Spotted Fevers- Rickettsia
Clin Diagn Lab Immunol. 2001 July; 8(4): 788–796.
doi: 10.1128/CDLI.8.4.788-796.2001.
PMCID: PMC96144
Copyright © 2001, American Society for Microbiology
Quantitative Analyses of Variations in the Injury of Endothelial Cells Elicited by 11 Isolates of Rickettsia rickettsii
Marina E. Eremeeva,1* Gregory A. Dasch,2† and David J. Silverman1
ABSTRACT
Eleven isolates of spotted fever group rickettsiae from the blood of patients or ixodid ticks from North and South America were characterized. All isolates were identified as Rickettsia rickettsii using restriction fragment length polymorphism analysis of a 532-bp rOmpA gene fragment obtained by PCR.
The ability of the R. rickettsii isolates to elicit cytopathic effects and parameters of oxidative injury were examined in cultured human EA.hy 926 endothelial cells.
Cytopathic effects were determined by direct observation of infected cultures, by measuring the release of cytoplasmic lactate dehydrogenase (LDH), and by determination of intracellular pools of peroxide and reduced glutathione. Four biotypes of R. rickettsii were defined.
Group I included two highly cytopathic isolates from Montana, Bitterroot and Sheila Smith, and three isolates from Maryland, North Carolina, and Brazil.
These isolates rapidly damaged cells, released large amounts of cytoplasmic LDH, caused accumulation of intracellular peroxide, and depleted intracellular pools of reduced glutathione. Group II contained three isolates, two from Montana, Hlp#2 and Lost Horse Canyon, and an isolate from Colombia, which were similar to group I but caused either lower responses in LDH release or smaller changes in intracellular peroxide levels.
The group III isolates, Sawtooth from Montana and 84JG from North Carolina, caused lower cellular injury by all measures. Group IV isolate Price T from Montana was the least cytopathic and caused minimal alterations of all parameters measured.
Understanding the molecular basis for the varied cellular injury caused by different isolates of R. rickettsii may contribute to improved treatment of Rocky Mountain spotted fever and to the rapid identification of those isolates which are more likely to cause fulminant disease.
Continued at Link Bleow
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC96144/?tool=pubmed
Emerg Infect Dis. 1998 Apr–Jun; 4(2): 179–186.
PMCID: PMC2640117
Rickettsial pathogens and their arthropod vectors.
A. F. Azad and C. B. Beard
University of Maryland School of Medicine, Baltimore, USA.
A. F. Azad: aazad@umaryland.edu
This article has been cited by other articles in PMC.
Abstract
Rickettsial diseases, important causes of illness and death worldwide, exist primarily in endemic and enzootic foci that occasionally give rise to sporadic or seasonal outbreaks. Rickettsial pathogens are highly specialized for obligate intracellular survival in both the vertebrate host and the invertebrate vector.
While studies often focus primarily on the vertebrate host, the arthropod vector is often more important in the natural maintenance of the pathogen. Consequently, coevolution of rickettsiae with arthropods is responsible for many features of the host-pathogen relationship that are unique among arthropod-borne diseases, including efficient pathogen replication, long-term maintenance of infection, and transstadial and transovarial transmission.
This article examines the common features of the host-pathogen relationship and of the arthropod vectors of the typhus and spotted fever group rickettsiae.
Full Text
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2640117/pdf/9621188.pdf
Vector Borne Zoonotic Dis. 2010 Dec 13. [Epub ahead of print]
Infrequency of Rickettsia rickettsii in Dermacentor variabilis Removed from Humans, with Comments on the Role of Other Human-Biting Ticks Associated with Spotted Fever Group Rickettsiae in the United States.
Stromdahl EY, Jiang J, Vince M, Richards AL.
1 Entomological Sciences Program, U.S. Army Public Health Command , Aberdeen Proving Ground, Maryland.
Abstract
Abstract From 1997 to 2009, the Tick-Borne Disease Laboratory of the U.S. Army Public Health Command (USAPHC) (formerly the U.S. Army Center for Health Promotion and Preventive Medicine) screened 5286 Dermacentor variabilis ticks removed from Department of Defense (DOD) personnel, their dependents, and DOD civilian personnel for spotted fever group rickettsiae using polymerase chain reaction and restriction fragment length polymorphism analysis.
