HISTOPATHOLOGICAL FINDINGS IN A NATURALLY Neospora caninum-INFECTED COW AND ITS LIVE FOETUS

GUAL I; CAMPERO LM; LISCHINSKY L; MORRELL EL; MORÉ G; VENTURINI MC; MOORE DP

Tandil

Congreso; IX REUNIÓN ARGENTINA DE PATOLOGÍA VETERINARIA 8vo SEMINARIO DE LA FUNDACIÓN "CHARLES LOUIS DAVIS"; 2014

UNCPBA

Neospora caninum is a protozoan agent causing severe reproductive and economic losses worldwide. The agent is transmitted congenitally from the dam to the fetus with high efficiency; showing a balanced relationship between parasite and host. Little is known about the factors involved in the recrudescence of a latent infection in pregnancy, congenital transmission and eventually abortion. The aim of the present work was to describe histopathological lesions in the central nervous system (CNS) of a naturally Neospora-infected cow, its placenta and its live fetus. A pregnant 10 years old Angus cow was euthanized. The cow was seropositive to N. caninum with an indirect fluorescent antibody test (IFAT) titer of 1:3200. The fetus had 49cm and weighted 8kg; suggesting a pregnancy of approximately 6 months old. No macroscopic lesions were observed in any specimen analyzed. Several tissues were collected for microscopic analysis including uterus and placenta. All samples were processed by standard histological procedures and stained with hematoxylin and eosin. Tissue samples having lesions characteristic of Neospora-infection were analyzed twice or by triplicate using immunohistochemistry (IHC). A total of 59 sections were analyzed (38 sections from the cow, 7 sections from the placenta and 14 from the fetus). Histopathological results revealed light multifocal lymphocytic interstitial myocarditis, light lymphocytic meningoencephalitis with perivascular cuffing, multifocal gliosis and mineralization in the endothelium of some vessels in the cortex and the brain stem from the dam. Mild lymphocytic metritis was also observed. A moderate multifocal lymphoplasmahistiocytic placentitis with areas of necrosis, fibrosis and mineralization was evident in the stalk and in the base of the caruncle. On the other hand, the fetus presented a moderate lymphocytic meningoencephalitis with perivascular cuffing, foci of gliosis, congestion, hemorrhage and necrosis, and congestion and hemorrhage in meninges. There was also a severe multifocal lymphocytic myositis with foci of necrosis and hemorrhage in retroocular muscles, diaphragm and the skeletal muscles. Moderate multifocal interstitial lymphocytic myocarditis, severe multifocal lymphocytic glossitis, moderate multifocal lymphocytic hepatitis and a moderate lymphocytic pneumonia accompanied in some cases with areas of necrosis and hemorrhage, lymphocytic perilymphangitis and periarteriolar lymphocytic infiltration, and moderate interstitial lymphocytic nephritis were observed. In the pre-scapular lymph node, there was a severe congestion in medullary sinuses. Specific antibodies against N. caninum were demonstrated in fetal fluids by IFAT with a titer of 1:3200. All samples from the dam and the fetus were negative by IHC; however scarce tachyzoites were observed on the placenta. The CNS from the dam was negative by PCR with the pairs of primers Np6+/Np21+, whereas placenta and CNS from the fetus were positive. Even though there were histopathological lesions compatible with N. caninum, and the infection was confirmed by the presence of antibodies by IFAT and by the detection of the parasite by PCR, the fetus was still alive and would probably have born with a chronic infection. Since Neospora-infections are efficiently transmitted from the dams to their fetuses trough the placenta, caution should be taken when performing diagnosis of bovine abortion. Diagnosis must be based in the context of reproductive problems within the herd and the absence of other pathogens causing abortion in cattle.