Simple and sensitive haemagglutination and haemagglutination inhibition assays were developed for psittacine beak and feather disease (PBFD) virus and serum antibody, respectively. The assays were used in the examination of samples from 73 birds clinically affected with PBFD. High antigen titres (log2 9 to log2 12) were detected in feathers, faeces and cloacal contents of PBFD-affected birds. Antigen was not detected in either faecal or feather samples from 20 normal galahs (Eolophus roseicapillus) and 9 normal sulphur crested cockatoos (Cacatua galerita). After kaolin treatment and haemadsorption of serum, haemagglutination inhibition (HI) antibody titres could not be detected in serum from 42 PBFD-affected birds, whereas serum HI titres from 64 normal psittacine birds ranged from less than log2 1 to log2 8. Serum and yolk HI antibody responses of 6 PBFD virus-inoculated layer hens were measured. Pre-inoculation chicken sera contained high concentrations of non-specific haemagglutination inhibitors (not detected in chloroform-extracted yolk), which were removed by kaolin treatment and haemadsorption.

A haemagglutination inhibition assay was used to detect antibody to psittacine beak and feather disease virus in sera from wild sulphur crested cockatoos (Cacatua galerita), galahs (Eolophus roseicapillus), short-billed corellas (Cacatua sanguinea), eastern long-billed corellas (Cacatua tenuirostris) and other psittacine birds in New South Wales. The seroprevalence of psittacine beak and feather disease ranged from 41% to 94% in different flocks, indicating infection with the virus is widespread in wild populations.

Clinical and laboratory findings in 15 unreported cases of avian cryptococcosis from Australia were collated and contrasted with 11 cases recorded in the literature. Cryptococcus species produced localized invasive disease of the upper respiratory tract of captive parrots living in Australia. This resulted in signs referable to mycotic rhinitis or to involvement of structures contiguous with the nasal cavity, such as the beak, sinuses, choana, retrobulbar space and palate. Parrots of widely differing ages were affected and of the seven birds for which sex was determinable, six were male. Cryptococcus bacillisporus (formerly C. neoformans var. gattii) accounted for four of five infections in which the species or variety was determinable, suggesting that exposure to eucalyptus material may be a predisposing factor. In these cases, Cryptococcus appeared to behave as a primary pathogen of immunocompetent hosts. One tissue specimen was available from an Australian racing pigeon with minimally invasive subcutaneous disease; immunohistology demonstrated a C. neoformans var. grubii (formerly C. neoformans var. neoformans serotype A) infection, presumably subsequent to traumatic inoculation of yeast cells into the subcutis. Two similar cases had been reported previously in pigeons domiciled in America. Data for parrots, one pigeon and other birds studied principally in America and Europe (and likely infected with C. neoformans) suggested a different pattern of disease, more suggestive of opportunistic infection of immunodeficient hosts. In this cohort of patients, the organism was not restricted to cool superficial sites such as the upper respiratory tract or subcutis. Instead, infections typically penetrated the lower respiratory tract or disseminated widely to a variety of internal organs. Finally, three captive North Island brown kiwis, one residing in Australia, the other two in New Zealand, died as a result of severe diffuse cryptococcal pneumonia (two cases) or widely disseminated disease (one case). C. bacillisporus strains were isolated from all three cases, as reported previously for another kiwi with disseminated disease in New Zealand.

SUMMARYA simple method for concentrating psittacine beak and feather disease virus (PBFDV) from crude feather suspensions is described. The addition of 10% polyethylene glycol (MW 6000 to 9000) to feather suspensions facilitated the precipitation and pelleting of PBFDV by low speed centrifugation. Pellets were resuspended in one-twentieth of the original volume with caesium chloride (CsCl) buffer and subjected to isopycnic ultracentrifugation. Peak haemagglutination activity (HA) occurred at 1.35 g/ml in PBFDV CsCl gradients. CsCl purified virus agglutinated galah (Eolophus roseicapillus), eastern long-billed corella (Cacatua tenuirostris), sulphur-crested cockatoo (Cacatua galerita), Major Mitchell's cockatoo (Cacatua leadbeateri) and gang gang cockatoo (Callocephalon fimbriatum) erythrocytes, but not those of 19 other avian or five mammalian species. PBFDV agglutinated galah erythrocytes at 4°C and 37°C over a wide range of pH and no change in HA titre was observed when PBFDV was treated with chloroform. HA persisted in PBFDV suspensions heated to 80°C for 30 min, but was not detected after incubation at higher temperatures. High HA titres were detected in the feathers, serum, liver and kidneys of PBFD-affected birds.

PCR-dot blot detection of C psittaci in birds appears to be more sensitive than cell culture isolation in this study. C psittaci infection of birds may occur in clinically normal captive birds.