Neurological manifestation of Brazilian spotted fever in childhood

Rocky Mountain Spotted Fever is a rickettsial disease caused by the bacteria Rickettsia rickettsii. In Brazil, the disease is known as Brazilian spotted fever (BSF), being the most significant tick-borne disease in the country. Among the affected patients, only 5% of cases occur in children aged one to nine years. Typical symptoms of the disease are fever, rash, headache and digestive symptoms. Neurological manifestations such as seizures, aphasia and hemiparesis have been described in few patients. This study aimed to describe the case of an infant diagnosed with BSF who presented severe signs of neurological manifestation.

[Fatal case of co-infected of rickettiosis and dengue virus in Mexico]

BACKGROUND

Rocky Mountain spotted fever (RMSF) is a disease spread by an infected tick and it is lethal if patient is not treated on time. Symptom similarities with other exanthematous diseases may delay the diagnosis, which leads to its mortality.

CLINICAL CASE

We show the lethal case of a patient with medical record of high blood pressure and no history of travel, who lived in Sonora, Mexico. At the beginning, it was suspected that the patient had a dengue virus infection, which was confirmed positive by an ELISA test. Patient’s rapid deterioration, multi-organic failure and the characteristics of her exanthema led to the suspicion of the presence of RMSF. We started doxycycline treatment; however, patient died after seven days of evolution. It was confirmed a co-infection of Rickettssia spp. and dengue virus.

CONCLUSION

In rickettsial endemic zones, treatment with doxycycline should be employed in patients with similar symptoms, even though there is evidence of the presence of other etiologic agents.

[Complications and cause of death in mexican children with rocky mountain spotted fever]

BACKGROUND

Rocky Mountain spotted fever is a life threatening disease caused by Rickettsia rickettsia, characterized by multisystem involvement.

METHODS

We studied 19 dead children with Rocky Mountain spotted fever. All children who were suspected of having rickettsial infections were defined as having Rocky Mountain spotted fever by serology test and clinical features. Through the analysis of each case, we identified the clinical profile and complications associated to the death of a patient.

RESULTS

In nine (69.2%) of 13 cases that died in the first three days of admission, the associated condition was septic shock. Others complications included respiratory distress causes by non-cardiogenic pulmonary edema, renal impairment, and multiple organ damage.

CONCLUSIONS

The main cause of death in this study was septic shock. The fatality rate from Rocky Mountain spotted fever can be related to the severity of the infection, delay in diagnosis, and delay in initiation of antibiotic therapy. Pulmonary edema and cerebral edema can be usually precipitated by administration of excess intravenous fluids.

[Rocky Mountain spotted fever in Mexican children: Clinical and mortality factors]

OBJECTIVE

Characterize clinical manifestations and predictors of mortality in children hospitalized for spotted fever.

MATERIALS AND METHODS

Cross-sectional study in 210 subjects with a diagnosis of Rocky Mountain spotted fever (RMSF) in a pediatric hospital in Sonora, from January 1st, 2004 to June 30th, 2015. Data were analyzed using descriptive statistics and multivariate logistic regression.

RESULTS

An upward trend was observed in RMSF morbidity and mortality. Fatality rate was 30%.Three predictors were associated with risk of death: delay ≥ 5 days at the start of doxycycline (ORa= 2.95, 95% CI 1.10-7.95), acute renal failure ((ORa= 8.79, 95% CI 3.46-22.33) and severe sepsis (ORa= 3.71, 95% CI 1.44-9.58).

CONCLUSIONS

RMSF causes high mortality in children, which can be avoided with timely initiation of doxycycline. Acute renal failure and severe sepsis are two independent predictors of death in children with RMSF.

[Severe spotted fever by Rickettsia rickettsii, in tourist in the Argentine Northwest]

On the fifth day after leaving the Parque Nacional El Rey, province of Salta, Argentina, where she made rural tourism, a woman of Italian origin, aged 47, developed an acute fever followed by a petechial and purpuric rash that progressed rapidly to multiorgan failure. She died on the sixth day after hospitalization. There were references to tick bites and a skin lesion similar to tache noire was found. The autopsy showed generalized vasculitis, ascites, pulmonary edema, acute tubular necrosis and portal centrilobular necrosis. Spleen and liver tissue were processed for PCR Rickettsia spp, based on the detection of the gltA gene. The result was positive. The amplicons obtained were sequenced and the results were compared with the preset sequences on the BLAST program, 99% coinciding with R. rickettsii. The low sensitivity of the health system to recognize this disease and the insufficient information generated from tourism-related media are factors that affect the delay to implement effective treatment and appropriate prevention standards.

