Babesiosis is another blood disease caused by a parasite (this time a protozoan) carried by several species of infected ticks.
Symptoms can range from anemia and skin blotches to uncontrollable bleeding and shock. Fever and poor condition are common.
Babesiosis can be diagnosed by clinical signs and history, direct examination of the blood, or titration of a blood sample.
Babesiosis is a disease known around the world. It is caused by a protozoan that parasitizes red blood cells of domestic and wild animals, and occasionally people. The organism is transmitted to a host by the bite of infected Ixodid ticks such as the brown dog tick and black-legged tick. Various other tick species have also been incriminated.
The major financial impact of babesiosis is on the cattle industry (B. bigemina and B. bovis) but infections in humans and dogs are becoming a concern. Two species of the parasite are found in U.S. dogs: Babesia canis and B. gibsoni. In the United States, the disease is most prevalent in the southeast, but pockets of infection exist in the northeastern states as well. Cats also can be infected with Babesia organisms (B. felis, B. cati, B. pantherae, B. herpailura), but these organisms are reportedly not present in the United States.
Humans have been infected with Babesia canis, but only rarely. Most commonly, infections in humans occur due to Babesia microti, which is transmitted by the deer tick, I. scapularis. Numerous cases have been documented, including co-infection with Borrelia burgdorferi and Babesia microti in people living in Massachusetts and Connecticut.
When an infected tick bites, the Babesia protozoa enter the host's red blood cells. Babesia organisms begin to multiply. As a result of the host immune system's attempt to eliminate the organism, and because of the organism itself, anemia often results. Young dogs are most susceptible to infection. If heavily parasitized, they can present in a severe state of hemorrhagic shock.
Less dramatic but equally serious, dogs can show a state called disseminated intravascular coagulation (DIC), in which platelet numbers have dwindled sharply and small hemorrhages have developed in the skin and mucous membranes. A dog with chronic disease typically shows signs of fever, loss of appetite, and poor body condition. If diagnosis of disease is not made by history and clinical signs alone, the organism can be detected in a sample of blood from the capillaries of the ear or tail tip which has been smeared onto a slide and treated with Giemsa stain. Titers can be assessed by immunofluorescence. If titers are greater than 1:80, a positive diagnosis can usually be made.
Diminazen aceturate and imidicarb dipropionate are the two most widely used drugs to treat babesiosis. Long-acting tetracyclines reduce the severity of disease if treatment is started early. Supportive therapy may include intravenous fluids and blood transfusions.