First isolation ofRickettsia helvetica fromIxodes ricinus ticks in France

Two rickettsial isolates recovered fromIxodes ricinus ticks in Puy-de-Dôme (Central France) were characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Western blot immunoassay, restriction fragment length polymorphism analysis, and sequencing of a portion of the citrate-synthase gene. By these methods, the isolates appeared to be identical to a member of the spotted fever group rickettsiae,Rickettsia helvetica. This first isolation ofRickettsia helvetica in France has epidemiologic importance; a serosurvey on Mediterranean spotted fever conducted previously in Puy-de-Dôme, where the infection is not endemic, demonstrated a high seroprevalence of nonspecific antibodies directed against spotted fever group rickettsiae lipopolysaccharides, and thus the possibility of infection due to a rickettsia different fromRickettsia conorii was suggested. The isolation ofRickettsia helvetica in anthropophilic ticks in the same area further supports this hypothesis.     

五例恙虫病东方体感染基因型及其基因变异

目的旨在了解浙闽地区人群恙虫病东方体感染的基因型,并分析其基因变异。 方法从浙闽地区5例散发恙虫病发热期患者血中分离病原体并进行细胞培养;提取感染细胞DNA,巢式PCR扩增完整恙虫病东方体56-kD型特异性抗原（TSA）基因和热休克蛋白基因（groESL）并测序;采用MEGA 7.0软件,进行序列比对和系统发育分析。 结果病原学确认5例恙虫病患者,并分离到恙虫病东方体菌株。序列比对表明,5菌株中有2株的56-kD TSA基因和groESL基因100%一致,另2菌株的此二个基因序列一致性亦为100%,分别将两组菌暂时命名为浙江-1型和浙江-2型。56-kDa TSA基因比对和系统发育分析表明,浙江-1型和浙江-2型分别与台湾-A基因型和Gilliam-C基因型亲缘较近（98.45%和98.50%）,但有明显变异;另1株菌Wuj/2014与台湾-A基因型高度相似（99.94%）。56-kDa TSA基因各基因型支系的时间树分析表明,台湾-A基因型、浙江-1型和浙江-2型3支系与祖先的分歧时间相对其他原型株晚,尤其是浙江-2型,说明这些基因型或亚型在恙虫病东方体的进化过程中出现较晚。 结论本研究病例所感染恙虫病东方体基因型不同,可能为未被认识的新的基因亚型,迫切需要进行全基因组测序确认,并探讨其基因变异与人恙虫病严重程度间的关系。     

Boutonneuse fever in Portugal: 1995-2000. Data of a state laboratory

From 1995 through 2000, 3239 clinical samples were tested for rickettsiosis at the Center for Vectors and Infectious Diseases Research – National Health Institute in Portugal. Boutonneuse fever due to R. conorii Malish or R. conorii Israel was laboratory confirmed in 374 samples (11.5%). Clinical and epidemiological features are discussed.     

Murine typhus in Tunisia: A neglected cause of fever as a single symptom

Objectives

We had for aim to describe the epidemiologic and clinic characteristics of murine typhus in a series of 43 serologically confirmed cases, in our region.

Patients and methods

Serologic screening for IgG and IgM against Rickettsia typhi was performed in 1024 patients during three years (2006–2008). The characteristics of patients with a positive serology were examined retrospectively. One hundred and seventy sera obtained from blood donors were tested to detect IgG against R. typhi to determine the seroprevalence of the infection.

Results

There was evidence of recent R. typhi infection in 43 patients (4.2%) during the study period, and 3.7% of blood donors had IgG against R. typhi. The mean age of patients was 43.1 years and the sex-ratio was 1.04. Among the patients, 58.1% were from rural areas. No patient reported any exposure to rats or rat-fleas. There were more cases during the summer and fall. The most frequent complaint was fever as a single symptom (67.5%). A cutaneous rash was reported in 44.1% and headache in 60.5% of patients. Among the patients, 44.1% presented with thrombopenia and 47.2% with elevated liver enzymes.

Conclusion

Murine typhus seems to be frequent in Tunisia. This infection could be a threat for travellers. Serology should be performed systematically in patients with fever as a single symptom since its clinical presentation is non-specific.     

Antigens of Rickettsia conorii recognized by seropositive healthy people from Salamanca (Central-West Spain)

The antigenic reactivity in Western immunoblotting assay of individual Rickettsia conorii components with sera of healthy people living in Salamanca Province, an endemic zone of Mediterranean spotted fever, is evaluated. Polypeptides of molecular weights 100 kDa (92.7%), 135 kDa (75.6%), 160 kDa (70.7%) and 115 kDa (48.8%) were recognized by a higher proportion of sera with indirect immunofluorescent antibody test titers 1:80. Reaction with apparent rickettsial lipopolysaccharide was found in 15 (36.6%) of these samples. The involvement of different rickettsial strains, atypical routes of inoculation, varying content of the inoculum, and host factors may be determinants of the clinical expression of the spotted fever group rickettsial infection in people who produce antibodies reactive with Rickettsia conorii antigens.     

