Diagnosis of duck plague in waterfowl by polymerase chain reaction

A recently developed polymerase chain reaction (PCR) assay was used for dia gnosis of duck plague in waterfowl tissues from past and current cases of w aterfowl mortality and to identify duck plague virus in combined cloacal/or al-pharyngeal swab samples from healthy mallards (Anas platyrhynchos) after a disease outbreak. The PCR was able to detect viral DNA from all the indi vidual or pooled tissues assayed from 10 waterfowl, including liver and spl een samples from three Muscovy ducks (Cairina moschata domesticus) that did not yield virus isolates. The strong staining intensity of the PCR product s from the waterfowl tissues indicated that large amounts of virus were pre sent, even when virus was not isolated. Duck plague DNA was also detected i n a cloacal swab sample from a wood duck (Aix sponsa) carcass submitted for diagnosis. The PCR assay identified duck plague DNA in 13 swab samples tha t produced virus isolates from carrier mallards sampled in 1981 after a duc k plague die-off. The duck plague PCR clearly demonstrated the ability to q uickly diagnose duck plague in suspect mortality cases and to detect virus shed by carrier waterfowl.