Heartwater (also referred to as cowdriosis, nintas and ehrlichiosis) is a tick-borne disease of both domestic and wild ruminants. It is caused by Ehrlichia ruminantium (formerly known as Cowdria ruminantium) which is an intracellular gram-negative coccal bacterium.
This disease is spread by Bont ticks and causes Hydro-pericardium - with straw coloured to reddish pericardial fluid collecting around the heart or in the lungs of infected animals. This is the reason why the illness is called ‘Heartwater ’.
Heartwater will significantly decrease yield, with regards to the breeding of game that are susceptible to the disease, in areas where it is prevalent. These areas are namely parts of Southern Africa below the Sahara Desert as well as in surrounding islands including Madagascar, and the Caribbean.
Ruminants Commonly Affected by Heartwater
Heartwater has been proven to infect:
Most wildlife species appear to carry the organism of Heartwater asymptomatically, however serious illness may occur.
Transmission of Heartwater
Heartwater is transmitted by ticks which become infected as larvae or nymphs who can transmit the disease as nymphs or adults. In South Africa this illness is transmitted by the Amblyomma hebraeum ‘African Bont Tick’ where adult ticks prefer to feed on large hosts such as giraffe, buffalo, eland and cattle. Nymphs will feed on the same hosts as the adults and also on small antelope, scrub hares, helmeted Guinea fowls, and tortoises.
These ticks become infected by feeding on acutely ill animals or those which are infected asymptomatically, and then spread Heartwater by moving between hosts. Illness may also be transferred from mother to calf during colostrum. Where Blesbok, Black Wildebeest, Blue Wildebeest, African Buffalo, Eland, Giraffe, Greater kudu and Sable antelope become the host, infections have been detected for up to six months.
It is important to note that the Heartwater organism is extremely fragile and cannot survive outside of a host for more than a few hours.