Prevalence of antibodies to Rickettsia conorii Coxiella burnetii and Rickettsia typhi in Salamanca province (Spain). Serosurvey in the human population

The Salamanca Province of Spain is an endemic zone for Mediterranean spotted fever. In this area, only one case of Q fever has been reported and typhus group rickettsial diseases have never been diagnosed. To obtain a panoramic view of the presence of antibodies to the most ubiquitous rickettsial agents, 400 sera specimens from a statistically representative sample of the human population of Salamanca City and its surrounding province were subjected to indirect microimmunofluorescent test for antibodies against Rickettsia conorii, Coxiella burnetii, phase II, and Rickettsia typhi antigens. Titers 1:40 to R. conorii were found in 73.5% of the sera. Positivity was more common in subjects who reported closer contact with the natural environment and/or with domestic animals. Seropositivity to C. burnetii, phase II, was detected in 50.2% of sera. These positive cases were related to rural environmental factors and to prevoius contact with animals. The frequency of antibodies increased with age showing a progressive exposure to the rickettsial antigen. The prevalence of antibodies to R. conorii and C. burnetii in the human population of Salamanca Province is higher than that reported from any other geographic zone. The study of antibodies to R. typhi showed that 12.5% of the sera had titers 1:40. According to our results, seropositivity to this rickettsial antigen cannot be related to any particular group of population nor interpreted totally as cross reactivity with R. conorii. Our data show a wide distribution of R. conorii and C. burnetii antigens in Salamanca Province, and also indicate the presence of R. typhi antigens in this area.     

Diagnosis of rickettsial diseases: A perspective

Rickettsioses have nonspecific clinical manifestations, making them difficult to diagnose in a clinical setting. Laboratory testing is usually needed to confirm the diagnosis.Rickettsial isolation is a sensitive and specific diagnostic technique, but the hazards associated with handling pathogenic rickettsiae usually preclude isolation attempts in most laboratories. Rickettsiae can also be detected in infected tissues by fluorescein-labeled antisera or by immunoperoxidase staining, but these techniques lack sensitivity, except when applied to postmortem tissue specimens. However, rickettsial DNA can be detected in acute phase blood specimens by polymerase chain reaction (PCR) technology, and this technique offers the prospect of prompt diagnosis and treatment.Serologic testing remains the most frequently used approach to diagnosis, although antibody tests usually fail to identify rickettsioses early enough to affect the management of individual patients. Available serologic techniques vary considerably in their sensitivity and specificity. Enzyme-linked immunosorbent assays (ELISA) are extremely sensitive, but the general unavailability of specific diagnostic antigens reduces the specificity of this and other serologic techniques. Molecular characterization of rickettsial antigens may soon allow the production of peptide antigens that are specific for each species and could maximize the specificity of test results.No diagnostic technique has any value unless it is applied successfully to the appropriate patient population. Improved surveillance of rickettsial diseases is urgently needed to identify specific areas in which rickettsioses are endemic. Such surveillance data would promote awareness of rickettsioses among local physicians and increase the probability that individual patients with rickettsioses would be identified promptly and receive appropriate therapy early in the course of their illness.Presented at the 4th International Symposium on Rickettsiae and Rickettsial Diseases, Pietany, C.S.F.R., 1–6 October, 1990.     

African tick bite fever – Papulovesicular exanthem with fever after staying in South Africa

In the wake of expanding international tourism, rickettsioses are increasingly observed also in central Europe. African tick bite fever is a recently described, acute febrile illness with characteristic skin lesions.It is caused by Rickettsia africae, which is transmitted to humans by ticks of the Amblyomma genus. A 60‐year‐old woman presented with a papulovesic‐ular exanthem, fever, and headache after returning from South Africa. A purple nodule with central necrosis (“tache noire”or “inoculation eschar”) was noticed on the lower leg. Antibodies against rickettsia of the spotted fever group were detected serologically. Oral doxycycline led to clearance of the disease after few days of treatment.     

Boutonneuse fever transmitted by conjunctival inoculation

Summary We report three cases (two adult males and a 12-year-old child) of boutonneuse fever produced by inoculation of the conjunctival mucosa (probably through accidental entry ofR. conorii fluid into the eyes through rubbing or splashing). All three patients developed similar symptoms of disease, including high fever, headache, maculopapular exanthem, and conjunctivitis, and none had tache noire. Specific immunofluorescent antibodies appeared in these patients' serum mostly after the 2nd week; agglutinins to Proteus OX-19, OX-2 (Weil-Felix reaction) were found. Cure was obtained by oral tetracycline. Conjunctival inoculation ofR. conorii producing boutonneuse fever is very rare; this report will probably be one of the first published in the medical literature.