Babesiosis

An illness caused by the parasite Babesia which is transmitted from animals to humans by ticks. In the US, it is typically contracted in the Northeast or Midwest — in southern New England or New York State and in Wisconsin or Minnesota. The signs and symptoms include fever, chills, sweating, myalgias (muscle aches), fatigue, hepatosplenomegaly (enlargement of the liver and spleen) and hemolytic anemia (anemia due to break-up of red cells). Symptoms typically occur after an incubation period of 1 to 4 weeks and can last several weeks. The disease is more severe in patients who are immunosuppressed, splenectomized (lack their spleen), or elderly. It can cause death. Treatment involves antibiotics, usually clindamycin and quinine. The parasite: While more than 100 species of Babesia have been reported, only a few have been identified as causing human infections. Babesia microti and Babesia divergens have been identified in most human cases, but variants (considered different species) have been recently identified. Little is known about the occurrence of Babesia species in malarial areas where Babesia can easily be misdiagnosed as Plasmodium (the agent of malaria). The life cycle of the parasite: (This contains some technical information.) The B. microti life cycle involves two hosts, which includes a rodent, primarily the white-footed mouse, Peromyscus leucopus. During a blood meal, a Babesia-infected tick introduces sporozoites into the mouse host. Sporozoites enter erythrocytes and undergo asexual reproduction (budding). In the blood, some parasites differentiate into male and female gametes although these cannot be distinguished at the light microscope level. The definitive host is a tick, in this case the deer tick, Ixodes dammini (I. scapularis). Once ingested by an appropriate tick, gametes unite and undergo a sporogonic cycle resulting in sporozoites. Transovarial transmission (also known as vertical, or hereditary, transmission) has been documented for "large" Babesia spp. but not for the "small" babesia, such as B. microti. Humans enter the cycle when bitten by infected ticks. During a blood meal, a Babesia-infected tick introduces sporozoites into the human host. Sporozoites enter erythrocytes and undergo asexual replication (budding). Multiplication of the blood stage parasites is responsible for the clinical manifestations of the disease. Humans are, for all practical purposes, dead-end hosts and there is probably little, if any, subsequent transmission that occurs from ticks feeding on infected persons. However, human to human transmission can occur through blood transfusions.

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A disease caused by infection with a species of the protozoan Babesia, transmitted by ticks. In animals, the disease is characterized by fever, malaise, listlessness, severe anemia, and hemoglobulinuria; the death rate frequently is higher in adult than in young animals. SYN: piroplasmosis.

- human b. a rare human disease caused by infection with Babesia species (most frequently B. divergens in Europe and B. microti in the U.S.) that has been fatal in some splenectomized individuals.

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ba·be·si·o·sis bə-.bē-zē-'ō-səs n, pl -o·ses -.sēz infection with or disease caused by babesias called also babesiasis

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ba·be·si·o·sis (bə-be″ze-oґsis) any of various tickborne diseases due to infection with protozoa of the genus Babesia, occurring in wild and domestic mammals and as a zoonosis in humans. Called also babesiasis and piroplasmosis.