What is the characteristic of Rickettsia?
The rickettsiae are rod-shaped or variably spherical, nonfilterable bacteria, and most species are gram-negative. They are natural parasites of certain arthropods (notably lice, fleas, mites, and ticks) and can cause serious diseases—usually characterized by acute, self-limiting fevers—in humans and other animals.
When was Rickettsia first described?
Simeon Burt Wolbach is credited for the first detailed description of the pathogenic agent that causes R. rickettsii in 1919. He clearly recognized it as an intracellular bacterium which was seen most frequently in endothelial cells.
What is Rickettsia Virus?
The rickettsiae are a diverse collection of obligately intracellular Gram-negative bacteria found in ticks, lice, fleas, mites, chiggers, and mammals. They include the genera Rickettsiae, Ehrlichia, Orientia, and Coxiella. These zoonotic pathogens cause infections that disseminate in the blood to many organs.
What is the structure of a 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 is the classification of Rickettsia?
AlphaproteobacteriaRickettsia / Class
Classification. The genus Rickettsia encompasses a large group of obligate intracellular, Gram-negative bacteria that fall under the family Rickettsiaceae, order Rickettsiales, class Alphaproteobacteria, phylum Proteobacteria.
What is the vector of Rickettsia typhi?
In the case of rickettsial typhi, the vectors are lice and fleas. The bacteria are transmitted via infected faeces that are either inhaled or rubbed into the skin/mucous membranes.
What is the classification of rickettsia?
Why is rickettsia a unique 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 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 are the three main groups of rickettsia?
Historically, Rickettsia were classified into three major groups based on serological characteristics, namely the ‘typhus group’, ‘spotted fever group’ and ‘scrub typhus group’.
What is Rickettsia typhi?
Rickettsia typhi (formerly R. mooseri ), a typhus group rickettsia, is the etiologic agent of murine or endemic typhus. Rickettsia typhi is transmitted primarily by the rat flea, Xenopsylla cheopis, although lice and mites are also potential vectors.
What is the etiologic agent of Rickettsia?
Authors: Max Maurin, M.D., Ph.D., Didier Raoult, M.D., Ph.D. Microbiology. Rickettsia species are gram negative, strictly intracellular bacilli that multiply within the cytosol of endothelial cells. Rickettsia typhi (formerly R. mooseri), a typhus group rickettsia, is the etiologic agent of murine or endemic typhus.
How does Rickettsia rickettsiae spread?
Rickettsia. Pathogenesis Rickettsia and Orientia species are transmitted by the bite of infected ticks or mites or by the feces of infected lice or fleas. From the portal of entry in the skin, rickettsiae spread via the bloodstream to infect the endothelium and sometimes the vascular smooth muscle cells.
What is murine typhus (endemic typhus)?
Murine (endemic) typhus is a rickettsial disease with a worldwide distribution. The etiologic agent, Rickettsia typhi, is harbored by rodents and transmitted to humans by fleas. The disease occurs in epidemics and may be clinically mild, although it can cause severe and fatal cases.