Question of the Day

Amblyomma spp. are vectors for Ehrlichia ruminatium (formerly Cowdria ruminatium), the causative agent of heartwater disease in ruminants. The clinical progression of this case and the pericardial effusion seen on necropsy (as identified by the blue arrow) are classical for acute heartwater disease.

Animals may just be found dead with peracute disease.

Definitive diagnosis typically requires necropsy with microscopic evaluation of stained brain tissue.

This disease is endemic in parts of Africa and the Caribbean but is considered a foreign animal disease in the mainland Americas.

Dermacentor spp. are vectors for Babesia caballi in horses, Anaplasma marginale in cattle, Rickettsia rickettsii (Rocky Mountain spotted fever), Powassan virus, as well as the agents of Q fever and tularemia, among other infectious diseases throughout the world.

Face flies (Musca autumnalis) are an important vector for eyeworm (Thelazia spp.) and Mycoplasma bovis, one agent of infectious bovine keratoconjunctivitis of ruminants.

Horseflies (Tabanid spp.) can be vectors for bovine leukosis virus, the cause of enzootic bovine leukosis and lymphosarcoma.

Image courtesy of Alan R. Walker.