Rickettsial Diseases

2017 ◽  
Author(s):  
Lisa Sun ◽  
Michael V. Johnston
Keyword(s):  
Endothelial Cells ◽  
Q Fever ◽  
Spotted Fever ◽  
The United States ◽  
Dermacentor Variabilis ◽  
Farm Animals ◽  
Spotted Fever Group ◽  
Rocky Mountain Spotted Fever ◽  
The World ◽  
The Brain

Tick-borne rickettsioses are emerging as more important health problems throughout the world. The spotted fever group including Rickettsia rickettsia can cause encephalopathy, meningitis and brain damage by selectively targeting capillary endothelial cells in the brain, and stimulating inflammation, capillary leakage, hemorrhage, and intravascular coagulation. Rickettsia are are arthropod-borne gram-negative coccobacilli bacteria and are obligate intracellular organisms that do not survive in artificial medium. In North and South America, the most common rickettsial disorder is rocky mountain spotted fever (RMSF) transmitted by the dog tick Dermacentor variabilis or the wood tick Dermacentor andersoni. A characteristic “starry sky” pattern can be seen on MRI imaging of the brain in some patients with RMSF encephalopathy and is thought to reflect the organisms targeting of brain endothelial cells in capillaries the white matter. Early treatment with doxycycline is curative and reverses signs of encephalopathy if given within a few day of onset, but delayed treatment can be associated with permanent neurological disability. The typhus group of rickettsia bacteria include R. prowazekii, which causes epidemic typhus and R. typhi, which causes murine typhus (endemic) typhus in tropical and subtropical parts of the world. Flying squirrels and humans carry R prowazekii and rats are carry R. typhi. Q fever caused by the rickettsia organism Coxiella burnetti is transmitted from farm animals including sheep and is seen throughout the world including the United States.

scholarly journals Dermacentor variabilis is the Predominant Dermacentor spp. (Acari: Ixodidae) Feeding on Dogs and Cats Throughout the United States

2021 ◽  
Author(s):  
Kathryn T Duncan ◽  
Meriam N Saleh ◽  
Kellee D Sundstrom ◽  
Susan E Little
Keyword(s):  
United States ◽  
Spotted Fever ◽  
Rocky Mountain ◽  
The United States ◽  
Dermacentor Variabilis ◽  
Western United States ◽  
Its2 Region ◽  
Rrna Gene ◽  
Rocky Mountain Spotted Fever ◽  
Dermacentor Albipictus

Abstract Throughout North America, Dermacentor spp. ticks are often found feeding on animals and humans, and are known to transmit pathogens, including the Rocky Mountain spotted fever agent. To better define the identity and distribution of Dermacentor spp. removed from dogs and cats in the United States, ticks submitted from 1,457 dogs (n = 2,924 ticks) and 137 cats (n = 209 ticks) from veterinary practices in 44/50 states from February 2018-January 2020 were identified morphologically (n = 3,133); the identity of ticks from regions where Dermacentor andersoni (Stiles) have been reported, and a subset of ticks from other regions, were confirmed molecularly through amplification and sequencing of the ITS2 region and a 16S rRNA gene fragment. Of the ticks submitted, 99.3% (3,112/3,133) were Dermacentor variabilis (Say), 0.4% (12/3,133) were D. andersoni, and 0.3% (9/3,133) were Dermacentor albipictus (Packard). While translocation of pets prior to tick removal cannot be discounted, the majority (106/122; 87%) of Dermacentor spp. ticks removed from dogs and cats in six Rocky Mountain states (Montana, Idaho, Wyoming, Nevada, Utah, and Colorado) were D. variabilis, suggesting this species may be more widespread in the western United States than is currently recognized, or that D. andersoni, if still common in the region, preferentially feeds on hosts other than dogs and cats. Together, these data support the interpretation that D. variabilis is the predominant Dermacentor species found on pets throughout the United States, a finding that may reflect recent shifts in tick distribution.

scholarly journals Significant Growth by Rickettsia Species within Human Macrophage-Like Cells Is a Phenotype Correlated with the Ability to Cause Disease in Mammals

Pathogens ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 228
Author(s):  
M. Nathan Kristof ◽  
Paige E. Allen ◽  
Lane D. Yutzy ◽  
Brandon Thibodaux ◽  
Christopher D. Paddock ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Spotted Fever ◽  
Growth Characteristic ◽  
Human Macrophage ◽  
Rickettsia Conorii ◽  
Spotted Fever Group ◽  
Rocky Mountain Spotted Fever ◽  
Phagocytic Cells ◽  
Pathogenic Potential ◽  
Rickettsia Species

