COMMENTARY

Are Various Babesia Species a Missed Cause for Hypereosinophilia? A Follow-up on the First Reported Case of Imatinib Mesylate for Idiopathic Hypereosinophilia

James L. Schaller, MD, MAR; Glenn A. Burkland, DMD; PJ Langhoff

Disclosures

February 27, 2007

Discussion

As of January 2007, many new species of Babesia have been identified and many have no specific human testing available in routine national laboratories.[2] The manual CBC used to identify Babesia and also a similar-appearing RBC parasite, malaria, is unreliable; malaria in allopathic centers is often missed, especially if the numbers of intracellular parasites are low.[27,28,29] The patient in this case had 2 close relatives in the same home with likely babesiosis diagnosed by some common symptoms and lab results. While treatments should not fully diagnose an illness, his positive response to 3 malaria medications used in babesiosis treatment is noteworthy.

Spontaneous unexplained remissions have been reported in HES patients with different treatments in the past, eg, interferon-alpha.[30] Because this patient has been free of HES lab findings for 5 years, we feel that he is probably outside the range of possible "cyclic eosinophil oscillations."[16]

Could interferon-alpha and imatinib control a Babesia-induced idiopathic HES? We do not know. However, low doses of natural human interferon alpha significantly inhibit the development of B microti infection in mice.[31]

Further, another partially related interferon, IFN-gamma, has antiparasitic benefits, including against Babesia.[32,33]

Imatinib has many mechanisms, and its ability to treat parasitic agents is not known. The tyrosine kinase system, however, is one target for the medication. Babesia contains a highly active protein kinase.[34] Viruses, bacteria, and parasites manipulate tyrosine kinase and related pathways of their hosts to achieve efficient entry, replication, and exit during their infectious cycles.[27]

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