Chlamydial infections in animals
Chlamydophila caviae : guinea pig
infections
Naturally occurring chlamydial agents were isolated from conjunctival scrapings of guinea pigs by
Murray (1964). There were further descriptions of natural chlamydial infections in guinea pigs, associated with
inclusion conjunctivitis, by
Gordon et al. (1966) and Kazdan et al.
(1967).
Formerly classified as Chlamydia psittaci, and as immunotype 8 (Perez-Martinez and
Storz, 1985), these chlamydiae have been reclassified as Chlamydophila caviae
(Everett et al., 1999).
Symptomatic disease was found predominantly in young animals, typically 4-8 weeks
old, the conjunctiva being the usual site of infection. In some animals, the disease was
virtually asymptomatic, whereas in others, clinical signs ranged from a mild inflammatory
conjunctivitis with a slight yellowish-white discharge, to a severe conjunctivitis with profuse purulent exudate which sealed
the affected eyelids. Experimental infection of the guinea pig eye using eye
drops causes a moderate to severe conjunctivitis with a watery to mucopurulent discharge.
Keratitis with pannus or micropannus developed in most infected
animals and chlamydial inclusions were identified in conjunctival scrapings.
This clearly establishes the causal role of C. caviae in this condition. The
kerato-conjunctivitis was self-limiting and cleared within 3-4 weeks.
Complement fixing antibodies to the GPIC agent were not detected in guinea pigs with natural conjunctivits,
nor in experimentally infected animals. Guinea pigs inoculated intraperitoneally
developed a transient fever lasting for 2 days,
then recovered. However, guinea pigs inoculated intracerebrally with high doses
of the organism died within twenty hours (Storz,
1971).
Natural infection of a guinea pig herd was observed by
Storz (1964), on a farm where sheep and cattle had chlamydial infections. Over a period of several months,
epizootic disease resulted in high mortality rates among new born and young guinea pigs. Chlamydiae were isolated from the brains and other organs of affected animals. Some animals were
uncoordinated, and some had watery diarrhoea. It seems likely that the agent responsible for
this natural outbreak in guinea pigs was cattle derived, not C. caviae.
The guinea pig is an important experimental model of chlamydial genital tract infection in humans
(Mount et al., 1973).Guinea pigs with primary conjunctivitis
develop immunity to reinfection of the eyes or the genital tract (Mount et al.,
1973; Ahmad et al., 1977).
Both humoral immunity and cell-mediated immunity are required for resolution of genital infection
(Rank et al.,
1981; 1989).
C. caviae strains are closely related, and show high specificity for guinea pigs as
the natural host. The basis for this host specificity is not known.
NEXT: C.
pecorum: Introduction
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