What type of organism is Rickettsia?

What type of organism is Rickettsia?

The rickettsiae are a diverse collection of obligately intracellular Gram-negative bacteria found in ticks, lice, fleas, mites, chiggers, and mammals. They include the genera Rickettsiae, Ehrlichia, Orientia, and Coxiella. These zoonotic pathogens cause infections that disseminate in the blood to many organs.

What is the habitat of Rickettsia?

Habitat in the Host Cell- Rickettsia rickettsii is a parasite of eukaryotic cells and needs two hosts, normally an arthropod vector (American dog tick and Rocky Mountain wood tick) and a mammal host (any mammalian can pick up the bacterium Rickettsia rickettsii).

What are the characteristics of Rickettsia?

The rickettsiae are rod-shaped or variably spherical, nonfilterable bacteria, and most species are gram-negative. They are natural parasites of certain arthropods (notably lice, fleas, mites, and ticks) and can cause serious diseases—usually characterized by acute self-limiting fevers—in humans and other animals.

What is Rickettsia in biology?

Rickettsiae are bacterial obligate intracellular parasites ranging from harmless endosymbionts to the etiologic agents of some of the most devastating diseases known to mankind.

Why is Rickettsia a unique bacteria?

The rickettsia are bacteria which are obligate intracellular parasites. They are considered a separate group of bacteria because they have the common feature of being spread by arthropod vectors (lice, fleas, mites and ticks).

What are the three main groups of Rickettsia?

Classification. The classification of Rickettsia into three groups (spotted fever, typhus, and scrub typhus) was initially based on serology. This grouping has since been confirmed by DNA sequencing. All three of these groups include human pathogens.

What causes Rickettsia?

Most rickettsial organisms are transmitted by the bites or infectious fluids (such as feces) inoculated into the skins from ectoparasites such as fleas, lice, mites, and ticks. Inhaling bacteria or inoculating conjunctiva with infectious material may also result in infection.

Is Rickettsia a mycoplasma?

Chlamydiae, rickettsiae and mycoplasmas are a miscellaneous group of organisms with properties common to both bacteria and viruses. Although they are categorized together in this chapter for the sake of convenience, they differ markedly from each other and cause divergent human diseases.

What is the causative agent of Rickettsia?

Rickettsia rickettsii is the causative agent of Rocky Mountain spotted fever (RMSF) and the prototypic member of the genus Rickettsia. The basic biologic features of R. rickettsii and how it produces disease will be reviewed here.

Is Rickettsia heterotrophic or autotrophic?

(1988), includes infectious agents, nitrogen-fixing symbionts, and pigmented autotrophic/heterotrophic taxa. The rickettsias are very small intracellular parasites of vertebrates, usually with a very complex lifecycle involving an invertebrate intermediate host.

Is Rickettsia the same as rickets?

The term “rickettsia” has nothing to do with rickets (which is a deficiency disease resulting from lack of vitamin D); the bacterial genus Rickettsia instead was named after Howard Taylor Ricketts, in honor of his pioneering work on tick-borne spotted fever.

What is Rickettsia slovaca?

Rickettsia slovaca is a pathogenic, tick-borne, spotted fever group (SFG) rickettsiae that was initially isolated in 1968 from a Dermacentor marginatus tick in Slovakia.

Is Rickettsia rickettsii a human pathogen?

Among these other rickettsiae, only R. felis, R. parkeri, and R. massiliae are currently recognized as human pathogens. R. rickettsii is a rare agent in nature, infecting < or =1% individuals in a few tick populations.

Where are Rickettsia sibirica infections found?

Rickettsia sibirica infections were diagnosed among a group of paleontologists doing field investigations in Mongolia, and human infections with a novel strain have been documented in France and Africa. 67 Cristina Socolovschi, Didier Raoult, in Hunter’s Tropical Medicine and Emerging Infectious Disease (Ninth Edition), 2013

Does Rickettsia harm the tick?

The Rickettsia does not harm the tick. In the United States, transmission occurs most often after a bite of the American dog tick (Dermacentor variabilis), the Rocky Mountain wood tick (Dermacentor andersoni), or the brown dog tick (Rhipicephalus sanguineus).