Placental lesions associated with abortion and stillbirth in goats naturally infected by Neospora caninum

Abstract

Neospora caninum has been described as a parasite that sporadically causes reproductive problems in goats. Several aspects of the pathogenesis of neosporosis in naturally infected goats remain to be established. The aims of the present study were to characterize the placental lesions in goats naturally infected by N. caninum and to evaluate several diagnostic techniques for effective detection of this protozoan in the goat placenta. Some placentas in this study originated from abortion and stillbirth in which there were severe lesions. The lesions were characterized mainly by necrosis involving the mesenchyme of the chorionic villi and trophoblast cells often alongside mononuclear inflammation and in some cases with neutrophilic infiltration. N. caninum DNA was detected in these placentas, but parasite structures were not visualized through immunohistochemistry (IHC). However, five of 11 placentas from N. caninum-infected goats that gave birth to healthy kids had histological lesions characterized by mononuclear inflammation. Of these 11 placentas, N. caninum DNA was detected in seven, and N. caninum tachyzoites were detected in only one of these seven placentas using IHC. The present study demonstrates that severe lesions in the placenta are associated with abortion and stillbirth in caprine neosporosis and the placental alterations are likely involved in abortion pathogenesis. Moreover, the results highlight the importance of using more than one diagnostic technique for the detection of the protozoan in placentas because N. caninum cannot be reliably detected by histological and immunohistochemical tests.

Congenital Transmission of Apicomplexan Parasites: A Review

“…Congenital neosporosis affects mainly dogs and cattle, but occasionally also horses, sheep, and deer (Dubey, 2003), leading to abortion, stillbirth, and weak offspring (Mesquita et al, 2018). In sheep, congenital transmission rates are high, reaching values between 66.7 and 93% (González-Warleta et al, 2018).…”

“…Thus, multiple necrotic lesions, thickening of the chorionic plate, and mineralization of necrotic foci can be observed in the infected ovine placenta. Notably, both the oocysts (sexual state) and tachyzoites (rapidly dividing parasite stage) of N. caninum can be detected in placental tissue (Mesquita et al, 2018;Al-Shaeli et al, 2020;Figure 4A). In the fetus, N. caninum causes severe damage to the brain, heart, lung, and liver (Al-Shaeli et al, 2020).…”

Serological response to Neospora caninum infection in goats and agreement between three diagnostic techniques to detect caprine neosporosis

“…The occurrence of reproductive disorders in goats that are seropositive for N. caninum suggest that neosporosis is a significant cause of abortion and neonatal deaths in caprine herds (Moreno et al 2012, Mesquita et al 2018. N. caninum congenital transmission rates in goats may be as high as those reported to cattle.…”