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SEROLOGICAL INDICATION OF CONGENITAL TRANSMISSION OF NEOSPORA CANINUM, BUT NOT TOXOPLASMA GONDII IN NEOTROPICAL DEER
Neospora caninum and Toxoplasma gondii are important apicomplexan parasites that may cause abortion or neurologic disease in their intermediate hosts. Their definitive host are canids and felids, respectively, and both have similar live cycles and clinical presentation. The aim of this study was to evaluate the seroprevalence of N. caninum and T. gondii in two populations of captivi deer, species: Mazama gouazoubira (n=17), M. nana (n=3), M. nemorivaga (n=6), M. americana (n=23), M. bororo (n=5), Ozotocerus bezoarticos (n=3), Odocoileus virginianus (n=2) and Blastocerus dichotomus (n=26). Blood was collected after pharmacological or physical restrain or during lordosis reflex of estrus behavior and the animals had a minimal age of one year at the moment of the procedure. Serum samples were obtained by centrifugation and stored at -20°C. Detection of antibodies was performed by Indirect Fluorescent Antibody Test (IFAT) and serum samples and the positive and negative control were diluted at 1:25 to N. caninum test and 1:40 to T. gondi test. Prevalence of antibodies was 40.22% and 26.43% to N. caninum and T. gondii, respectively. For better evaluation of the results, genealogical trees were drawn (Fig 1). The trees showed that positive mothers to N. caninum had positive sons and negative mothers had negative sons, in the vast majority of cases. Untested mothers usually give birth to siblings with similar results (all positives or all negatives). None of positive animals with known genealogy had negative mothers. Nevertheless, regarding T.gondii, there is no relation of seropositivity and animals’genealogy. The results from this study strongly suggest that the major rote of N. caninum deer infection is transplacental, and it may be the responsible for maintaining the parasite in the population, meanwhile there was no sign of congenital T. gondii transmission in deer. Congenital transmission of N. caninum seems to be the primary route of infection in caws. Sheep studies revealed a vertical transmission rate of 15.4% to N. caninum and 38.9% to T. gondii. Transplacental transmission of these parasites can be estimated from the number of seropositive offsprings born from seropositive mothers, soon after their birth and before ingestion of colostrum, however, in the present study, the blood collection from the fawns soon after the birth was impracticable. Even so, adult animal’s results suggest that the congenital infection rate can be up to 89% to N. caninum, and 0% to T. gondii (considering seropositives mothers with positive sons). The congenital transmission rate in deer differs from those reported in domestic animals, being higher in N. caninum and lower in T. gondii.
Apicomplexan parasites; transplacental transmission, serology, genealogy.
Maria Helena Mazzoni Baldini, Carla Roberta Freschi, Eveline Zanetti, Rosângela Zacarias Machado, José Maurício Barbanti Duarte