Myocardial Involvement in Rocky Mountain Spotted Fever: A Case Report and Review

Rocky Mountain Spotted Fever (RMSF), caused by Rickettia rickettsii, is a serious tickborne illness that is endemic in the southeastern United States. Although it is most commonly known as a cause of fever and rash, it can have systemic manifestations. The myocardium may rarely be involved, with symptoms that can mimic those of acute coronary syndromes. This report describes a case of serologically proven RMSF causing symptomatic myocarditis, manifested by chest pain, elevated cardiac enzyme levels, and decrease myocardial function. After treatment with antibiotics, the myocarditis resolved. Thus, although unusual, the clinician should be aware of myocardial disease in patients with appropriate exposure histories or other clinical signs of RMSF. Close monitoring and an aggressive approach are essential to reduce mortality rates.

Central Nervous System Dysfunction Associated With Rocky Mountain Spotted Fever Infection in Five Dogs

Five dogs from the northeastern United States were presented with clinical signs of neurological disease associated with Rocky Mountain spotted fever (RMSF) infection. Four of the five dogs had vestibular system dysfunction. Other neurological signs included paresis, tremors, and changes in mentation. All of the dogs had an elevated indirect fluorescent antibody titer or a positive semiquantitative enzyme screening immunoassay titer for Rickettsia rickettsii at the time of presentation. Although a higher mortality rate has been reported for dogs with neurological symptoms and RMSF infection, all of the dogs in this study improved with appropriate medical therapy and supportive care.

ORCHITIS IN TWO DOGS WITH ROCKY MOUNTAIN SPOTTED FEVER

Two dogs with testicular swelling were sonographically diagnosed with orchitis and were subsequently diagnosed with Rocky Mountain spotted fever (RMSF). Use of both gray scale and color Doppler sonography allowed for differentiation of orchitis from neoplasia and torsion. While only experimentally induced RMSF is reported to cause orchitis in dogs, it should be considered in any dog with vascular insult to the testes, especially when other signs of systemic illness are involved.

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.

Rocky Mountain Spotted Fever as a Cause of Macular Star Figure

An 86-year-old woman with a history of tick bites in the previous months developed subnormal visual acuity in both eyes, keratic precipitates, anterior chamber and vitreous cells, optic disc edema, retinal hemorrhages, and retinal arteriolar sheathing. She had no fever or skin rash. Three weeks later, binocular macular star figures appeared. Brain imaging was negative; cerebrospinal fluid disclosed a lymphocytic pleocytosis and elevated protein. The serum Rickettsia rickettsii antibody test was markedly positive, establishing a diagnosis of Rocky Mountain Spotted Fever (RMSF) as the cause of the ophthalmic findings. Despite treatment with oral doxycycline, these findings improved only modestly. Although neuroretinitis has been previously described in RMSF, macular star has not been documented.

Expression analysis of the T-cell-targeting chemokines CXCL9 and CXCL10 in mice and humans with endothelial infections caused by rickettsiae of the spotted fever group

Rocky Mountain spotted fever and other related diseases are systemic infections caused by rickettsiae. These obligatory intracellular bacteria target the endothelium, offering an appealing model to study the interactions between endothelial cells and T lymphocytes. We investigated the mRNA expression of chemokines known to target CD8+ T cells and CD4(+) T-helper 1 cells in the lungs of C3H/HeN mice infected with Rickettsia conorii with the purpose of identifying evidence for a role of chemokines in the immune clearance of rickettsiae from the vasculature. The expression of the CXCR3 ligands CXCL9 and CXCL10 was significantly higher than the other chemokines investigated. We validated the relevance of these results in the animal model through the analysis of tissues from humans with Rocky Mountain spotted fever. We then characterized the kinetics and localization of expression of CXCL9 and CXCL10 in lungs, brain, and liver of mice infected with lethal or sublethal doses of R. conorii by a combination of quantitative real-time polymerase chain reaction and immunohistochemistry. Interestingly, the peak of expression of these chemokines occurred 4 days before CD8+ T cells infiltrated the infected tissues. Our results suggest that CXCL9 and CXCL10 may play a role early during the immune response against rickettsial infections.

