Objective:
Introduction: Babesiosis, caused by apicomplexan parasites from the Babesia genus, is primarily transmitted by Ixodes scapularis ticks and occasionally through blood transfusion, organ transplantation, and congenital means. While over 100 species have been identified, including Babesia microti, Babesia divergens, Babeisa (B.) duncani, and the yet unnamed MO-1 strain, B. duncani is primarily found on the West Coast. However, its presence in the northeastern US is now emerging.
Background:
Case Summary: The 22-year-old presented with fever and joint pains, having recently traveled to Israel and stayed in rural Pennsylvania. He had no recollection of tick or mosquito bite. Labs were remarkable for leukopenia, low absolute neutrophil count, elevated lactate dehydrogenase, and ALT/AST levels. Initially, he was treated for suspected Lyme disease with doxycycline, but the treatment was switched to Amoxicillin and Rifampin due to a headache. Serology and cerebrospinal fluid (CSF) studies for cytomegalovirus (CMV), Epstein-Barr virus (EBV), varicella-zoster virus (VZV), herpes simplex virus (HSV), Anaplasma, Rickettsia, West Nile, cryptococcus, and parvovirus were negative. Brain MRI showed subarachnoid space infection. CSF studies showed normal glucose, a slightly elevated protein with a white count of 44, with 99% monocyte predominance. Serology testing for B. duncani returned positive. He was treated with azithromycin and atovaquone for 7 days.
Conclusions:
Discussion: Babesiosis occurrences are rare in Pennsylvania, and B. duncani cases are even rarer. The unique presentation involves a traveler with unexplained neutropenia, thrombocytopenia, and hemolytic anemia, initially unresponsive to doxycycline. Evidence suggests potential antibiotic resistance of B. duncani, complicating treatment with standard agents like atovaquone and azithromycin.
In conclusion, this case underscores the need for heightened awareness and testing for B. duncani in suspected tick-borne illnesses, especially in regions where its emergence is noted. The complex clinical presentation and potential antibiotic resistance underline the challenging nature of managing this pathogen.