infectious diseases
Babesiosis
Diagnosis of Babesiosis
Light microscopy of blood smears Serologic and polymerase chain reaction-based tests Most patients with babesiosis do not remember a tick bite, but they may reside in or report a history of travel to an endemic region. Babesiosis is usually diagnosed by findingBabesiain blood smears, but differentiation fromPlasmodiumspecies can be difficult. Tetrad forms (the so-called Maltese cross formation), although not common, are unique toBabesiaand helpful diagnostically. Serologic and polymerase chain reaction (PCR)–based tests are available. Antibody detection by indirect fluorescent antibody (IFA) testing usingB. microtiantigens can be helpful in patients with low-level parasitemia but may be falsely negative in those infected with otherBabesiaspecies. PCR-based assays can help differentiateBabesiafromPlasmodium falciparumif blood smear findings are ambiguous, confirm infection in patients with low parasitemia, and identify theBabesiaspecies. 