Serology of a Neospora abortion outbreak on a dairy farm in New Zealand: a case study.
OBJECTIVE
To describe the kinetics of serological titres after an abortion outbreak in April-May 1995 due to Neospora caninum affected 17 dairy cows in a herd of 320.


METHODS
Thirty-five cows, that had either aborted, carried mummified calves, were not pregnant or calved normally were: bled several times at regular intervals and the sera tested for Neospora antibodies in the indirect fluorescence antibody test (IFAT).


RESULTS
Maximal IFAT titres of up to 1:4000 occurred within 6 weeks of the abortion outbreak, decreased over the next 2 months to < or = 1:200 and remained at this level until the next scheduled bleed a further 2 months later. A rise in titres was subsequently observed in the cows that had aborted or were not pregnant (at the time of the abortions) or had carried mummified foetuses. Seroconversion was also observed in some of the control cows, which had, up until then, remained seronegative. A dog and cat in contact with the cows in the herd investigated were, however, negative in the IFAT.


CONCLUSIONS
Maximal serological titres in Neospora abortions are observed within weeks of the abortion event and then quickly return to very low levels. Subsequently, a recrudescence of titres can be observed in infected cows during the next pregnancy, without it being associated with repeat abortions.
Cox
B T
BT
Lincoln Animal Health Laboratory, MAF Quality Management, P.O. Box 24, Lincoln, New Zealand.
Reichel
M P
MP
Griffiths
L M
LM