Molecular and serological detection of Neospora caninum in multiple tissues and CSF in asymptomatic infected stray dogs

Neospora caninum is an Apicomplexan parasite. It causes paralysis and neuromuscular disorders in dogs and abortion in cattle. Although contamination with N. caninum is common in stray dogs, most of the dogs are infected with subclinical neosporosis.
The objective of this study was to evaluate the presence of N. caninum in multiple tissues and cerebrospinal fluid (CSF) using Nested-PCR technique. Furthermore, the N. caninum specific antibody was detected in serum of examined dogs by indirect enzyme-linked immunosorbent assay (ELISA).
Forty two stray dogs of mixed breeds captured from districts of Tehran, Iran, were examined physically and euthanized. A commercially indirect ELISA kit was used to detect the anti-N. caninum antibodies in serum. Nested PCR was applied to analyze the extracted DNA from brain, skeletal muscle, CSF, liver, spleen and mandibular lymph nodes for Nc5 gene.
Indirect ELISA assay for N. caninum antibody was positive in a seven years old male dog (2.22%). Out of 42 stray dogs whose multiple organs were examined using Nested PCR, 15 samples (35%) were positive. The highest presence of N. caninum was found in skeletal muscle with 30% (13/42) frequency, followed by CSF (26.2%) (11/42), brain (19%) (8/42), liver (7.14%) (3/42), lymph node (4.62%) (2/42) and spleen samples (0/42).
These results suggest that serology tests can underestimate the carrier of N. caninum in dogs compared to PCR test which directly detect the presence of the parasite. Nested-PCR might be a potential alternative for the histological methods to detect N. caninum in dog’s tissues.