Hemostatic/fibrinolytic protein changes in C3H/HeN mice infected with Rickettsia conorii--a model for Rocky Mountain spotted fever

Changes in plasma hemostatic and fibrinolytic proteins were determined during courses of a murine model of fatal and non-fatal Rocky Mountain spotted fever. C3H/HeN mice were infected with Rickettsia conorii and coagulation and histopathologic studies were performed at prescribed periods of time. A significant decrease in plasma factor VIII activity and rise in plasma factor V procoagulant activity correlated with a fatal infection. Factor VII levels were unchanged; factor XI levels dropped early in the course in the lethally infected animals, but returned to normal. Factor XII, high molecular weight kininogen, and prekallikrein levels were unchanged by the sublethal infection. Prekallikrein levels fell during the lethal infection. Antithrombin concentrations were decreased significantly in all animals, but plasma plasminogen levels did not change in either group of animals. Nonocclusive thrombi were microscopically observed rarely and only in animals surviving a sublethal infection. A fall in tissue plasminogen activator activity and a rise in plasminogen activator inhibitor activity highly correlated with a lethal outcome. Lethal infection with R. conorii is associated with primary endothelial cell injury resulting in decreased tissue plasminogen activator and increased plasminogen activator inhibitor.

Hemostatic changes in Rocky Mountain spotted fever and Mediterranean spotted fever

Rocky Mountain spotted fever and Mediterranean spotted fever are rickettsial infections primarily of endothelial cells that normally have a potent anticoagulant function. As a result of endothelial cell infection and injury, the hemostatic system is perturbed and shows changes that vary widely from a minor reduction in the platelet count (frequently) to severe coagulopathies, such as deep venous thrombosis and disseminated intravascular coagulation (rarely). Changes favoring a hypercoagulable state include endothelial injury and release of procoagulant components, activation of the coagulation cascade with thrombin generation, platelet activation, increased antifibrinolytic factors, consumption of natural anticoagulants, and possibly high levels of coagulation-promoting cytokines. Yet, most studies have been performed on endothelial cell cultures that provide nonphysiologic, reductionistic, experimental conditions. The lack of flow, platelets, and WBCs makes these experiments far from simulating the response of endothelial cells in the human body. Coagulopathies and thrombotic events should be considered as potential complications of severe Rocky Mountain spotted fever and Mediterranean spotted fever.

Acute disseminated encephalomyelitis after Rocky Mountain spotted fever

Although acute disseminated encephalomyelitis has been observed after a variety of viral infections and an occasional bacterial infection, it has not been reported in association with rickettsial infections. Reported is a 7-year-old male with magnetic resonance images and clinical manifestations suggestive of acute disseminated encephalomyelitis after a tick bite and serologically proven Rocky Mountain spotted fever.

Life-threatening rashes: dermatologic signs of four infectious diseases

Four infectious diseases that are associated with high rates of morbidity and mortality are Rocky Mountain spotted fever, meningococcal disease, staphylococcal toxic shock syndrome, and streptococcal toxic shock syndrome. These diseases necessitate a timely diagnosis and treatment, which may be facilitated by recognition of the characteristic cutaneous findings. Herein the clinical manifestations, diagnosis, and management are presented, with emphasis on the dermatologic signs of each disease. A dermatology consultation can be valuable, but all physicians should be familiar with the cutaneous findings of these potentially life-threatening diseases.

Dual infection with Ehrlichia chaffeensis and a spotted fever group rickettsia: a case report

Well-documented cases of simultaneous human infection with more than one tick-borne pathogen are rare. To our knowledge only two dual infections have been reported: simultaneous human infection with the agent of human granulocytic ehrlichiosis and Borrelia burgdorferi and simultaneous human infection with B. burgdorferi and Babesia microti (1-2). Rocky Mountain spotted fever has long been known to be endemic in North Carolina; cases of human ehrlichial infection were recognized there soon after Ehrlichia chaffeensis was recognized as an important cause of tick-borne disease in the southeastern United States. Because both Rocky Mountain spotted fever and ehrlichiosis are prevalent in North Carolina, occasional cases of simultaneous human infection by rickettsial and ehrlichial agents would not be surprising; however, no such cases seem to have been reported.

