Tissue distribution of psittacid herpesviruses in latently infected parrots, repeated sampling of latently infected parrots and prevalence of latency in parrots submitted for necropsy.

Psittacid herpesvirus-1 (PsHV-1) is the cause of an acute fatal disease in parrots and is implicated as the cause of papillomatous lesions of the digestive tract. Not all infections cause disease and some parrots are infected asymptomatically. Latently infected parrots are potential sources for virus dissemination. Tissues from parrots that died spontaneously with a history of coming from flocks where a PsHV-1 outbreak had occurred were examined for PsHV-1 DNA. Fourteen of 16 parrots examined were infected with at least 1 variant of PsHV-1; of these 13 (93%) had viral DNA in either or both the oral and cloacal mucosa, suggesting that most latently infected parrots could be detected by sampling these sites. Nine of 9 parrots shown to be infected 5 years prior to this study were positive again on repeat sampling and were infected with the same virus genotype. Opportunistic sampling of parrots submitted for diagnostic necropsy indicated that the prevalence of PsHV-1 in parrots in the sampled population was approximately 9.3%. PsHV-1 genotypes 1, 2, and 3 were found in these birds, but genotype 4 was not. Six necropsy specimens were found to be infected with two PsHV-1 genotypes and it was concluded that infection with one serotype did not protect against infection with another. Psittacid herpesvirus 2 (PsHV-2) was identified in 4 African grey parrots and a blue and gold macaw. Prior to this study PsHV-2 had only been found in African grey parrots.