Natural postnatal Neospora caninum infection in cattle can persist and lead to endogenous transplacental infection

Abstract

A serological follow-up study of 3.5 years duration was done of a dairy herd that had experienced a mass seroconversion to Neospora caninum following a point source exposure shortly before the 17th of January 2000. A total of 913 blood samples of 244 animals at seven sampling dates were used to investigate the seroprevalence dynamics in the herd.Most postnatally infected cattle remained seropositive during the period of investigation but 11 animals became seronegative after 6-27 months indicating transient infection. Six animals seroconverted later than the main group of 45 animals and 5 animals became seronegative after at least two seropositive records possibly due to a low infection dose or difference in the haplotypes of the infected animals. In total 58% (14/24) of the offspring of postnatally infected dams was seropositive. Nine of 16 (56%) daughters originating from inseminations after the postnatal infection of their dams were seropositive indicating endogenous transplacental infection. #

Neospora caninum: evaluation of vertical transmission in slaughtered dairy cows (Bos taurus)

“…Fluctuations in the results similar to these have previously been described (McINNES et al, 2006;DIJKSTRA et al, 2008;MORÉ et al, 2009;YAO et al, 2009;MARQUES et al, 2011). McInnes et al (2006) reported that there was no correlation between the serological tests on dams and the PCR on their fetuses, and a high percentage of infected fetuses had serologically negative dams.…”

Occurrence of abortions induced by Neospora caninum in dairy cattle from Santa Catarina, southern Brazil

“…Several factors can affect the PCR techniques; sensitivity, specificity, parasite detectability in the presence of host DNA and defective templates, mainly linked to quality of DNA extraction, additionally a false positive result due to contamination at nested-PCR is reported (MÜLLER et al, 2001;MARQUES et al, 2011). Fluctuating of N. caninum antibody levels in naturally infected cows was previously described (CARDOSO et al, 2012;CONRAD et al, 1993;DIJKSTRA et al, 2008;KYAW et al, 2005;MARQUES et al, 2011). The observation that some infected dams can exhibit negative antibody values during any gestational period, particularly Neospora at parturition or abortion was previously demonstrated (BENAVIDES et al, 2012;NOGAREDA et al, 2007).…”

Infectious Agents

“…40 Also, transplacental infection may be more likely to occur in dams that were themselves prenatally infected compared with postnatally infected dams. 41 The risk of abortion was positively correlated with N. caninum-specific antibodies in individual animals 42 and severity of fetal Neosporaassociated lesions also increased with higher maternal seropositivity. 43 Cows with high antibody titers (≥400) showed higher vertical transmission frequency (94.8%) than cows with low antibody titers of 25-200 (14.8%).…”