Persisting impairment following Rocky Mountain Spotted Fever: a case report

A patient initially presented in the emergency room with fever, confusion, and a petechial rash. Rocky Mountain Spotted Fever (RMSF) was diagnosed and appropriate treatment was initiated. He subsequently became obtunded and required mechanical ventilation and temporary cardiac pacing. Four weeks later, he presented to our rehabilitation unit with ataxia, hyperreflexia and upper motor neuron signs, dysesthesias, sensorimotor axonopathy demonstrated by electrodiagnostic studies, and a global decrement in cognitive capability. Although he significantly improved in functional mobility and self-care, he exhibited little improvement in his cognitive impairment at 6-month follow-up. An understanding of the natural history of, and long-term impairments associated with, RMSF will be helpful to physiatrists in developing rehabilitation care plans and in assisting such patients with community re-entry.

Predictors of prognosis and risk of acute renal failure in patients with Rocky Mountain spotted fever

BACKGROUND

Acute renal failure has long been associated with severe Rocky Mountain spotted fever (RMSF). Despite many descriptions of the protean manifestations of this disease, relatively little is known concerning the risk factors for acute renal failure. Only a few studies have examined the outcome of patients infected with Rickettsia rickettsii who develop renal insufficiency, and these studies had methodological problems.

OBJECTIVE

To study the incidence, risk factors, and outcomes of acute renal failure in a large group of hospitalized patients with definite or probable RMSF.

METHODS

The clinical records of 114 patients with definite or probable RMSF were retrospectively reviewed to identify clinical and biochemical abnormalities at the time of admission that were associated with the development of acute renal failure and subsequent mortality. Renal failure was defined as a serum creatinine (Cr) above 2 mg/dL. Logistic regression was used to study the association between these variables and the outcomes during hospitalization: death and the development of acute renal failure.

RESULTS

The mortality rate in this series was 14%; 19% of the patients developed acute renal failure. The development of acute renal failure increased the odds ratio (OR) of dying by a factor of 17 (P = 0.001). Factors at the time of hospitalization that were associated at a univariate level with subsequent mortality included elevated serum Cr, increased age, increased level of AST, increased level of bilirubin, decreased serum sodium and platelet count, the presence of neurological involvement, and being male. Both the presence of neurological involvement and an elevated serum Cr at presentation were independently associated with increased mortality by multivariate analysis. Three patients developed acute renal failure that required hemodialysis, and only 1 of these 3 patients survived; he was ultimately discharged with a normal serum Cr. Factors at presentation that were associated with the development of acute renal failure included increased bilirubin, increasing age, thrombocytopenia, and the presence of neurological involvement. Both age and decreased platelet count at presentation were independently associated with the development of acute renal failure by multivariate analysis.

CONCLUSION

Acute renal failure was a frequent complication of RMSF in this series of patients from a tertiary referral medical center. The presence of acute renal failure was strongly associated with death. Clinical and biochemical variables are useful in predicting which patients will develop acute renal failure.

Guillain-Barré syndrome associated with Rocky Mountain spotted fever: case report and review

We report a case of Guillain-Barré syndrome (GBS) associated with Rocky Mountain spotted fever (RMSF). The patient initially presented with fever, rash, and an altered mental status, and he responded to therapy with intravenous doxycycline; serological data confirmed RMSF. Concurrent physical findings and results of cerebrospinal fluid analysis and nerve conduction studies were compatible with GBS. Although neurological complications of RMSF are common, no known associations between RMSF and GBS were found in the literature. An association between possible infection with Rickettsia conorii and GBS was reported in a French study in 1968. To our knowledge, this is the first reported association between RMSF and GBS.

Tissue factor mRNA expression in the endothelium of an intact umbilical vein

Tissue factor (TF) mRNA expression was measured by in situ hybridization in the endothelium of the intact human umbilical vein after infection with Rickettsia rickettsii. At 4 hours, R rickettsii organisms were clearly visible within approximately 70% of endothelial cells by immunocytochemical staining. Quantitation of TF mRNA expression revealed that the level within endothelial cells of the infected vein was significantly greater (3.7-fold, P < .0001) than that detected in uninfected endothelial cells. Serial sections of the umbilical cord vein were processed for in situ hybridization, and immunocytochemical staining and showed TF expression in those endothelial cells that contained R rickettsii organisms. Immunocytochemical staining for TF antigen at 6 hours was negative, but TF was clearly demonstrated within macrophages and fibroblasts of both control and infected umbilical cords. These studies demonstrate that the vascular endothelial cell, ex vivo, can be directly induced to express TF mRNA. This observation has not heretofore been clearly demonstrated except for in cultured endothelial cells. Since R rickettsii infection induces thrombotic vascular occlusions in patients with Rocky Mountain Spotted Fever, the results imply a potential role for endothelial cell TF in the pathogenesis of thrombotic disease.

