唐山地区蜱传斑点热群立克次体分子流行病学

根据已发表的长角血蜱16SrRNA序列及斑点热群立克次体外膜蛋白A（OmpA）基因序列设计2对特异性引物,对唐山地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,抽检样本建立分子系统进化树。结果表明,在315份蜱DNA样本中检测出25份阳性样本,阳性率为7.94%;序列分析结果显示唐山地区长角血蜱携带立克次体同处于一个分支,与日本株立克次体同源性最高（93.30%）,其次是福建株立克次体（92.11%）,黑龙江立克次体绥芬株（90.45%）、虎林株（90.42%）。结论得出唐山地区蜱传斑点热感染较严重,分子进化分析结果显示唐山地区蜱传斑点热群立克次体可能为一新种。     

Infection by spotted fever rickettsiae in people, dogs, horses and ticks in Londrina, Parana State, Brazil

Spotted fever is a disease caused by bacteria from the genus Rickettsia of the spotted fever group (SFG). Rickettsia rickettsii is likely the main agent of Brazilian spotted fever (BSF). With the objective of gathering information on the circulation of SFG rickettsiae in Londrina, Parana state, ticks from dogs and horses and also blood from dogs, horses and humans were collected in a neighbourhood of the city which presented potential for circulation of rickettsiae between hosts and vectors. Amblyomma cajennense, Dermacentor nitens, and Rhipicephalus sanguineus ticks were subjected to Polymerase Chain Reaction targeting a fragment of the Rickettsia gltA gene. This specific gene encodes the enzyme citrate synthase of Rickettsia spp., and results on all ticks were negative. Human and animal sera were tested by Indirect Immunofluorescence Assay in which R. rickettsii and R. parkeri were used as antigens. Sera from 4.7% human, 2.7% canine and 38.5% equine were positive for R. rickettsii. For R. parkeri, 0.9% human, 2.7% canine and 11.5% equine samples were positive. All samples reactive to R. parkeri also reacted to R. rickettsii. An epidemiological questionnaire was applied, but there were no statistically significant results. Comparison of our serological results with previous studies in Brazil, among BSF endemic and non-endemic areas, indicates that there is no established rickettsial infection in the study area, a statement corroborated with our molecular analysis. Nonetheless, as humans of the present study are highly exposed to tick infestations, health education within the population is needed to obtain efficient tick control.     

Molecular detection of rickettsial agents in ticks and fleas collected from a European hedgehog (Erinaceus europaeus) in Marseilles, France

The European hedgehog (Erinaceus europaeus) is a synanthropic nocturnal insectivore commonly found in the countryside and in the parks and gardens. Because hedgehogs are already involved in the transmission of a number of zoonoses, including salmonellosis and ringworm, we decided to study their possible role in the epidemiology of the spotted fever group of Rickettsia. We collected ticks and fleas from a hedgehog that was captured in the city of Marseilles in France. Using a genus-specific quantitative PCR (qPCR) analysis followed by a species-specific qPCR analysis for positive samples, we observed that 91.7% (11/12) of the Rhipicephalus sanguineus ticks were positive for Rickettsia massiliae and 99.2% (128/129) of the Archaeopsylla erinacei fleas were positive for Rickettsia felis. Hedgehogs carry infected ectoparasites and then likely ensure the dissemination of spotted fever group Rickettsiae, and their epidemiological role requires further investigation.     

Rickettsiae in arthropods collected from the North African Hedgehog (Atelerix algirus) and the desert hedgehog (Paraechinus aethiopicus) in Algeria

Hedgehogs have become a popular pet despite their potential role in zoonotic disease transmission. We conducted an entomological study in a mountainous region of northeast Algeria in which we collected 387 fleas (Archeopsylla erinacei) and 342 ticks (Rhipicephalus sanguineus and Haemaphysalis erinacei) from Paraechinus aethiopicus and Atelerix algirus hedgehogs. Of the hedgehogs sampled, 77.7% and 91% were infested with fleas and ticks, respectively. Significantly more ticks and fleas were collected from A. algirus than from P. aethiopicus. Rickettsia felis was detected in 95.5% of fleas and R. massiliae was detected in 6.25% of Rh. sanguineus ticks by molecular tools. A new Rickettsia species of the spotted fever group was detected in 11.25% of Rh. sanguineus and in 77% of H. erinacei ticks. Overall, we show that hedgehogs can act as hosts for ectoparasites infected with several rickettsial agents. These data justify a more detailed investigation of animal reservoirs for Rickettsiae.     

