Potomac horse fever (PHF) is an acute but potentially fatal febrile, meaning fever, enterocolitis illness caused by the bacterium Neorickettsia risticii previously named Ehrlichia risticii, causing colic, fever, and diarrhea in endemic parts of the United States. Potomac horse fever is the common name for many different varieties this illness was given, for example, equine monocytic erhlichiosis and equine erhlichial colitis. It was first discovered in 1979 and named after the Potomac River Valley in Maryland, USA. The Potomac river valley is home to numerous caddis and may flies, which is the helminth vector of this atrocious illness.
The causative agent of Potomac horse fever is a member of the Ehrlichieae family. Neorickettsia …show more content…
During those summer months the state of Maryland has the largest number of reported cases, taking up almost 70 percent of the nine hundred reported. Potomac Horse Fever is said to be transmitted by horses accidentally ingesting infected small aquatic flies, primarily May flies and Caddis flies that are infected with Neorickettsia risticii by consuming the larvae of infected snails. Other cases have shown that any aquatic life that carries the larvae and is ingested by the horse can transmit the illness. When the bacteria has been ingested, it starts to infect the cells lining the horses gastrointestinal tract and the mucosal cells of the large colon. This is what causes the inflammation, “colitis”, impaired absorption by the colon, and diarrhea. The fever in most cases are due to the body’s immune response to the infection. The incubation period which means, the time during which a disease establishes itself in the body. During this time the animal is infected with Potomac Horse Fever, but does not show clinical signs yet. The incubation period for Potomac Horse Fever is typically 3-9 days. Horses may start to show a fever, depression and possibly laminitis on day 5 and diarrhea about day 14 post