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The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status.
Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report. It resembles a Gram-negative coccus, the colour varying from lilac purple to blue, varying between 0. They most often occur in clumps from 1 or 2 to several thousand in a vacuole in the cytoplasm of endothelial cells.
Generally the small and medium-sized organisms occur in large colonies, while the larger ones occur in small colonies. Pleomorphic forms; horseshoe, ring and bacillary shaped, are frequently seen in those colonies that contain very large organisms Pienaar, The ultrastructural morphology of Ehrlichia reveals that they occur within a bilaminar membrane-bound cytoplasmic vacuole, each organism consisting of a wall, made up of 2 membranes, and an internal structure consisting of electron dense and electron-pale areas.
Some authors differentiate elementary, intermediate and reticulated bodies Prozesky et al. Traditional rickettsial taxonomy assigned Cowdria ruminantium as the sole member of the genus Cowdria in the tribe Ehrlichieae. This was one of three tribes within the family Rickettsiaceae in the order Rickettsiales which initially encompassed all intracellular bacteria but from which the Chlamydiae were later removed Moulders, The obligate intracellular nature of E.
In , Dumler et al. The genus Ehrlichia now includes E. In this reorganization, E. Also see the website: www. Clonal origin of emerging populations of Ehrlichia ruminantium in Burkina Faso. Infection, Genetics and Evolution, 10 7 Epidemiology and Infection, 2 ; 23 ref. Different organisms associated with heartwater as shown by analysis of 16S ribosomal RNA gene sequences. Veterinary Parasitology, 71 4 ; 50 ref.
Cowdry EV, a. Studies on the etiology of heartwater I. Observation of a rickettsia, Rickettsia ruminantium n. Journal of Experimental Medicine, 42 2 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.
International Journal of Systematic and Evolutionary Microbiology, Molecular detection of Ehrlichia ruminantium infection in Amblyomma variegatum ticks in The Gambia.
Experimental and Applied Acarology, 42 1 Point seroprevalence survey of Ehrlichia ruminantium infection in small ruminants in the Gambia. Clinical and Diagnostic Laboratory Immunology, 12 4 A transmission electron microscopical study of the life cycle of Cowdria ruminantium in vitro. Journal of the South African Veterinary Association, 63 2 The tick-borne rickettsia Cowdria ruminantium has a Chlamydia-like developmental cycle. Onderstepoort Journal of Veterinary Research, 58 4 ; 46 ref.
Morphology and development of Cowdria ruminantium in Amblyomma ticks. Onderstepoort Journal of Veterinary Research, 54 3 ; 18 ref. Ultrastructural features of Cowdria ruminantium in midgut epithelial cells and salivary glands of nymphal Amblyomma hebraeum. Onderstepoort Journal of Veterinary Research, 54 1 ; 17 ref. Amblyomma variegatum in cattle in Marie Galante, French Antilles: prevalence, control measures, and infection by Ehrlichia ruminantium.
OIE Handistatus, Paris, France: Office International des Epizooties. Heartwater infection cowdriosis in a Sitatunga Tragelaphus spekei in Nigeria. Journal of Wildlife Diseases, 23 2 Pienaar JG, Electron microscopy of Cowdria Rickettsia ruminantium Cowdry, in the endothelial cells of the vertebrate host.
Onderstepoort Journal of Veterinary Research, 37 1 Heartwater serology: some problems with the interpretation of results. Onderstepoort Journal of Veterinary Research, 54 3 ; 19 ref.
The heterogenicity of Cowdria ruminantium stocks: cross-immunity and serology in sheep and pathogenicity to mice. Onderstepoort Journal of Veterinary Research, 56 3 ; 23 ref. Heartwater: an in vitro study of the ultrastructure of Cowdria ruminatium. Onderstepoort Journal of Veterinary Research, 53 3 The map1 gene of Cowdria ruminantium is a member of a multigene family containing both conserved and variable genes. Biochemical and Biophysiological Research Communications, 2 Genome size and genetic map of Cowdria ruminantium.
Microbiology, 10 Journal of Clinical Microbiology, 29 11 ; [;Abstract number refers to VB volume 63 ]; 43 ref. Journal of Wildlife Diseases. One or more of the features that are needed to show you the maps functionality are not available in the web browser that you are using.
Toggle navigation. Datasheet Ehrlichia ruminantium. Don't need the entire report? Generate a print friendly version containing only the sections you need. Generate report. With permission of the editor. Title Vector Caption Amblyomma variegatum tropical bont tick ; adult, female. Title Histology Caption Cowdria ruminantium organisms in a Giemsa-stained brain smear original x Heartwater organisms in a Giemsa-stained brain smear original x Title Vector Caption Amblyomma hebraeum: male.
Title Vector Caption Amblyomma hebraeum: female. Title Histology Caption Brain smear from a goat. Colonies of Cowdria ruminantium are the granular blue areas in the cytoplasm of the capillary endothelial cells.
Diseases Table Top of page heartwater. Distribution Table Top of page The distribution in this summary table is based on all the information available. Pathogen Characteristics Top of page E. Taxonomy Traditional rickettsial taxonomy assigned Cowdria ruminantium as the sole member of the genus Cowdria in the tribe Ehrlichieae. Veterinary Parasitology, 71 4 ; 50 ref Cowdry EV, a. Distribution Maps Top of page You can pan and zoom the map. Unsupported Web Browser: One or more of the features that are needed to show you the maps functionality are not available in the web browser that you are using.
Please consider upgrading your browser to the latest version or installing a new browser. Top of page. Title Adult. Title Vector. Title Histology. Cowdria ruminantium organisms in a Giemsa-stained brain smear original x Brain smear from a goat.
OIE Handistatus ; Okoh et al.
Natural History of Ehrlichia Ruminantium
Summary Heartwater is a notifiable disease that is listed by the World Organisation for Animal Health. It is caused by Ehrlichia ruminantium, an obligately intracellular Gram-negative bacterium in the order Rickettsiales and the family Anaplasmataceae. The disease is borne byticks in the genus Amblyomma and causes heartwater, or cowdriosis, in wild and domestic ruminants, primarily in Africa, but also in parts of the Caribbean. The disease was recognised in South Africa in the 19th Century and determined to be tick borne in , while the organism was identified in and first cultured in vitro in This latter achievement boosted research into the disease at a time when biology was moving into the molecular genetic age. Over the last 20 years, there have been significant improvements in our understanding of E.
Heartwater--Ehrlichia Ruminantium Infection
Heartwater also known as cowdriosis , nintas, and ehrlichiosis is a tick-borne rickettsial disease of domestic and wild ruminants. 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.
Metrics details. The invasion of West Africa by Rhipicephalus microplus during the past decade has changed the ecological situation of the agent of heartwater Ehrlichia ruminantium in this area. Before, its local vector, Amblyomma variegatum, was the most abundant tick species found on livestock. Today, the abundance of the R. We investigated the potential of this new ecological situation to impact the circulation of E. This screening was applied on field samples of 24 R. The PCR detected E.