Mancha negra o «tache noire» en la fiebre botonosa mediterránea / Black spot or «tache noire» in mediterranean spotted fever

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High serum CXCL10 in Rickettsia conorii infection is endothelial cell mediated subsequent to whole blood activation.

BACKGROUND: The pathophysiological hallmark of Rickettsia conorii (R. conorii) infection comprises infection of endothelial cells with perivascular infiltration of T-cells and macrophages. Although interferon (IFN)-γ-induced protein 10 (IP-10)/CXCL10 is induced during vascular inflammation, data on CXCL10 in R. conorii infection is scarce. METHODS: Serum CXCL10 was analyzed in two cohorts of southern European patients with R. conorii infection using multiplex cytokine assays. The mechanism of R. conorii-induced CXCL10 release was examined ex vivo using human whole blood interacting with endothelial cells. RESULTS: (i) At admission, R. conorii infected patients had excessively increased CXCL10 levels, similar in the Italian (n=32, ∼56-fold increase vs controls) and the Spanish cohort (n=38, ∼68-fold increase vs controls), followed by a marked decrease after recovery. The massive CXCL10 increase was selective since it was not accompanied with similar changes in other cytokines. (ii) Heat-inactivated R. conorii induced a marked CXCL10 increase when whole blood and endothelial cells were co-cultured. Even plasma obtained from R. conorii-exposed whole blood induced a marked CXCL10 release from endothelial cells, comparable to the levels found in serum of R. conorii-infected patients. Bacteria alone did not induce CXCL10 production in endothelial cells, macrophages or smooth muscle cells. CONCLUSIONS: We show a massive and selective serum CXCL10 response in R. conorii-infected patients, likely reflecting release from infected endothelial cells characterized by infiltrating T cells and monocytes. The CXCL10 response could contribute to T-cell infiltration within the infected organ, but the pathologic consequences of CXCL10 in clinical R. conorii infection remain to be defined.

Shell-vial culture, coupled with real-time PCR, applied to Rickettsia conorii and Rickettsia massiliae-Bar29 detection, improving the diagnosis of the Mediterranean spotted fever.

Rickettsia conorii and Rickettsia massiliae-Bar29 are related to Mediterranean spotted fever (MSF). They are intracellular microorganisms. The Shell-vial culture assay (SV) improved Rickettsia culture but it still has some limitations: blood usually contains low amount of microorganisms and the samples that contain the highest amount of them are non-sterile. The objectives of this study were to optimize SV culture conditions and monitoring methods and to establish antibiotic concentrations useful for non-sterile samples. 12 SVs were inoculated with each microorganism, incubated at different temperatures and monitored by classical methods and real-time PCR. R. conorii was detected by all methods at all temperatures since 7th day of incubation. R. massiliae-Bar29 was firstly observed at 28°C. Real-time PCR allowed to detected it 2-7 days earlier (depend on temperature) than classical methods. Antibiotics concentration needed for the isolation of these Rickettsia species from non-sterile samples was determined inoculating SV with R. conorii, R. massiliae-Bar29, biopsy or tick, incubating them with different dilutions of antibiotics and monitoring them weekly. To sum up, if a MSF diagnosis is suspected, SV should be incubated at both 28°C and 32°C for 1-3 weeks and monitored by a sensitive real-time PCR. If the sample is non-sterile the panel of antibiotics tested can be added.

Relative sensitivity of conventional and real-time PCR assays for detection of SFG Rickettsia in blood and tissue samples from laboratory animals.

Studies on the natural transmission cycles of zoonotic pathogens and the reservoir competence of vertebrate hosts require methods for reliable diagnosis of infection in wild and laboratory animals. Several PCR-based applications have been developed for detection of infections caused by Spotted Fever group Rickettsia spp. in a variety of animal tissues. These assays are being widely used by researchers, but they differ in their sensitivity and reliability. We compared the sensitivity of five previously published conventional PCR assays and one SYBR green-based real-time PCR assay for the detection of rickettsial DNA in blood and tissue samples from Rickettsia- infected laboratory animals (n = 87). The real-time PCR, which detected rickettsial DNA in 37.9% of samples, was the most sensitive. The next best were the semi-nested ompA assay and rpoB conventional PCR, which detected as positive 18.4% and 14.9% samples respectively. Conventional assays targeting ompB, gltA and hrtA genes have been the least sensitive. Therefore, we recommend the SYBR green-based real-time PCR as a tool for the detection of rickettsial DNA in animal samples due to its higher sensitivity when compared to more traditional assays.

Mediterranean spotted fever in southeastern Romania.

