Acute splenic pathology on CT in patients with babesiosis

To better understand the occurrence of splenic disease as a potential manifestation of babesiosis by retrospectively estimating the frequency of acute splenic injury on abdominal and pelvic CT in a cohort of patients with active babesia infection.

In a search of our single institution, suburban teaching community hospital database, 57 patients were found to have positive babesia infection between the years 2021-2023. 29 of these patients underwent abdominal and pelvic CT (22 with and 7 without intravenous contrast), and 3 underwent abdominal ultrasound without any CT. The imaging was reviewed for the presence or absence of splenic abnormalities, and for follow-up imaging. Parasitemia levels at the time of imaging were also reviewed; parasitemia levels < 4% are associated with mild to moderate disease, whereas parasitemia levels > 4% are associated with severe disease.

21/32 (66%) patients who underwent any type of abdominal imaging (ultrasound, MRI, and CT) had splenomegaly. Of the 22 patients who had IV contrast-enhanced CT scans, 6 were found to have splenic infarction (27%). One of these 22 patients had multiple rounded non-peripheral hypoenhancing foci on both CT and MRI which did not meet criteria for infarction, in association with splenomegaly, and which resolved after treatment. 0/6 patients in the splenic infarction group had parasitemia levels greater than 4%, while 4 of the 16 patients (4/16) without infarction had parasitemia levels of greater than 4%.

Our study showed that splenic disease in patients with babesiosis mostly took the form of splenomegaly, and in a substantial minority of patients as splenic infarction. There were no cases of splenic rupture and perisplenic hematoma in our case series, likely reflecting a limitation of the relatively small study size. Concordant with prior studies, we found no identifiable association between parasitemia levels and the presence of splenic infarction.