Rickettsia felis

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Rickettsia felis
Scientific classification Red Pencil Icon.png
Domain: Bacteria
Phylum: Proteobacteria
Class: Alphaproteobacteria
Order: Rickettsiales
Family: Rickettsiaceae
Genus: Rickettsia
Species group: Spotted fever group
R. felis
Binomial name
Rickettsia felis
Bouyer et al., 2001 [1] emend. La Scola et al., 2002 [2]

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. [3] 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.

Bacteria A domain of prokaryotes – single celled organisms without a nucleus

Bacteria are a type of biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a number of shapes, ranging from spheres to rods and spirals. Bacteria were among the first life forms to appear on Earth, and are present in most of its habitats. Bacteria inhabit soil, water, acidic hot springs, radioactive waste, and the deep portions of Earth's crust. Bacteria also live in symbiotic and parasitic relationships with plants and animals. Most bacteria have not been characterised, and only about half of the bacterial phyla have species that can be grown in the laboratory. The study of bacteria is known as bacteriology, a branch of microbiology.

In biology, a pathogen is also known as an infectious agent, or a germ. In the oldest and broadest sense, a pathogen is anything that can produce disease; the term came into use in the 1880s. Typically the term pathogen is used to describe an infectious microorganism or agent, such as a virus, bacterium, protozoan, prion, viroid, or fungus. Small animals, such as certain kinds of worms and insect larvae, can also produce disease but such animals are usually, in common parlance, referred to as parasites rather than pathogens. The scientific study of microscopic, pathogenic organisms is called microbiology, while the study of disease that may include these pathogens is called pathology. Parasitology, meanwhile, is the scientific study of parasites and the organisms that host them.

Cat domesticated feline

The cat or domestic cat is a small carnivorous mammal. It is the only domesticated species in the family Felidae. The cat is either a house cat, kept as a pet; or a feral cat, freely ranging and avoiding human contact. A house cat is valued by humans for companionship and for its ability to hunt rodents. About 60 cat breeds are recognized by various cat registries.


Transmission and concerns

Until recently, fleas have been the recognised vectors of Rickettsia felis and it is present in cat flea populations of North and South America, Southern Europe, Africa, Thailand and Australia. Human infection usually results from flea feces coming into contact with scratched or broken skin. [4]

Vector (epidemiology) agent that carries and transmits an infectious pathogen into another living organism

In epidemiology, a disease vector is any agent who carries and transmits an infectious pathogen into another living organism; most agents regarded as vectors are organisms, such as intermediate parasites or microbes, but it could be an inanimate medium of infection such as dust particles.

More recently, some authorities have published increasing concerns about the role of more and more species of arthropod vectors of this organism; Rickettsia felis has by now been detected in many arthropods in the wild, including various species of mites, ticks, blood-sucking bugs in the genus Cimex, sucking lice, flea species of various types, both free-living and "sticktight fleas", and various other biting insects. [5] In particular there is concern about the prevalence of Rickettsia felis in regions such as parts of sub-Saharan Africa, in mosquito genera such as Anopheles , Aedes , Mansonia , and Culex ; all of these genera include species that are challenging to control and have long been recognised as effective vectors of various important human and animal diseases. [5]

Arthropod phylum of animals

An arthropod is an invertebrate animal having an exoskeleton, a segmented body, and paired jointed appendages. Arthropods form the phylum Euarthropoda, which includes insects, arachnids, myriapods, and crustaceans. The term Arthropoda as originally proposed refers to a proposed grouping of Euarthropods and the phylum Onychophora. Arthropods are characterized by their jointed limbs and cuticle made of chitin, often mineralised with calcium carbonate. The arthropod body plan consists of segments, each with a pair of appendages. The rigid cuticle inhibits growth, so arthropods replace it periodically by moulting. Arthopods are bilaterally symmetrical and their body possesses an external skeleton. Some species have wings.

Mite common name for small arachnids

Mites are small arthropods belonging to the class Arachnida and the subclass Acari. The term "mite" refers to the members of several groups in Acari but it is not a clade, and excludes the ticks, order Ixodida. Mites and ticks are characterised by the body being divided into two regions, the cephalothorax or prosoma, and an opisthosoma. The scientific discipline devoted to the study of ticks and mites is called acarology.

