Surveillance for Coxiella burnetii animal reservoirs in Hong Kong suggests low zoonotic risk of Q-fever from local animals including ruminants, companion animals and rodents.

In Hong Kong, the average annual incidence of Q-fever in humans was one case per year from 2008 to 2023. The prevalence of C. burnetii infection in animals in Hong Kong is not reported. This study aimed to identify potential domestic and wild animal reservoirs of C. burnetii to inform human exposure risks from local animals. A cross-sectional study was conducted to detect infection and/or exposure using biological samples from 1118 animals including 377 ruminants (200 feral cattle, 35 water buffalo, 142 goats), 216 rats and 525 owned or unowned dogs and cats between 2020 and 2023. PCR to detect C. burnetii IS1111 DNA was performed on reproductive tissues, liver, faeces, blood, and/or vaginal swabs from 866 animals, and sera from 691 animals were tested for antibodies against C. burnetii by ELISA. C. burnetii DNA was not detected in any sample. While C. burnetii antibodies were not detected in any bovine or canine sera, 2/157 (1.3%) cats and 1/142 (0.7%) goats were seropositive. No evidence of active C. burnetii infection was detected in any of the 866 tested animals. Evidence of exposure was found only in cats and goats, albeit at low frequency. No evidence of a role for rodent reservoirs of C. burnetii in Hong Kong was identified. The sporadic serological evidence and the absence of molecular evidence of active infection in key reservoir species, along with the limited local livestock population, suggest that the risk of acquiring C. burnetii infection from exposure to local animals in Hong Kong is low.