Rocky Mountain spotted fever presenting with acute monarticular arthritis

This report describes a 30-year-old man who presented with an acute multisystem illness which was diagnosed as Rocky Mountain spotted fever (RMSF). Near the time of admission the patient was noted to have a newly developed aseptic monarticular arthritis of the right knee. The arthritis resolved in association with resolution of his systemic illness. To our knowledge, there have been no prior reports of acute arthritis in association with RMSF.

Long-term sequelae of Rocky Mountain spotted fever

Twenty-five patients with definite or probable Rocky Mountain spotted fever (RMSF) who were hospitalized for > or = 2 weeks were identified from our database of 105 patients. Follow-up information was collected for 20 patients, per telephone and/or medical records. The remaining five patients were lost to follow-up or died. Nine patients had > or = 1 long-term sequelae (defined as complications related to an original acute infection with Rickettsia rickettsii that persisted for > or = 1 year following hospital discharge). The ages of patients with sequelae ranged from 2 to 74 years (mean and median, 38 years); duration of follow-up ranged from 1 to 18 years (mean, 11 years). The mean lengths of hospitalization for patients with and without long-term sequelae were 47 days and 20 days, respectively (P < .05). Long-term neurological sequelae included paraparesis; hearing loss; peripheral neuropathy; bladder and bowel incontinence; cerebellar, vestibular, and motor dysfunction; and language disorders. Nonneurological sequelae consisted of disability from limb amputation and scrotal pain following cutaneous necrosis. These data suggest that significant long-term morbidity is common in patients with severe illness due to RMSF.

Persistence of rickettsiae in the partially viable gangrenous margins of amputated extremities 5 to 7 weeks after onset of Rocky Mountain spotted fever

A case of Rocky Mountain spotted fever complicated by gangrene of the extremities required amputation and showed persistent rickettsial infection in the margins of the gangrene at 5 and 7 weeks after onset of illness. Rickettsial organisms were demonstrated by immunoperoxidase staining in the viable endothelial cells in the ischemic margins of the gangrenous tissue. We conclude that the cellular, humoral, and pharmacologic components that lead to eradication of the rickettsiae were not delivered to the ischemic margins at effective antirickettsial concentrations.

Rocky Mountain spotted fever: a seasonal alert

Rocky Mountain spotted fever occurs during seasonal tick activity. A history of exposure to tick-containing habitats within the 3- to 12-day incubation period is a key epidemiological factor. The signs of fever, headache, myalgia, nausea, vomiting, and anorexia at onset of infection are difficult to distinguish from those of self-limited viral infections. Rash usually appears later and, if present, progresses through a sequence of stages and distribution that are never pathognomonic. The effects of disseminated Rickettsia rickettsii infection of endothelial cells include increased vascular permeability, edema, hypovolemia, hypotension, prerenal azotemia, and, in life-threatening cases, pulmonary edema, shock, acute tubular necrosis, and meningoencephalitis. In severe cases, fluid management is a challenge. The clinical diagnosis, which is difficult, is rarely assisted by laboratory findings because antibodies are usually detected only in convalescence, and immunohistologic methods for detection of rickettsiae are unavailable in most clinics. Doxycycline is the treatment of choice except for pregnant or allergic patients, who are treated with chloramphenicol.

Dermatologic manifestations of arthropod-borne diseases

The arthropod-borne rickettsial, borrelial, and bacterial diseases of North America are a diverse group of disorders that produce a wide variety of cutaneous abnormalities. These dermatologic abnormalities are often valuable clinical clues that may reveal or suggest the correct diagnosis to the astute clinician. We review the usual and unusual dermatologic manifestations of Rocky Mountain spotted fever, murine and sylvatic typhus, rickettsialpox, ehrlichiosis, Lyme disease, tick-borne relapsing fever, Colorado tick fever, and tularemia. In some of these diseases, skin manifestations may be diagnostic; in others, dermatologic findings may be the initial and only clues that leads to the initiation of life-saving therapy. In other arthropod-borne infections, the appearance or evolution of the skin rash may be characteristic enough to suggest the proper diagnosis.