Rickettsia montanensis (171/5286 = 3.2%) and Rickettsia amblyommii (7/5286 = 0.1%) were detected in a small number of samples, but no ticks were found positive for Rickettsia rickettsii, the agent of Rocky Mountain spotted fever (RMSF) until May 2009, when it was detected in one D. variabilis male removed from a child in Maryland.
This result was confirmed by nucleotide sequence analysis of the rickettsial isolate and of the positive control used in the polymerase chain reaction, which was different from the isolate.
Lethal effects of rickettsiostatic proteins of D. variabilis on R. rickettsii and lethal effects of R. rickettsii infection on tick hosts may account for this extremely low prevalence. Recent reports of R. rickettsii in species Rhipicephalus sanguineus and Amblyomma americanum ticks suggest their involvement in transmission of RMSF, and other pathogenic rickettsiae have been detected in Amblyomma maculatum.
The areas of the U.S. endemic for RMSF are also those where D. variabilis exist in sympatry with populations of A. americanum and A. maculatum. Interactions among the sympatric species of ticks may be involved in the development of a focus of RMSF transmission.
On the other hand, the overlap of foci of RMSF cases and areas of A. americanum and A. maculatum populations might indicate the misdiagnosis as RMSF of diseases actually caused by other rickettsiae vectored by these ticks.
Further studies on tick vectors are needed to elucidate the etiology of RMSF.
PMID: 21142953 [PubMed - as supplied by publisher]
Spotted Fever Group- Army
Vector Borne Zoonotic Dis. 2010 Dec 13. [Epub ahead of print]
Infrequency of Rickettsia rickettsii in Dermacentor variabilis Removed from Humans, with Comments on the Role of Other Human-Biting Ticks Associated with Spotted Fever Group Rickettsiae in the United States.
Stromdahl EY, Jiang J, Vince M, Richards AL.
1 Entomological Sciences Program, U.S. Army Public Health Command , Aberdeen Proving Ground, Maryland.
Abstract
Abstract From 1997 to 2009, the Tick-Borne Disease Laboratory of the U.S. Army Public Health Command (USAPHC) (formerly the U.S. Army Center for Health Promotion and Preventive Medicine) screened 5286 Dermacentor variabilis ticks removed from Department of Defense (DOD) personnel, their dependents, and DOD civilian personnel for spotted fever group rickettsiae using polymerase chain reaction and restriction fragment length polymorphism analysis.
Rickettsia montanensis (171/5286 = 3.2%) and Rickettsia amblyommii (7/5286 = 0.1%) were detected in a small number of samples, but no ticks were found positive for Rickettsia rickettsii, the agent of Rocky Mountain spotted fever (RMSF) until May 2009, when it was detected in one D. variabilis male removed from a child in Maryland.
This result was confirmed by nucleotide sequence analysis of the rickettsial isolate and of the positive control used in the polymerase chain reaction, which was different from the isolate.
Lethal effects of rickettsiostatic proteins of D. variabilis on R. rickettsii and lethal effects of R. rickettsii infection on tick hosts may account for this extremely low prevalence.
Recent reports of R. rickettsii in species Rhipicephalus sanguineus and Amblyomma americanum ticks suggest their involvement in transmission of RMSF, and other pathogenic rickettsiae have been detected in Amblyomma maculatum.
The areas of the U.S. endemic for RMSF are also those where D. variabilis exist in sympatry with populations of A. americanum and A. maculatum. Interactions among the sympatric species of ticks may be involved in the development of a focus of RMSF transmission.
On the other hand, the overlap of foci of RMSF cases and areas of A. americanum and A. maculatum populations might indicate the misdiagnosis as RMSF of diseases actually caused by other rickettsiae vectored by these ticks. Further studies on tick vectors are needed to elucidate the etiology of RMSF.
PMID: 21142953 [PubMed - as supplied by publisher]
PLoS Pathog. 2007 Oct; 3(10): e116.
Published online 2007 Oct 26. doi: 10.1371/journal.ppat.0030116
PMCID: PMC2042005
PMID: 17967056
Surveillance of Arthropod Vector-Borne Infectious Diseases Using Remote Sensing Techniques: A Review
Satya Kalluri,* Peter Gilruth, David Rogers, and Martha Szczur
B. Brett Finlay, Editor
Author information Copyright and License information Disclaimer
University of British Columbia, Canada
* To whom correspondence should be addressed. E-mail: moc.noehtyar@irullak_aytas
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2042005/?tool=pubmed