Three Cases of Human Babesiosis, Italy, 2017-2020

Abstract

We report 3 cases of babesiosis in Italy caused by Babesia species that are rarely reported in humans. The circulation of Babesia spp. among vectors, animals, and humans might be more common than previously thought, and babesiosis might be an underdiagnosed and emerging disease in Italy and Europe.

Keywords: Babesia; Italy; One Health; arthropod-borne diseases; babesiosis; parasites; piroplasmosis; tick-borne; ticks; vector-borne infections; zoonoses.

Figure 1

Blood smears showing Babesia spp. trophozoites in study of 3 cases of human babesiosis, Italy, 2017–2020. Smears were stained with Giemsa stain. A, B) B. canis canis identified in patient 1. Original magnification ×630. C) B. vulpes identified in patient 3. Original magnification ×1,000 (oil immersion).

Figure 2

Phylogenetic analysis of the Babesia spp. in study of 3 cases of human babesiosis, Italy, 2017–2020. 18S ribosomal RNA gene sequences were amplified from the 3 clinical isolates from Italy. Arrows indicate the Babesia isolates from the 3 patients. Tree was inferred by using the maximum-likelihood method with 1,000 bootstrap replicates. Tree with the highest log likelihood (−3,487.14) is shown. Bootstrap values (cutoff at 80%) are indicated at specific branch nodes. 18S ribosomal RNA gene (partial) from Cytauxzoon felis protozoan parasite was used as the outlier. Tree not drawn to scale.