Neorickettsia risticii

rdf:langString Neorickettsia risticii

rdf:langString Neorickettsia risticii

rdf:langString Neorickettsia risticii

rdf:langString Neorickettsia risticii

rdf:langString Neorickettsia

rdf:langString Neorickettsia risticii phylogenetic tree based on 16S rRNA gene sequences

rdf:langString N. risticii

rdf:langString Ehrlichia risticii

rdf:langString Neorickettsia risticii, formerly Ehrlichia risticii, is an obligate intracellular gram negative bacteria that typically lives as an endosymbiont to parasitic flatworms, specifically flukes. N. risticii is the known causative agent of equine neorickettsiosis (also known as Potomac horse fever (PHF)), which gets its name from its discovery near the Potomac River in Maryland and Virginia. N. risticii was first recovered from horses in this region in 1984 but was not recognized as the causative agent of PHF until 1979. Potomac horse fever is currently endemic in the United States but has also been reported with lower frequency in other regions, including Canada, Brazil, Uruguay, and Europe. PHF is a condition that is clinically important for horses since it can cause serious signs such as fever, diarrhea, colic, and laminitis. PHF has a fatality rate of approximately 30%, making this condition one of the concerns for horse owners in endemic regions N. risticii is typically acquired in the middle to late summer near freshwater streams or rivers, as well as on irrigated pastures. This is a seasonal infection because it relies on the ingestion of an arthropod vector, which are more commonly found on pasture in the summer months. Although N. risticii is a well known causative agent for PHF in horses, it may act as a potential pathogen in cats and dogs as well. Not only has N. risticii been successfully cultured from monocytes of dogs and cats, but cats have become clinically ill after experimental infection with the bacteria. In addition, N. risticii has been isolated and cultured from human histiocytic lymphoma cells.