Feline chlamydiosis (review)

Introduction. Feline chlamydiosis is a disease caused by Chlamydia felis, it is characterized by conjunctivitis (unilateral or bilateral), lacrimation and lesions of the respiratory and reproductive tracts. This pathogen is a gram-negative bacterium with a strictly obligate intracellular parasitic nature. In the early 1940s, Chlamydia were considered an intermediate link between viruses and bacteria. Until the 1960s, Chlamydia were classified as viruses due to their small size and inability to grow on artificial nutrient media. Their unique two-phase developmental cycle allows the pathogen to persist in the body of an animal or human for a long time without clinical manifestations. Treatment of chlamydiosis must be systemic, addressing both etiological therapy (use of antibiotics) and symptomatic therapy. Immunity against chlamydiosis is weak, with cellular immunity being more important than humoral immunity. Currently, both attenuated and inactivated vaccines are available on the market, which can protect against the clinical manifestation of the disease but not against infection. Chlamydiosis is a globally widespread disease, with detection rates showing a consistent year-on-year increase.

Objective. To review and systematize current data on feline chlamydiosis caused by Chlamydia felis.

Results. The article reviews global prevalence data of feline chlamydiosis. It examines the biological properties of the infectious agent, the clinical signs of the disease, and the pathological findings. Data on immunity are presented, and disease control measures are discussed.

Conclusion. Chlamydia felis is a worldwide spread pathogen capable of infecting not only cats and other animals but also humans, which indicates its zoonotic potential. Such factors as complex life cycle, adeptness at host immune evasion and ability to establish persistent infections hinder its effective eradication. The required extended treatment regimens and propensity for chronic infections compromise companion animal welfare and pose a risk of transmission to humans.  A more profound understanding of Chlamydia felis pathogenesis is essential for developing effective treatment and prevention strategies.

1. Sostaric-Z uckermann I. C., Borel N., Kaiser C., Grabarevic Z., Pospischil A. Chlamydia in canine or feline coronary arteriosclerotic lesions. BMC Research Notes. 2011; 4:350. https://doi.org/10.1186/1756-0500-4-350

2. Sibitz C., Rudnay E. C., Wabnegger L., Spergser J., Apfalter P., Nell B. Detection of Chlamydophila pneumoniae in cats with conjunctivitis. Veterinary Ophthalmology. 2011; 14 (Suppl. 1): 67–74. https://doi.org/10.1111/j.1463-5224.2011.00919.x

3. Fukushi H., Hirai K. Genetic diversity of avian and mammalian Chlamydia psittaci strains and relation to host origin. Journal of Bacteriology. 1989; 171 (5): 2850–2855. https://doi.org/10.1128/jb.171.5.2850-2855.1989

4. Sanderson H., Vasquez M., Killion H., Vance M., Sondgeroth K., Fox J. Fatal Chlamydia psittaci infection in a domestic kitten. Journal of Veterinary Diagnostic Investigation. 2021; 33 (1): 101–103. https://doi.org/10.1177/1040638720966960

5. Lewin A. C., Hicks S. K., Carter R. T. A review of evidence- based management of infectious ocular surface disease in shelter- housed domestic cats. Veterinary Ophthalmology. 2023; 26 (Suppl. 1): 47–58. https://doi.org/10.1111/vop.13063

6. Chan I., Dowsey A., Lait P., Tasker S., Blackwell E., Helps C. R., Barker E. N. Prevalence and risk factors for common respiratory pathogens within a cohort of pet cats in the UK. Journal of Small Animal Practice. 2023; 64 (9): 552–560. https://doi.org/10.1111/jsap.13623

7. Longbottom D., Coulter L. J. Animal chlamydioses and zoonotic implications. Journal of Comparative Pathology. 2003; 128 (4): 217–244. https://doi.org/10.1053/jcpa.2002.0629

8. Sykes J. E. Feline chlamydiosis. Clinical Techniques in Small Animal Practice. 2005; 20 (2): 129–134. https://doi.org/10.1053/j.ctsap.2004.12.018

