Thus the incidence of Babesiosis in man is not well known. What however is known is that frequently anti-babesia antibodies are found in African people, indicating that they easily contratct babesiosis without suffering from major symptoms of disease. Humans become infected with Babesia when they accidently intrude into a natural disease cycle . In the eastern and midwestern U.S., the disease is known since 1966. Human cases often turn out to be caused by Babesia microti of rodents.
Human infections tend to be mild and self limiting, and most probably are never diagnosed.
Transfusion with blood or blood componenet from asymptomatic donors may result in human babesiosis. However, such a risk is minimal. Tick Vectors Transmission of Babesia microti from one host to another generally takes place through direct tick-host contact . In the northeastern United States, the enzootic cycle is maintained principally by the interactions between immature blacklegged ticks and white-footed mice. In general, larvae acquire the infection when feeding on Babesia microti -infected mice.