What is rickettsial Disease?
Rickettsial infections and related infections (such as anaplasmosis, ehrlichiosis, and Q fever) are caused by an unusual type of bacteria that can live only inside the cells of another organism. Most of these infections are spread through ticks, mites, fleas, or lice.
What is the classification of rickettsial infection?
Rickettsial Classification Rickettsia and Orientia are obligate-intracellular, Gram-negative bacteria primarily associated with arthropods. Historically, Rickettsia were classified into three major groups based on serological characteristics, namely the ‘typhus group’, ‘spotted fever group’ and ‘scrub typhus group’.
What are the characteristics of Rickettsia?
CHARACTERISTICS: Rickettsia rickettsii is an obligate intracellular alpha proteobacteria that belongs to the Rickettsiacae family(1,2,3). It is a small (0.2-0.5 µm by 0.2-0.3 µm) pleomorphic, gram-negative coccobacillus which multiplies by binary fission and has both DNA and RNA(1,2,3).
How is Rickettsia transmitted?
Most rickettsial organisms are transmitted by the bites or infectious fluids (such as feces) inoculated into the skins from ectoparasites such as fleas, lice, mites, and ticks. Inhaling bacteria or inoculating conjunctiva with infectious material may also result in infection.
How is rickettsial infection treated?
Treatment of Rickettsial Infections Rickettsial infections respond promptly to early treatment with the antibiotics doxycycline (preferred) or chloramphenicol. These antibiotics are given by mouth unless people are very sick. In such cases, antibiotics are given intravenously.
Is Ehrlichia a rickettsial disease?
Ehrlichiosis and anaplasmosis are caused by rickettsial-like bacteria. Ehrlichiosis is caused mainly by Ehrlichia chaffeensis; anaplasmosis is caused by Anaplasma phagocytophilum. Both are transmitted to humans by ticks. Symptoms resemble those of Rocky Mountain spotted fever except that a rash is much less common.
What is difference between Rickettsia and bacteria?
The rickettsia are bacteria which are obligate intracellular parasites. They are considered a separate group of bacteria because they have the common feature of being spread by arthropod vectors (lice, fleas, mites and ticks).
What is the structure of rickettsia?
The structure of the typical rickettsia is very similar to that of Gram-negative bacteria. The typical envelope consists of three major layers: an innermost cytoplasmic membrane, a thin electron dense rigid cell wall and an outer layer.
What causes rickettsia?
Rickettsiae and rickettsia-like bacteria are usually spread to people through the bites of ticks, mites, fleas, or lice that previously fed on an infected animal. Ticks, mites, fleas, and lice are called vectors because they spread (transmit) organisms that cause disease from one host to another.
What causes Rickettsia?
Rickettsia species cause Rocky Mountain spotted fever, rickettsialpox, other spotted fevers, epidemic typhus, and murine typhus.
What is Rickettsia Wikipedia?
Rickettsia is a genus of nonmotile, gram-negative, nonspore-forming, highly pleomorphic bacteria that may occur in the forms of cocci (0.1 μm in diameter), bacilli (1–4 μm long), or threads (up to about 10 μm long).
How did the bacteria Rickettsia get its name?
The term “rickettsia” has nothing to do with rickets (which is a deficiency disease resulting from lack of vitamin D ); the bacterial genus Rickettsia was named after Howard Taylor Ricketts, in honor of his pioneering work on tick-borne spotted fever.
What kind of animal transmits Rickettsia to humans?
Rickettsia species are transmitted by numerous types of arthropod, including chigger, ticks, fleas, and lice, and are associated with both human and plant disease.
What kind of tick is Rickettsia helvetica found in?
Rickettsia helvetica, previously known as the Swiss Agent, is a bacterium found in Dermacentor reticulatus and other ticks which has been implicated as a suspected but unconfirmed human pathogen.
How big is the genome of Rickettsia rickettsii?
R. rickettsii is shown to have a genome size of around 2,100 kb. This number was determined via pulsed-field gel electrophoresis. Since R. rickettsii needs a moving vector to contract the disease to a viable host it is more likely that this pathogen has moderately low virulence levels.
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