Chlamydial infections in other animals: Vertebrates
Chlamydial or Chlamydiae-like infections occur
in an enormously diverse range of animal species, from the humble Amoeba
and Hydra through arthropods, insects, molluscs, marsupials, birds,
reptiles and mammals to humans. Arguably this is the widest host species range
of any group of microorganisms. However, adequate identification of the apparent Chlamydiales
responsible associated with these infections is often lacking.
Mammals
Among mammals, chlamydiae have been isolated from rabbits, ferrets and opossums
(Storz, 1988). In rabbits chlamydiae cause spontaneous abortion (Parker et al.,
1966) and pneumonia (Storz, 1988). Many strains and colonies
of mice are inapparently infected with chlamydial agents (Karr, 1943). Isolates were recovered from
the lungs of clinically normal mice. Chlamydial strains have also been isolated from
seemingly healthy wild rodents (Eddie et al., 1969). These respiratory isolates were
probably strains of Chlamydia muridarum, formerly classed as the mouse biovar of C. trachomatis.
There are a number of reports of chlamydial infections in buffaloes. Gupta et al. (1976) described pneumonia in a buffalo calf,
while Dhingra et al. (1980) isolated chlamydiae from the lungs of buffaloes
with pneumonia. Rowe et al. (1978) recovered a Chlamydia psittaci-like agent from
wild African buffalo. More recently, chlamydial encephalomyelitis was diagnosed in water buffalo calves in southern Italy. Infected animals were affected with
recumbency, depression and limb paralysis, but fever was not observed. A chlamydial isolate from a calf was shown to be C. pecorum
by ompA PCR and by sequencing the 16S-23S intergenic spacer region (Magnino et al., 2000a).
C. pecorum was also recovered from the lungs of a wild chamois in the Italian
Alps which had pneumonia (Magnino et al., 2000b).
Serological surveys suggest that chlamydial infections
occur in a large range of mammals including monkeys, wild boar and hedgehogs (Storz,
1988); deer in the USA (Debbie, 1967; Taylor, 1996) and Italy (Giovannini et al.,
1988) and reindeer in Lapland (Neuvonen, 1976). Four species of wild ruminants from a nature reserve in Spain,
(fallow deer, mouflon, red deer and Spanish ibex), were infected with chlamydiae.
These species apparently acted as reservoirs of chlamydial infection; transmission between wild and domestic ruminants (sheep and goats) occurred through grazing on the same pastures
(Cubero-Pablo et al., 2000). An epizootic of infectious keratoconjunctivitis occurred in free-ranging mule deer in Utah, and chlamydiae, as well as other organisms, were isolated
(Taylor, 1996). An examination of sera from reindeer in Lapland, Finland, revealed antibodies to Chlamydia
. In another study, Serological evidence of chlamydial infection was also
reported in antelope (Mansell et al., 1995) and in captive Arabian oryx from
various countries (Greth et al. , (1992). Chlamydiae were isolated from fur seals
in the Canadian Arctic by Eddie et al. (1966) while systemic infection with chlamydiae led to major mortalities in snowshoe hares and muskrats in Saskatchewan, Canada
(Spalatin et al., 1965).
Birds
More than 200 species of bird are known
to be infected by chlamydiae [see Chlamydophila
psittaci].
Reptiles
There are a number of reports of chlamydial infection and disease in reptiles. In an examination of different chameleon species from Tanzania, one lizard became ill and Chlamydia-like organisms were demonstrated in inclusions in macrophages from
the spleen and liver (Jacobson and Telford, 1990). Chlamydia were responsible for moderate levels of
death among farmed green sea turtles in the Cayman Islands (Homer et al.,
1994). Clinical signs included lethargy, anorexia and an inability to dive. Post-mortem
study showed necrotising
myocarditis, as well as
sub-acute pneumonia, and chronic or active
enteritis. A disease syndrome
in farmed, hatchling Nile crocodiles, consisting of acute hepatitis and oedema,
is caused by C. psittaci (Huchzermeyer et al., 1994). Chlamydial infection is
also a major disease problem on crocodile farms in Zimbabwe. Fortunately these
infections respond to oxytetracycline treatment. Cold-blooded vertebrates might represent
a source of chlamydial infection for warm-blooded hosts. Subsequently, Huchzermeyer (1997) indicated
a potential risk to human health arising from crocodile and possibly ostrich meat.
Although chlamydial infections are common on some crocodile farms in southern Africa,
there is little evidence of chlamydial infection in ostriches.
Amphibians
PCR studies indicate that a pneumonia and anaemia
disease syndrome in wild giant barred frogs in Australia is probably
caused by the koala biovar of Chlamydophila pneumoniae.
This was thought by the authors to be the first report of a chlamydial strain infecting both
warm and cold blooded host. The giant barred frog has the distinction of being
the fourth known host for C. pneumoniae, in addition to humans, koalas and horses. Chlamydial infections have also been described in another amphibian species, the African clawed
frog (Newcomer et al., 1982). A chlamydial isolate was recovered from animals dying of spontaneous disease, and was used to
reproduce the disease on inoculation into other frogs. A similar lethal outbreak
was described by Howerth (1984). Infected frogs had liver lesions, degeneration and inflammation of kidneys, myocarditis and necrosis of
the spleen. In a later Reed et al., (2000) isolated C. pneumoniae from African clawed
frogs among whom an epizootic of chlamydiosis had caused death in 90% of the breeding colony.
Fish
The agent causing epitheliocystis disease of
the gills in fish is considered to be Chlamydia or a Chlamydia-like organism. Wolke et al. (1970) found chlamydial infection causing chronic gill disease in Connecticut striped bass and white perch. Moribund opaleye fish were
also shown to be infected with Chlamydia
spp., although other pathogens were present (Kent et al., 1988). Chlamydial infection caused epitheliocystis disease in cultured
pacu, a tropical fish species in Brazil, leading to heavy mortality (Szakolczai et al., 1999). Epitheliocystis was also detected in sea bream by Crespo et al. (1999). Electron microscopy findings
suggested that the infection in sea bream may have been caused by a unique, pleomorphic,
and unknown Chlamydia-like agent.
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