Ehrlichia
Encyclopedia
Ehrlichia is a genus
of rickettsiales
bacteria. They are transmitted by ticks. Several species can cause infection (Ehrlichiosis
) in humans. The genus is named after German microbiologist Paul Ehrlich
. These diseases are considered zoonotic
as the main reservoir for the pathogen is in animal, usually mammal
species.
Ehrlichia are obligately intracellular pathogens and are transported between cells through the host cell filopodia during initial stages of infection, whereas, in the final stages of infection the pathogen ruptures the host cell membrane.
A new species of Ehrlichia has been discovered inside the deer tick Ixodes scapularis
. This newly found organism has only been isolated from deer ticks in Wisconsin and Minnesota in the USA. The species is known as Ehrlichia Wisconsin HM543746
.
during the 19th century. Its tick-borne nature was determined in 1900. The organism itself was demonstrated 1925 when it was recognized to be a rickettsia
. It was initially named Rickettsia ruminantium, and is currently named Ehrlichia ruminantium. In 1945 a "infection and treatment" method for livestock was developed. This is still the only commercially available "vaccine" against the disease, which is not a true vaccine, but intentional exposure to the disease with monitoring and antibiotic
treatment if needed. In 1985 the organism was first propagated reliably in tissue culture.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of rickettsiales
Rickettsiales
The Rickettsiales, also called rickettsias, are an order of small proteobacteria. Most of those described survive only as endosymbionts of other cells. Some are notable pathogens, including Rickettsia, which causes a variety of diseases in humans...
bacteria. They are transmitted by ticks. Several species can cause infection (Ehrlichiosis
Ehrlichiosis
Ehrlichiosis is a tick-borne disease of dogs usually caused by the organism Ehrlichia canis. Ehrlichia canis is the pathogen of animals. Humans can become infected by E. canis and other species after tick exposure. German Shepherd dogs are thought to be particularly affected by the disease, other...
) in humans. The genus is named after German microbiologist Paul Ehrlich
Paul Ehrlich
Paul Ehrlich was a German scientist in the fields of hematology, immunology, and chemotherapy, and Nobel laureate. He is noted for curing syphilis and for his research in autoimmunity, calling it "horror autotoxicus"...
. These diseases are considered zoonotic
Zoonosis
A zoonosis or zoonoseis any infectious disease that can be transmitted from non-human animals to humans or from humans to non-human animals . In a study of 1415 pathogens known to affect humans, 61% were zoonotic...
as the main reservoir for the pathogen is in animal, usually mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
species.
Ehrlichia are obligately intracellular pathogens and are transported between cells through the host cell filopodia during initial stages of infection, whereas, in the final stages of infection the pathogen ruptures the host cell membrane.
A new species of Ehrlichia has been discovered inside the deer tick Ixodes scapularis
Ixodes scapularis
Ixodes scapularis is commonly known as the deer tick or blacklegged tick , and in some parts of the USA as the bear tick. It is a hard-bodied tick of the eastern and northern Midwestern United States...
. This newly found organism has only been isolated from deer ticks in Wisconsin and Minnesota in the USA. The species is known as Ehrlichia Wisconsin HM543746
Ehrlichia Wisconsin HM543746
Ehrlichia Wisconsin HM543746 is an unnamed tick bacteria that spread through Minnesota and Wisconsin in 2009 and is similar to Ehrlichia muris....
.
History
The first ehrlichial disease was first recognized in South AfricaSouth Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
during the 19th century. Its tick-borne nature was determined in 1900. The organism itself was demonstrated 1925 when it was recognized to be a rickettsia
Rickettsia
Rickettsia is a genus of non-motile, Gram-negative, non-sporeforming, highly pleomorphic bacteria that can present as cocci , rods or thread-like . Being obligate intracellular parasites, the Rickettsia survival depends on entry, growth, and replication within the cytoplasm of eukaryotic host cells...
. It was initially named Rickettsia ruminantium, and is currently named Ehrlichia ruminantium. In 1945 a "infection and treatment" method for livestock was developed. This is still the only commercially available "vaccine" against the disease, which is not a true vaccine, but intentional exposure to the disease with monitoring and antibiotic
Antibiotic
An antibacterial is a compound or substance that kills or slows down the growth of bacteria.The term is often used synonymously with the term antibiotic; today, however, with increased knowledge of the causative agents of various infectious diseases, antibiotic has come to denote a broader range of...
treatment if needed. In 1985 the organism was first propagated reliably in tissue culture.
See also
- Human granulocytic ehrlichiosis (now called Human granulocytic anaplasmosis)
- Human monocytic ehrlichiosisHuman monocytic ehrlichiosisHuman monocytotropic ehrlichiosis is a form of ehrlichiosis associated with Ehrlichia chaffeensis.This bacteria is an obligate intracellular pathogen affecting monocytes and macrophages.-Ecology & Epidemiology:...
- Ehrlichiosis (canine)
- Cowdria ruminantiumCowdria ruminantium-Introduction:Heartwater is a tick-borne rickettsial disease of domestic and wild ruminants. It is caused by Cowdria ruminantium - an intracellular gram-negative coccal bacterium...
(Ehrlichia ruminantium)
External links
- Ehrlichia genomes and related information at PATRIC, a Bioinformatics Resource Center funded by NIAID
- Forum discution and clinical presentation (RO) Clinical experiences about ehrlichia and coinfections at dogs in Romania
- http://www.jsonline.com/features/health/126733503.html Newly discovered species of Ehrlichia found in deer ticks