Molecular detection of Babesia spp. in community and privately-owned cats in Hong Kong

Domestic cats are susceptible to infection with at least 11 Babesia spp. A few species are associated with babesiosis, particularly in South Africa, but most feline Babesia infections are subclinical. In Hong Kong, where dogs are commonly infected with B. gibsoni, a single infection in a cat with novel species B. hongkongensis is reported.
The aim of this study was to investigate the frequency of detection of Babesia spp. in cats in Hong Kong. Residual whole-blood DNA from free-roaming healthy community-owned cats (n=239), privately-owned cats undergoing diagnostic investigations (n=112) collected between January 2021 and March 2023 was used. Signalment and clinical data, where available, were recorded. DNA samples testing positive for housekeeping gene GAPDH on cPCR were tested for Babesia DNA using a pan-Babesia mitochondrial Cytochrome B cPCR, and a B. hongkongensis-specific 18S rRNA cPCR. Positive samples were confirmed by sequencing and comparative sequence analysis using the GenBank nucleotide database.
B. hongkongensis was detected in 4/239 (1.67%) community cats, and 0/112 privately-owned cats. B. gibsoni was detected in 0/239 community cats and 1/112 (0.89%) owned cats. The B. gibsoni-infected cat had signs consistent with babesiosis (anaemia, thrombocytopenia), although parasitaemia was subsequently cleared while signs persisted.
Cats in Hong Kong can be infected with B. hongkongensis or B. gibsoni, albeit at low frequency. Whether or not B. gibsoni contributed to clinical signs in the infected cat is unclear. Molecular surveillance of cats with and without risk factors for Babesia infection in the region is warranted.