Survey of ixodid tick species on domestic cats in Japan

Various species of ixodid ticks, attached to domestic cats in Japan, were identified in spring (April to June) and autumn (September to November). In the spring, a total of 282 ticks, including 61 larvae, 70 nymphs, 127 females and 24 males were collected from 126 cats. Of these, 264 were identified up to the species level. In the spring, Haemaphysalis longicornis was the most frequently (39.7%, 50/126) found tick species on feline hosts, followed by Ixodes ovatus (35.0%, 44/126), Ixodes nipponensis (15.9%, 20/126) and Haemaphysalis flava (9.5%, 12/126). Small numbers of Haemaphysalis megaspinosa, Haemaphysalis japonica, Ixodes persulcatus, Ixodes granulatus and Amblyomma testudinarium were also recovered. H. longicornis was the most frequently found tick species on cats around riversides or river basins, while I. ovatus and I. nipponensis were more frequently found on cats kept near woodland or related areas. I. nipponensis was more frequently found on castrated males. No major statistical differences in the frequency of tick attachment among sex, age or hair length for the three major tick species were found. Of 205 ticks including 173 (84.4%) larvae, 27 (13.2%) nymphs, 4 (2.0%) females and 1 (0.5%) male recovered from 62 cats in autumn, only 32 (15.6%) were identified. Most of the larvae were fully- or partly-engorged Haemaphysalis spp., and it was difficult to identify them further by morphological characterization.     

Rocky Mountain spotted fever in an urban canine population

A survey for the prevalence of Rocky Mountain spotted fever antibodies in dogs from a well-defined endemic area in Columbus, Ohio (Franklin County), was conducted during the summer of 1981. Seventy-three blood samples from dogs in this area were tested by microimmunofluorescence for antibodies to Rickettsia rickettsii and other rickettsial antigens. Thirty-three (45.2%) of these samples were positive for R rickettsii, with titers ranging from 1:8 to 1:2,048. For comparison, 137 blood samples from dogs at the Franklin County Dog Pound also were tested. One dog (0.7%) from the comparison group was seropositive to R rickettsii, with a 1:64 titer. The results indicated a nidus of this disease within the city of Columbus, Ohio.     

Detection of rickettsial DNA in ixodid ticks recovered from dogs and cats in Japan

DNA from ticks recovered from 1137 dogs and 133 cats from all over Japan were examined for Rickettsia infection by citrate synthase gene (gltA)-based PCR and partial nucleotide sequencing. A total of 91 dog tick samples and 18 cat tick samples showed a single band of the appropriate size in the nested PCR. Sequence analysis was successfully performed on 102 samples. DNA of Rickettsia japonica or closely related Rickettsia spp. strains were detected from 38 ticks in 16 prefectures mainly in western Japan. The other 33, detected from 13 prefectures including Hokkaido and Okinawa, were found to be Rickettsia helvetica or closely related strains. A total of 29 DNA that showed highest homology with Rickettsia akari or closely related strains were detected in 19 prefectures, widespread throughout Japan. Rickettsia canada-like DNA was detected from Haemaphysalis sp. removed from a dog in Fukuoka, and ;Candidatus Rickettsia tarasevichiae'-like DNA was from Ixodes sp. removed from a dog in Hokkaido.     

Tick infestation of sika deer (Cervus nippon) in the western part of Yamaguchi Prefecture,Japan

Ticks were collected from 94 sika deer (Cervus nippon) hunted in the western part of Yamaguchi Prefecture, Japan from August to November 1999, and March to July 2000. Haemaphysalis longicornis and H. yeni were the dominant species from April to August, while H. flava and H. megaspinosa were dominant in October, November and March. This is the first report of H. yeni in the mainland of Japan. Small numbers of H. kitaokai, Amblyomma testudinarium and Ixodes ovatus were also recorded.     

