Congenital Transmission of in Naturally Infected Dogs.

Congenital transmission (CT) of in dogs has not been clearly demonstrated, even though dogs are important reservoirs of this agent. Seventeen late pregnant dogs seropositive for were selected, and a total of 84 fetuses were obtained. Blood and heart tissues from the fetuses and dams, and placental tissue from dam were collected. All tissues were analyzed by quantitative polymerase chain reaction (qPCR) for DNA (DNA) and inflammatory infiltrate and pathology by histological examination. CT was determined when physical, histological, or molecular evidence of was detected in blood or tissues of the fetuses. A general transmission frequency of 59% was found, and 0.20 ± 0.24 of fetuses per litter were infected. Dams that were qPCR positive for DNA in cardiac tissue or blood displayed a transmission frequency of 100% and 67%, respectively. The highest parasite burden was noted in dams that were positive for DNA in both blood (82E-01 ± 1.54E-01) and cardiac (5.28E+03 ± 8.85E+03) tissues. In fetuses, higher parasitic burden in blood and cardiac tissue was found in those carried by dams that were seropositive and qPCR positive for DNA in cardiac tissue and blood. No amastigote nests were recorded in the cardiac tissue of fetuses in the histopathological studies, but typical lesions of infection were identified in all fetuses where CT occurred. CT of occurred at a high frequency in naturally infected pregnant dogs from the endemic areas.