9. Halánová M., Sulinová Z., Čisláková L., Trbolová A., Páleník L., Weissová T., et al. Chlamydophila felis in cats – are the stray cats dangerous source of infection? Zoonoses and Public Health. 2011; 58 (7): 519–522. https://doi.org/10.1111/j.1863-2378.2011.01397.x

10. Fontbonne A. Infertility in queens: Clinical approach, experiences and challenges. Journal of Feline Medicine and Surgery. 2022; 24 (9): 825–836. https://doi.org/10.1177/1098612x221118752

11. Sachse K., Bavoil P. M., Kaltenboeck B., Stephens R. S., Kuo C.-C., Rosselló- Móra R., Horn M. Emendation of the family Chlamydiaceae: proposal of a single genus, Chlamydia, to include all currently recognized species. Systematic and Applied Microbiology. 2015; 38 (2): 99–103. https://doi.org/10.1016/j.syapm.2014.12.004

12. Wu S.-M., Huang S.-Y., Xu M.-J., Zhou D.-H., Song H.-Q., Zhu X.-Q. Chlamydia felis exposure in companion dogs and cats in Lanzhou, China: A public health concern. BMC Veterinary Research. 2013; 9:104. https://doi.org/10.1186/1746-6148-9-104

13. Ulbert Á. B., Juhász H., Karácsony Z., Bencze K., Deim Z., Burián K., Terhes G. The occurrence of Chlamydia felis in cats and dogs in Hungary. Pathogens. 2024; 13 (9):771. https://doi.org/10.3390/pathogens13090771

14. Hughes L., Visser S., Heddema E., de Smet N., Linssen T., Wijdh R. J., Huis in ‘t Veld R. Zoonotic transmission of Chlamydia felis from domestic cats; A case series of chronic follicular conjunctivitis in humans. New Microbes and New Infections. 2024; 59:101412. https://doi.org/10.1016/j.nmni.2024.101412

15. Jazi S., Mokhtari A., Kahrizsangi A. E. Molecular detection of Chlamydia psittaci and Chlamydia felis in human keratoconjunctivitis cases. Bulgarian Journal of Veterinary Medicine. 2020; 23 (1): 130–137. https://doi.org/10.15547/bjvm.2124

16. Wons J., Meiller R., Bergua A., Bogdan C., Geißdörfer W. Follicular conjunctivitis due to Chlamydia felis – case report, review of the literature and improved molecular diagnostics. Frontiers in Medicine. 2017; 4:105. https://doi.org/10.3389/fmed.2017.00105

17. Chen J., Long J., Zhou H., Huang C., Zhu Y., Wang R., et al. Isolation and characterization of Chlamydia felis and its pathogenesis in cats. Veterinary Microbiology. 2024; 295:110128. https://doi.org/10.1016/j.vetmic.2024.110128

18. Miyashita N., Fukano H., Mouri K., Fukuda M., Yoshida K., Kobashi Y., et al. Community- acquired pneumonia in Japan: a prospective ambulatory and hospitalized patient study. Journal of Medical Microbiology. 2005; 54 (4): 395–400. https://doi.org/10.1099/jmm.0.45920-0

19. Corsaro D., Venditti D. Detection of novel Chlamydiae and Legionellales from human nasal samples of healthy volunteers. Folia Microbiologica. 2015; 60 (4): 325–334. https://doi.org/10.1007/s12223-015-0378-y

20. Laroucau K., Di Francesco A., Vorimore F., Thierry S., Pingret J. L., Bertin C., et al. Multilocus variable- number tandem- repeat analysis scheme for Chlamydia felis genotyping: comparison with multilocus sequence typing. Journal of Clinical Microbiology. 2012; 50 (6): 1860–1866. https://doi.org/10.1128/jcm.00417-12

21. Marti I., Pisano S. R. R., Wehrle M., Meli M. L., Hofmann- Lehmann R., Ryser-D egiorgis M. P. Severe conjunctivitis associated with Chlamydia felis infection in a free-ranging Eurasian lynx (Lynx lynx). Journal of Wildlife Diseases. 2019; 55 (2): 522–525. https://doi.org/10.7589/2018-05-142

