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.
The study indicates a low risk of Q-fever from local animals in Hong Kong, with no active C. burnetii infections detected.
Where it sits
this study against the rest of the buserelin corpusSummary and findings
A cross-sectional study in Hong Kong tested 1118 animals for Coxiella burnetii infection to assess zoonotic risk. PCR and ELISA tests found no active infection, with seropositivity in 1.3% of cats and 0.7% of goats. The study suggests a low risk of Q-fever from local animals.
Abstract
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.
Background
This study addresses the potential zoonotic risk of Q-fever in Hong Kong, where the average annual incidence in humans is one case. Understanding animal reservoirs of Coxiella burnetii is crucial for assessing human exposure risks. Previous data on the prevalence of C. burnetii in local animals were not available, making this study significant for public health surveillance.
Methods
A cross-sectional study was conducted from 2020 to 2023, involving 1118 animals including ruminants, rodents, and companion animals. PCR testing was performed on 866 animals to detect C. burnetii DNA, and ELISA was used on sera from 691 animals to test for antibodies. The study aimed to detect infection and exposure in these animals.
Results
C. burnetii DNA was not detected in any of the 866 animals tested. Serological evidence of exposure was found in 1.3% of cats and 0.7% of goats. No active infection was detected, and no evidence suggested a role for rodent reservoirs in Hong Kong.
Interpretation
The absence of C. burnetii DNA and low seropositivity rates suggest a minimal zoonotic risk from local animals. The findings align with the low incidence of Q-fever in humans in Hong Kong. However, the cross-sectional design limits the ability to assess temporal trends or causality.
Key findings
- 1 case of Q-fever per year in humans from 2008 to 2023.
- 1118 animals tested between 2020 and 2023.
- 0% C. burnetii DNA detected in 866 animals.
- 1.3% seropositivity in cats, n=157.
- 0.7% seropositivity in goats, n=142.
Limitations
- Cross-sectional design
- No prevalence data for C. burnetii in animals
- Limited to Hong Kong
- No temporal trend analysis