Detection of DNA closely related to 'Candidatus Rickettsia principis' in Haemaphysalis danieli recovered from cattle in Xinjiang Uygur Autonomous Region Area, China

Tick DNA samples from cattle in Xinjiang Uygur Autonomous Region Area, China, were examined for Rickettsia infection by citrate synthase gene-based PCR and sequencing. Four positive samples were detected from Haemaphysalis danieli and high levels of similarity were found with recently detected 'Candidatus Rickettsia principis.'     

High prevalence of “Candidatus Rickettsia amblyommii” in Amblyomma ticks from a Spotted Fever Endemic Region in North Argentina

Ticks from an endemic Spotted Fever region in Argentina were analysed by PCR for Spotted Fever Group Rickettsiae. DNA of “Candidatus Rickettsia amblyommii” was found in 21.3% of Amblyomma hadanii and in 44.0% of A. neumanni. Amblyomma sculptum (formerly A. cajennense) and Haemaphysalis juxtakochi were negative for rickettsial DNA. DNA of Rickettsia rickettsii, the etiological agent of the clinical cases reported within the studied region was not detected in the analysed sample.     

Implications of presumptive fatal Rocky Mountain spotted fever in two dogs and their owner

A dog was examined because of petechiation, an inability to stand, pale mucous membranes, a possible seizure, and thrombocytopenia. Tick-borne illness was suspected, but despite treatment, the dog died. Eight days later, a second dog owned by the same individual also died. The dog was not examined by a veterinarian, but Rocky Mountain spotted fever (RMSF) was suspected on the basis of clinical signs. Two weeks after the second dog died, the owner was examined because of severe headache, fever, nausea, vomiting, decreased appetite, lethargy, and a fine rash on the body, face, and trunk. Despite intensive treatment for possible RMSF, the owner died. Although results of an assay for antibodies to Rickettsia rickettsii were negative, results of polymerase chain reaction assays of liver, spleen, and kidney samples collected at autopsy were positive for spotted fever group Rickettsia spp. These cases illustrate how dogs may serve as sentinels for RMSF in humans and point out the need for better communication between physicians and veterinarians when cases of potentially zoonotic diseases are seen.     

Serologic and molecular characterization of tickborne pathogens in lions (Panthera leo) from the Fasano Safari Park, Italy.

Lions (Panthera leo) are an endangered species threatened by illegal hunting, habitat loss, and infectious diseases. Little is known about the tick-borne pathogens that infect lions and could contribute to population declines. The objective of this study was to characterize Rickettsia spp., Anaplasma phagocytophilum, and Coxiella burnetii infections in 10 lions from the Fasano Safari Park in Italy by serology, polymerase chain reaction, and sequence analysis. Although animals did not show clinical signs of tick-borne diseases, evidence of infection with C. burnetii, spotted fever group Rickettsia sp., and A. phagocytophilum were found in 50%, 20%, and 10% of the lions, respectively. One of the lions tested positive for all three pathogens. This study is the first report of molecular evidence of infection with C. burnetii, Rickettsia sp., and A. phagocytophilum in lions and provides evidence that these felids become infected and serve as hosts for tick-transmitted bacteria.     

长角血蜱孤雌生殖与两性生殖种群的CO I基因序列的特征性差异

长角血蜱是我国常见的一种硬蜱,在自然界存在孤雌生殖和两性生殖的种群。本研究通过对分离的长角血蜱孤雌生殖上海株、安徽株和山东株的线粒体细胞氧化酶I（COI）基因部分序列进行了测定,并与国内其他单位所测定的两性或孤雌生殖的多株长角血蜱COI基因序列进行了比对分析。结果发现,长角血蜱孤雌生殖种群与两性生殖种群的COI基因序列存在特征性差异;COI基因序列可应用于长角血蜱的孤雌生殖种群和两性生殖种群的快速鉴定。     

