Family cluster of Rocky Mountain spotted fever.
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Soon after a patient from Tennessee died of Rocky Mountain spotted fever (RMSF), several family members developed symptoms suggestive of the disease and were treated presumptively for RMSF. Fifty-four persons visiting the index patient's home were interviewed; serum samples were collected from 35. Three additional cases of RMSF were confirmed, all of which occurred in first-degree relatives. Time spent at the family home and going into the surrounding woods were significantly associated with developing antibodies to Rickettsia rickettsii. Ticks were collected and examined for rickettsiae by polymerase chain reaction analysis. Because hyperendemic foci and family clusters of RMSF can occur, when a case is suspected clinicians should be vigilant for signs and symptoms consistent with R. rickettsii infection in other persons who may have been similarly exposed. (+info)
Consequences of delayed diagnosis of Rocky Mountain spotted fever in children--West Virginia, Michigan, Tennessee, and Oklahoma, May-July 2000.
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Patients with Rocky Mountain spotted fever (RMSF), a tickborne infection caused by Rickettsia rickettsii, respond quickly to tetracycline-class antibiotics (e.g., doxycycline) when therapy is started within the first few days of illness; however, untreated RMSF may result in severe illness and death. Persons aged <10 years have the highest age-specific incidence of RMSF. This report summarizes the clinical course and outcome of RMSF in four children from four regions of the United States and underscores the need for clinicians throughout the United States to consider RMSF in children with rash and fever, particularly those with a history of tick bite or who present during April-September when approximately 90% of RMSF cases occur. (+info)
Incidence of Rocky Mountain spotted fever among American Indians in Oklahoma.
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OBJECTIVE: Although the state of Oklahoma has traditionally reported very high incidence rates of Rocky Mountain spotted fever (RMSF) cases, the incidence of RMSF among the American Indian population of the state has not been studied. The authors used data from several sources to estimate the incidence of RMSF among American Indians in Oklahoma. METHODS: The authors retrospectively reviewed an Indian Health Service (IHS) hospital discharge database for 1980-1996 and available medical charts from four IHS hospitals. The authors also reviewed RMSF case report forms submitted to the Centers for Disease Control and Prevention (CDC) for 1981-1996. RESULTS: The study data show that American Indians in the IHS Oklahoma City Area were hospitalized with RMSF at an annual rate of 48.2 per million population, compared with an estimated hospitalization rate of 16.9 per million Oklahoma residents. The majority of cases in the IHS database (69%) were diagnosed based on clinical suspicion rather than laboratory confirmation. The incidence of RMSF for Oklahoma American Indians as reported to the CDC was 37.4 cases per million, compared with 21.6 per million for all Oklahoma residents (RR 1.7, 95% confidence interval [CI] 1.5, 2.1). CONCLUSIONS: Rates derived from the IHS database may not be comparable to state and national rates because of differences in case inclusion criteria. However, an analysis of case report forms indicates that American Indians n Oklahoma have a significantly higher incidence of RMSF than that of the overall Oklahoma population. Oklahoma American Indians may benefit from educationa campaigns emphasizing prevention of tick bites and exposure to tick habitats. (+info)
Rocky Mountain spotted fever in the United States, 1993-1996.
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During 1993 through 1996, 2,313 cases of Rocky Mountain spotted fever (RMSF) were reported to the Centers for Disease Control and Prevention (CDC) by 42 states and the District of Columbia through the National Electronic Telecommunications System for Surveillance (NETSS). During this same interval, 1,752 case report forms (CRFs) were submitted to CDC and 1,253 (70%) of the cases were categorized as confirmed RMSF by laboratory testing. On the basis of analyses performed with NETSS data, the average annual RMSF incidence during 1993-1996 was 2.2 cases per million persons; the incidence rose from 1.8 in 1993 to 3.3 per million persons in 1996. Incidence for confirmed cases was highest among children 5-9 years of age (3.7 per million) and lowest among individuals older than 70 years of age (1.4 per million). The south Atlantic region accounted for the largest proportion of confirmed cases (52%). The case-fatality rate was highest among persons 70 years of age and older (9.0%) and lowest among adults 40-49 years of age (0.6%). (+info)
Exposure of guinea pigs to Rickettsia rickettsii by aerosol, nasal, conjunctival, gastric, and subcutaneous routes and protection afforded by an experimental vaccine.
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Guinea pigs were inoculated with Rocky Mountain spotted fever by the aerosol, conjunctival, subcutaneous, intragastric, and intranasal routes. Rickettsial infection was produced by all routes except intragastric. All animals with clinical signs of disease developed agglutinating antibody, and most developed a cell-mediated immune response. Disease produced by all experimental routes (except intragastric) was indistinguishable. The tissue culture-derived inactivated vaccine produced in this laboratory protected guinea pigs against an aerosol challenge. (+info)
Natural infection of dogs on Cape Cod with Rickettsia rickettsii.
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Four isolates of rickettsiae from sick dogs on Cape Cod, Mass., were serologically identical to isolates of Rickettsia rickettsii from human patients with Rocky Mountain spotted fever. The antigenic analysis used the indirect fluorescent-antibody test and antisera prepared in mice to each of the isolates and to reference strains of R. rickettsii and Rickettsia montana. Serological responses of infected dogs were specific for R. rickettsii, although antibodies to R. montana were also detected in the sera of most of the canines. (+info)
Tick-borne diseases.
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Tick-borne diseases are the most common vector-borne illnesses in the United States. Lyme disease is the most common, but several others also occur. The ehrlichioses have only been identified as agents of human disease in the United States in the past few decades, and knowledge about them is still evolving. Rocky Mountain spotted fever is relatively common and can be severe, especially in children, if the diagnosis is not made quickly. Tularemia has long been known to cause disease in humans, but there is renewed interest because of its potential as a biologic warfare agent. These diseases can be severe or even fatal. Most of them are easily treatable when identified early. These diseases result from a variety of infectious agents including bacteria, rickettsia, viruses and protozoa, or they may be caused by substances produced by the tick. Most of these diseases present initially with nonspecific symptoms and are often difficult to recognize. Few definitive diagnostic tests are available. Therefore, knowledge of the epidemiology and common presentations, as well as the diagnostic options and treatments available, are important issues for family physicians. (+info)
Spotted fever in Brazil: a seroepidemiological study and description of clinical cases in an endemic area in the state of Sao Paulo.
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During 1985-1995, illnesses clinically and epidemiologically compatible with Brazilian spotted fever were identified in 17 patients in the county of Pedreira, in the state of Sao Paulo, Brazil. Spotted-fever group rickettsial infection was confirmed by serology and/or immunostaining of tissues in 10 of these patients. Immunostaining confirmed infection in a 37-year-old pregnant patient, although rickettsial antigens were not demonstrable in the tissues of the fetus. A serosurvey was conducted in four localities in the county to determine the prevalence of subclinical or asymptomatic infections with spotted fever group rickettsiae. Five hundred and twenty-five blood samples were tested by an indirect immunofluorescence assay for antibodies reactive with Rickettsia rickettsii. Twenty-two (4.2%) of these samples demonstrated titers > or = 1:64. The results indicate that Brazilian spotted fever is endemic within this region of Brazil. (+info)