features of seropositive persons suggest distinct epidemiology, ecology, and risks.     

Human monocytotropic ehrlichiosis, Missouri

To determine the incidence, clinical and laboratory characteristics, and utility of molecular diagnosis of human monocytotropic ehrlichiosis (HME) in the primary care setting, we conducted a prospective study in an outpatient primary care clinic in Cape Girardeau, Missouri. One hundred and two patients with a history of fever for 3 days (>37.7 degrees C), tick bite or exposure, and no other infectious disease diagnosis were enrolled between March 1997 and December 1999. HME was diagnosed in 29 patients by indirect immunofluorescent antibody assay and polymerase chain reaction (PCR). Clinical and laboratory manifestations included fever (100%), headache (72%), myalgia or arthralgia (69%), chills (45%), weakness (38%), nausea (38%), leukopenia (60%), thrombocytopenia (56%), and elevated aspartate aminotransferase level (52%). Hospitalization occurred in 41% of case-patients. PCR sensitivity was 56%; specificity, 100%. HME is a prevalent, potentially severe disease in southeastern Missouri that often requires hospitalization. Because clinical presentation of HME is nonspecific, PCR is useful in the diagnosis of acute HME.     

Seasonal dynamics of Anaplasma phagocytophila in a rodent-tick (Ixodes trianguliceps) system,United Kingdom

We investigated the reservoir role of European wild rodents for Anaplasma phagocytophila using polymerase chain reaction (PCR) analysis of blood collected from individually tagged rodents captured monthly over 2 years. The only tick species observed in the woodland study site was Ixodes trianguliceps, and ruminant reservoir hosts were not known to occur. A. phagocytophila infections were detected in both bank voles and wood mice but were restricted to periods of peak nymphal and adult tick activity. Most PCR-positive rodents were positive only once, suggesting that rodent infections are generally short-lived and that ticks rather than rodents may maintain the infection over winter. Bank voles were more likely to be PCR positive than wood mice, possibly because detectable infections are longer lived in bank voles. This study confirms that woodland rodents can maintain A. phagocytophila in Great Britain in the absence of other reservoir hosts and suggests that I. trianguliceps is a competent vector.     

Ehrlichia chaffeensis infections among HIV-infected patients in a human monocytic ehrlichiosis-endemic area

Manifestations of human monocytic ehrlichiosis (HME), a tick-borne infection caused by Ehrlichia chaffeensis, range from asymptomatic disease to fulminant infection and may be particularly severe in persons infected with HIV. We conducted a serologic study to determine the epidemiology of HME in HIV-positive patients residing in an HME-endemic area. We reviewed charts from a cohort of 133 HIV-positive patients who were seen during the 1999 tick season with symptoms compatible with HME (n=36) or who were asymptomatic (n=7). When available, paired plasma samples obtained before and after the tick season were tested by using an indirect immunofluorescence assay (IFA) to detect antibodies reactive to E. chaffeensis. Two symptomatic incident cases were identified by IFA, resulting in a seroincidence of 6.67% among symptomatic HIV-positive participants with paired samples available for testing and 1.64% overall. The baseline seroprevalence of HME was 0%. In contrast to infection in immunocompetent patients, E. chaffeensis infection in HIV-positive persons typically causes symptomatic disease.     

