Rocky Mountain spotted fever presenting as thrombotic thrombocytopenic purpura

A patient presented with findings compatible with thrombotic thrombocytopenic purpura. The diagnosis of Rocky Mountain spotted fever was also considered because the patient was a hunter in a tick-infested area. He was treated for both diagnoses. The patient recovered and a diagnosis of Rocky Mountain spotted fever was confirmed by serologic methods. Clinical symptoms and hematologic parameters of severe Rocky Mountain spotted fever may resemble thrombotic thrombocytopenic purpura, implying that there may be similarities in the pathophysiology of both disorders.     

Case Report: Co-Infection of Rickettsia rickettsii and Streptococcus pyogenes: Is Fatal Rocky Mountain Spotted Fever Underdiagnosed?

Rocky Mountain spotted fever, a tick-borne disease caused by Rickettsia rickettsii, is challenging to diagnose and rapidly fatal if not treated. We describe a decedent who was co-infected with group A β-hemolytic streptococcus and R. rickettsii. Fatal cases of Rocky Mountain spotted fever may be underreported because they present as difficult to diagnose co-infections.     

Reactogenicity, immunogenicity, and efficacy of a chick embryo cell-derived vaccine for Rocky Mountain spotted fever

A new formalin-inactivated vaccine prepared by sucrose density gradient centrifugation of tissue culture-grown Rickettsia rickettsii was evaluated for safety and immunogenicity in a placebo-controlled, double-blind study. Most of the 52 seronegative adult vaccinees, 88% after the first and 66% after the second dose, experienced brief, mild (mostly local) reactions, but only 50% exhibited a systemic immune response to vaccination. Six unvaccinated volunteers (controls) and 16 of these vaccinees were challenged with R rickettsii one month after vaccination. Vaccine efficacy was 25%; all six controls and 12 of 16 vaccinees developed typical Rocky Mountain spotted fever. The incubation period was longer, the duration of constitutional symptoms shorter, and the height of fever lower in ill vaccinees than in controls. The vaccine provided only partial protection against Rocky Mountain spotted fever but ameliorated the illness.     

Myocardial function in Rocky Mountain spotted fever: echocardiographic assessment

Nine patients with Rocky Mountain spotted fever underwent M-mode echocardiographic examination. Increased left ventricular dimension was found in 2 patients and decreased left ventricular shortening fraction in 7. Diminished mean velocity of circumferential fiber shortening, increased left ventricular systolic time intervals ratio, and increased mitral valve E point to ventricular septal separation were found in 6 patients. One patient died and at necropsy diffuse myocarditis was present. Repeat echocardiographic examination was available in the remaining 8 patients at follow-up (mean 10 months). Abnormal E mitral point to ventricular septal separation remained in 3 patients and decreased left ventricular shortening fraction in 2; in 1 there was also increased left ventricular end-diastolic dimension. Thus abnormal left ventricular function and chamber enlargement are frequently present in patients with Rocky Mountain spotted fever.     

Infection of human vascular endothelial cells by Rickettsia rickettsii

Rocky Mountain spotted fever is caused by Rickettsia rickettsii, an obligate intracellular bacterial parasite. The organism primarily attacks endothelial cells and occasionally attacks smooth-muscle cells of small blood vessels. An effective means of examining host-parasite interaction in Rocky Mountain spotted fever would be to use an in vitro model system with a host-cell type that is similar in structure and function to the putative target cell in human infections. Because human umbilical-vein endothelial cells in culture retain many, if not all, of their characteristic properties in vivo and because they also share many properties of capillary endothelium, the use of this endothelial cell system is appropriate in the study of the interaction between R rickettsii and the cell that is principally parasitized in humans. Uptake by umbilical-vein endothelial-cell cultures of R rickettsii is dose dependent. The organism replicates in both the nucleus and cytoplasm of infected cells and exhibits early cell-to-cell spread without detectable host-cell injury.     

A fatal urban case of rocky mountain spotted Fever presenting an eschar in san jose, costa rica

Abstract. This study reports the first urban human case of Rocky Mountain spotted fever caused by Rickettsia rickettsii, in Costa Rica. An 8-year-old female who died at the National Children's Hospital 4 days after her admission, and an important and significant observation was the presence of an "eschar" (tache noire), which is typical in some rickettsial infections but not frequent in Rocky Mountain spotted fever cases.     

