|Species group:||Typhus group|
(Wolbach and Todd, 1920) Philip, 1943
Rickettsia typhi is a species of infectious bacterium of the genus Rickettsia ; it is the causative agent of Murine typhus.
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, rods 1–4 μm long, or threads of up to about 10 μm long. 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 honour of his pioneering work on tick-borne spotted fever.
Murine typhus is a form of typhus transmitted by fleas, usually on rats. Murine typhus is an under-recognized entity, as it is often confused with viral illnesses. Most people who are infected do not realize that they have been bitten by fleas.
The genome is similar to that of Rickettsia prowazekii .
Rickettsia prowazekii is a species of gram-negative, alphaproteobacteria, obligate intracellular parasitic, aerobic Bacillus bacteria that is the etiologic agent of epidemic typhus, transmitted in the feces of lice. In North America, the main reservoir for R. prowazekii is the flying squirrel. R. prowazekii is often surrounded by a protein microcapsular layer and slime layer; the natural life cycle of the bacterium generally involves a vertebrate and an invertebrate host, usually an arthropod, typically the human body louse. A form of R. prowazekii that exists in the feces of arthropods remains stably infective for months. R. prowazekii also appears to be the closest free-living relative of mitochondria, based on genome sequencing.
Typhoid fever, also known simply as typhoid, is a bacterial infection due to Salmonella typhi that causes symptoms. Symptoms may vary from mild to severe and usually begin six to thirty days after exposure. Often there is a gradual onset of a high fever over several days; weakness, abdominal pain, constipation, headaches, and mild vomiting also commonly occur. Some people develop a skin rash with rose colored spots. In severe cases there may be confusion. Without treatment, symptoms may last weeks or months. Diarrhea is uncommon. Other people may carry the bacterium without being affected; however, they are still able to spread the disease to others. Typhoid fever is a type of enteric fever, along with paratyphoid fever.
Epidemic typhus is a form of typhus so named because the disease often causes epidemics following wars and natural disasters. The causative organism is Rickettsia prowazekii, transmitted by the human body louse.
The house mouse is a small mammal of the order Rodentia, characteristically having a pointed snout, large rounded ears, and a long and hairy tail. It is one of the most abundant species of the genus Mus. Although a wild animal, the house mouse has benefited significantly from associating with human habitation to the point that truly wild populations are significantly less common than the semi-tame populations near human activity.
Scrub typhus or bush typhus is a form of typhus caused by the intracellular parasite Orientia tsutsugamushi, a Gram-negative α-proteobacterium of family Rickettsiaceae first isolated and identified in 1930 in Japan.
Coxiella burnetii is an obligate intracellular bacterial pathogen, and is the causative agent of Q fever. The genus Coxiella is morphologically similar to Rickettsia, but with a variety of genetic and physiological differences. C. burnetii is a small Gram-negative, coccobacillary bacterium that is highly resistant to environmental stresses such as high temperature, osmotic pressure, and ultraviolet light. These characteristics are attributed to a small cell variant form of the organism that is part of a biphasic developmental cycle, including a more metabolically and replicatively active large cell variant form. It can survive standard disinfectants, and is resistant to many other environmental changes like those presented in the phagolysosome.
The Weil–Felix test is an agglutination test for the diagnosis of rickettsial infections. It was first described in 1916. By virtue of its long history and of its simplicity, it has been one of the most widely employed tests for rickettsia on a global scale, despite being superseded in many settings by more sensitive and specific diagnostic tests.
The Oriental rat flea, also known as the tropical rat flea, is a parasite of rodents, primarily of the genus Rattus, and is a primary vector for bubonic plague and murine typhus. This occurs when the flea has fed on an infected rodent and bites a human, although this flea can live on any warm blooded mammal.
A rickettsiosis is a disease caused by intracellular bacteria.
Orientia tsutsugamushi is a mite-borne bacterium belonging to the family Rickettsiaceae and is responsible for a disease called scrub typhus in humans. It is a natural and an obligate intracellular parasite of mites belonging to the family Trombiculidae. With a genome of only 2.4–2.7 Mb, it has the most repeated DNA sequences among bacterial genomes sequenced so far. The disease, scrub typhus, occurs when infected mite larvae accidentally bite humans. Primarily indicated by undifferentiated febrile illnesses, the infection can be complicated and often fatal.
Rickettsia conorii is a Gram-negative, obligate intracellular bacterium of the genus Rickettsia that causes human disease called Boutonneuse fever, Mediterranean spotted fever, Israeli tick typhus, Astrakhan spotted fever, Kenya tick typhus, Indian tick typhus, or other names that designate the locality of occurrence while having distinct clinical features. It is a member of the spotted fever group and the most geographically dispersed species in the group, recognized in most of the regions bordering on the Mediterranean Sea and Black Sea, Israel, Kenya, and other parts of North, Central, and South Africa, and India. The prevailing vector is the brown dog tick, Rhipicephalus sanguineus. The bacterium was isolated by Emile Brumpt in 1932 and named after A. Conor who, in collaboration with A. Bruch, provided the first description of boutonneuse fever in Tunisia in 1910.
Typhus, also known as typhus fever, is a group of infectious diseases that include epidemic typhus, scrub typhus and murine typhus. Common symptoms include fever, headache, and a rash. Typically these begin one to two weeks after exposure.
Typhus vaccines are vaccines developed to protect against typhus. As of 2017 they are not commercially available.
Rickettsia australis is a bacterium that causes a medical condition called Queensland tick typhus. The probable vectors are the tick species, Ixodes holocyclus and Ixodes tasmani. Small marsupials are suspected reservoirs of this bacterium.
Flying squirrel typhus is a condition characterized by a rash of early macules, and, later, maculopapules.
Rickettsia felis is a species of bacterium, the pathogen that causes cat-flea typhus in humans. In cats the disease is known as flea-borne spotted fever. Rickettsia felis also is regarded as the causative organism of many cases of illnesses generally classed as fevers of unknown origin in humans in Africa.
Rickettsia sibirica is a species of Rickettsia. This bacterium is the etiologic agent of North Asian tick typhus, which is also known as Siberian tick typhus. The ticks that transmit it are primarily various species of Dermacentor and Haemaphysalis.
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