查菲埃立克体重组120kDa抗原的初步应用研究

目的　克隆查菲埃立克体 12 0kDa膜表面抗原蛋白基因 ,获得纯化的重组蛋白。方法　根据查菲埃立克体(91HE17) 12 0kDa抗原蛋白基因序列设计特异性引物 ,PCR扩增查菲埃立克体 12 0kDa抗原蛋白的基因片段 ;用限制性内切酶酶切PCR扩增产物后与 pUC18载体相连接 ,经酶切和序列分析证实后 ,将目标片段定向插入原核表达载体pProEXHTB中构建pProEXHTB/ p12 0重组质粒 ;将重组质粒转化E coliDH5α ,并使转化子在IPTG的诱导下进行蛋白质表达 ;运用亲和层析和电洗脱法对重组蛋白进行纯化。结果　克隆到一大小为 10 80bp的查菲埃立克体 12 0kDa抗原蛋白的基因片段 ,用该基因与表达质粒连接 ,成功构建了重组表达质粒 ;SDS -PAGE分析显示 :在IPTG诱导下 ,重组表达质粒转化的大肠杆菌产生一分子量为 4 7kDa的目标蛋白 ,免疫印迹证明该重组蛋白能与查菲埃立克体免疫血清发生反应。用纯化的重组蛋白作免疫斑点分析 ,76份被检血清中有 2份为可疑阳性 ,但经IFA复核为阴性。结论　查菲埃立克体 12 0kDa重组抗原蛋白具有免疫反应活性 ,为以重组蛋白为基础的人单核细胞埃立克体病的血清学诊断试剂盒制备和疫苗的研制奠定了基础。     

北京市农村人群及家畜嗜吞噬无形体和查菲埃立克体感染状况调查

目的调查北京市农村人群及家畜新发查菲埃立克体和嗜吞噬无形体感染状况。方法按地理位置选择北京市西北(延庆)、东北(密云)及东南(通州)地区3个植被率较高的旅游县(区)。按在册户籍随机以家庭为单位,调查并采集562人及90只山羊、71头牛和2只家犬血液标本,按WHO推荐间接免疫荧光方法(mlFA)检测血清lgG抗体。动物血球提取DNA扩增无形体16SrRNA基因并测序分析。结果人群查菲埃立克体和嗜吞噬无形体抗体阳性率分别为16．5％和14．O％;山羊和牛嗜吞噬无形体抗体阳性率分别为2．3％和O;2只家犬未检测到相应抗体。山羊、牛无形16SrRNA扩增阳性率分别为48．9％和23．9％16SrRNA序列(228bp)分析显示,3类优势流行株无明显地理分布特征。结论北京市农村人群存在查菲埃立克体和嗜吞噬无形体感染．调查地区家畜存在无形体感染。     

Ehrlichia chaffeensis Infection of Sika Deer, Japan

To determine whether Ehrlichia chaffeensis exists in Japan, we used PCR to examine blood from sika deer in Nara, Japan. Of 117 deer, 36 (31%) were infected with E. chaffeensis. The E. chaffeensis 16S rRNA base and GroEL amino acid sequences from Japan were most closely related to those of E. chaffeensis Arkansas.     

Red fox (Vulpes vulpes) play an important role in the propagation of tick-borne pathogens

The red fox (Vulpes vulpes) is the most widespread free-living carnivore in the world. Over the years, foxes have been recognized as hosts for a number of tick-borne pathogens. However, their role as reservoirs for zoonotic tick-borne diseases is poorly understood. The aim of our study was to investigate tick-borne pathogens in the red fox population in the Czech Republic. Out of 117 red foxes, 110 (94.02%) individuals tested positive for the presence of at least one pathogen by the combined PCR and sequencing approach. Hepatozoon canis was the most frequently detected pathogen (n = 95; 81.2%), followed by Babesia vulpes (n = 75; 64.1%). Babesia canis was not detected in our study. Four (3.42%) red foxes were positive for Candidatus Neoehrlichia sp., 3 (2.56%) for Anaplasma phagocytophilum, and one red fox (0.85%) tested positive for the presence of Ehrlichia sp. DNA. Overall, DNA of spirochetes from the Borrelia burgdorferi s.l. complex was detected in 8.6% of the foxes and B. miyamotoi in 5.12% of the samples. As a carnivore found in all ecosystems of Central Europe, foxes obviously contribute to transmission of tick-borne pathogens such as A. phagocytophilum, B. burgdorferi s.l., and B. myiamotoi. In addition, foxes apparently harbour a community of pathogens, associated with this host in local ecological context, dominated by H. canis and B. vulpes (possibly also Candidatus Neoehrlichia sp.). These species have the potential to spread to the domestic dog population and should be included in the differential diagnosis of febrile diseases with hematologic abnormalities in dogs.