Potomac Horse Fever (PHF) is a potentially-fatal febrile illness affecting horses caused by the intracellular bacterium Neorickettsia risticii. PHF is also known as Shasta River Crud and Equine Monocytic Ehrlichiosis. It was first described in areas surrounding the Potomac River northwest of Washington, D.C., in the 1980s, but cases have been described in many other parts of the United States, such as Minnesota, California, and Pennsylvania. Currently, it is found in more than 40 U.S. states and Canada.
Lymnaeidae, common name the pond snails, is a taxonomic family of small to large air-breathing freshwater snails, aquatic pulmonate gastropod mollusks, that belong to the clade Hygrophila.
Physella is a genus of small, left-handed or sinistral, air-breathing freshwater snails, aquatic pulmonate gastropod mollusks in the family Physidae.
Pleurocera is a genus of freshwater snails with an operculum, aquatic gastropod mollusks in the family Pleuroceridae.
Pleuroceridae, common name pleurocerids, is a family of small to medium-sized freshwater snails, aquatic gilled gastropod mollusks in the superfamily Cerithioidea.These snails have an operculum and typically a robust high-spired shell.
Galba is a genus of small air-breathing freshwater snails, aquatic pulmonate gastropod mollusks in the family Lymnaeidae, the pond snails.
Pomacea is a genus of freshwater snails with gills and an operculum, aquatic gastropod mollusks in the family Ampullariidae, the apple snails. The genus is native to the Americas; most species in this genus are restricted to South America.
Nanophyetus salmincola is a food-borne intestinal trematode parasite prevalent on the Pacific Northwest coast. The species may be the most common trematode endemic to the United States.
The Cerithioidea is a superfamily of marine, brackish water and freshwater gastropod containing more than 200 genera. The Cerithoidea are included unassigned in the subclass Caenogastropoda. The original name of this superfamily was Cerithiacea, in keeping with common superfamily endings at the time.
Freshwater snails are gastropod mollusks which live in fresh water. There are many different families. They are found throughout the world in various habitats, ranging from ephemeral pools to the largest lakes, and from small seeps and springs to major rivers. The great majority of freshwater gastropods have a shell, with very few exceptions. Some groups of snails that live in freshwater respire using gills, whereas other groups need to reach the surface to breathe air. In addition, some are amphibious and have both gills and a lung. Most feed on algae, but many are detritivores and some are filter feeders.
Semisulcospiridae, common name semisulcospirids, is a family of freshwater snails, aquatic gilled gastropod mollusks with an operculum, in the superfamily Cerithioidea.
Semisulcospira is a genus of freshwater snails with an operculum, an aquatic gastropod mollusks in the family Semisulcospiridae.
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, 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.
Juga plicifera, common name pleated juga, and Graceful keeled horn snail is a species of small freshwater snail with an ovate and corneous operculum, ranging in size from 16mm to 35mm long. The snail is dextrally coiled with about 15 whorls and 10 to 12 axial plicae on each whorl. It is an aquatic gastropod mollusk in the family Semisulcospiridae.
Elimia potosiensis, common name the pyramid elimia, is a species of freshwater snail with an operculum, an aquatic gastropod mollusk in the family Pleuroceridae.
Semisulcospira libertina is a species of freshwater snail with an operculum, an aquatic gastropod mollusk in the family Semisulcospiridae. Widespread in east Asia, it lives in China, Taiwan, Korea, Japan, and the Philippines. In some countries it is harvested as a food source. It is medically important as a vector of clonorchiasis, paragonimiasis, metagonimiasis and others.