Risk factors for bacterial zoonotic pathogens in acutely febrile patients in Mpumalanga Province,South Africa

Endemic zoonoses, such as Q fever and spotted fever group (SFG) rickettsiosis, are prevalent in South Africa, yet often undiagnosed. In this study, we reviewed the demographics and animal exposure history of patients presenting with acute febrile illness to community health clinics in Mpumalanga Province to identify trends and risk factors associated with exposure to Coxiella burnetii, the causative agent of Q fever, and infection by SFG Rickettsia spp. Clinical and serological data and questionnaires elucidating exposure to animals and their products were obtained from 141 acutely febrile patients between 2012 and 2016. Exposure or infection status to C. burnetii and SFG Rickettsia spp. was determined by presence of IgG or IgM antibodies. Logistic regression models were built for risk factor analysis. Clinical presentation of patients infected by SFG rickettsiosis was described. There were 37/139 (27%) patients with a positive C. burnetii serology, indicative of Q fever exposure. Patients who had reported attending cattle inspection facilities (“dip tanks”) were 9.39 times more likely to be exposed to Q fever (95% CI: 2.9–30.4). Exposure risk also increased with age (OR: 1.03, 95% CI: 1.002–1.06). Twenty‐one per cent of febrile patients (24/118) had evidence of acute infection by SFG Rickettsia spp. Similarly, attending cattle inspection facilities was the most significant risk factor (OR: 8.48, 95% CI: 1.58–45.60). Seropositivity of females showed a significant OR of 8.0 when compared to males (95% CI: 1.49–43.0), and consumption of livestock was associated with a decreased risk (OR: 0.02, 95% CI: 0.001–0.54). A trend between domestic cat contact and SFG rickettsiosis was also noted, albeit borderline non‐significant. In this endemic region of South Africa, an understanding of risk factors for zoonotic pathogens, including exposure to domestic animals, can help clinic staff with diagnosis and appropriate therapeutic management of acutely febrile patients as well as identify target areas for education and prevention strategies.     

Rickettsial infection in domestic mammals and their ectoparasites in El Valle de Antón, Coclé, Panamá

The present research evaluated the presence of Rickettsia spp. on ectoparasites of horses and dogs (using PCR techniques), and their sera (using immunofluorescence assay) in El Valle de Antón town in Panama. A total of 20 horses and 20 dogs were sampled, finding four species of ectoparasites on dogs (the ticks Rhipicephalus sanguineus, Amblyomma ovale, Amblyomma oblongoguttatum, and the flea Ctenocephalides felis), and two tick species on horses (Amblyomma cajennense and Dermacentor nitens). DNA of Rickettsia amblyommii was found in pools of A. cajennense, D. nitens, and R. sanguineus, while Rickettsia felis was detected in C. felis pools. Overall, 70% (14/20) and 65% (13/20) of the horses and dogs, respectively, were seroreactive (titer ≥ 64) to spotted fever group rickettsiae. Sera from six dogs and five horses reacted to R. amblyommii antigens with titers at least four-fold higher than those for the other antigens tested (Rickettsia bellii, Rickettsia parkeri, Rickettsia rhipicephali, R. felis, and R. rickettsii). These serological results, coupled with our molecular findings, suggest that these dogs and horses were infected by Rickettsia amblyommii. More studies need to be realized afford to identify the Rickettsia species responsible for other serological and molecular positive results, and their ecological importance.     

Detection of a spotted fever group Rickettsia in the tick Haemaphysalis juxtakochi in Rondonia, Brazil