Rocky Mountain spotted fever in Argentina

We describe the first molecular confirmation of Rickettsia rickettsii, the cause of Rocky Mountain spotted fever (RMSF), from a tick vector, Amblyomma cajennense, and from a cluster of fatal spotted fever cases in Argentina. Questing A. cajennense ticks were collected at or near sites of presumed or confirmed cases of spotted fever rickettsiosis in Jujuy Province and evaluated by polymerase chain reaction assays for spotted fever group rickettsiae. DNA of R. rickettsii was amplified from a pool of A. cajennense ticks and from tissues of one of four patients who died during 2003-2004 after illnesses characterized by high fever, severe headache, myalgias, and petechial rash. The diagnosis of spotted fever rickettsiosis was confirmed in the other patients by indirect immunofluorescence antibody and immunohistochemical staining techniques. These findings show the existence of RMSF in Argentina and emphasize the need for clinicians throughout the Americas to consider RMSF in patients with febrile rash illnesses.     

Eosinophilic meningitis caused by Rocky Mountain spotted fever

Eosinophilic meningitis was documented in a patient with Rocky Mountain spotted fever. Rickettsial disease should be considered a diagnostic possibility in patients with cerebrospinal fluid eosinophilia.     

Tick-borne diseases in the United States: Rocky Mountain spotted fever and Colorado tick fever. A review.

The historical, clinical, ecological, and epidemiological features of Rocky Mountain spotted fever and Colorado tick fever, the two important tick-borne diseases in the United States, are reviewed. Rocky Mountain spotted fever, once considered a disease of the past, has again become a measurable public health problem. Its nationwide incidence has steadily increased since 1960 and has reached record proportions in 1976. The various factors responsible for this trend as well as for the mortality rates, which in spite of availability of effective antibiotics ranges from 5 to 10%, are discussed. Education of the public about ticks and their potential role as vectors of Rickettsia rickettsii and/or Colorado tick fever virus, and about the clinical manifestations of Rocky Mountain spotted fever, is considered the best means for preventing high incidence and mortality from these diseases.     

A comparison of the complement fixation, indirect fluorescent antibody, and microagglutination tests for the serological diagnosis of rickettsial diseases.

Three techniques for the serological diagnosis of Rocky Mountain spotted fever were compared by testing 417 sera from 178 patients who very probably did not have rickettsial infections and 88 sera from 41 patients who very probably had Rocky Mountain spotted fever (SF). The techniques were complement fixation (CF), indirect fluorescent antibody (IFA), and microagglutination (MA). To avoid possible degradation during unnecessary purification, the antigens were prepared by methods that were as simple as possible. In the CF tests of 417 sera from patients with nonrickettsial diseases there was only one titer of 8 and none at higher dilutions, whereas with the IFA and MA tests 4-8% of the sera reacted with SF antigens and 4-20% reacted with murine typhus (MT) antigens; the evidence indicated that these reactions were not caused by specific rickettsial antibody. With the SF sera, it could be seen that the IFA test was the most sensitive and the MA test was the least sensitive at each interval after infection. Moreover, the IFA results showed the least number of confusing cross-reactions with MT antigens and the MA test showed the most. The relative advantages of the three tests in serodiagnosis of rickettsial diseases are discussed.     

Left ventricular dysfunction in Rocky Mountain spotted fever

Rocky Mountain spotted fever is a serious infectious disease that continues to occur with increasing incidence in various areas of the United States. A high case-fatality ratio (11%) persists in spite of availability of adequate chemotherapeutic agents, and the cardiac involvement may play an important role in the final outcome of some cases. To assess the effect of the disease on left ventricular function 13 patients underwent M-mode echocardiographic examination on admission to a children's hospital. Increased left ventricular dimension was found in 3 patients and decreased left ventricular shortening fraction in 9. Diminished mean velocity of circumferential fiber shortening and increased left ventricular systolic time interval ratios were found in 8 patients and increased mitral valve E point to ventricular septal separation in 9. One patient died and biventricular dilatation with diffuse myocarditis was seen at autopsy. Repeat echo examination was available in 11 patients at follow-up (mean 5 months). Abnormal E mitral point to ventricular septal separation remained in 4 patients and decreased left ventricular shortening fraction in 2. The long-term prognosis for this group is unknown. Myocardial involvement is frequently present in Rocky Mountain spotted fever; close monitoring and aggressive therapeutic approach are essential if the high case-fatality ratio is to be reduced.     

Fatal viscerotropic Rocky Mountain spotted fever. Report of a case diagnosed by immunofluorescence.