Rickettsia are significant sources of tick-borne diseases in humans worldwide. In North America, two species in the spotted fever group of Rickettsia have been conclusively associated with disease of humans: Rickettsia rickettsii, the causative agent of Rocky Mountain spotted fever, and Rickettsia parkeri, the cause of R. parkeri rickettsiosis. Previous work in our lab demonstrated non-endothelial parasitism by another pathogenic SFG Rickettsia species, Rickettsia conorii, within THP-1-derived macrophages, and we have hypothesized that this growth characteristic may be an underappreciated aspect of rickettsial pathogenesis in mammalian hosts. In this work, we demonstrated that multiple other recognized human pathogenic species of Rickettsia, including R. rickettsii, R. parkeri, Rickettsia africae, and Rickettsiaakari can grow within target endothelial cells as well as within PMA-differentiated THP-1 cells. In contrast, Rickettsia bellii, a Rickettsia species not associated with disease of humans, and R. rickettsii strain Iowa, an avirulent derivative of pathogenic R. rickettsii, could invade both cell types but proliferate only within endothelial cells. Further analysis revealed that similar to previous studies on R. conorii, other recognized pathogenic Rickettsia species could grow within the cytosol of THP-1-derived macrophages and avoided localization with two different markers of lysosomal compartments; LAMP-2 and cathepsin D. R. bellii, on the other hand, demonstrated significant co-localization with lysosomal compartments. Collectively, these findings suggest that the ability of pathogenic rickettsial species to establish a niche within macrophage-like cells could be an important factor in their ability to cause disease in mammals. These findings also suggest that analysis of growth within mammalian phagocytic cells may be useful to predict the pathogenic potential of newly isolated and identified Rickettsia species.

Infections due to Rickettsia and Related Organisms

2017 ◽  
Author(s):  
Lucas S Blanton
Keyword(s):  
Q Fever ◽  
Spotted Fever ◽  
Dynamic Change ◽  
Clinical Manifestations ◽  
Rocky Mountain ◽  
Febrile Illness ◽  
American Southwest ◽  
Diagnostic Methods ◽  
Spotted Fever Group ◽  
Rocky Mountain Spotted Fever

Infections caused by organisms of the genus Rickettsia, Orientia, Ehrlichia, Anaplasma, and Coxiella occur throughout the world and are important, yet often overlooked, causes of febrile illness. They are transmitted by ticks, lice, mites, fleas, and, in the case of Coxiella, infected aerosols. Some are considered emerging and reemerging infectious diseases, as exemplified by the emergence of Rocky Mountain spotted fever in the American Southwest and Mexico; the reemergence of murine typhus in parts of Texas; and the discovery of new pathogens, such as Ehrlichia muris–like agent. Manifestations are usually of an acute undifferentiated febrile illness, with associated headache, malaise, myalgias, and varying frequency of rash. Since confirmation of diagnosis is often retrospective, requiring the dynamic change in antibody titers from acute and convalescent phase sera, clinical recognition for empirical treatment is imperative. Indeed, timely treatment is effective at abating symptoms and preventing complications. This review discusses important aspects of the epidemiology, clinical manifestations, diagnostic methods, and treatment of infections caused by Rickettsia and related organisms.  This review contains 5 figures, 9 tables, and 50 references. Key words: anaplasmosis, ehrlichiosis, Q fever, Rocky Mountain spotted fever, scrub typhus, spotted fever group rickettsioses, typhus group rickettsioses

scholarly journals Molecular Detection of Spotted Fever Group Rickettsiae (Rickettsiales: Rickettsiaceae) in Dermacentor variabilis (Acari: Ixodidae) Collected Along the Platte River in South Central Nebraska

2019 ◽  
Vol 57 (2) ◽  
pp. 519-523
Author(s):  
Brandon E Luedtke ◽  
Julie J Shaffer ◽  
Estrella Monrroy ◽  
Corey W Willicott ◽  
Travis J Bourret
Keyword(s):  
Spotted Fever ◽  
Rocky Mountain ◽  
Dermacentor Variabilis ◽  
Amblyomma Americanum ◽  
Spotted Fever Group ◽  
Rocky Mountain Spotted Fever ◽  
Rickettsia Species ◽  
Platte River ◽  
Rickettsia Rickettsii ◽  
South Central