Although cases of Mediterranean spotted fever (MSF) have been reported for decades in southeastern Romania, there are few published data. We retrospectively studied 339 patients, diagnosed with MSF at the National Institute of Infectious Diseases "Prof. Dr. Matei Bals" between 2000 and 2011, in order to raise awareness about MSF in certain regions of Romania. According to the Raoult diagnostic criteria 171 (50.4%) had a score >25 points. Mean age was 52.5 years. One hundred and fifty-five (90.6%) patients were from Bucharest and the surrounding region. Almost all patients presented with fever (99.4%) and rash (98.2%), and 57.9% had evidence of a tick bite. There were no recorded deaths. Serologic diagnosis was made by indirect immunofluorescence assay. Of the 171 patients, serology results for R. conorii were available in 147. One hundred and twenty-three (83.7%) of them had a titer IgG ≥1:160 or a fourfold increase in titer in paired samples. MSF is endemic in southeastern Romania and should be considered in patients with fever and rash even in the absence of recognized tick exposure. Since the disease is prevalent in areas highly frequented by tourists, travel-associated MSF should be suspected in patients with characteristic symptoms returning from the endemic area.

Levels of certain endothelial biomarkers during the acute phase and convalescence in patients with different severity of Mediterranean spotted fever.

INTRODUCTION: Mediterranean spotted fever (MSF) is a tick-borne disease caused by Rickettsia conorii subspp. conorii. It is transmitted by the bite of the tick Rhipicephalus sanguineus. Modified by the rickettsial invasion, the micro-vascular endothelium acquires an activated inflammatory phenotype and initiates secretion of cytokines and expression of cell adhesion molecules (CAMs) and chemoattractans. AIM: This study aims at investigating the alterations in the soluble cellular adhesion molecules (sCAMs) and chemokine MCP-1 levels in patients with MSF of varying severity in the acute and convalescence stage in order to assess their diagnostic and prognostic value. MATERIALS AND METHODS: The soluble forms of cellular adhesion molecules (sCAMs)--sE-selectin and sP-selectin, the intercellular (sICAM-1) and vascular (sVCAM-1) adhesion molecules as well as the monocyte chemoattractant protein-1 (MCP-1) were studied in the sera of 80 patients with MSF. The presence of MSF was confirmed serologically by indirect fluorescence assay (IFA). In order to study disease dynamics, serum samples from 80 patients were drawn on day 1 following the onset of rash; in 60 patients (part of the surveyed 80) a second sample was taken in the convalescence period--14 days post hospital discharge. The investigation was focused on mild, moderate and severe forms of MSF. Enzyme linked immune-sorbent assay was used for sCAMs determination (Quantikine IVD colorimetric RESULTS: Overall, in the acute stage, patients presented with increased levels of sE-selectin, sICAM-1, sVCAM-1 and MCP-1, whereas sP-selectin level was decreased. The levels of sE-selectin, sICAM-1 and sVCAM-1 were significantly elevated in mild, moderate and severe forms of the disease with sE-selectin level exhibiting a plateau tendency and sICAM and sVCAM levels demonstrating an upward trend from mild towards severe MSF forms. MCP-1 level was elevated only in severe MSF. In all forms of MSF, in the convalescence period, sICAM-1, sVCAM-1 and MCP-1 concentration returned to reference levels whereas sE-selectin level persisted elevated. In the convalescence stage, sP- selectin concentration also showed an upward tendency, which in severe forms of MSF slightly exceeded the level in controls. sP-selectin levels correlated directly with platelet count, whereas sICAM-1 and sVCAM-1 levels showed a reverse correlation, sE-selectin, sICAM-1 and MCP-1 levels directly correlated with aminotransferase activity (ALT and/or AST). CONCLUSION: The soluble forms of CAMs reflect the endothelial inflammatory potential. There is evidence that endothelium activation is more potent in severe forms of MSF. Assessment of the endothelial response in the course of the disease is an important predictor of the outcome, the choice of therapeutic approach and disease prognosis.

Dynamics in serum cytokine responses during acute and convalescent stages of Mediterranean spotted fever.

