What is the clinical history of babesiosis?

Updated: Apr 01, 2021
  • Author: Rachel E Strength, MD; Chief Editor: Michael Stuart Bronze, MD  more...
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The spectrum of babesiosis manifestations is broad, ranging from a silent infection to a fulminant malaria-like disease with fever and chills that results in severe hemolysis and, occasionally, death. Symptoms are thought to be related to the degree of red blood cell (RBC) parasitemia, though this is not always the case.

In the United States, infection with B. microti in otherwise healthy individuals often remains subclinical; however, symptomatic infection is common in asplenic, elderly, and immunocompromised patients. In Europe, because bovine babesiosis due to B. divergens and B. bovis mostly occurs in patients who are asplenic, infections are generally clinically overt and frequently fatal.

Patients typically report a history of travel to an endemic area between May and September. This is the period during which the Ixodes tick is in its infectious nymph stage. Because the nymph, the primary vector, is only 2 mm in diameter when engorged, most patients do not recall a tick bite. The incubation period after the tick bite is usually 1-3 weeks but may occasionally be as long as 9 weeks.

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