Rocky Mountain Spotted Fever: Epidemiology of an Increasing Problem

Hattwick, Michael A. W.

doi:10.7326/0003-4819-84-6-732

Cited by 124 publications

(44 citation statements)

References 13 publications

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“…Comparisons of strain virulence must also be considered in the context of various recognized, and possibly other, as-yet-unidentified host factors that affect the severity of RMSF. 34 Patients who are 40 years of age and African-American males with glucose-6-phosphate dehydrogenase deficiency have consistently higher casefatality rates 34,[42][43][44][45] ; however, neither of these cohorts were represented disproportionately in our series. In fact, among United States case-patients, significantly more young children and fewer persons 40 were represented when compared with national surveillance statistics for fatal RMSF in the United States during 1983-2007.…”

Section: 41mentioning

confidence: 83%

“…42,52 The United States case-fatality rates for RMSF diminished considerably during the second half of the 20th century as physicians discovered effective antibiotic therapies and supportive medical treatment of this disease 43 ; since 1995, fewer than 10 fatal cases of RMSF have been reported annually in the United States. 24 Nonetheless, the actual burden of fatal RMSF remains difficult to assess, and contemporary estimates of the case-fatality rate are confounded by underreporting of laboratory-confirmed deaths.…”

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confidence: 99%

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Phylogeography of Rickettsia rickettsii Genotypes Associated with Fatal Rocky Mountain Spotted Fever

Paddock¹,

Denison²,

Lash³

et al. 2014

The American Society of Tropical Medicine and Hygiene

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Abstract. Rocky Mountain spotted fever (RMSF), a tick-borne zoonosis caused by Rickettsia rickettsii, is among the deadliest of all infectious diseases. To identify the distribution of various genotypes of R. rickettsii associated with fatal RMSF, we applied molecular typing methods to samples of DNA extracted from formalin-fixed, paraffin-embedded tissue specimens obtained at autopsy from 103 case-patients from seven countries who died of RMSF. Complete sequences of one or more intergenic regions were amplified from tissues of 30 (29%) case-patients and revealed a distribution of genotypes consisting of four distinct clades, including the Hlp clade, regarded previously as a non-pathogenic strain of R. rickettsii. Distinct phylogeographic patterns were identified when composite case-patient and reference strain data were mapped to the state and country of origin. The phylogeography of R. rickettsii is likely determined by ecological and environmental factors that exist independently of the distribution of a particular tick vector.

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Section: 41mentioning

confidence: 83%

mentioning

confidence: 99%

Phylogeography of Rickettsia rickettsii Genotypes Associated with Fatal Rocky Mountain Spotted Fever

Paddock¹,

Denison²,

Lash³

et al. 2014

The American Society of Tropical Medicine and Hygiene

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“…This has been shown in two previous studies in which persons without a recognized history of tick exposure regularly comprised 10-20% of the spotted fever cases. 22,23 Further work on the natural host(s), vectors, and isolation of rickettsiae may provide more insights into SFG rickettsiae in Malaysia.…”

Section: Resultsmentioning

confidence: 99%

Seroepidemiologic survey of Orientia tsutsugamushi, Rickettsia typhi, and TT118 spotted fever group rickettsiae in rubber estate workers in Malaysia.

