''Rickettsia conorii'' is a

Gram-negative Gram-negative bacteria are bacteria that, unlike gram-positive bacteria, do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. Their defining characteristic is that their cell envelope consists ...

bacterium Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among the ...

of the genus ''

Rickettsia ''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). The genus was n ...

'' 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 A spotted fever is a type of tick-borne disease which presents on the skin. They are all caused by bacteria of the genus '' Rickettsia''. Typhus is a group of similar diseases also caused by ''Rickettsia'' bacteria, but spotted fevers and typhus a ...

group and the most geographically dispersed species in the group, recognized in most of the regions bordering on the

Mediterranean Sea The Mediterranean Sea ( ) is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean basin and almost completely enclosed by land: on the east by the Levant in West Asia, on the north by Anatolia in West Asia and Southern Eur ...

and

Black Sea The Black Sea is a marginal sea, marginal Mediterranean sea (oceanography), mediterranean sea lying between Europe and Asia, east of the Balkans, south of the East European Plain, west of the Caucasus, and north of Anatolia. It is bound ...

Israel Israel, officially the State of Israel, is a country in West Asia. It Borders of Israel, shares borders with Lebanon to the north, Syria to the north-east, Jordan to the east, Egypt to the south-west, and the Mediterranean Sea to the west. Isr ...

Kenya Kenya, officially the Republic of Kenya, is a country located in East Africa. With an estimated population of more than 52.4 million as of mid-2024, Kenya is the 27th-most-populous country in the world and the 7th most populous in Africa. ...

, and other parts of

North North is one of the four compass points or cardinal directions. It is the opposite of south and is perpendicular to east and west. ''North'' is a noun, adjective, or adverb indicating Direction (geometry), direction or geography. Etymology T ...

, Central, and

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...

, and

India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...

. The prevailing

vector Vector most often refers to: * Euclidean vector, a quantity with a magnitude and a direction * Disease vector, an agent that carries and transmits an infectious pathogen into another living organism Vector may also refer to: Mathematics a ...

is the brown dog tick, ''

Rhipicephalus sanguineus ''Rhipicephalus sanguineus'', commonly called the brown dog tick, kennel tick, or pantropical dog tick, is a species of tick found worldwide, but more commonly in warmer climates. This species is unusual among ticks in that its entire biological ...

''. 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 Tunisia, officially the Republic of Tunisia, is a country in the Maghreb region of North Africa. It is bordered by Algeria to the west and southwest, Libya to the southeast, and the Mediterranean Sea to the north and east. Tunisia also shares m ...

in 1910. The genome of the bacterium has been sequenced and four subspecies have been identified. Genomes of intracellular or parasitic bacteria undergo massive reduction compared to their free-living relatives. Examples include Rickettsia for alpha proteobacteria, T. whipplei for Actinobacteria, Mycoplasma for Firmicutes (the low G+C content Gram-positive), and Wigglesworthia and Buchnera for gamma proteobacteria. Some of the largest virions like ''

Megavirus chilense ''Megavirus'' is a viral genus, phylogenetically related to '' Acanthamoeba polyphaga mimivirus'' (APMV). In colloquial speech, ''Megavirus chilense'' is more commonly referred to as just "Megavirus". Until the discovery of pandoraviruses in 2 ...

'', ''

Pandoravirus ''Pandoravirus'' is a proposed genus of giant virus, first discovered in 2013. It is the third largest in physical size of any known viral genus, behind Pithovirus and Megaklothovirus. Pandoraviruses have double stranded DNA genomes, with t ...

'', ''

Pithovirus ''Alphapithovirus'', is a genus of giant virus known from two species, '' Alphapithovirus sibericum'', which infects amoebas, and '' Alphapithovirus massiliense''. It is DNA-based and is a member of the nucleocytoplasmic large DNA viruses clade ...

'' and ''

Mimivirus ''Mimivirus'' is a genus of giant viruses, in the family ''Mimiviridae''. It is believed that Amoeba serve as their natural hosts. It also refers to a group of phylogenetically related large viruses. In colloquial speech, APMV is more commonly ...

'' are comparable in size to miniature bacteria like T. whipplei and Rickettsia conorii.

References

Further reading