A Prospective Cohort Longitudinal Study of Human Acute Babesiosis: Quality of Life and Severity of Symptoms Through 1-Year Follow-up

Background Babesiosis, caused by the parasitic blood-borne piroplasm Babesia microti, is emerging in the Northern hemisphere. We aimed to study long-term symptoms of patients with B microti infection in New York. Methods A prospective longitudinal cohort study of human babesiosis was conducted at Stony Brook University Hospital. Inclusion criteria were age ≥18 years with positive blood smear for Babesia spp. Symptoms were assessed in patients at presentation and at 1, 6, and 12 months by 3 validated surveys: a visual analog scale, a quality of life (QOL) questionnaire, and the 36-Item Short Form Survey (SF-36). Results In total, 38 patients with acute B microti infection (26% female; age range, 54–73 years) were enrolled from 2020 to 2022. Compared with baseline, the visual analog scale total symptom scores (with high scores representing worse status) significantly decreased at 6-month follow-up for the immunocompetent (n = 9; P < .001) and immunocompromised groups (n = 6; P < .001). Scores remained significantly higher in the immunocompromised group (ratio, 2.6; P = .045). At 1-year follow-up, the scores in the 2 groups tended to be similar (ratio, 0.9; P = .82). Within QOL concept scores (with low scores representing worse status), physical functioning significantly increased after 6 months of follow-up in both cohorts (immunocompetent, n = 10 [P = .004]; immunocompromised, n = 5 [P = .008]) but was still significantly lower in the immunocompromised group at that time (ratio, 0.7; P < .001). By the 12-month follow-up, physical functioning scores in the 2 groups appeared to converge, though the difference remained borderline significant (ratio, 0.9; P = .06). Conclusions The time to convalescence was similar among patients with babesiosis, though immunocompromised patients tended to have more prolonged symptoms and worsened QOL after babesiosis at 1-year follow-up, compared with immunocompetent patients.