Abstract Dermacentor variabilis is the predominant tick species in Nebraska and is presumed to be the primary vector of Rickettsia rickettsii associated with cases of Rocky Mountain spotted fever (RMSF). Interestingly, RMSF cases in Nebraska have increased on a year-to-year basis, yet the prevalence of R. rickettsii in D. variabilis ticks has not been established for Nebraska. Here we sought to set a baseline for the prevalence of R. rickettsii and other spotted fever group (SFG) rickettsiae harbored by D. variabilis ticks. Over a 3-yr period, D. variabilis were collected along the Platte River in south central Nebraska. Individual tick DNA was analyzed using endpoint PCR to identify ticks carrying SFG rickettsiae. In total, 927 D. variabilis were analyzed by PCR and 38 (4.1%) ticks tested positive for SFG rickettsiae. Presumptive positives were sequenced to identify the Rickettsia species, of which 29 (76%) were R. montanensis, 5 (13%) were R. amblyommatis, 4 (11%) were R. bellii, and R. rickettsii was not detected. These data indicate that R. rickettsii is likely at a low prevalence in south central Nebraska and spillover of R. amblyommatis into D. variabilis is likely occurring due to the invasive lone star tick (Amblyomma americanum). In addition, our data suggest that R. montanensis and R. amblyommatis could be associated with the increase in SFG rickettsiae infections in Nebraska. This information will be of value to clinicians and the general public for evaluating diagnosis of disease- and risk-associated environmental exposure, respectively.

Rickettsial infection

2018 ◽  
Author(s):  
Tom Fletcher ◽  
Nick Beeching
Keyword(s):  
Q Fever ◽  
Spotted Fever ◽  
Rocky Mountain ◽  
Blood Feeding ◽  
Spotted Fever Group ◽  
Rocky Mountain Spotted Fever ◽  
Obligate Intracellular ◽  
Rickettsia Rickettsii ◽  
Rickettsial Infections ◽  
The Us

Rickettsial infections are caused by a variety of obligate intracellular, Gram-negative bacteria from the genera Rickettsia, Orientia, Ehrlichia, and Anaplasma. Rickettsia is further subdivided into the spotted fever group and the typhus group. Bartonella and Coxiella burnetii bacteria are similar to rickettsiae and cause similar diseases. The range of recognized spotted fever group infections is rapidly expanding, complementing long-recognized examples such as Rocky Mountain spotted fever (Rickettsia rickettsii) in the US, and Australian tick typhus (Rickettsia australis), as well as those in southern Europe and Africa. Animals are the predominant reservoir of infection, and transmission to people is usually through ticks, mites, fleas, or lice, during blood-feeding or from scarification of faeces deposited on the skin. This chapter focuses on the two of the most relevant infections encountered in UK practice: African tick typhus, and Q fever.

scholarly journals New Tick Defensin Isoform and Antimicrobial Gene Expression in Response to Rickettsia montanensis Challenge

2007 ◽  
Vol 75 (4) ◽  
pp. 1973-1983 ◽  
Author(s):  
Shane M. Ceraul ◽  
Sheila M. Dreher-Lesnick ◽  
Joseph J. Gillespie ◽  
M. Sayeedur Rahman ◽  
Abdu F. Azad
Keyword(s):  
Gene Expression ◽  
Phylogenetic Analyses ◽  
Spotted Fever ◽  
Expression Patterns ◽  
Dermacentor Variabilis ◽  
Etiologic Agent ◽  
Gene Expression Patterns ◽  
Spotted Fever Group ◽  
Hard Tick ◽  
Rocky Mountain Spotted Fever

ABSTRACT Recent studies aimed at elucidating the rickettsia-tick interaction have discovered that the spotted fever group rickettsia Rickettsia montanensis, a relative of R. rickettsii, the etiologic agent of Rocky Mountain spotted fever, induces differential gene expression patterns in the ovaries of the hard tick Dermacentor variabilis. Here we describe a new defensin isoform, defensin-2, and the expression patterns of genes for three antimicrobials, defensin-1 (vsnA1), defensin-2, and lysozyme, in the midguts and fat bodies of D. variabilis ticks that were challenged with R. montanensis. Bioinformatic and phylogenetic analyses of the primary structure of defensin-2 support its role as an antimicrobial. The tissue distributions of the three antimicrobials, especially the two D. variabilis defensin isoforms, are markedly different, illustrating the immunocompetence of the many tissues that R. montanensis presumably invades once acquired by the tick. Antimicrobial gene expression patterns in R. montanensis-challenged ticks suggest that antimicrobial genes play a role during the acquisition-invasion stages in the tick.

scholarly journals Detection of Rickettsiae, Borreliae, and Ehrlichiae in Ticks Collected from Walker County, Texas, 2017–2018

Insects ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 315 ◽  
Author(s):  
Nicole L. Mendell ◽  
Erin S. Reynolds ◽  
Lucas S. Blanton ◽  
Meghan E. Hermance ◽  
Andres F. Londoño ◽  
...  
Keyword(s):  
Ixodes Scapularis ◽  
Spotted Fever ◽  
The United States ◽  
Dermacentor Variabilis ◽  
Amblyomma Americanum ◽  
Molecular Evidence ◽  
Spotted Fever Group ◽  
Questing Ticks ◽  
Report Data ◽  
Spotted Fever Group Rickettsia

