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Kopal Kulkarni, 2007,
Stanford University
Parasites & Pestilence: Infectious Public Health Challenges
Prof. D. Scott Smith,


Babesiosis is rare illness which is caused by the Babesia protozoan parasite. The parasite is most often transmitted by ticks but in infrequent cases has been passed by blood transfusion.

Though it most commonly affects cattle, there are several forms of Babesia which can infect humans. In the U.S., where the most cases of babesiosis have been recorded, Babesia microti is the prevalent form of the parasite.  In Europe and other parts of the world, Babesia divergens is found to infect humans.

When a person has babesiosis, they will often have a clinical presentation similar to malaria (fever, chills and fatigue) and can suffer from symptoms that range from life-threatening to unnoticeable. Though antibiotics can be used to treat babesiosis, the best option is to prevent the disease by taking precautions against being bitten by ticks, which harbour the parasite.