Incubation Period


Sketch of I. scapularis.
Ticks ingest Babesia while feeding, and the parasite multiplies within the tick's gut wall. The organisms then spread to the salivary glands; their inoculation into a vertebrate host by a tick larva, nymph, or adult completes the cycle of transmission.

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Incubation period is from 1-4 weeks.
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Patients may show symptoms of malaise, anorexia, and fatigue, followed several days later by fever and drenching sweats often accompanied by headache. The fever may be spiking or persistent or even low grade. Jaundice, dark urine, nausea, and vomiting occur with hemolysis. Physical examination is usually unremarkable except for mild splenomegaly and/or hepatomegaly which are seen in about a quarter of infected patients. The illness may continue for weeks or months. The presence of a rash, adenopathy, or objective joint, muscle, or neurologic findings should suggest another diagnosis. Immunosuppressed patients, splenectomized individuals, and the elderly have the most severe illness. Infections caused by B. divergens tend to be more severe (frequently fatal if not appropriately treated) than those due to B. microti, where clinical recovery usually occurs.
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The I. scapularis sketch is from

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