Cases of tick-borne diseases, including spotted fever rickettsioses, borreliosis, babesiosis, anaplasmosis and ehrlichiosis, in the United States and territories have more than doubled from 2004 to 2016 and account for 77% of all vector-borne disease reports. In an effort to inform control efforts, the presence of tick-borne pathogens and their vectors was assessed in a recreational park in Walker County, Texas. Here we report data from questing ticks collected on three dates from June 2017 to June 2018. The majority of ticks collected were Amblyomma americanum (96.69%) followed by three additional tick species: Dermacentor variabilis (2.59%), Ixodes scapularis (0.52%), and A. maculatum (0.21%). Ticks were pooled and tested for molecular evidence of bacterial and viral pathogens, respectively. All of the 68 pools of A. americanum had molecular evidence of the spotted fever group rickettsia, Rickettsia amblyommatis. Additionally, six (8.82%) of the A. americanum pools contained sequences matching Ehrlichia chaffeensis, the pathogen responsible for human monocytotropic ehrlichiosis, and 11 (16.18%) for E. ewingii. Three of the A. americanum pools demonstrated evidence of Borrelia lonestari. The presence of etiologic agents of known human disease in this study merits the continued surveillance efforts of ticks and their pathogens in areas where they could pose risks to public health.

Spotted fever group rickettsiae in immature and adult ticks (Acari: Ixodidae) from a focus of Rocky Mountain spotted fever in Connecticut

1985 ◽  
Vol 31 (12) ◽  
pp. 1131-1135 ◽  
Author(s):  
Louis A. Magnarelli ◽  
John F. Anderson ◽  
Willy Burgdorfer ◽  
Robert N. Philip ◽  
W. Adrian Chappell
Keyword(s):  
Spotted Fever ◽  
Fluorescent Antibody ◽  
Rocky Mountain ◽  
Dermacentor Variabilis ◽  
Etiologic Agent ◽  
Ixodid Ticks ◽  
Spotted Fever Group ◽  
Rocky Mountain Spotted Fever ◽  
Serum Samples ◽  
Rickettsia Rickettsii

Immature and adult ixodid ticks were collected during 1983 and 1984 in Newtown, Connecticut, an area endemic for Rocky Mountain spotted fever (RMSF), to determine prevalence of infection by spotted fever group (SFG) rickettsiae. Direct fluorescent-antibody (FA) staining revealed SFG organisms in 6 (1.8%) of 332 Dermacentor variabilis larvae, 5 (7.8%) of 64 D. variabilis nymphs, and in 2 (40%) of 5 Ixodes cookei nymphs removed from small- and medium-sized mammals. Hemolymph tests detected rickettsia-like organisms in 15 (8.8%) of 170 D. variabilis adults; 8 specimens retested by direct FA were negative. In contrast, hemocytes from 5 (8.6%) of 58 Ixodes texanus females contained organisms that stained positively in both hemolymph and direct FA tests. An indirect microimmunofluorescence test identified specific antibodies to Rickettsia rickettsii, the etiologic agent of RMSF, in serum samples from a chipmunk, raccoons, and white-footed mice. Results indicate that immature or adult ticks of at least three species may be involved in the maintenance and transmission of SFG rickettsiae at Newtown.

Mosquito and Tick-borne Illnesses in the United States. Guidelines for the Recognition and Empiric Treatment of Zoonotic Diseases in the Wilderness.

2019 ◽  
Vol 19 (3) ◽  
pp. 238-257
Author(s):  
Suresh Antony
Keyword(s):  
United States ◽  
Lyme Disease ◽  
Spotted Fever ◽  
Disease Process ◽  
Rocky Mountain ◽  
The United States ◽  
Health Care Facilities ◽  
Diagnostic Tools ◽  
Rocky Mountain Spotted Fever ◽  
Number Of Patients

Background:In the United States, tick-borne illnesses account for a significant number of patients that have been seen and treated by health care facilities. This in turn, has resulted in a significant morbidity and mortality and economic costs to the country.Methods:The distribution of these illnesses is geographically variable and is related to the climate as well. Many of these illnesses can be diagnosed and treated successfully, if recognized and started on appropriate antimicrobial therapy early in the disease process. Patient with illnesses such as Lyme disease, Wet Nile illness can result in chronic debilitating diseases if not recognized early and treated.Conclusion:This paper covers illnesses such as Lyme disease, West Nile illness, Rocky Mountain Spotted fever, Ehrlichia, Tularemia, typhus, mosquito borne illnesses such as enteroviruses, arboviruses as well as arthropod and rodent borne virus infections as well. It covers the epidemiology, clinical features and diagnostic tools needed to make the diagnosis and treat these patients as well.

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