The tick genus Haemaphysalis is represented by four species in the New World, of which only the species Haemaphysalis leporispalustris has been associated with Rickettsiae. The present study reports for the first time the presence of a Rickettsia strain in the tick Haemaphysalis juxtakochi. A free-living male of H. juxtakochi, collected in the state of Rondonia, Western Amazon, Brazil, was subjected to DNA extraction and tested by PCR targeting the four rickettsial genes: gltA, 17-kDa, ompA and ompB. The nucleotide sequences obtained from the PCR products were, by BLAST analyses, closest to Rickettsia rhipicephali sharing 99.7% (1147/1150), 98.8% (429/434), 99.0% (486/491) and 99.0% (809/817) identities with the partial sequences of the gltA, 17-kDa, ompA and ompB genes, respectively. Phylogenetic analyses inferred from the four rickettsial genes showed a high-degree of similarity of this H. juxtakochi-Rickettsia with R. rhipicephali. These two agents grouped together in all trees, always with high bootstrap support (75-96%). This study gives molecular evidence for the presence of a Rickettsia species, designated as strain R300, in the tick H. juxtakochi from the Western Amazon area of Brazil. Genetic analyses showed R300 to be closely related to R. rhipicephali.     

Rocky Mountain spotted fever

Rocky Mountain spotted fever is an endemic tickborne disease found throughout the United States and other regions of the world. Exposure may result in a spectrum of disease from subclinical infection to severe or fatal multiorgan collapse. The disease is maintained in nature in Ixodid tick vectors and their hosts. The most important ticks in the United States are Dermacentor variabilis and Dermacentor andersoni. Small mammals are the natural reservoirs in the wild. Dogs become infected when a tick harboring Rickettsia rickettsii feeds on the dog. Dogs do not develop sufficient rickettsemia to act as a reservoir in the transmission of Rickettsia rickettsii. Thus, although dogs act as sentinels to the presence of the disease, they cannot directly transmit infection. Signs in early stages of disease often are nonspecific. The most characteristic laboratory abnormality is thrombocytopenia, but serologic testing is necessary for confirmation of infection. Tetracycline and chloramphenicol are effective antibiotics to treat infection. Treatment should continue for 14 to 21 days to allow host immune defenses to develop and eradicate the organism. Prevention requires avoidance of tick-infested areas and rapid removal of ticks should exposure occur.     

家兔抗长角血蜱免疫模型的建立及对长角血蜱成蜱生长发育的影响

每隔2周用长角血蜱成蜱定量感染家兔,成功构建了具有不同抵抗力的家兔免疫模型。ELISA检测结果表明,家兔血清中的抗体效价从初次叮咬后第3周开始呈阳性,随着叮咬次数的增加抗体水平逐渐上升,第11周时达到高峰。具有一定抵抗力的家兔对长角血蜱成蜱的吸血和生长发育影响显著,其抗体水平与长角血蜱成蜱在兔体的吸血周期、死亡率成正相关,与雌蜱的饱血脱落率、饱血体重成负相关。结果进一步证明,蜱的唾液腺是其主要的免疫器官之一。家兔抗体水平的持续期足以使长角血蜱完成一个世代,可以满足试验需求,是抗蜱免疫研究理想的阳性对照模型。同时,血清中特异性抗体的效价也可以作为判断动物对长角血蜱抵抗力强弱的重要指标之一。     

Tick infestation and spotted-fever group Rickettsia in shelter dogs, California, 2009

In response to an outbreak of Rocky Mountain spotted fever (RMSF) in Baja California in early 2009, dogs at two shelters in neighbouring Imperial County, California, were evaluated for ectoparasites. Brown dog ticks (Rhipicephalus sanguineus), a recognized vector for RMSF, were found on 35 (30%) of 116 dogs but all ticks tested negative for Rickettsia rickettsii by PCR.     

双芽巴贝斯虫在长角血蜱肠内发育的形态学研究

以耳袋法将长角血蜱(Haemaphysalis longicornis)幼虫饲于实验感染双芽巴贝斯虫(Babesia bigemina)牛,幼虫饱血后24h内,其肠管内容物中红细胞内、外见有单梨子型(3.5～4.5μm×1.2～2.6μm)和双梨子型(4.1～4.8μm×1.8～3.0μm)两种裂殖体.饱血后24～48h,随着裂殖体细胞膜及核变性而发生形态变化.48～72h,绝大多数裂殖体出现溶解.72h后,这些裂殖体从肠道消失.其后,在蜱肠上皮及血淋巴中也未能找到双芽巴贝斯虫体.本实验从形态学上证明双芽巴贝斯虫在长角血蜱若虫肠道内不能发育.