Tee¹,

Kamalanathan²,

Suan³

et al. 1999

The American Journal of Tropical Medicine and Hygiene

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Abstract. The seroprevalence of Orientia tsutsugamushi, Rickettsia typhi, and TT118 spotted fever group (SFG) rickettsiae in 300 rubber estate workers in Slim River, Malaysia was determined in December 1996 and March 1997. In December, which was the wet season, 23.3%, 3.0%, and 57.3% of the population had antibodies detected against the three rickettsiae, respectively. The highest seropositive rate of 40% was detected for single infection with SFG rickettsiae, followed by a rate of 15.3% for both O. tsutsugamushi and SFG rickettsiae among the rubber estate workers. Subjects less than 21 years old had a lower seroprevalence of SFG rickettsiae compared with the other age groups. Indians had a higher seroprevalence of O. tsutsugamushi compared with other ethnic groups. Rubber tappers had a higher seroprevalence of SFG rickettsiae compared with other occupational groups. During the dry season in March 1997, there was a significant increase in the seroprevalence of R. typhi. The seroconversion rates for IgM against O. tsutsugamushi, R. typhi, and SFG rickettsiae were 5.7%, 12.3%, and 15.1%, respectively, during the fourmonth period. Significant variations of antibody titers towards the three rickettsiae was noted among subjects who were bled twice. This suggests a significant and continual exposure of rubber estate workers to the three rickettsiae.Rickettsial infections are major causes of febrile illnesses throughout the Asia-Pacific region. 1 The gram-negative, obligate intracellular bacteria that cause these infections are transmitted by arthropods and infect vertebrates. Rickettsiae can be grouped into three antigenically defined groups: scrub typhus, typhus, and spotted fever. Scrub typhus infection, which is caused by Orientia tsutsugamushi (previously known as Rickettsia tsutsugamushi), 2 is endemic in the western Pacific region and has been reported as the most frequent infection (19.3%) among febrile hospitalized patients in rural areas of Malaysia. 3 Murine typhus is caused by infection with a typhus group rickettsiae, Rickettsia typhi, and was once considered a sporadic and uncommon cause of illness in Malaysia. 4,5 However, in 1977, a high prevalence of this infection in the human and rodent population was reported. 6 The seroprevalence of spotted fever group (SFG) rickettsiae TT118 among febrile patients was 0.3% in Mentakab Hospital 3 and 16% in a study conducted in Sabah. 5 There is no information on the etiologic agent of tick typhus in Malaysia.In a serologic survey conducted in 1994-1995, it was shown that sera from a large proportion of febrile outpatients at a health center in Slim River, a small town located on the middle-northern west coast of Peninsular Malaysia, were reactive to antigens of O. tsutsugamushi, R. typhi, and SFG rickettsiae. 7 The majority of these patients were agricultural workers: mostly rubber tappers, oil palm plantation workers, and farmers. The objectives of the present study were to assess in more detail the seroprevalence of O. tsutsugamushi, R. typhi, and SFG rickettsia...

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“…Increasing age is followed by a higher fatality 33 , males have higher risk of dying than females despite the age group 10 and glucose 6-phosphate dehydrogenase (G6PD) deficiency, commonly identified in black individuals, seems related to severe and/or fatal disease. In the United States this deficiency affects approximately 12% of African-American males (CDC webpage).…”

Section: Discussionmentioning

confidence: 99%

Rickettsial spotted fever in capoeirão Village, Itabira, Minas Gerais, Brazil

Vianna

Horta

Sangioni

et al. 2008

Rev. Inst. Med. trop. S. Paulo

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SUMMARYThe present study investigated the infection by spotted fever rickettsia in an endemic area for Brazilian spotted fever (BSF; caused by Rickettsia rickettsii) in Minas Gerais State, Brazil. Human, canine and equine sera samples, and Amblyomma cajennense adult ticks collected in a rural area of Itabira City, Minas Gerais State were tested for rickettsial infection. Through Immunofluorescence Assay (IFA) we demonstrated the presence of antibodies anti-R. rickettsii in 8.2%, 81.3% and 100% of the human, canine and equine sera, respectively. None of the 356 tick specimens analyzed were positive for Rickettsia by the hemolymph test or Polymerase Chain Reaction technique (PCR) for the htrA and the gltA genes. Our serological results on horses and dogs (sentinels for BSF) appoint for the circulation of a SFG Rickettsia in the study area, however in a very low infection rate among the A. cajennense tick population.

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Rocky Mountain Spotted Fever: Epidemiology of an Increasing Problem

Cited by 124 publications

References 13 publications

Phylogeography of Rickettsia rickettsii Genotypes Associated with Fatal Rocky Mountain Spotted Fever

Phylogeography of Rickettsia rickettsii Genotypes Associated with Fatal Rocky Mountain Spotted Fever

Seroepidemiologic survey of Orientia tsutsugamushi, Rickettsia typhi, and TT118 spotted fever group rickettsiae in rubber estate workers in Malaysia.

Rickettsial spotted fever in capoeirão Village, Itabira, Minas Gerais, Brazil

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