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) - 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.