Detection of Herpesviruses in Cockatoos (Cacatuidae) in Europe

Avian herpesviruses, including psittacid herpesvirus 1 (PsHV1; <i>Iltovirus psittacidalpha1</i>), are of particular concern in avian collections because they can lead to severe disease with high mortality. In recent years, distinct novel avian alphaherpesviruses were detected in wild cockatoos originating from Victoria, Australia. These were further characterized as cacatuid herpesvirus 1 (CaHV1) and cacatuid herpesvirus 2 (CaHV2). The cockatoos affected by these viruses exhibited severe signs of disease attributed to concurrent infections with other pathogenic agents. The clinical significance of these novel herpesviruses remains unknown, and no information on the pathogenicity and prevalence of these viruses is available. During routine diagnostic testing, 2 clinically healthy pet sulphur-crested cockatoos (<i>Cacatua galerita</i>) from Vienna, Austria, tested positive for a CaHV. To gain more information on the prevalence of this virus in cockatoos kept in Europe, a retrospective evaluation of samples from cockatoos submitted to a European diagnostic laboratory between 2016 and 2023 was initiated. In total, 468 samples from cockatoos were evaluated. Herpesviruses were detected in 16 (3.4%, 95% confidence interval: 1.8-5.1) samples. Fourteen of the positive samples were further screened, 13 were most closely related to the previously described CaHVs, and 1 was psittacid herpesvirus 1. Phylogenetic analysis of amino acid sequences from 11 of the detected herpesviruses showed that 5 were identical to CaHV1, 2 were distinct but closely related to CaHV1, and 3 were identical to one another and clustered with CaHV1 and CaHV2 but on a separate branch. Due to the lack of further information from these positive tested cockatoos, the clinical importance of these viruses remains unknown.