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.     

Novel PCR exclusion assay to detect spotted fever group rickettsiae in the lone star tick (Amblyomma americanum)

The lone star tick (Amblyomma americanum) is the most common and abundant human-biting tick in the southeastern United States where spotted fever rickettsioses frequently occur. However, the role of this tick in transmitting and maintaining pathogenic and non-pathogenic spotted fever group rickettsiae (SFGR) remains poorly defined. This is partially due to the high prevalence and abundance of Rickettsia amblyommatis in most populations of A. americanum. Many molecular assays commonly employed to detect rickettsiae use PCR primers that target highly conserved regions in the SFGR so low abundance rickettsia may not be detected when R. amblyommatis is present. It is costly and inefficient to test for low abundance rickettsial agents with multiple individual specific assays even when they are multiplexed, as most samples will be negative. Real time PCR assays may also be hampered by inadequate limits of detection (LODs) for low abundance agents. We exploited the absence of an otherwise relatively SFGR-conserved genome region in R. amblyommatis to design a hemi-nested PCR-assay which has a sensitivity of 10 copies in detecting the presence of most SFGR, but not R. amblyommatis in DNA of infected lone star ticks. This deletion is conserved in 21 isolates of R. amblyommatis obtained from multiple states. We demonstrated the assay’s utility by detecting a pathogenic SFGR, Rickettsia parkeri, in 15/50 (30 %) of field collected A. americanum ticks that were previously screened with conventional assays and found to be positive for R. amblyommatis. These co-infected ticks included 1 questing female, 6 questing nymphs, and 8 attached males. The high prevalence of R. parkeri among host-attached ticks may be due to several variables and does not necessarily reflect the risk of disease transmission from attached ticks to vertebrate hosts. This novel assay can provide accurate estimates of the prevalence of less common SFGR in A. americanum and thus improve our understanding of the role of this tick in the maintenance and transmission of the SFGR commonly responsible for human rickettsioses.     

Rickettsia parkeri in Amblyomma maculatum ticks, North Carolina, USA, 2009-2010

We detected Rickettsia parkeri in 20%-33% of Amblyomma maculatum ticks sampled in North Carolina. Results highlight the high frequencies of R. parkeri-infected ticks in the state with the highest annual incidence of Rocky Mountain spotted fever. Epidemiologic studies are needed to definitively link R. parkeri to cases of spotted fever rickettsiosis.     

Rickettsia parkeri infection in domestic dogs, Southern Louisiana, USA, 2011

The association between companion animals and tick-borne rickettsial disease has long been recognized and can be essential to the emergence of rickettsioses. We tested whole blood from dogs in temporary shelters by using PCR for rickettsial infections. Of 93 dogs, 12 (13%) were positive for Rickettsia parkeri, an emerging tick-borne rickettsiosis.     

Rickettsial Infections Causing Acute Febrile Illness in Urban Slums,Brazil

We conducted enhanced acute febrile illness surveillance in an urban slum community in Salvador, Brazil. We found that rickettsial infection accounted for 3.5% of urgent care visits for acute fever. Our results suggest that rickettsiae might be an underrecognized, treatable cause of acute febrile illness in impoverished urban populations in Brazil.     

Acute spotted fever rickettsiosis among febrile patients, Cameroon

Although potential arthropod vectors are abundant in Cameroon, acute febrile illnesses are rarely evaluated for arboviral or rickettsial infections. Serum samples from 234 acutely febrile patients at clinics in Tiko and Buea, Cameroon, were examined for antibodies to Rickettsia africae and African alphaviruses and flaviviruses. These serum samples did not contain antibodies against typhoid, and blood malarial parasites were not detected. Serum samples of 32% contained immunoglobulin M antibodies reactive with R. africae by immunofluorescence assay and were reactive with outer membrane proteins A and B of R. africae by immunoblotting. These findings established a diagnosis of acute rickettsiosis, most likely African tick-bite fever. Hemagglutination inhibition testing of the serum samples also detected antibodies to Chikungunya virus (47%) and flaviviruses (47%). High prevalence of antibodies to arboviruses may represent a major, previously unrecognized public health problem in an area where endemic malaria and typhoid fever have been the principal diagnostic considerations.     