UNLABELLED: Mediterranean spotted fever (MSF) is a re-emerging rickettsiosis in Bulgaria after 20 years of absence (1972-1992), and it has since been affecting many people annually in the endemic regions of the country. The role of cytokines in MSF is still in the focus of research due to their complex participation in the immune pathogenesis of the disease. AIM: To study the changes in the serum cytokine concentrations in MSF patients. PATIENDS AND METHODS: Eighty patients with MSF and 20 healthy controls were enrolled in the study. The pro-inflammatory and immunoregulatory cytokines IL-1beta, TNF-a, IL-6, IL-8, IL-12, IFN-gamma, IL-2, and IL-10 were studied in the burst of disease, at clinical recovery stage, and two weeks later. The disease etiology was verified by indirect IFA in the Referral Rickettsiosis Laboratory. The cytokine levels were determined by ELISA (BioSource Europe S.A). RESULTS: In the disease flare up patients showed a manifold increase in the activity of IL-1beta (p < 0.01), TNF-alpha (p < 0.001), IL-6 (p < 0.001), and IL-8 (p < 0.001) compared with the controls. Significant elevation in IFN-gamma and IL-12 values (p < 0.001) was also found. The increase in the immunoregulatory IL-10 also reached statistical significance (p < 0.001), while the rise in IL-2 did not (p > 0.05). Followed in dynamics, only IL-1beta and IL-6 measured up the control levels at the time of clinical recovery. Two weeks later, in the early convalescence IL-12 and TNF-alpha further diminished but did not normalize their values. CONCLUSION: Our findings show that MSF is characterized by a Th1 cytokine profile. The patient's immune system responds by proinflammatory and immunoregulatory cytokine production that accompanies the rickettsial vasculitis and contributes to the healing process. The latter is probably not fully achieved in the early convalescent period, according to our data concerning some pro-inflammatory cytokines' elevation at this period.

Sensorineural hearing loss complicating severe rickettsial diseases: report of two cases.

Sub-acute focal neurological manifestations are reported rarely in systemic rickettsial diseases and are considered to be secondary to immune-mediated mechanisms. We present two cases of transient sensorineural hearing loss complicating the course of severe rickettsial diseases caused by Rickettsia typhi and Rickettsia conorii, respectively. The diagnosis was based on the presence of high IgM antibodies and the prompt response to doxycycline treatment. In both cases, hearing loss presented during convalescence and resolved automatically without administration of specific treatment.

Rickettsia conorii in humans and dogs: a seroepidemiologic survey of two rural villages in Israel.

The prevalence of IgG-antibodies reactive with an Israeli strain of Rickettsia conorii (Israeli strain 487), the agent of Israeli spotted fever, was examined in humans and dogs from two rural villages in Israel where the disease has been reported in humans. Sixty-nine of 85 (81%) canine sera and 14 of 136 (10%) of human sera had anti-R. conorii antibodies. No direct association could be made between seropositivity of people and ownership of a seropositive dog. This study indicates that exposure to spotted fever group rickettsiae was highly prevalent among dogs compared with humans in the two villages examined, probably reflecting a greater exposure rate of canines to the tick vector. These results support a previous suggestion that canine serology could be a sensitive indicator for the presence and magnitude of human exposure to R. conorii.

[Abnormal liver function in Mediterranean spotted fever]. / Interessamento epatico in corso di febbre bottonosa del Mediterraneo.

In this study we retrospectively assessed the prevalence of impaired liver function in all 49 patients suffering from Mediterranean Spotted Fever (MSF) consecutively admitted to our department over the last four years. The main parameters of liver function and ultrasound of upper abdomen were performed at entry and at the end of treatment. At admission mean values of transaminases were above the normal limits and significantly higher when compared to mean serum levels at recovery. 55% and 51% of patients had serum values of GOT and GPT, respectively, above the normal limits versus 1% and 2% at the end of treatment. Mean serum values of alkaline phosphatase (AP) were within the normal limits at entry in hospital, but 22 of them had serum values above the normal limits. The same proportion was seen for gamma glutamiltranspeptidase values. Eighteen patients (36.7%) had both transaminases and AP above the normal limits. There were no significant differences among serum values of albumin, bilirubin and gamma globulin before and after therapy. Platelet count, on the contrary, was significantly reduced at admission (p < 0.0001). At ultrasound half of the patients showed hepatomegaly with a hepatitis-like pattern and 39% of patients had splenomegaly. In conclusion, this study confirms previous data from the literature showing a high frequency of liver impairment during the course of MSF, which is usually mild-moderate. In a few cases, however, the increase of transaminases could be serious and the recovery delayed, but never, in our experience, has there been progression toward chronic liver disease.

The seroprevalence of human infection with Rickettsia slovaca, in an area of northern Spain.

