This article needs additional citations for verification . (March 2015) (Learn how and when to remove this template message)
|Species group:||Typhus group|
da Rocha-Lima, 1916
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.
Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the gram-staining method of bacterial differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wall sandwiched between an inner cytoplasmic cell membrane and a bacterial outer membrane.
Alphaproteobacteria is a class of bacteria in the phylum Proteobacteria. Its members are highly diverse and possess few commonalities, but nevertheless share a common ancestor. Like all Proteobacteria, its members are gram-negative and some of its intracellular parasitic members lack peptidoglycan and are consequently gram variable.
An obligate parasite or holoparasite is a parasitic organism that cannot complete its life-cycle without exploiting a suitable host. If an obligate parasite cannot obtain a host it will fail to reproduce. This is opposed to a facultative parasite, which can act as a parasite but does not rely on its host to continue its life-cycle. Obligate parasites have evolved a variety of parasitic strategies to exploit their hosts. Holoparasites and some hemiparasites are obligate.
Henrique da Rocha Lima, a Brazilian doctor, discovered this bacterium in 1916. He named it after his colleague Stanislaus von Prowazek, who had died from typhus in 1915. Both Prowazek and Rocha Lima had been infected with typhus while studying its causative agent in a prison hospital in Hamburg, Germany. [ citation needed ] It is stained gram-negative.[ citation needed ]This bacterium lacks flagella and is aerobic.
Henrique da Rocha Lima was a Brazilian physician, pathologist and infectologist born in Rio de Janeiro. With his friend, Stanislaus von Prowazek, he described what would later be known as Rickettsia prowazekii, the pathogen of epidemic typhus. Rocha Lima named the organism after Prowazek and American bacteriologist Howard Taylor Ricketts (1871-1910).
Stanislaus Josef Mathias von Prowazek, Edler von Lanow, born Stanislav Provázek, was a Czech zoologist and parasitologist, who along with pathologist Henrique da Rocha Lima (1879-1956) discovered the pathogen of epidemic typhus.
Hamburg is the second-largest city in Germany with a population of over 1.8 million.
The genome of R. prowazekii is reduced, being about 1Mb in size and encoding 834 proteins.Some strains encode 866 proteins. That is, they do not encode all the proteins required to live on their own. Missing activities have to be provided by its host, a eukaryotic cell. For this reason, R. prowazekii has sometimes been regarded as a model for the intracellular bacterial ancestor of mitochondria.
The mitochondrion is a double-membrane-bound organelle found in most eukaryotic organisms. Some cells in some multicellular organisms may, however, lack them. A number of unicellular organisms, such as microsporidia, parabasalids, and diplomonads, have also reduced or transformed their mitochondria into other structures. To date, only one eukaryote, Monocercomonoides, is known to have completely lost its mitochondria. The word mitochondrion comes from the Greek μίτος, mitos, "thread", and χονδρίον, chondrion, "granule" or "grain-like". Mitochondria generate most of the cell's supply of adenosine triphosphate (ATP), used as a source of chemical energy.
Vaccines against R. prowazekii were developed in the 1940s, and were highly effective in reducing typhus deaths among U.S. soldiers during World War II. Immunity following recovery from infection with, or by immunization against, R. prowazekii is lifelong in most cases. However, R. prowazekii can establish a latent infection, which can reactivate after years or decades (referred to as Brill-Zinsser disease). Treatment with tetracycline antibiotics is usually successful.
World War II, also known as the Second World War, was a global war that lasted from 1939 to 1945. The vast majority of the world's countries—including all the great powers—eventually formed two opposing military alliances: the Allies and the Axis. A state of total war emerged, directly involving more than 100 million people from over 30 countries. The major participants threw their entire economic, industrial, and scientific capabilities behind the war effort, blurring the distinction between civilian and military resources. World War II was the deadliest conflict in human history, marked by 50 to 85 million fatalities, most of whom were civilians in the Soviet Union and China. It included massacres, the genocide of the Holocaust, strategic bombing, premeditated death from starvation and disease, and the only use of nuclear weapons in war.
In biology, immunity is the balanced state of multicellular organisms having adequate biological defenses to fight infection, disease, or other unwanted biological invasion, while having adequate tolerance to avoid allergy, and autoimmune diseases.
Virus latency is the ability of a pathogenic virus to lie dormant (latent) within a cell, denoted as the lysogenic part of the viral life cycle. A latent viral infection is a type of persistent viral infection which is distinguished from a chronic viral infection. Latency is the phase in certain viruses' life cycles in which, after initial infection, proliferation of virus particles ceases. However, the viral genome is not fully eradicated. The result of this is that the virus can reactivate and begin producing large amounts of viral progeny without the host being infected by new outside virus, denoted as the lytic part of the viral life cycle, and stays within the host indefinitely.
