KERATOCONJUNCTIVITIS OF THE KOALA, Phascolarctos cinereus, CAUSED BY Chlamydia psittaci

Abstract

Chlamydia psittaci was cultured from 29 of 35 koalas (Phascolarctos cinereus) with keratoconjunctivitis. The disease progressed from acute to chronic stages over some months, with a known duration of at least 2 years. One recovered carrier was found. Up to 29% of koalas in some populations were clinically affected. A seasonal spread of infection was indicated by the high percentage of acutely affected cases found in summer. There was no evidence of susceptibility being related to age or sex. The sera of all chronically affected koalas had complement fixation test titres against chlamydial group antigen of 80 or above; in acute cases the titre ranged from 0 to 320. Of normal koalas, 84% were serologically negative, 16% had chlamydial antibody. A titre of 80 or more considered in conjunction with ocular disease could be taken as presumptive evidence of a chlamydial etiology. Chlamydial keratoconjunctivitis may be the ocular disease which was associated with the decline of koala numbers between the years 1885 and 1930.

Preliminary Characterisation of Tumor Necrosis Factor Alpha and Interleukin-10 Responses to Chlamydia pecorum Infection in the Koala (Phascolarctos cinereus)

“…C. pecorum infection in koalas has been associated with cystitis, proliferative conjunctivitis and chronic, fibrotic disease of the urogenital tract leading to infertility and death [13], [14], [15], [9], [16], [12]. In non-koala hosts, the role of cell mediated immunity (CMI) as the major immune response generated by the host against chlamydial infection is acknowledged [17], [18], [19].…”

Novel molecular markers of Chlamydia pecorum genetic diversity in the koala (Phascolarctos cinereus)

“…For the purpose of this research paper, we will refer to koala C. pecorum strains using this proposed nomenclature. While each of these are responsible for a number of disease states in a wide range of animals (including humans), the prevalence and transmission of C. pneumoniae and C. pecorum throughout Australian koala populations has contributed to a significant decline in koala numbers and remain a critical threat to the koala's continued survival [6-8]. …”

“…Notably, C. pecorum is also recognised as a pathogen and causative agent of polyarthritis and abortion in sheep and cattle [11]. In the koala, clinical manifestations of C. pecorum include ocular infection leading to conjunctival scarring and blindness, respiratory tract infection, urinary tract infection causing incontinence, and genital tract infection potentially leading to infertility [6,7,12-14]. The latter disease signs have been implicated in lowered reproductive rates in wild koala populations in several parts of Australia, highlighting the need to understand this complex host-parasite relationship for the purpose of effective management and control strategies [8].…”

Chlamydial Persistence: beyond the Biphasic Paradigm

“…In addition, unresolved respiratory C. pneumoniae infection may contribute to the pathogenesis of chronic inflammatory lung diseases, such as asthma (43) and chronic obstructive pulmonary disease (15). Similar Chlamydia-associated chronic diseases and their sequelae occur in many animals, for example, trachoma-like blindness (25) or infertility (71) in koalas and polyarthritis in sheep (117).…”