22. Luu L. D. W., Kasimov V., Phillips S., Myers G. S. A., Jelocnik M. Genome organization and genomics in Chlamydia: whole genome sequencing increases understanding of chlamydial virulence, evolution, and phylogeny. Frontiers in Cellular and Infection Microbiology. 2023; 13:1178736. https://doi.org/10.3389/fcimb.2023.1178736

23. Feodorova V. A. Genomnye i postgenomnye tekhnologii v izuchenii i diagnostike khlamidiozov = Genomic and postgenomic technologies in the study and diagnosis of chlamydial infections. Metody komp’yuternoi diagnostiki v biologii i meditsine – 2020: sbornik statei Vserossiiskoi shkoly-seminara (Saratov, 18–19 noyabrya 2020 g.) = Methods of computer diagnostics in biology and medicine – 2020: proceedings of the All- Russian school-s eminar (Saratov, November 18–19, 2020). Saratov: Saratovskii istochnik; 2020; 19–22. https://elibrary.ru/jgjgai (in Russ.)

24. McManus C. M., Levy J. K., Andersen L. A., McGorray S. P., Leutenegger C. M., Gray L. K., et al. Prevalence of upper respiratory pathogens in four management models for unowned cats in the Southeast United States. The Veterinary Journal. 2014; 201 (2): 196–201. https://doi.org/10.1016/j.tvjl.2014.05.015

25. Ju H., Yang D., Jin J., Wang J., Li X., Yang X., et al. Spectrum detection and analysis of the epidemiological characteristics of infectious pathogens in the feline respiratory tract. Archives of Virology. 2024; 169 (9):177. https://doi.org/10.1007/s00705-024-06093-5

26. Ohya K., Takahara Y., Kuroda E., Koyasu S., Hagiwara S., Sakamoto M., et al. Chlamydophila felis CF0218 is a novel TMH family protein with potential as a diagnostic antigen for diagnosis of C. felis infection. Clinical and Vaccine Immunology. 2008; 15 (10): 1606–1615. https://doi.org/10.1128/cvi.00134-08

27. Kiełbowicz Z., Płoneczka- Janeczko K., Bania J., Bierowiec K., Kiełbowicz M. Characteristics of the bacterial flora in the conjunctival sac of cats from Poland. Journal of Small Animal Practice. 2015; 56 (3): 203–206. https://doi.org/10.1111/jsap.12304

28. Konyaev S. V. Prevalence of causative agents of respiratory infections in cats and dogs in Russia. Russian Veterinary Journal. 2020; (1): 9–13. https://doi.org/10.32416/2500-4379-2020-20201-9-13 (in Russ.)

29. Strugovschikov A. Yu., Pudovkin N. A., Salautin V. V. Features of the spread of Chlamydia infection in Moscow. International Bulletin of Veterinary Medicine. 2020; (2): 21–25. https://elibrary.ru/qikmft (in Russ.)

30. Gruffydd- Jones T., Addie D., Belák S., Boucraut-B aralon C., Egberink H., Frymus T., et al. Chlamydophila felis infection: ABCD guidelines on prevention and management. Journal of Feline Medicine and Surgery. 2009; 11 (7): 605–609. https://doi.org/10.1016/j.jfms.2009.05.009

31. Azuma Y., Hirakawa H., Yamashita A., Cai Y., Rahman M. A., Suzuki H., et al. Genome sequence of the cat pathogen, Chlamydophila felis. DNA Research. 2006; 13 (1): 15–23. https://doi.org/10.1093/dnares/dsi027

32. Feodorova V. A., Lyapina А. М., Khizhnyakova М. А., Zaitsev S. S., Saltykov Y. V., Subbotina I. А., et al. Chlamydia of animals and humans. Moscow: Nauka; 2019. 135 p. https://doi.org/10.7868/9785020402492 (in Russ.)

