Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content +++ Key Features ++ Babesia microti is a malaria-like protozoan that infects humans bitten by infected Ixodes scapularis (deer tick) After inoculation, the protozoan penetrates erythrocytes and starts an asynchronous cycle that causes hemolysis In the United States, the majority of cases occur in the Northeast and upper Midwest from May to October Infection is a transfusion-transmissible disease Incubation period is 1–4 weeks after tick bite, or 1–9 weeks after blood transfusion +++ Clinical Findings ++ Approximately half of infected children are asymptomatic Symptoms are nonspecific and most commonly include Sustained or cyclic fever up to 40.9°C Shaking chills Sweats Other associated nonspecific symptoms include Malaise Fatigue Anorexia Arthralgias Myalgias Headache Physical examination findings are usually minimal but may include Hepatosplenomegaly Jaundice Dark urine Disease is usually self-limited, causing symptoms for 1–2 weeks with fatigue that may persist for months Hemolytic anemia and thrombocytopenia are common +++ Diagnosis ++ Babesial parasites are identified in blood by microscopic evaluation of thin or thick blood smears or by polymerase chain reaction (PCR) amplification of babesial DNA Babesia parasites are intraerythrocytic organisms that resemble Plasmodium falciparum ring forms The tetrad form (Maltese cross), if visualized, is pathognomonic Specific serologic tests are also available through the Centers for Disease Control and Prevention (CDC) +++ Treatment ++ Azithromycin (10 mg/kg up to 500 mg on the first day, followed by 5 mg/kg up to 250 mg/day) in combination with atovaquone (20 mg/kg, up to 750 mg, twice a day) for 7–10 days Treatment of choice for mild to moderate disease Causes fewer adverse side effects than other regimens. Clindamycin (10 mg/kg, up to 600 mg, every 8 hours) in combination with quinine (8 mg/kg, up to 650 mg, every 8 hours) is standard of care for severely ill patients Longer courses of treatment may be needed in immunocompromised patients Partial or complete RBC exchange transfusion is indicated for persons with Severe babesiosis, as indicated by high-grade parasitemia (≥ 10%) Significant hemolysis Renal, hepatic, or pulmonary compromise Your Access profile is currently affiliated with '[InstitutionA]' and is in the process of switching affiliations to '[InstitutionB]'. Please click ‘Continue’ to continue the affiliation switch, otherwise click ‘Cancel’ to cancel signing in. Get Free Access Through Your Institution Learn how to see if your library subscribes to McGraw Hill Medical products. Subscribe: Institutional or Individual Sign In Username Error: Please enter User Name Password Error: Please enter Password Forgot Password? Forgot Username? Sign in via OpenAthens Sign in via Shibboleth