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Zoonotic diseases are still proving to be a global issue despite a vast amount of research occurring in this area. Due to their infectious nature and resistance concerns, many scientists are trying to develop treatments, but prevention is always better than a cure, so promotion and improvement of current and future immunisation therapies is key. These diseases are spread from vertebrate animals to humans, examples including rabies, whereby the Rhabdoviridae family of viruses is transmitted by dogs. However rabies is among the extensive array of zoonotic diseases that can be prevented by vaccination [1]. Contributions that would help tackle the prevalence of zoonotic diseases include promoting global immunisation, investing in diagnostic methods to improve detectability and limiting human-wildlife interaction where zoonotic diseases are more common [2].
Among the collection of zoonotic pathogens are several Chlamydia species, including Chlamydia suis, C. pecorum and C. psittaci, which infect livestock, and C. felis and C. caviae which infect domestic pets [3]. More specifically, species such as C. felis are responsible for conjunctivitis in cats but also commonly infect their upper respiratory tract, as both locations are mucosal, and this allows the bacteria to thrive [3]. C. felis is a Gram-negative bacterium that is obligately intracellular so cannot survive outside the host, hence why close contact is essential for transmission [4]. Recently, the zoonotic potential of C. felis was investigated by Ulbert et al., who studied the occurrence of C. felis in cats and dogs from a veterinary clinic, a cat shelter and households [3]. Conjunctival swabs were taken from the animals and subject to molecular detection; the positivity rate was 33.3% for cats and 40.0% for dogs [3]. As anticipated, environment appeared to have an impact on occurrence; positivity rates in cat shelters were 37.2%, in the veterinary clinic it was 42.4% and 11.7% for domestic pets [3]. They also detected for other bacterial and fungal species by culture-based examinations; a Whitley A45 Workstation was used to culture for any anaerobes [3]. Through culture-based examination, 103 species were identified with 97 being bacterial and 6 being fungal [3].
For animal and public health, it is important to understand the prevalence of zoonotic infections, including those caused by C. felis as results like these show that there is an occurrence in every environment our pets and ourselves encounter.
Written by DWS Microbiologist Kirsty McTear
References
- Koury R, Warrington S J. Rabies [Internet]. STATPEARLS; 2022. Available from: https://www.ncbi.nlm.nih.gov/books/NBK448076/
- Pal M, Firaol Tariku, Upadhyay D, Ravindra Zende. Current Innovations in the Diagnosis and Immunization of Emerging and Re-Emerging Zoonoses. American Journal of Epidemiology and Infectious Disease. 2024 Jun 18;12(2):23–8.
- Ulbert A B, Juhász H, Karácsony Z, Bencze K, Deim Z, Burián K, et al. The Occurrence of Chlamydia felis in Cats and Dogs in Hungary. Pathogens. 2024 Sep 6;13(9):771.
- Tasker S., et al. GUIDLINE for Chlamydia felis [Internet]. ABCD Vets. 2024. Available from: https://abcdcatsvets.org/guideline-for-chlamydia-felis/?pdf=5023
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