A case of fatal viscerotropic Rocky Mountain spotted fever with virtual absence of cutaneous lesions was diagnosed at autopsy by specific immunofluorescent demonstration of Rickettsia rickettsii in spleen, kidney, epididymis and skin. The clinical presentation was that of insidious onset of fever, renal failure, hypotension, hyponatremia and obtundation over a 10 day period. The patient had respiratory insufficiency, hypocalcemia, increases in creatinine phosphokinase (CPK), serum glutamic oxaloacetic transaminase (SGOT), serum glutamic pyruvic transaminase (SGPT), lactic dehydrogenase (LDH), alkaline phosphatase, billirubin and serum phosphate, grand mal seizure, myalgia and unremitting shock with death occurring on day 12 of illness. Postmortem examination revealed severe vasculitis with interstitial nephritis and multifocal tubular necrosis, pericholangitis with bile stasis, glial nodules in the brain, multifocal rhabdomyonecrosis, interstitial pneumonitis and mild interstitial myocarditis. Risk factors which this patient shared with other patients with fatal Rocky Mountain spotted fever were failure to recognize a rash, failure to obtain a tick bite history, male sex, black race and age greater than 30 years.     

Seroprevalence and seroconversion for tick-borne diseases in a high-risk population in the northeast United States

PURPOSE: To determine the prevalence of serologic reactivity, the 1-year incidence of seroconversion, and the frequency of multiple infections, and their associations with symptoms in a group of volunteers at high risk for tick-borne infections in New York state. METHODS: We performed a seroepidemiologic study of Lyme borreliosis, 2 of the ehrlichioses, Rocky Mountain spotted fever, and babesiosis among 671 participants who lived or worked in a high-risk area (mainly in eastern Long Island, New York) for tick-borne diseases. Sera were collected in the winters of 1994 and 1995. Signs and symptoms of tick-borne disease were monitored monthly by mail and telephone. Lyme borreliosis serologies were done by enzyme-linked immunosorbent assay and Western blot. Rocky Mountain spotted fever serologies were initially screened using Dip-S-Ticks, followed by specific indirect immunofluorescence. Ehrlichiosis serologies were determined by epifluorescent microscopy, as were antibodies to Babesia microti. RESULTS: Of the 671 participants, 88 (13%) had antibodies to > or = 1 tick-borne organisms, including 34 (5% of the total) with antibodies to Borrelia burgdorferi. Twenty-seven participants had evidence of exposure to B. burgdorferi at baseline. Seven participants (1%) seroconverted during the course of the study, 5 of whom were symptomatic for Lyme borreliosis. Antibodies to spotted fever group rickettsiae were seen in 28 participants (4%), 22 of whom were positive at baseline and 6 of whom seroconverted during the observation period. None of the seropositive patients had any symptoms or signs of infection. Twenty-four participants (3%) had serologic evidence of exposure to Ehrlichia (all but one to Ehrlichia equi); 5 (0.7%) seroconverted during the observation period, including 3 subjects who were asymptomatic. Antibodies to B. microti were seen in 7 participants (1%), including one asymptomatic seroconversion during the year of observation. There was evidence of possible dual infection in 5 patients. CONCLUSION: In a high-risk population, there was evidence of exposure to 5 tick-borne pathogens; however, many infections were asymptomatic, and coinfections were rare.     

Mediterranean spotted fever in an American woman

Mediterranean spotted fever is common in southern Europe, the Middle East, and North Africa, but is unknown in the United States. It has a clinical picture resembling Rocky Mountain spotted fever, but it is a milder disease. We report a case of Mediterranean spotted fever in a young American woman returning from Morocco and review the clinical picture of this disease.     

Incidence, clinical observations and risk factors in the severe form of Mediterranean spotted fever among patients admitted to hospital in Marseilles 1983-1984

Seven of 142 cases (5%) of Mediterranean spotted fever admitted to hospital in Marseilles in 1983 and 1984 were severe. All of them were confirmed by specific laboratory tests. The disease resembles Rocky Mountain spotted fever with purpuric exanthem, confusion, renal insufficiency, hypoxaemia, thrombocytopenia, hyponatraemia and hypocalcaemia. Two patients died. The predisposing factors for severity were old age, alcoholism, heavy smoking, respiratory insufficiency and glucose-6-phosphate dehydrogenase deficiency.     