Tick-borne infections. What starts as a tiny bite may have a serious outcome

Tick-borne illnesses are being reported increasingly often. Unlike Lyme disease, which tends to be indolent, Rocky Mountain spotted fever and ehrlichiosis can kill and so must be recognized and treated promptly. These diseases require clinical diagnosis, because laboratory confirmation with antibody tests takes too long. Tetracycline hydrochloride, doxycycline (Doryx, Vibramycin), or chloramphenicol (Chloromycetin) treatment is effective. Other diseases (eg, babesiosis, tularemia) are encountered occasionally and can also be fatal but are treatable with antibiotics.

Rocky Mountain spotted fever complicated by gangrene: report of six cases and review

Although mortality due to fulminant Rocky Mountain spotted fever (RMSF) is well appreciated, the ability of the disease to cause survivors to become permanently disabled is not as widely known. We report six cases of RMSF complicated by gangrene. Although four patients required multiple limb and/or digital amputations, only one death resulted. Our review of the English-language literature revealed 23 additional cases of RMSF complicated by gangrene. Pathophysiologically, gangrene is most likely related to small-vessel occlusion. Skin necrosis and gangrene in association with RMSF are the extreme end on a continuum from reversible to irreversible skin and tissue damage caused by Rickettsia rickettsii. Most patients with RMSF have a typical skin rash that resolves without sequelae. Some patients develop minute cicatrices marking the location of focal cutaneous necrosis; for other patients, digital ischemia occurs transiently or evolves to produce severe ischemic changes without gangrene that result in permanent impairment. At the far end of this clinical continuum are patients who develop gangrene requiring amputation.

Cutaneous signs of internal disease in the elderly

The elderly are prone to several systemic diseases that have their own particular cutaneous markers. These include pruritus, pigmentary changes, and the various manifestations associated with diabetes mellitus, among others. Physician recognition of the cutaneous signs of internal disorders will prompt early diagnosis and prompt treatment of the primary disease.

Rocky Mountain spotted fever. A clinical review based on 48 confirmed cases, 1943-1986

We reviewed 48 cases of Rocky Mountain spotted fever seen between 1943 and 1986. The data provided a view of the diverse presentations and manifestations of this disease. Exposure to a rural environment or to dogs was the rule, and over two-thirds of patients specifically remembered tick exposure. Clinical presentation was highly variable. Although fever, headache, and rash were each common, only 62% had the complete triad. Neurological symptoms and signs were common in this series. Cerebrospinal fluid abnormalities, particularly leukocytosis, were the rule in those patients who underwent lumbar puncture. Neurologic sequelae occurred in several patients. Multiple other organ systems were involved at presentation or during the course of illness--gastrointestinal, cardiovascular, pulmonary, renal, muscular, hematologic. These manifestations could, and often did, confuse physicians seeing these patients initially. They further accounted for the diverse complications seen. Outcome was good in this series. Mortality rate was 2%, and most patients recovered without sequelae. However, morbidity during hospitalization was often severe. Even in an endemic area with high index of suspicion, the diagnosis of RMSF was often delayed, usually because of failure of the physician to consider this possibility at initial presentation. This series emphasizes the importance of considering RMSF in any febrile patient in an endemic area, regardless of "atypical" presentation or apparent lack of tick exposure.

Ocular manifestations of Rocky Mountain spotted fever in dogs

Dogs were examined ophthalmoscopically to determine the prevalence and type of ocular lesions associated with naturally acquired Rocky Mountain spotted fever (RMSF). In a consecutive series of 11 dogs with serologically confirmed RMSF, 9 had ocular involvement reflecting various degrees of vascular damage, including subconjunctival hemorrhage, hyphema, anterior uveitis, iris stromal hemorrhage, retinal petechiae, and focal areas of retinal edema and perivascular inflammatory cell infiltrate. The ophthalmic lesions generally were mild, and most resolved without complication after systemic administration of appropriate antibiotics. The high prevalence of ocular lesions in these dogs suggested that critical ophthalmologic evaluation is a useful diagnostic tool for the early detection and management of RMSF in dogs.

Meningoencephalitis as a major manifestation of Rocky Mountain spotted fever

Although our two patients had very different courses, both illustrate the gravity of rickettsial meningoencephalitis. The presence of neurologic signs and symptoms is ominous and should be recognized as a possible manifestation of Rocky Mountain spotted fever. A high index of suspicion for RMSF needs to be maintained in patients with an acute febrile illness, especially in endemic areas, even during periods other than "tick season," and in patients without a rash.