Tick order of arachnids

Ticks are small arachnids, typically 3 to 5 mm long, part of the order Parasitiformes. Along with mites, they constitute the subclass Acari. Ticks are ectoparasites, living by feeding on the blood of mammals, birds, and sometimes reptiles and amphibians. Ticks had evolved by the Cretaceous period, the most common form of fossilisation being immersed in amber. Ticks are widely distributed around the world, especially in warm, humid climates.

The mosquito species Anopheles gambiae , which is notorious mainly as a malaria vector, has been demonstrated to be a competent vector for Rickettsia felis. More unexpectedly, cells of some important disease vector species of mosquitoes in the genus Aedes, which is most commonly seen as a vector for arboviruses, support growth of Rickettsia felis. [6] In addition, in tropical regions where Aedes albopictus and Aedes aegypti are established disease vectors and ectoparasites of humans, patients have tested positive for Rickettsia felis. To some authorities this suggests that Aedes species might be able to infect their hosts with Rickettsia felis, and that patients in, or returning from, the tropics with fevers of unknown origin, should be tested for Rickettsia felis infection. They see as very real, the possibility that Rickettsia felis might be the next mosquito-borne pathogen to emerge as a multi-continental disease outbreak. [6]

<i>Anopheles gambiae</i> species of insect

The Anopheles gambiae complex consists of at least seven morphologically indistinguishable species of mosquitoes in the genus Anopheles. The complex was recognised in the 1960s and includes the most important vectors of malaria in sub-Saharan Africa, particularly of the most dangerous malaria parasite, Plasmodium falciparum. It is one of the most efficient malaria vectors known.


Arbovirus is an informal name used to refer to any viruses that are transmitted by arthropod vectors. The word arbovirus is an acronym. The word tibovirus is sometimes used to more specifically describe viruses transmitted by ticks, a superorder within the arthropods. Arboviruses can affect both animals, including humans, and plants. In humans, symptoms of arbovirus infection generally occur 3–15 days after exposure to the virus and last 3 or 4 days. The most common clinical features of infection are fever, headache, and malaise, but encephalitis and hemorrhagic fever may also occur.


Human cases of Rickettsia felis were diagnosed in Australia in 2009, these were the first reported human infections in Australia. [7] The infected individuals were family members who had been exposed to flea bites from infested kittens. In this cluster an otherwise healthy nine-year-old girl was admitted to hospital with fever and a rash. This later worsened three days later when her lungs filled with fluid and she was admitted to intensive care. [8]

Related Research Articles

<i>Rickettsia</i> type of bacteria that causes typhus, among other diseases

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.

<i>Wolbachia</i> genus of prokaryotes

Wolbachia is a genus of gram-negative bacteria that infects arthropod species, including a high proportion of insects, and also some nematodes. It is one of the most common parasitic microbes and is possibly the most common reproductive parasite in the biosphere. Its interactions with its hosts are often complex, and in some cases have evolved to be mutualistic rather than parasitic. Some host species cannot reproduce, or even survive, without Wolbachia colonisation. One study concluded that more than 16% of neotropical insect species carry bacteria of this genus, and as many as 25 to 70% of all insect species are estimated to be potential hosts.

<i>Rickettsia rickettsii</i> species of prokaryote

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.

Tick-borne diseases, which afflict humans and other animals, are caused by infectious agents transmitted by tick bites. Tick-borne illnesses are caused by infection with a variety of pathogens, including rickettsia and other types of bacteria, viruses, and protozoa. Because individual ticks can harbor more than one disease-causing agent, patients can be infected with more than one pathogen at the same time, compounding the difficulty in diagnosis and treatment. As of 2016, 16 tick-borne diseases of humans are known.

<i>Bartonella</i> genus of prokaryotes

Bartonella is a genus of Gram-negative bacteria. It is the only genus in the family Bartonellaceae. Facultative intracellular parasites, Bartonella species can infect healthy people, but are considered especially important as opportunistic pathogens. Bartonella species are transmitted by vectors such as ticks, fleas, sand flies, and mosquitoes. At least eight Bartonella species or subspecies are known to infect humans.