A focus of dogs and Rickettsia massiliae-infected Rhipicephalus sanguineus in California

A recurrent focus of Rhipicephalus sanguineus infestation was investigated in a suburban area of southern California after reports of suspected Rocky Mountain spotted fever in two dogs on the same property. Abundant quantities of Rh. sanguineus were collected on the property and repeatedly from each dog, and Rickettsia massiliae DNA was detected by polymerase chain reaction (PCR). Whole blood and serum samples from four dogs were tested by using PCR and microimmunofluorescent assay for antibodies against spotted fever group rickettsiae. Serum samples from all four dogs contained antibodies reactive with R. massiliae, R. rhipicephali, R. rickettsii, and 364D Rickettsia but no rickettsial DNA was detected by PCR of blood samples. Serum cross-absorption and Western blot assays implicated R. massiliae as the most likely spotted fever group rickettsiae responsible for seropositivity. To our knowledge, this is the first detection of R. massiliae in ticks in California.     

Rickettsia rickettsii and Rickettsia montana from Ixodid ticks in Connecticut

Dermacentor variabilis, infected with spotted fever group rickettsiae, parasitized 8 of 70 raccoons captured in Newtown, Connecticut. The spotted fever agent, Rickettsia rickettsii, was isolated and identified from 4 adult D. variabilis and from 1 nymphal Ixodes texanus removed from raccoons. This verifies the presence of this etiologic agent in ticks in an area where 6 people had clinical signs and symptoms of Rocky Mountain spotted fever (RMSF) and antibodies to R. rickettsii. These are the first isolations of R. rickettsii from D. variabilis in southern New England and the first identified rickettsiae from I. texanus. No rickettsiae were isolated from Ixodes muris or I. cookei. Rickettsia montana was recovered in Vero cell culture from a D. variabilis collected in East Haddam, Connecticut where RMSF is not known to be prevalent.     

High rates of Rickettsia parkeri infection in Gulf Coast ticks (Amblyomma maculatum) and identification of "Candidatus Rickettsia andeanae" from Fairfax County, Virginia

The Gulf Coast tick, Amblyomma maculatum, is a vector of Rickettsia parkeri, a recently identified human pathogen that causes a disease with clinical symptoms that resemble a mild form of Rocky Mountain spotted fever. Because the prevalence of R. parkeri infection in geographically distinct populations of A. maculatum is not fully understood, A. maculatum specimens collected as part of a tick and pathogen surveillance system in Fairfax County, Virginia, were screened to determine pathogen infection rates. Overall, R. parkeri was found in 41.4% of the A. maculatum that were screened. Additionally, the novel spotted fever group Rickettsia sp., tentatively named "Candidatus Rickettsia andeanae," was observed for the first time in Virginia.     

Studies of the coagulation and complement systems during experimental Rocky Mountain spotted fever in rhesus monkeys.

We studied the coagulation and complement systems during Rocky Mountain spotted fever in Macaca mulatta experimentally infected with Rickettsia rickettsii. Ninety-one percent of monkeys infected intravenously with a high dose (10(6) plaque-forming units [pfu]) and 56% of monkeys infected with low doses (10(-1)-10(2) pfu) of R. rickettsii died after two to four days of illness. With the onset of fever and rickettsemia, animals developed hyperfibrinogenemia, mild thrombocytopenia, prolonged prothrombin and activated thromboplastin times, and increased serum fibrin/fibrinogen degradation products (FDP). Rickettsemia, thrombocytopenia, and FDP were greater in fatally ill monkeys than in survivors. Hemolytic titers of the second and third components of complement were not depressed except in a single surviving monkey that developed peripheral gangrenous ecchymoses at a time when both rickettsemia and agglutinating antibody were present. Thus, although activation and consumption of complement may occur during Rocky Mountain spotted fever, the hemostatic disturbances in fulminant infections seem to be a direct effect of the infectious vasculitis.     

Rickettsiosen der Zeckenbissfieber-Gruppe

Rickettsioses are among the most frequent causes of febrile diseases in travelers, as shown in several studies in the last years. Furthermore, since 1991, with the introduction of new testing methods, 8 new Rickettsia species (or new diseases) have been described. Typical symptoms of rickettsial infections are high fever, headaches and myalgias, frequently associated with a rash and/or an inoculation eschar ("tache noire") at the site of tick bite. The rapid recognition of a rickettsiosis and the immediate start of appropriate antibiotic therapy are important because some rickettsioses (e. g. the Rocky Mountain spotted fever) are associated with relevant morbidity and mortality. This paper reviews the spotted fever group rickettsioses.