Neospora caninum–specific antibodies in free-ranging white-lipped peccaries (tayassu pecari) from the peruvian amazon: detection of antibodies in serum and evaluation of indirect fluorescent antibody test with heterologous secondary antibody

Neospora caninum is a coccidian parasite originally reported in dogs and widely prevalent in numerous species of wild and domestic animals and has as definitive hosts some species of canids. The white-lipped peccary (WLP) (Tayassu pecari) is a Tayassuidae mammal, found from Mexico to south of Brazil and north of Argentina. It is a game species with great economic importance in the Peruvian Amazon. Blood samples from 101 WLPs were collected from near or within three different conservation reserves located in the southeastern region of the Peruvian Amazon. For the detection of antibodies against N. caninum, indirect fluorescent antibody tests (IFAT) were performed using collared peccary (Pecari tajacu) and swine (Sus scrofa domesticus) heterologous secondary antibodies. For both IFAT tests, the cutoff was 1:50. Positive samples were titrated by a two fold serial dilution. In addition to IFAT, samples were also analyzed using an immunoblotting test (IB) with anti-swine conjugate. To confirm the viability of the anti-swine conjugate, the results of these samples previously tested by a modified agglutination test (MAT) for Toxoplasma gondii were used as reference. From the total of 101 samples tested, 5 (4.9%) were N. caninum positive by the three tests and an extra sample was positive by both IFATs and negative in the IB. Comparing both IFATs and considering IB as the gold standard, the relative sensitivity of IFATs was 100%, the specificity was 98.9%, the positive predictive value was 83.3%, and the negative predictive value was 100%. The agreement between tests was characterized by a κ value of 0.904 (95% confidence interval, 0.717 to 1.0) and an SE of 0.095. This is the first report of N. caninum antibodies in free-ranging T. pecari, and swine and collared peccary conjugate can be used as a secondary antibody for detection of antibodies in Tayassu species.