Serological analysis of Chlamydophila abortus in Australian sheep and implications for the rejection of breeder sheep for export.
OBJECTIVE
To examine the incidence of positive results in a complement fixation test (CFT) and enzyme-linked immunosorbent assay (ELISA) for Chlamydophila abortus in Australian sheep and how this incidence differs with state of origin, age, sex, breed and property. To examine the consequences in relation to rejection of breeder sheep for export.


METHODS
Collection of blood samples from 891 sheep on 109 properties in southern Australia. All samples had a unique, coded property identification.


METHODS
The samples were tested using the Institut Pourquier Chlamydophila abortus antibody ELISA (rELISA) and a CFT. Residual maximum likelihood analyses of the sample to positive ratio of the corrected optical density for the rELISA and generalised linear mixed model analyses of the CFT outcomes were carried out.


RESULTS
The sample to positive ratio of the corrected optical density values of the rELISA did not differ between sex, age, breed or state of origin, but differed greatly between properties. The CFT outcome did not differ between age, breed or state of origin, but differed greatly between properties and was more often positive with rams than with ewes.


CONCLUSIONS
Positive outcomes to C. abortus antibody tests are very common in Australia. Rams have a particularly high incidence of positive results with the CFT. Rejection of sheep and property consignments is likely to be very common with all tests and situations examined except for the CFT (at 1:32 dilution) in ewes.
McCauley
L M E
LM
Department of Primary Industries, 475 Mickleham Road, Attwood, Victoria 3049, Australia. Lisette.McCauley@dhs.vic.gov.au
Lancaster
M J
MJ
Butler
K L
KL
Ainsworth
C G V
CG
D000034:Abortion, Veterinary / Q000382:microbiology; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood*; D001315:Australia; D023501:Chlamydophila / Q000276:immunology*; D023521:Chlamydophila Infections / Q000097:blood / Q000150:complications / Q000453:epidemiology / Q000662:veterinary*; D003132:Commerce; D003168:Complement Fixation Tests / Q000662:veterinary; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D005260:Female; D016013:Likelihood Functions; D008297:Male; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000662:veterinary; D012737:Sex Factors; D012756:Sheep; D012757:Sheep Diseases / Q000097:blood* / Q000453:epidemiology / Q000382:microbiology
D000907:Antibodies, Bacterial