33. Borel N., Polkinghorne A., Pospischil A. A review on chlamydial diseases in animals: still a challenge for pathologists? Veterinary Pathology. 2018; 55 (3): 374–390. https://doi.org/10.1177/0300985817751218

34. Ravichandran K., Anbazhagan S., Karthik K., Angappan M., Dhayananth B. A comprehensive review on avian chlamydiosis: a neglected zoonotic disease. Tropical Animal Health and Production. 2021; 53 (4):414. https://doi.org/10.1007/s11250-021-02859-0

35. Bressan M., Rampazzo A., Kuratli J., Marti H., Pesch T., Borel N. Occurrence of Chlamydiaceae and Chlamydia felis pmp9 typing in conjunctival and rectal samples of Swiss stray and pet cats. Pathogens. 2021; 10 (8):951. https://doi.org/10.3390/pathogens10080951

36. Vafin R. R., Ravilov R. H., Gaffarov H. Z., Ravilov A. Z., Iskhakov G. M., Bakirov I. H. Comparative characteristic of the strains of khlamidiosis on the omp1-gene. Veterinarnaya praktika. 2007; (3): 54–59. https://elibrary.ru/knpdej (in Russ.)

37. Harley R., Herring A., Egan K., Howard P., Gruffydd- Jones T., Azuma Y., et al. Molecular characterisation of 12 Chlamydophila felis polymorphic membrane protein genes. Veterinary Microbiology. 2007; 124 (3–4): 230–238. https://doi.org/10.1016/j.vetmic.2007.04.022

38. Di Francesco A., Baldelli R. Feline chlamydiosis in Italy: PCR amplification and analysis of the ompA and groEL-homolog genes. New Microbiologica. 2002; 25 (3): 341–344. https://pubmed.ncbi.nlm.nih.gov/12173777

39. Semenov V. M., Semenov D. M., Khvorik D. F., Kozin V. N., Bazhin Yu. A., Dmitrachenko T. I., et al. Chlamydia infection. Vitebsk: Vitebsk State Order of Peoples’ Friendship Medical University; 2006. 205 p. https://elibrary.ru/emcwop (in Russ.)

40. Aldyakov A. V., Konanova T. E. Chlamidiosis in cats. Vestnik Chuvash State Agricultural Academy. 2021; (2): 53–57. https://elibrary.ru/nsylpm (in Russ.)

41. Ravilov A. Z., Ghaffarov Kh. Z., Ravilov R. H. Chlamydiosis in animals. Kazan: Fen; 2004. 368 p. (in Russ.)

42. Klose S. M., De Souza D. P., Devlin J. M., Bushell R., Browning G. F., Vaz P. K. A “plus one” strategy impacts replication of felid alphaherpesvirus 1, Mycoplasma and Chlamydia, and the metabolism of coinfected feline cells. mSystems. 2024; 9 (10): e00852-24. https://doi.org/10.1128/msystems.00852-24

43. Pawlikowska- Warych M., Śliwa-Dominiak J., Deptuła W. Chlamydial plasmids and bacteriophages. Acta Biochimica Polonica. 2015; 62 (1): 1–6. https://doi.org/10.18388/abp.2014_764

44. Gladin D. P., Korolyuk A. M., Drobot I. V., Kirillova N. P., Kozlova N. S., Annenkova I. D. Chlamydia and chlamydiosis. Russian Biomedical Research. 2021; 6 (4): 37–46. https://elibrary.ru/olcqbo (in Russ.)