A canine vector-borne disease (CVBD) is one of "a group of globally distributed and rapidly spreading illnesses that are caused by a range of pathogens transmitted by arthropods including ticks, fleas, mosquitoes and phlebotomine sandflies." CVBDs are important in the fields of veterinary medicine, animal welfare, and public health. Some CVBDs are of zoonotic concern.

Medical entomology

The discipline of medical entomology, or public health entomology, and also veterinary entomology is focused upon insects and arthropods that impact human health. Veterinary entomology is included in this category, because many animal diseases can "jump species" and become a human health threat, for example, bovine encephalitis. Medical entomology also includes scientific research on the behavior, ecology, and epidemiology of arthropod disease vectors, and involves a tremendous outreach to the public, including local and state officials and other stake holders in the interest of public safety, finally in current situation related to one health approach mostly health policy makers recommends to widely applicability of medical entomology for disease control efficient and best fit on achieving development goal and to tackle the newly budding zoonotic diseases. Thoughtful to have and acquaint with best practice of Med. Entomologist to tackle the animal and public health issues together with controlling arthropods born diseases by having Medical Entomologists’ the right hand for bringing the healthy world [Yon w].

A rickettsiosis is a disease caused by intracellular bacteria.

<i>Rickettsia conorii</i> species of prokaryote

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.

Mosquito-borne disease

Mosquito-borne diseases or mosquito-borne illnesses are diseases caused by bacteria, viruses or parasites transmitted by mosquitoes. They can transmit disease without being affected themselves. Nearly 700 million people get a mosquito-borne illness each year resulting in over one million deaths.

African tick bite fever spotted fever that has material basis in Rickettsia africae, which is transmitted by ticks

African tick bite fever (ATBF) is a bacterial infection spread by the bite of a tick. Symptoms may include fever, headache, muscles pains, and a rash. At the site of the bite there is typically a red skin sore with a dark center. Onset usually occur 4–10 days after the bite. Complications are rare, however may include joint inflammation. Some people do not develop symptoms.

North Asian tick typhus, also known as Siberian tick typhus, is a condition characterized by a maculopapular rash.

Flea-borne spotted fever is a condition characterized by a rash of maculopapules or furuncles.

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.

Didier Raoult is a French biologist. He holds MD and Ph.D. degrees and specializes in infectious diseases.

Rickettsia honei is a species of Rickettsia.

<i>Rickettsia sibirica</i> species of prokaryote

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.

Rickettsia massiliae is a tick-borne pathogenic spotted fever group Rickettsia species.

Spondweni virus (SPOV) is an arbovirus, or arthropod-borne virus, which is a member of the family Flaviviridae and the genus Flavivirus. It is part of the Spondweni serogroup which includes two species, Zika virus (ZIKV) and the Spondweni virus (SPONV). The Spondweni virus was first isolated in Nigeria in 1952, and ever since, SPONV transmission and activity have been reported throughout Africa. Its primary vector of transmission is the sylvatic mosquito Aedes circumluteolus, though it has been isolated from several different mosquito genera. Transmission of the virus into humans can lead to a viral infection known as Spondweni fever, with symptoms ranging from headache and nausea to myalgia and arthralgia. However, SPONV is phylogenetically close to the ZIKV, it is commonly misdiagnosed as ZIKV along with other viral illnesses.

This is a timeline of typhus, describing major events such as epidemics and key medical developments.


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  2. La Scola B, Meconi S, Fenollar F, Rolain JM, Roux V, Raoult D (November 2002). "Emended description of Rickettsia felis (Bouyer et al. 2001), a temperature-dependent cultured bacterium". Int. J. Syst. Evol. Microbiol. 52 (Pt 6): 2035–41. doi:10.1099/00207713-52-6-2035. PMID   12508865.
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  5. 1 2 Brown, Lisa D. Macaluso, Kevin R. Rickettsia felis, an Emerging Flea-Borne Rickettsiosis. Curr Trop Med Rep (2016) 3: 27. doi:10.1007/s40475-016-0070-6
  6. 1 2 Parola, Philippe. Musso, Didier. Raoult, Didier. Rickettsia felis: the next mosquito-borne outbreak? The Lancet Infectious Diseases, Volume 16, Issue 10, 1112 - 1113
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  8. Medew J (6 January 2011). "Deadly cat-flea disease hits Australia". The Age.