Vertical transmission and kinetic of antibodies anti-Neospora caninum in naturally infected lambs in the semiarid region of Brazil

Abstract

Aimed with this study to evaluate vertical transmission of Neospora caninum in naturally infected sheep and to monitor the kinetics of antibodies against this protozoon in their lambs. Therefore, 48 pregnant ewes, from five herds, were divided into two groups: G1 - positive for anti-N. caninum antibodies, with 19 animals; and G2 - seronegative, with 29 animals. Blood samples were taken from the ewes and their lambs, immediately after birth, before ingesting colostrum, and 2, 7, 14, 21, 28, 35, 42, 49 and 56 days after birth. Analysis on serum antibodies was performed using the indirect immunofluorescent antibody test. Among the 19 seropositive mothers, six (31.6%) gave birth to lambs seropositive before ingesting colostrum and it was found that these lambs remained positive until the end of the study (56 days). Only one of the lambs, from a ewe that presented an antibody titer of 200, seroconverted after ingestion of colostrum. All the lambs that had been born from negative mothers remained negative throughout the experimental period. It was concluded that transplacental transmission was an important form of diffusion of N. caninum in the herds studied and that seropositive lambs maintained circulating antibodies during the period analyzed.

Dynamics of Neospora caninum-Associated Abortions in a Dairy Sheep Flock and Results of a Test-and-Cull Control Programme

“…Similarly, a 93% endogenous transplacental transmission rate was described in another sheep flock in Spain [8]. As in previous studies carried out in cattle and sheep [45][46][47], we also found that seropositive sheep with high antibody titres were more likely to have seropositive offspring. Thus, individual N. caninum-specific antibody levels can also be used as a predictive tool for identifying animals with a high risk of endogenous transplacental transmission.…”

“…As in cattle, endogenous transplacental transmission (due to reactivation of latent N. caninum infections during pregnancy) has been found to be highly successful in sheep (96.6% of gestations) [9] and in goats (71.4-100% vertical transmission rate) [42,43]. However, other studies in sheep described low vertical transmission rates (15-31%) without associated abortions [44,45]. In this flock, endogenous transplacental transmission was the main route of parasite transmission since 86.5% of the offspring born from N. caninum seropositive sheep were seropositive.…”

Seroprevalence and associated factors with Neospora caninum infection in sheep and goats slaughtered in the state of Paraíba, Brazil

“…The occurrence of a high rate of endogenous vertical transmission in naturally infected sheep (6/ 19 -31.6%) was observed in the semi-arid region of the state of Paraíba, Brazil, in which chronically infected females gave birth to clinically healthy animals, but infected and with potential for transmissibility to future offspring or to the definitive host (Feitosa et al, 2021). Vertical transmission seems to be of greater importance in the perpetuation of the parasite in small ruminants when compared to horizontal transmission, since the same female can transmit the protozoan to several subsequent generations, making the occurrence and maintenance of the disease in the herd possible even in the absence of the definitive host (Pereira et al, 2021).…”

Toxoplasma gondii and Neospora caninum infections in sheep and goats in Switzerland: Seroprevalence and occurrence in aborted foetuses

“…Reactivation of chronic N. caninum infection during pregnancy and endogenous transplacental transmission of the parasite to the offspring is known to be a common event in cattle, but the information on the efficiency of vertical transmission in small ruminants is still limited ( Lindsay and Dubey, 2020 ). Nevertheless, there is initial evidence that this way of transmission is also efficient in the ovine and caprine hosts ( de Oliveira Junior et al, 2020 ; Feitosa et al, 2021 ; González-Warleta et al, 2018 ; Pereira et al, 2021 ; Sánchez-Sánchez et al, 2021b ).…”