PBFD is caused by a circovirus which kills the cells of feathers and the beak. It is a naturally occurring infection in Australian cockatoos but it is found in all types of parrots as well as lovebirds, cockatiels, budgies and parakeets. African greys are particularly badly affected. PBFD is a dreadful disease which normally results in the death of affected birds and the decimation of young birds in infected collections. Chronically affected birds become immunosuppressed and may succumb to other diseases due to their depressed immune system. A positive result from a bird with no feather problems or other clinical signs may mean either that the bird is a carrier or that it has been recently exposed to the virus. In these cases we recommend isolating the bird and re-testing in about 90 days. We also recommend that the second sample is collected directly from a vein by venipuncture to avoid contamination. The majority of birds which are merely exposed will develop an immune response and eliminate the infection. Those still positive at the second test should be considered as carriers. One day they are likely to show the disease, and become potential source of infection to other birds.

Avian Polyoma (also known as Budgerigar Fledgling Disease) is most prevalent in macaws, conures, eclectus parrots, ring-necked parrots, lovebirds, cockatiels and budgies although it occurs in all psittacine species. It is most commonly recognised in chicks in the nest. Swollen bellies, tremors, weak wobbly chicks, or abnormal feathers may be seen. Larger psittacine species may live longer and show diarrhoea or regurgitation. Classical infections seem to affect larger species at around 7 weeks of age and can kill within a few hours of the first signs with chicks showing large bruise-like haemorrhages under the skin. Adult birds are also affected. Signs resemble those of septicaemia and hepatitis. Some infected adult birds may not show any signs but may become carriers shedding the virus Embryonic death or decreased hatchability can also be caused by Polyomavirus. Polyoma is transmitted primarily bird to bird but it is also thought to be transmitted via the egg.

Chlamydophila Psittaci infections in exotic birds represent a very common clinical problem. Signs range from acute devastating disease to poor feathering. Chlamydophila Psittaci may manifest itself as an upper respiratory infection with nasal, and or ocular discharge, diarrhoea, or a combination of all. In young birds clinical sings can include rough plumage, low body temperature, tremor, lethargy, conjunctivitis, dyspnea, emaciation, sinusitis, yellow to greenish droppings or greyish watery droppings may also be seen. Adult birds may develop symptoms such as tremors, lethargy, ruffled feathers, progressive weight loss, greenish diarrhoea, occasional conjunctivitis, and high levels of urates in droppings. Birds infected with Chlamydophila Psittaci may develop one or several of these symptoms as the disease progresses. In some cases, birds may be infected but show no signs. These cases are of concern because these birds may become carriers and shed the organism. A major concern with Chlamydophila Psittaci is that it can be transmitted between human and animals. Chlamydophila Psittaci is related to Chlamydia Trachomatis, the most common human STD, and Chlamydophila pneumonia, a cause of human pneumonia. Incubation periods in caged birds vary from days to weeks and longer. Most commonly this period is approximately 3 to 10 days. Latent infections are common and active disease may occur several years after exposure. The incubation period of this disease is however difficult to assess due to these chronically infected birds that develop persistent, asymptomatic infections.