Import risk analysis: Llamas (Lama glama) and alpacas (Vicugna ...

23. Chlamydophila spp.
23.1. HAZARD IDENTIFICATION
23.1.1. Aetiological agent
Chlamydophila abortus and Chlamydophila psittaci. The taxonomy of the species was
revised in 1999 (Everett et al 1999). The genus Chlamydophila was formerly Chlamydia
and there is confusion in the older literature about the taxonomy of some species. The
taxonomy of the family Chlamydiaceae is grouped into two genera (Chlamydia and
Chlamydophila) and nine species based on DNA sequence analysis (Everett et al 1999;
Longbottom 2008).
23.1.2. OIE list
Enzootic abortion of ewes is listed, and the causative agent is C. abortus.
23.1.3. New Zealand status
Chlamydophila abortus is exotic and is an unwanted, notifiable organism (MAF 2009).
Chlamydophila pecorum has been isolated in New Zealand (Mackereth & Stanislawek
2002).
23.1.4. Epidemiology
C. abortus is primarily a pathogen of sheep and goats (Aitken 1983), but also infects cattle.
In these respective species it causes the diseases called enzootic abortion of ewes and
epizootic bovine abortion.
C. abortus does not occur in Australia but is endemic in North America and the EU. Chile
recently reported confirmed infection to the OIE but without clinical signs (OIE 2009b).
Transmission probably occurs by the faecal-oral and venereal routes. Persistent infections
of male accessory glands and the presence of C. abortus in semen have been described
(Storz et al 1976; Andersen 2004). Ewes that have aborted remain long-term intestinal
carriers (Aitken 1983) and may also be chronically infected in their reproductive tracts
(Papp et al 1994; Papp et al 1998; Andersen 2004; Teankum et al 2006). Bulls may remain
carriers and excrete the organism in semen for at least 18 months (Domeika et al 1994).
The incubation period is variable. Some animals become infected in one season and remain
infected and abort in the subsequent season, while in other cases abortion may occur in the
same season as infection (Aitken 1983).
The disease is diagnosed by demonstration or isolation of the organism in placental
material. Diagnostic techniques include examination of suitably stained smears, antigen
detection ELISA, PCR, demonstration of organisms in tissue section by direct staining or
immunostaining, or isolation of the organism in tissue culture or embryonated eggs
(Dagnall & Wilsmore 1990; Thomas et al 1990; Domeika et al 1994; Szeredi & Bacsadi
2002; Andersen 2004; Longbottom 2008; OIE 2009a). PCR tests are available for the
detection of the organism in semen (Teankum et al 2006). Serological testing is unable to
differentiate between the exotic C. abortus and endemic C. pecorum. They can be
differentiated by sequence analysis of the 16S rRNA (Mackereth & Stanislawek 2002).
80 ● Import risk analysis: Llamas and alpacas from specified countries MAF Biosecurity New Zealand