45. Elwell C., Mirrashidi K., Engel J. Chlamydia cell biology and pathogenesis. Nature Reviews Microbiology. 2016; 14 (6): 385–400. https://doi.org/10.1038/nrmicro.2016.30

46. Cheong H. C., Lee C. Y. Q., Cheok Y. Y., Tan G. M. Y., Looi C. Y., Wong W. F. Chlamydiaceae: diseases in primary hosts and zoonosis. Microorganisms. 2019; 7 (5):146. https://doi.org/10.3390/microorganisms7050146

47. Lisova V., Savchenko A. Pathomorphological characteristics of chlamydiosis in cats. Scientific Messenger LNUVMBT named after S. Z. Gzhytskyj. 2017; 19 (77): 11–14. https://elibrary.ru/ytalpz (in Ukrainian)

48. Caspe S. G., Hill H. Chlamydiosis in animals. Animals. 2024; 14 (21):3130. https://doi.org/10.3390/ani14213130

49. Nguyen D., Barrs V. R., Kelman M., Ward M. P. Feline upper respiratory tract infection and disease in Australia. Journal of Feline Medicine and Surgery. 2019; 21 (10): 973–978. https://doi.org/10.1177/1098612x18813248

50. Diagnosis and prevention of infectious diseases in dogs and cats: a guide for veterinary practitioners. Ed. by T. I. Aliper. Moscow: Zoovetkniga; 2017. 300 p. (in Russ.)

51. Wasissa M., Lestari F. B., Nururrozi A., Tjahajati I., Indarjulianto S., Salasia S. I. O. Investigation of chlamydophilosis from naturally infected cats. Journal of Veterinary Science. 2021; 22 (6): e67. https://doi.org/10.4142/jvs.2021.22.e67

52. Lisova V., Savchenko A. Histological changes in cats at chlamydiosis. Scientific Messenger LNUVMB. 2017; 19 (78): 158–161. https://elibrary.ru/zswrst (in Ukrainian)

53. Mills D. Diagnosis of Chlamydophila felis by conjunctival cytology in shelter cats. BSAVA Congress Proceedings. 2016; 527. https://www.bsavalibrary.com/content/chapter/10.22233/9781910443446.ch66sec5

54. Belova E. V., Kapustina T. A., Markina A. N., Parilova O. V. Laboratory diagnostics of respiratory chlamydia. Siberian Medical Review. 2019; (1): 5–16. https://doi.org/10.20333/2500136-2019-1-5-16 (in Russ.)

55. Scidmore M. A. Cultivation and laboratory maintenance of Chlamydia trachomatis. Current Protocols in Microbiology. 2006; 11A.1.1–11A.1.25. https://doi.org/10.1002/9780471729259.mc11a01s00

56. Zur N. V., Mironov A. Yu., Aleshkin V. A., Afanasjev S. S., Rubalskaya E. E., Afanasjev M. S., Rubalskii E. O. Actual aspects of laboratory diagnostics of urogenital chlamydial infections. Astrakhan Medical Journal. 2016; 11 (2): 16–32. https://elibrary.ru/wfaqab (in Russ.)

57. Rahman M. A., Azuma Y., Fukunaga H., Murakami T., Sugi K., Fukushi H., et al. Serotonin and melatonin, neurohormones for homeostasis, as novel inhibitors of infections by the intracellular parasite Chlamydia. Journal of Antimicrobial Chemotherapy. 2005; 56 (5): 861–868. https://doi.org/10.1093/jac/dki331

58. Squires R. A., Crawford C., Marcondes M., Whitley N. 2024 guidelines for the vaccination of dogs and cats – compiled by the Vaccination Guidelines Group (VGG) of the World Small Animal Veterinary Association (WSAVA). Journal of Small Animal Practice. 2024; 65 (5): 277–316. https://doi.org/10.1111/jsap.13718

59. Medova E. V., Pivovarenko E. A. Razreshayushchaya sposobnost’ metodov prizhiznennoi diagnostiki khlamidiinoi infektsii v populyatsii plotoyadnykh v usloviyakh urbanizirovannykh territorii = Sensitivity of ante-mortem diagnostic methods for chlamydial infection in carnivore populations within urban environments. Russian Journal of Veterinary Pathology. 2005; (4): 132–134. https://elibrary.ru/hsqenl (in Russ.)

60. Wong W. F., Chambers J. P., Gupta R., Arulanandam B. P. Chlamydia and its many ways of escaping the host immune system. Journal of Pathogens. 2019; 2019:8604958. https://doi.org/10.1155/2019/8604958