関: Ehrlichia ruminantium

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/10/19 19:25:45」(JST)

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Heartwater (also known as cowdriosis, nintas and ehrlichiosis) is a tick-borne rickettsial disease of domestic and wild ruminants. It is caused by Ehrlichia ruminantium (formerly Cowdria ruminantium)^[2] - an intracellular gram-negative coccal bacterium (also referred to as Rickettsia ruminantium). The disease is spread by bont ticks, which are members of the genus Amblyomma. Affected mammals include cattle, sheep, goats, antelope, and buffalo, but the disease has the biggest economic impact on cattle production in affected areas. The disease’s name is derived from the fact that fluid can collect around the heart or in the lungs of infected animals.^[3]

The disease is common in sub-Saharan Africa and some of the West Indian islands. It was first identified in sheep in South Africa in the 1830s, and had reached the Caribbean by 1980.^[3] The ticks which carry the disease occur in Africa and the Caribbean, and feed on a wide variety of vertebrate hosts. In the Caribbean, at least, the cattle egret has been implicated in the spread of heartwater since it colonized the islands in the 1950s.^[3] Animals often acquire the disease when moved on to heartwater infected grazing.

Cowdriosis is notifiable to the World Organisation for Animal Health.

Clinical signs

Clinical disease is more common in young animals and non-native breeds. The clinical signs of disease are caused by an increased vascular permeability and consequent oedema and hypovolaemia.

The symptoms include neurological signs such as tremors and head pressing, respiratory signs such as coughing and nasal discharge, and systemic signs such as fever and loss of appetite. Physical examination may reveal petechiae of the mucous membranes, tachycardia and muffled heart sounds. Cowdriosis can also cause reproductive and gastrointestinal disease. It is frequently fatal.

Diagnosis

On post-mortem examination, a light yellow transudate that coagulates on exposure to air is often found within the thorax, pericardium and abdomen. Most fatal cases will have the hydropericardium that gives the disease its common name. Pulmonary oedema and mucosal congestion are regularly seen along with frothy fluid in the airways and cut surfaces of the lungs.

To definitively diagnose the disease, C. ruminantium must be demonstrated either in preparations of the hippocampus under Giemsa staining or by histopathology of brain or kidney.

Treatment and control

Amblyomma hebraeum, a vector of Heartwater disease

During the early stages of disease animals may be treated with sulfonamides and tetracyclines. In advanced disease, prognosis is poor.

Tetracyclines can also be used prophylactically when animals are introduced into an area endemic with cowdriosis. A live blood vaccine is available for protection of young stock, but animals may require treatment for the disease post-vaccination. Ectoparasiticides dips can be used to reduce exposure the animals exposure to bont ticks. In areas endemic for heartwater there is likely to be use of dips against other ticks of domestic animals, such as Rhipicephalus (Boophilus) and Hyalomma species and this will usually contribute to control of vectors of Ehrlichia ruminantium.

References

^ Dumler JS, Barbet AF, Bekker CP; et al. (2001). "Reorganization of genera in the families Rickettsiaceae and Anaplasmataceae in the order Rickettsiales: unification of some species of Ehrlichia with Anaplasma, Cowdria with Ehrlichia and Ehrlichia with Neorickettsia, descriptions of six new species combinations and designation of Ehrlichia equi and 'HGE agent' as subjective synonyms of Ehrlichia phagocytophila". Int. J. Syst. Evol. Microbiol. 51 (Pt 6): 2145–65. doi:10.1099/00207713-51-6-2145. PMID 11760958.
^ http://www.ebi.ac.uk/2can/genomes/bacteria/Ehrlichia_ruminantium.html
^ ^a ^b ^c "Heartwater". Animal and Plant Health Inspection Service. U.S. Department of Agriculture. Retrieved 2008-04-13.

"Cowdriosis". WikiVet. Retrieved 2011-08-31.

UpToDate Contents

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1. エーリキアの生物学 biology of ehrlichiae

English Journal

A comparison of DNA extraction protocols from blood spotted on FTA cards for the detection of tick-borne pathogens by Reverse Line Blot hybridization.

Hailemariam Z1, Ahmed JS2, Clausen PH3, Nijhof AM4.
Ticks and tick-borne diseases.Ticks Tick Borne Dis.2017 Jan;8(1):185-189. doi: 10.1016/j.ttbdis.2016.10.016. Epub 2016 Nov 3.
An essential step in the molecular detection of tick-borne pathogens (TBPs) in blood is the extraction of DNA. When cooled storage of blood under field conditions prior to DNA extraction in a dedicated laboratory is not possible, the storage of blood on filter paper forms a promising alternative. We
PMID 27825733

Development of a Quantitative PCR Assay for Differentiating the Agent of Heartwater Disease, Ehrlichia ruminantium, from the Panola Mountain Ehrlichia.

Sayler KA1,2, Loftis AD3, Mahan SM4,5, Barbet AF4.
Transboundary and emerging diseases.Transbound Emerg Dis.2016 Dec;63(6):e260-e269. doi: 10.1111/tbed.12339. Epub 2015 Mar 24.
Panola Mountain Ehrlichia (PME) is an emerging Ehrlichia sp. reported in ten US states. Based on the sequence homology of all known genes, PME is closely related to Ehrlichia ruminantium (ER), the causative agent of heartwater. Heartwater is an economically important tick-borne disease of cattle, sh
PMID 25807955

Anaplasma, Ehrlichia and rickettsial pathogens in ixodid ticks infesting cattle and sheep in western Oromia, Ethiopia.

Teshale S1, Kumsa B1, Menandro ML2, Cassini R3, Martini M2.
Experimental & applied acarology.Exp Appl Acarol.2016 Oct;70(2):231-7. doi: 10.1007/s10493-016-0067-9. Epub 2016 Jul 13.
Although ticks are widely distributed in all agro-ecological zones of Ethiopia, information on tick-borne pathogens is scarce. This study was conducted to determine the presence of Anaplasma spp., Ehrlichia spp., and Rickettsia spp. in Rhipicephalus evertsi and Rhipicephalus (Boophilus) decoloratus
PMID 27411938

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★リンクテーブル★

リンク元	「カウドリア・ルミナンチウム」「コウドリア・ルミナンチウム」「Ehrlichia ruminantium」
関連記事	「Cowdria」

「カウドリア・ルミナンチウム」

Heartwater
Scientific classification
Kingdom:	Bacteria
Phylum:	Proteobacteria
Class:	Alpha proteobacteria
Order:	Rickettsiales
Family:	Rickettsiaceae
Genus:	Ehrlichia
Species:	E. ruminantium
Binomial name
	Ehrlichia ruminantium; (Dumler, 2001)