Rhipicephalus sanguineus will feed on a wide variety of mammals, but dogs are the preferred host in the U.S., and the population can reach pest proportions in houses and kennels.
R. sanguineus is one of the most important vectors of diseases in dogs worldwide. In the United States, R. sanguineus is a vector of the diseases in dogs: canine ehrlichiosis (Ehrlichia canis) and canine babesiosis (Babesia canis). In dogs, symptoms of canine ehrlichiosis include lameness and fever; those for babesiosis include fever, anorexia and anemia. R. sanguineus has not been shown to transmit the bacteria that causes Lyme disease in humans. In parts of Europe, Asia and Africa, it is a vector of Rickettsia conorii, known locally as Mediterranean spotted fever, boutenneuse fever, or tick typhus.
R. sanguineus can also transmit Rocky Mountain spotted fever in humans in the southwestern United States.