Neospora caninum, an intracellular protozoon, causes encephalomyelitis in dogs (Bjerkas I et al. 1984 Zentralblat fur Parasitenkunde 70, 271-274). For the past decade, neosporosis has been a main cause of abortion in dairy cattle worldwide (Anderson M et al. 2000 Anim. Reprod. Sci. 60-61, 417-431; Dubey JP 2003 Korean J. Parasitology 41, 1-16). Vertical transmission has been indicated as an important way of spreading neosporosis (Hall CA et al. 2005 Vet. Parasitology 31, 231-41); thus, we investigated whether the protozoon could be transferred by embryo production techniques. Blood samples were collected from 92 dairy cows with history of reproductive failure and abortion within the previous 90 days at 7 dairy farms in Tizayuca, Mexico. For serology evaluation, a commercial indirect ELISA kit (Civtest Bovis Neospora, Laboratories Hipra S.A, Girona, Spain), yielded 46.74% (43/92) positive results, 46.74% (43/92) negative results, and 6.52% (6/92) suspicious to N. caninum infection. Thirteen positive cows were chosen for uterine flush (UF), ovum pickup (OPU), and a blood sample collection. Lymphocytes from blood and cells within the UF and OPU collection fluids were collected after centrifugation and DNA was extracted. All samples were tested for the presence of N. caninum by PCR, using primers and protocols that amplified a 275-bp fragment of the genomic region (5-GGGTGAACCGAGGGAGTTG-3 and 5-CCTCCCAATGCGAACGAAA-3). The N. caninum vaccine (Bovilis® NeoGuard, Intervet, Santiago Tianguistenco, Mexico) was used as a positive control and water as a negative control. Uterine flush could not be obtained from 1 cow. From 13 cows seropositive to N. caninum, only 38% were positive to PCR from blood lymphocytes. In contrast, PCR amplification was obtained from OPU cell sediment in 92.31% (12/13) and in 33.33% (4/12) of UF. Of these 12 OPU- and 4 UF-positive samples, only 5 and 3 of their corresponding blood lymphocytes were positive. Our results using uterine and follicular fluid were contradictory to those published by Moskwa et al. (2008 Vet. Parasitology 158, 370-375) where oocytes and embryos were evaluated. These results indicate that N. caninum is present in the ovary and uterine lumen of the cows, suggesting a possible risk of neospora transmission during oocyte and embryo collection and transfer techniques.
UNAM and UPF.
Risk factor analysis associated with Neospora caninum in dairy cattle in Western Brazilian Amazon
