Babesiosis (Piroplasmosis)

Babesia canis, Blood smear, canine
original magnification x1000

Author : Dr Pierre Hébert
Translation by Dr. Khyali R. Mittal

Description: babesiosis is caused by a protozoan which is species specific. The trophozoites are found in the erythrocytes in several shapes such as round, ameboid, rods and the typical piriform morphology. The parasite multiplies by binary fission or budding within the erythrocyte and destroy the red cell intravascularly. Therefore hemoglobinuria is frequently observed in the acute phase of the infection.

The incubation period varies from 5 to 14 days depending on the species involved. The clinical signs of the acute phase are fever, anorexia, dehydratation, anemia, hemoglobinuria and icterus followed by death. The anemia is macrocytic-hypochromic and regenerative. The degree of anemia is disproportionate to the degree of parasitemia, thereby indicating hemolysis not only of parasitized red cells but also of some unparasitized erythrocytes (immune mechanism?). A unique finding with Babesia bovis and B. canis infections is that autoagglutination of both parasitized and nonparasitized erythrocytes blocks the capillaries of the skin and brain. DIC may occur as a complication of hemolytic anemia from babesiosis.

Blood examination is essential to demonstrate Babesia. If the organism is not found in the peripheral blood, capillary blood from an ear should be obtained and examined. The protozoan could be found in the erythrocytes of bone marrow, spleen and liver.

B. canis (specific for the dog) is large and piriform whereas B. gibsoni is smaller and non-piriform. The infection is encountered principally in the southeastern part of United States as well as in some countries of Europe. The young dogs are more fragile (susceptible) than the adult although there is a period of protection in the puppies (passive immunity) until the age of 8-12 weeks.