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.
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.
The Rickettsiales, informally called rickettsias, are an order of small Alphaproteobacteria that are endosymbionts of eukaryotic cells. 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 are the Wolbachia, which infect approximately two-thirds of all arthropods and nearly all filarial nematodes. Genetic studies support the endosymbiotic theory according to which mitochondria and related organelles developed from members of this group.
Rickettsia rickettsii is a gram-negative, intracellular, coccobacillus bacterium that is around 0.8 to 2.0 micrometers long. R. rickettsi is the causative agent of Rocky Mountain spotted fever. R. rickettsii is one of the most pathogenic Rickettsia strains. It affects a large majority of the Western Hemisphere and small portions of the Eastern Hemisphere.
Legionella pneumophila is a thin, aerobic, pleomorphic, flagellated, nonspore-forming, Gram-negative bacterium of the genus Legionella. L. pneumophila is the primary human pathogenic bacterium in this group and is the causative agent of Legionnaires' disease, also known as legionellosis.
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.
Francisella tularensis is a pathogenic species of Gram-negative coccobacillus, an aerobic bacterium. It is non-spore forming, non-motile and the causative agent of tularemia, the pneumonic form of which is often lethal without treatment. It is a fastidious, facultative intracellular bacterium which requires cysteine for growth. Due to its low infectious dose, ease of spread by aerosol, and high virulence, F. tularensis is classified as a Tier 1 Select Agent by the U.S. government, along with other potential agents of bioterrorism such as Yersinia pestis, Bacillus anthracis and Ebola virus. When found in nature, Francisella tularensis can survive for several weeks at low temperatures in animal carcasses, soil, and water. In laboratory, F. tularensis appears as small rods, and is grown best at 35-37°C.
Genome size is the total amount of DNA contained within one copy of a single genome. It is typically measured in terms of mass in picograms or less frequently in Daltons or as the total number of nucleotide base pairs typically in megabases. One picogram equals 978 megabases. In diploid organisms, genome size is used interchangeably with the term C-value. An organism's complexity is not directly proportional to its genome size; some single cell organisms have much more DNA than humans.
Bernhard Nocht Institute for Tropical Medicine; (BNITM) is a medical institution based in Hamburg, Germany which is dedicated to research, treatment, training and therapy of tropical and infectious diseases.
Sindbis virus (SINV) is a member of the Togaviridae family, in the alphavirus subfamily. The virus was first isolated in 1952 in Cairo, Egypt. The virus is transmitted by mosquitoes SINV causes sindbis fever in humans and the symptoms include arthralgia, rash and malaise. Sindbis fever is most common in South and East Africa, Egypt, Israel, Philippines and parts of Australia. Sindbis virus is an "arbovirus" (arthropod-borne) and is maintained in nature by transmission between vertebrate (bird) hosts and invertebrate (mosquito) vectors. Humans are infected with Sindbis virus when bitten by an infected mosquito. SINV has been linked to Pogosta disease in Finland, Ockelbo disease in Sweden and Karelian fever in Russia.
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.
Ehrlichia ewingii is a species of rickettsiales bacteria. It has recently been associated with human infection, and can be detected via PCR serological testing. The name Ehrlichia ewingii was proposed in 1992.
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.
Rickettsia typhi is a species of infectious bacterium of the genus Rickettsia; it is the causative agent of Murine typhus.
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. First recognized in 1979 in Ixodes ricinus ticks in Switzerland as a new member of the spotted fever group of Rickettsia, the Rickettsia helvetica bacterium was eventually isolated in 1993. Although R. helvetica was initially thought to be harmless in humans and many animal species, some individual case reports suggest that it may be capable of causing a non-specific fever in humans. In 1997 a man living in eastern France seroconverted to Rickettsia 4 weeks after onset of an unexplained febrile illness. In 2010, a case report indicated that tick-borne R. helvetica can also cause meningitis in humans.
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.
The National Institutes of Health (NIH) is the primary agency of the United States government responsible for biomedical and public health research. It was founded in the late 1870s and is now part of the United States Department of Health and Human Services. The majority of NIH facilities are located in Bethesda, Maryland. The NIH conducts its own scientific research through its Intramural Research Program (IRP) and provides major biomedical research funding to non-NIH research facilities through its Extramural Research Program.
The National Institute of Allergy and Infectious Diseases (NIAID) is one of the 27 institutes and centers that make up the National Institutes of Health (NIH), an agency of the United States Department of Health and Human Services (HHS). NIAID's mission is to conduct basic and applied research to better understand, treat, and prevent infectious, immunologic, and allergic diseases.