河北省西部山区蜱传斑点热群立克次体分子流行病学研究

目的 调查河北省西部山区蜱类斑点热群立克次体带菌情况,为蜱传斑点热群防控提供科学依据.方法 根据已发表斑点热群立克次体OmpA外膜蛋白基因序列设计特异性引物,对河北省西部山区采集的长角血蜱进行PCR检测,并对阳性样本进行测序和序列分析,建立分子系统进化树.结果 在1227份蜱DNA样本中检测出91份阳性,阳性率为7.42％;序列分析结果显示河北省西部山区长角血蜱携带立克次体与河北株暂定种(登录号:HQ651815、HQ651817、HQ651818、HQ651819、HQ651823、HQ651824)、福建株FUJ(登录号:AF169629)同处于一个分支,与河北株立克次体暂定种同源性最高(99.02％),其次是福建株(98.50％)、黑龙江立克次体绥芬株HLJ-054(登录号:AF179362)和黑龙江立克次体虎林株HL-93(登录号:AF179364)(98.13％)、日本株YM(登录号:U43795)(97.92％).结论 河北省西部山区蜱传斑点热群立克次体感染较为严重,应尽快制定防制措施,以免危及动物及人类健康.     

Isolation of Rickettsia rickettsii in Rocky Mountain Spotted Fever Outbreak,Panama

We report new cases of Rocky Mountain spotted fever in patients from Kinkantu, Ngäbe-Bugle indigenous comarca, Panama. We isolated Rickettsia rickettsii in cell culture after intraperitoneal inoculation of guinea pigs with tissues from a deceased patient. Our results indicate that Rocky Mountain spotted fever is emerging in this region.     

内蒙通辽市斑点热群立克次体W—88株的分离与鉴定

1988年我们自通辽市一例发热、头痛、临床诊断为"上感"、用青霉素、病毒灵治疗无效的病人,分离出一株斑点热群立克次体W-88株。经动物感染试验、鸡胚卵黄嚢培养和传代,达到立克次体纯培养,用泛影葡胺密度株度离心纯化,制出立克次饵抗原,用我室建立的抗西伯利亚立克次体群和种特异性单克隆抗体进行免疫荧光检测,与斑点热群立克次体7株国际标准株同从中国分离株对比鉴定。结果确定W-88株为西伯利亚立克次体,该例病人所患的疾病属北亚蜱传斑点热,此为我国在城市发现的北亚热病例首次报道。     

我国斑点热立克次体新种检测及其rOmpA基因序列分析

采用斑点热群立克次体特异引物扩增福建南部来源蜱标本和动物标本中的DNA,以发现我国可能存在的新种斑点热群立克次体.以立氏立克次体rOmpA基因序列中的相关序列为引物,扩增标本中rOmpA基因部分片段,用pGEM-T载体及其宿主菌进行阳性克隆筛选,阳性克隆经鉴定之后提取质粒DNA,进行序列测定.测定序列用Blast软件进行序列同源性比较并采集相关序列,用Bootstrip方法随机取样100次,用PHYLIP软件包进行聚类分析.共检测采自福建宁化地区的越原血蜱100只和野鼠类血标本38份.其中从越原血蜱(不同来源)扩增出斑点热立克次体基因片段,阳性率为15.04%(17/113);并从社鼠、黄胸鼠、褐家鼠扩增出阳性片段,以鼠类为单位计算其阳性率为44.73%.对寄生于野鼠的越原血蜱扩增的阳性片段序列分析表明新测序列与其它斑点热群立克次体的同一基因片段不同,其与日本立克次体同源性最高,核苷酸序列同源性为94%,推定的氨基酸序列同源性为89%.从病原学角度首次证实我国福建省存在日本立克次体近缘种立克次体,这对斑点热群立克次体的深入研究有重要意义.     

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.     

Rickettsia felis in Xenopsylla cheopis, Java, Indonesia

Rickettsia typhi and R. felis, etiologic agents of murine typhus and fleaborne spotted fever, respectively, were detected in Oriental rat fleas (Xenopsylla cheopis) collected from rodents and shrews in Java, Indonesia. We describe the first evidence of R. felis in Indonesia and naturally occurring R. felis in Oriental rat fleas.