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

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.

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 MORPHOLOGICAL STRUCTURE OF RICKETTSIAE

1943 ◽  
Vol 77 (4) ◽  
pp. 355-358 ◽  
Author(s):  
Harry Plotz ◽  
Joseph E. Smadel ◽  
Thomas F. Anderson ◽  
Leslie A. Chambers
Keyword(s):  
Vaccinia Virus ◽  
Q Fever ◽  
Spotted Fever ◽  
Morphological Structure ◽  
Rocky Mountain ◽  
Rocky Mountain Spotted Fever ◽  
Dense Granules ◽  
Endemic Typhus ◽  
Typhus Fever

The morphological structures of the rickettsiae of epidemic and endemic typhus fever, Rocky Mountain spotted fever, and Q fever are similar to one another and to certain bacteria. The rickettsial organisms in common with the elementary bodies of vaccinia virus and all bacteria would appear to have a limiting membrane which surrounds a substance that seems to be protoplasmic in nature; numbers of dense granules are embedded in the inner protoplasm.

RICKETTSIAL DISEASES OF ANIMALS TRANSMISSIBLE TO CHILDREN

PEDIATRICS ◽  
1958 ◽  
Vol 22 (2) ◽  
pp. 384-387
Author(s):  
Lauri Luoto
Keyword(s):  
Small Mammals ◽  
Q Fever ◽  
Natural Infection ◽  
Spotted Fever ◽  
Rocky Mountain ◽  
Amblyomma Americanum ◽  
Rocky Mountain Spotted Fever ◽  
Rickettsial Infections ◽  
Dog Tick ◽  
Rickettsial Diseases

BECAUSE rickettsial infections occur sporadically, pediatricians may not be as thoroughly familiar with them as they are with common diseases of children that are characterized by rash. Hence, the rickettsias are infrequently considered in the etiology of febrile exanthemas or fevers of undertermined origin. Rickettsial diseases of primary interest in this country are Rocky Mountain spotted fever, murine typhus, rickcttsialpox and Q fever. The agents causing these diseases exist as latent infections in arthropods and animals, and they are transmitted accidentally to man through well-defined channels of spread. An awareness of the epizootiology of rickettsial diseases in nature and of the means by which these agents are transmitted to man is helpful in establishing a diagnosis of a rickettsial disease. Therefore, salient features of the natural cycles of infection which may suggest a clinical diagnosis will be stressed, and characteristics of these diseases in children will be reviewed briefly. Rocky Mountain spotted fever is usually contracted during the spring or summer through the bite of an infected tick although infection also may be acquired by dermal contact with tissues of a crushed or improperly removed tick. The wood tick, Dermacentor andersoni, the dog tick, D. variabilis, and the lone-star tick, Amblyomma americanum, which are found, respectively, in the western, eastern, and southern United States are responsible for transmitting the organism to man. Natural infection with Rickettsia rickettsii in these species is maintained by transovarial passage of the agent and by the feeding of immature stages on infected small mammals. Environmental factors such as rainfall, temperature, food supply of small mammals, and prevalence of predators indirectly affect the abundance of ticks.

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