Equid Herpesvirus-Associated Abortion in Poland between 1977-2010

Equid herpesvirus 1 (EHV-1) isolation and direct immunofluorescence were performed on tissues from 452 aborted and stillborn foals, which were submitted to the Pathology Department of Wrocław University of Environmental and Life Sciences, Poland, from different farms in Poland between 1977 and 2010. Although case submissions were received year-round, the number of submitted abortions peaked in the month of January, and then gradually decreased until June. EHV-1-associated abortion or neonatal death was diagnosed in 106 cases. At the beginning of the investigations (late 70s), there were a few cases of the EHV-1 abortions, but in the first half of the 80s, EHV-1 was not isolated. Until 1990, the percentage of abortion ranged from 0% to 50%, reaching its peak in 1984. A similar situation was observed during the next two decades. In 1991, 1998, 2007, and 2008, there was no isolation, and the highest rate (50%) was noticed in 1996 and 2000. The results of this study indicate that EHV-1 in Poland remains an important cause of pregnancy loss in horses, despite extensive vaccinations.