An epidemiological survey was undertaken to explore human exposure to Rickettsia slovaca in two provinces of northern Spain. When IFAT were used to test 200 members of the general population for antibodies to rickettsiae of the spotted-fever group, six (3.3%) were found positive, presumably, since Dermacentor is one of the most common genera of human-biting tick in the study area, for antibodies to R. slovaca. Thirty-one (16.9%) of an additional 183 subjects who presented shortly after being bitten by ticks were also found seropositive. The difference in seroprevalence between the general and the tick-bitten populations was significant. Subject gender had no influence on seroprevalence in either population, although, in the tick-bitten group, age and occupation did have a significant influence on the prevalence recorded. Immunoblotting was used to confirm the presence of antibodies in the five subjects, all from the tick-bitten group, found to have acute infections. Three D. marginatus ticks obtained from three of these acute cases were found PCR-positive for R. slovaca DNA.

Characterisation of rickettsial diseases in a hospital-based population in Malta.

OBJECTIVE: The aim of the study was to characterise the causative agents of rickettsial disease in Malta. A secondary objective was to study the epidemiology of cases of rickettsial disease. METHODS: Cases admitted to St Luke's Hospital between June 2002 and May 2003 presenting with complaints of fever, headache, rash and/or an eschar were considered possible cases of rickettsial disease. A patient interview was conducted within 24h of admission. Paired sera were taken for serology and blood samples sent for rickettsial PCR and culture. Whenever an eschar was present, biopsies were taken for culture and immunohistochemical analysis. RESULTS: Thirty-three cases of possible rickettsial disease were identified. Although serological tests showed cross reactivities between different species of rickettsiae, one was diagnostic for Rickettsia conorii. None of the sera showed any cross-reactivity with Rickettsia typhi. There was one positive biopsy for R. conorii when tested by PCR and another was positive for spotted fever group Rickettsia by immunohistochemistry. CONCLUSION: Spotted fever rickettsiosis is endemic in Malta. Contrary to previous belief, none of the cases were due to murine typhus. The predominant causative agent of rickettsial disease in Malta is likely to be R. conorii, although the animal reservoir has still not been definitely identified.

Laboratory-confirmed Mediterranean spotted fever in a Japanese traveler to Kenya.

A Japanese traveler returning from Kenya became ill, presenting with fever and a prominent, generalized rash without an eschar. Results of the immunofluorescence antibody assay of the patient's sera performed in Japan were compatible with illness due to a spotted fever group (SFG) rickettsia, and a presumptive diagnosis of African SFG rickettsiosis, probably either Mediterranean spotted fever (MSF) or African tick-bite fever (ATBF), was rendered. To further define the disease diagnosis, sera were examined in France by Western immunoblotting combined with cross-adsorption, which confirmed the diagnosis of MSF but not of ATBF. Because of the need to further characterize the epidemiologic and clinical features of the two African SFG rickettsioses, clinicians are encouraged to contact a specialized laboratory when encountering such cases.

[Sub-Saharan traveler with papulovesicular exanthema and flu-like symptoms]. / Tropenrückkehrerin mit papulovesikulärem Exanthem und grippeähnlichen Beschwerden.

African tick bite fever (ATBF) is an infectious disease commonly observed in travelers to sub-Saharan Africa. Because the presentation of the disease is often not specific, ATBF is frequently not diagnosed or confused with Mediterranean spotted fever. We present the case of a 63-year-old woman with typical history and symptoms. The diagnosis of ATBF was serologically confirmed by immunofluoroscence. ATBF is an important differential diagnosis of fever in patients returning from sub-Saharan Africa.

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.

First isolation of Rickettsia conorii from human blood in Croatia.

AIM: To detect and isolate rickettsial strains from blood samples of patients with presumptive diagnosis of Mediterranean spotted fever (MSF) in the coastal region of south Croatia, and to compare the results with routine serology. METHODS: A "suicide" polymerase chain reaction (PCR), and a shell vial culture were done on samples of ethylenediamine tetra-acetic acid (EDTA) and citrate-anticoagulated blood samples. Indirect immunofluorescence was performed on sera collected from 17 patients clinically diagnosed with MSF during summer in three consecutive years, from 1998 to 2000. RESULTS: The primers used in PCR amplified the expected part of the rickettsia genomic DNA and Rickettsia conorii grew from the shell vial-cultured blood of a single patient. In 13 patients, the diagnosis was confirmed serologically by paired sera, whereas in 4 patients the diagnosis remained presumptive, since no paired sera were available. Analyzing sequences of the ompA and citrate synthase gene, respectively, derived from the shell vial isolate, a 100% similarity with Rickettsia conorii, strain Seven (Malish), was found. CONCLUSION: To the best of our knowledge, this is the first isolation of Rickettsia conorii from a human sample in Croatia, and the first proof of a causative agent of MSF in the country. Beside PCR-based methods and isolation, correct diagnosis of MSF could be still routinely reached by serology.