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Rickettsia rickettsii is a Gram-negative, intracellular, cocco-bacillus bacterium that was first discovered in 1902. [1] Having a reduced genome, the bacterium harvests nutrients from its host cell to carry out respiration, making it an organo-heterotroph.
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).
Rickettsia rickettsii (red dots) in the cell of a deer tick Scientific classification; Domain: Bacteria: Phylum: Pseudomonadota: Class: Alphaproteobacteria: Order: Rickettsiales: Family: Rickettsiaceae Pinkerton 1936 (Approved Lists 1980) Tribes and genera "Candidatus Arcanobacter" Martijn et al. 2015 "Candidatus Cryptoprodota" corrig ...
They are obligate intracellular parasites, and some are notable pathogens, including Rickettsia, which causes a variety of diseases in humans, and Ehrlichia, which causes diseases in livestock. Another genus of well-known Rickettsiales is the Wolbachia , which infect about two-thirds of all arthropods and nearly all filarial nematodes. [ 2 ]
Rickettsia rickettsii can be transmitted to human hosts through the bite of an infected tick. As with other bacterium transmitted via ticks, the process generally requires a period of attachment of 4 to 6 hours. However, in some cases a Rickettsia rickettsii infection has been contracted by contact with tick tissues or fluids. [19]
Examples of obligate intracellular bacteria include Rickettsia prowazekii and Rickettsia rickettsii, (Rocky Mountain spotted fever). [citation needed] Chlamydia are intracellular parasites. These pathogens can cause pneumonia or urinary tract infection and may be involved in coronary heart disease. [12]
Rickettsialpox - caused by Rickettsia akari, this disease is transmitted by mite bites and is generally milder than other rickettsial infections. Rocky Mountain spotted fever - caused by Rickettsia rickettsii, this disease is transmitted by tick bites and is prevalent in the Americas.
However, scrub typhus is still considered a rickettsiosis, even though the causative organism has been reclassified from Rickettsia tsutsugamushi to Orientia tsutsugamushi. [ citation needed ] Examples of rickettsioses include typhus , both endemic and epidemic, Rocky Mountain spotted fever , and Rickettsialpox .