[Mediterranean spotted fever due to contact with dog-tick]

Mediterranean spotted fever (MSF) is one of the tick-borne rickettsial infections caused by Rickettsia conorii. It is transmitted to humans by brown dog ticks (Rhipicephalus sanguineus). In this case report, a 16-years-old male patient who was diagnosed as MSF after an exposure to dog-tick in Bartin province (located at middle Black Sea region of Turkey) has been presented. His history revealed that, five days before admission to the hospital (on June, 2007) he had cleaned dog-ticks from his dog, and after 12 hours he found a stucked tick on his leg and he took it out right away with a tweezer. High fever, headache and generalized maculopapular rash including soles and palms and a black-colored lesion at the tick bite site developed three days later. In clinical examination, there was a black escar circled with a red-purple colored halo in front of the right tibia at the site of the tick bite showing high similarity to "tache noire" which was specific to MSF. Indirect immunofluorescence assay (IFA) for Rickettsia yielded negative result in the serum sample collected on admission day, however, it was found positive at 1/512 titer in the serum sample collected 10 days after admission. The patient has recovered completely without any complication after 10 days of doxycycline therapy. The aim of this presentation is to point out that MSF should be considered for the differential diagnosis of a patient with a history of tick bite, fever, maculopapular rash, headache, myalgia, arthralgia and especially with black escar during summer months in our country where the incidence of tick-borne infections has been increasing since recent years.

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.

First detection of spotted fever group rickettsiae in Ixodes ricinus from Italy

Ixodes ricinus from Italy were examined for the first time to detect whether rickettsiae were present. Using molecular methods, we detected three different spotted fever group rickettsiae, including Rickettsia helvetica. Our results raise the possibility that bacteria other than R. conorii are involved in rickettsial diseases in Italy.

[Spotted fever group rickettsial disease in Argentinean travelers]

During 1996, four patients that returned from South Africa suffering from rickettsiosis were attended at the Traveler's Medicine practice of our hospital. All of them presented fever, headache and cutaneous scar. One of these presented maculopapular rash, while the rest developed a vesicular rash. The Weil-Felix reaction was negative and the immunofluorescence test for Rickettsia conorii was positive in all cases. None of the patients remembered having been bitten by any insects, however all of them had been staying in or going through a wild environment. All the patients were treated with doxycycline and presented a good outcome.

Interleukin-12 in human boutonneuse fever caused by Rickettsia conorii

Interleukin (IL)-12 contributes to the resistance against a number of intracellular pathogens. We examined the potential biological role of IL-12 by studying peripheral blood mononuclear cells (PBMC), its production and its effect on cytokine synthesis in 20 Sicilian patients with boutonneuse fever (BF) caused by Rickettsia conorii. Data indicate that PBMC from acute BF patients were able to produce IL-12 in response to in vitro stimulation with rickettsial antigen (Ag): this production was higher than that detected in healed patients. Monocytes were the main source of IL-12 by PBMC from BF patients. IL-12 secretion by in vitro Ag-stimulated PBMC from BF patients was potentiated by recombinant interferon gamma (IFN-gamma) or anti-IL-10 monoclonal antibodies (MoAbs). Furthermore, the treatment with anti-IL-12 MoAbs reduced the IFN-gamma synthesis. These results indicate that treatment of PBMC from acute BF patients with IL-12 shifted the response toward a Th1-type cytokine response. Furthermore, IL-12 and IFN-gamma are interdependent and they may be associated with the immunity against rickettsias.

Visual loss in a returning traveller with tick typhus

Rickettsial diseases are increasingly found world-wide and should be considered in febrile patients returning from abroad. This case report describes the vasculitic complications of a patient returning from the Republic of South Africa with tick typhus.

Malignant boutonneuse fever and polymyalgia rheumatica: a coincidental association?

Mediterranean spotted fever is a tick-borne disease that is endemic in the Mediterranean basin from spring to autumn. Usually mild, the disease can be severe in some cases, especially when risk factors are encountered in patients or when treatment is delayed. The correlation between these malignant forms and patients' immunological disorders remains unclear, while the pathophysiology of the disease seems well known. A case of a malignant form of Mediterranean spotted fever is reported which occurred 2 months prior to the diagnosis of polymyalgia rheumatica. Evidence of immunological disorders consisted only in an antiphospholipid antibody associated with a transient lupus anticoagulant. No underlying risk factors other than the primary undiagnosed phase of polymyalgia rheumatica has been observed.

Release of soluble tumor necrosis factor receptors in Mediterranean spotted fever rickettsiosis

Tumor necrosis factor alpha (TNF) is a key cytokine in the defense against many intracellular pathogens, including Rickettsia conorii, the causative agent of Mediterranean spotted fever (MSF). The levels of two soluble TNF receptors (sTNFR-p55 and sTNFR-p75), the extracellular domains of the two cell surface receptors for TNF, were elevated in the acute-stage plasma samples from 20 patients with serologically confirmed MSF. The median values were 3.1 and 7.8 ng/ml for sTNFR-p55 and sTNFR-p75, respectively. sTNFR values correlated significantly with plasma TNF concentrations. Patients with severe MSF had higher values for both receptor fragments than patients with nonsevere disease. The differences were statistically significant for sTNFR-p55 (median, 5.8 versus 2.0 ng/ml; P = 0.008). Given the proportionately higher values for both TNF and sTNFR-p55 in patients with severe MSF, the sTNFR-p55/TNF ratios for the two patient subgroups did not differ (P = 0.5), while the sTNFR-p75/TNF ratios were significantly different (P = 0.01), with disproportionately lower values in patients with severe disease.

