Babesia in Domestic Ruminants

Abstract

Babesia spp. are intraerythrocytic tick-transmitted apicomplexan protozoans, considered to be the second most commonly found parasites in the blood of mammals after trypanosomes. Ever since the discovery of parasitic inclusions in erythrocytes of cattle by Victor Babes, a great number of Babesia species have been described, and thanks to the advances in microscopy, cell biology, and molecular biology techniques, our knowledge is continually expanding. Most Babesia species that affect domestic ruminants, including cattle, water buffalo, and small ruminants, are distributed in tropical and subtropical regions of the world. Acute Babesia infections of these animals are associated with fever, anemia, hemoglobinuria, and abortions and, in some cases, neurological symptoms, respiratory distress, and even death. Babesiosis outbreaks can be prevented by a combination of vaccination with living attenuated organisms and tick control programs. However, these control methods have numerous limitations, and, additionally, commercial live vaccines are only available for bovine babesiosis caused by B. bovis and B. bigemina. Our knowledge on relevant parasite molecules that act in the interface with the mammalian and tick hosts is rapidly increasing in the postgenomic era and will aid in the development of new and improvement of known immunotherapeutic interventions.