Diseases & Conditions


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Babesiosis (babesiasis)


A rare, sometimes fatal disease caused by a tick-borne virus similar to both LYME DISEASE and human granulocytic ehrlichiosis (HGE). Also known as Nantucket fever, it is most often seen in the elderly and those with impaired immune systems. Severe cases have been diagnosed in those who have had their spleen removed. Most cases of babesiosis have been reported in summer and fall in the northeastern United States, especially Nantucket, Massachusetts; Shelter Island, New York; and nearby islands. However, cases have recently been identified in the upper Midwest, the Pacific Coast states, and Europe. A related species has caused a babesiosis-like illness in Washington and California. The protozoa causing babesiosis was first identified by Roman bacteriologist Victor Babes, for whom the organism and the disease was named. Cause Babesiosis is caused by protozoa similar to those that cause MALARIA (the species Babesia microti); it is passed via the bite of ticks of the species Ixodes dammini. The tick is carried by meadow voles, mice, and deer. The disease can also be transmitted via contaminated blood transfusions. Symptoms Babesiosis typically causes mild illness in otherwise healthy people, but it can be overwhelming to those with impaired immune systems. Within one to 12 months after infection, symptoms appear, including fever, fatigue, and hemolytic anemia lasting from several days to several months. A person may also have the disease with no symptoms at all. It is not known if a past infection renders a patient immune. Diagnosis Molecular tests are being developed, but currently the disease is diagnosed by microscopic examination of blood smears. Treatment Standardized treatments have not been developed; however, a combination of ANTIMALARIAL DRUGS such as quinine and an antibiotic (clindamycin) are usually the drugs of choice. Prevention The spread of babesiosis can be curtailed with the control of rodents around houses and the use of tick repellents.