Experimental Leptospira borgpetersenii serovar hardjo infection of pregnant cattle.
OBJECTIVE
To observe the effect upon the foetus of experimental infection of pregnant cattle with Leptospira borgpetersenii serovar hardjo.


METHODS
A disease transmission study using pregnant cattle.


METHODS
Fourteen heifers serologically negative to L hardjo were artificially inseminated and later challenged with a north-Queensland isolate of L hardjo by conjunctival inoculation. The heifers were serologically monitored and their urine examined for the presence of leptospires using culture and fluorescent-antibody tests at appropriate intervals. Elective caesarean sections were performed on pregnant heifers at 6.5 weeks after the challenge. Foetuses were examined using serological, histopathological, microbiological and fluorescent-antibody tests.


RESULTS
Ten of the heifers became pregnant, but three subsequently aborted before challenge. After challenge, all 14 heifers seroconverted and L hardjo was isolated from the urine of 6 of the 7 pregnant heifers. No evidence of foetal L hardjo infection was detected. Two of the foetuses had histopatho-logical lesions consistent with Neospora sp infection.


CONCLUSIONS
It is likely that the isolate of L hardjo used in this study does not normally infect the foetus. Neospora sp may be a more significant cause of bovine reproductive wastage.
Smith
C R
CR
Dayboro Veterinary Surgery, School of Veterinary Science, University of Queensland.
McGowan
M R
MR
McClintock
C S
CS
Corney
B G
BG
Ketterer
P J
PJ
Smythe
L
L
Ward
W
W
D000818:Animals; D000907:Antibodies, Bacterial / Q000032:analysis / Q000097:blood / Q000276:immunology; D001947:Breeding; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology / Q000276:immunology / Q000635:transmission*; D005260:Female; D005315:Fetal Diseases / Q000382:microbiology* / Q000473:pathology; D005333:Fetus / Q000382:microbiology; D005455:Fluorescent Antibody Technique / Q000662:veterinary; D018445:Infectious Disease Transmission, Vertical / Q000662:veterinary*; D007919:Leptospira / Q000276:immunology / Q000302:isolation & purification*; D007922:Leptospirosis / Q000276:immunology / Q000635:transmission / Q000662:veterinary*; D011247:Pregnancy; D011793:Queensland / Q000453:epidemiology
D000907:Antibodies, Bacterial