Rickettsia conorii infection of C3H/HeN mice. A model of endothelial-target rickettsiosis

BACKGROUND

Rickettsial diseases result from disseminated intraendothelial cell infection. The clinically critical conditions, meningoencephalitis and interstitial pneumonia, are associated with multifocal rickettsial vascular injury.

EXPERIMENTAL DESIGN

C3H/HeN mice inoculated intravenously with either 2.25 x 10(3) or 2.25 x 10(5) Rickettsia conorii (Malish 7 strain) were observed for illness with sacrifice of animals for evaluation of pathologic lesions and host responses by light and electron microscopy, rickettsial content and location by plaque assay, immunohistology, and electron microscopy, and immune response by cytokine analyses and serology.

RESULTS

Mice inoculated with a high dose of rickettsiae established disseminated endothelial infection on day 1, became ill with progressive increase in rickettsiae on day 4, and died with vascular injury-based meningoencephalitis and interstitial pneumonia on day 5 or 6. Mice inoculated with the low rickettsial dose became ill on day 5 and recovered by day 10. Clearance of rickettsiae was associated with lymphohistiocytic perivasculitis. Rickettsial infection of Kupffer cells and hepatocytes led to the formation of transient hepatic granulomas. Infection-associated loss of the ability of spleen cells to secrete interleukin-2 on stimulation with concanavalin A suggested transient immunosuppression.

CONCLUSIONS

This experimental infection provides the best available model for rickettsial disease with endothelial infection and injury, immune rickettsial clearance, regeneration of endothelium, and repair of the vascular lesions.

[Meningoencephalitis due to Rickettsia conorii. Etiopathological, clinical and diagnostic aspects]

Boutonneuse fever (BF) is usually considered to be a benign rickettsiosis. However, severe presentations, resembling Rocky Mountain spotted fever, have been reported. There are few neurological complications, except in serious forms of the disease. We present a case of meningoencephalitis in a male adult suffering from BF, and we review the clinical, etiopathogenic and diagnostic aspects among the cases previously reported. We conclude that BF encephalitis would have the following characteristics: a) they mostly affect elderly males; b) they cause altered consciousness level, headaches and low rate of meningeal signs; c) absence of "tâche noir"; d) cerebrospinal fluid with slight pleocytosis and/or increased level of proteins, and normal glucose values; e) computerized tomography without significative changes, and f) high rate of morbidity and mortality. We emphasize that we should consider BF in the differential diagnosis of our environmental encephalitis.

Epidemiology of boutonneuse fever in western Sicily: accidental laboratory infection with a rickettsial agent isolated from a tick

A case is reported of an accidental laboratory infection with a strain of Spotted Fever-Group Rickettsiae freshly isolated from a tick collected in Western Sicily. Inoculation into the left thumb of cell-cultured organisms (10(5)/ml) gave rise to clinical signs and symptoms of Boutonneuse Fever after six days, i.e., a lesion at the point of inoculation, fever, headache, conjunctivitis and myalgias. Rickettsiae were isolated from acute-phase blood samples collected from the infected individual and IgM and IgG response was detected in the patient's serum by indirect immunofluorescence. Complete recovery was obtained after antibiotic treatment. Serologic analysis of the strain, together with analyses of the proteins of the isolate, documented that the isolate was Rickettsia conorii and was identical to prototype strain. The relationship of this infection to ongoing studies on the epidemiology of Boutonneuse Fever in Western Sicily is discussed.

[Mediterranean spotted fever in childhood. Prospective study of 130 cases]

Authors present a prospective study of 130 cases of Mediterranean spotted fever treated between 1983 and 1985 in two Departments of Paediatrics of the Valles Occidental, area near Barcelona. Thirty-eight percent of the children came from suburban areas, an urban areas, an urban or rural origin being less frequent. Previous contacts with dogs existed in 86% of the cases. Most frequent clinical signs were fever (100%) maculo-papular rash (97%) and arthromyalgias (70%). The "tache noire" was found in 87% of the cases. Presence of arthritis in two patients is underlined. Indirect immunofluorescence to Rickettsia conorii was positive (much greater than 1/40) in 75% of the cases. All patients improved after treatment with tetracycline or erythromycin. There were no relapse.

[Tick bite fever]

Tick bite fever (boutonneuse fever) is endemic in India, Africa and especially the Mediterranean countries. It is occasionally "imported" into central European countries by tourists. The exanthematic disease is caused by infection with Rickettsia conori, which is usually transmitted by the brown dog tick. A typical primary lesion at the site of the tick's bite is an important diagnostic hint. The treatment of choice are tetracyclines.

Importation into the United States from Africa of Rhipicephalus simus on a boutonneuse fever patient

Rhipicephalus simus Koch was removed from a human upon his return to Connecticut, U.S.A. from Kenya, Africa. This person became ill in Africa, exhibited clinical manifestations of boutonneuse fever and had a significant rise (greater than or equal to 8-fold) in IgM titer against spotted fever-group rickettsiae. Rickettsia conorii was probably the infectious agent.