Caloshua Macaw

     Disorders Affecting Multiple Body Systems of Pet Birds 

                                                                    Polyomavirus

Polyomavirus was first identified in budgerigars (budgies), then in other parrots and parakeets, and most recently has been shown to cause disease in finches. Polyomavirus can infect birds of all ages, but nestlings and juveniles are the most susceptible. Affected birds may have a lack of appetite, diarrhea, and generalized weakness, and the onset of these signs is usually rapid. Bruising of the skin and muscles may also occur, and the infection may target the heart, liver, and kidneys. Infection is usually fatal, and death may occur in 24 to 48 hours. If a bird survives, it may have abnormal feather growth, heart disease, and liver damage as an adult. Adult birds may be carriers of the virus and can spread infection. The prevalence of this virus in adult parrots and budgies is thought to be high.

Polyomavirus can be passed from the female to the egg, but most infections are spread by direct contact, feather dander, and exposure to feces. Exposed females may develop protective antibodies that are passed on to nestlings and may provide temporary immunity. Offspring from unexposed females are at higher risk of infection because they lack protective antibodies.

There is no treatment available for infected birds. Spread of the virus can be controlled through testing and isolation of all infected birds and by vaccination. Because infected adults shed the virus only under certain conditions, identifying infected adults can be difficult. Control during an outbreak can be maintained by disinfecting handfeeding utensils, incubators, and brooders and by vaccination. The chances of exposure to polyomavirus can be reduced by following standard hygiene procedures closely, preventing access to baby birds by visitors or any returned bird or outside bird, and using appropriate quarantine procedures for all new birds. Screening by a veterinarian should first be done to make sure that avian polyoma-virus is not already present.

A vaccine to prevent polyomavirus infection is available and is given in 2 doses. The first dose may be given by the veterinarian as early as 4 weeks of age to properly complete the vaccination series and allow full immunity to develop. Older birds receive 2 vaccines 2 to 4 weeks apart, then 1 booster annually. Both negative and positive adult and juvenile parrots can be vaccinated.

                                Pacheco's Disease (Pacheco's Herpesvirus)

Pacheco's disease is a highly contagious, fast-developing disease of parrots (psittacines) caused by a herpesvirus. This disease is associated with stress, which can cause healthy-looking birds that carry the virus to pass the infection to susceptible birds. It is spread by direct contact between birds, airborne secretions, or contamination of food or water with feces. Macaws, Amazon parrots, Monk parakeets, and conures are often involved in outbreaks of the disease. Old World species are less likely to be either carriers or susceptible to infection.

Infected birds may not show any signs of disease until just before dying. The birds are usually in good condition and have a good appetite. Fluffing, loss of energy, and watery feces are signs that sometimes can be seen in infected birds. Most birds do not recover from the infection. Diagnosis of Pacheco's disease must be made quickly in order to prevent further spread of the infection.

                                       Other Herpesvirus Infections

Other important herpesviruses of pet birds include the strain responsible for wart-like foot growths (called papillomas) in Cacatua species and an abnormal loss of color noted on the feet of macaws. The internal papillomatous disease of macaws (most notably green-wing macaws, Ara chloroptera) and Amazon parrots is thought to be caused by a herpesvirus related to the one causing Pacheco's disease. Amazon tracheitis (inflammation of the trachea), which is an uncommon infection, is also caused by a herpesvirus.

                                         Poxvirus Infections

Because of import restrictions, the poxvirus that was historically common in imported blue-fronted Amazon parrots is rarely seen in pet birds. However, poxvirus infections may still occur in canaries and pigeons and in several species of wild birds. These viruses are not contagious to psittacines (parrots).

Pet birds may show one of 3 different types of clinical signs. The first type, skin infection, is the most common. These birds have individual growths, small abscesses, or crusty scabs on the skin of unfeathered areas, such as the face (especially around the eyes and the mouth) and the legs and feet. The diphtheritic or “wet” form is the second type, which may follow the skin form or occur on its own. Swelling and discharges from the eyes are followed by injuries on the mucous membranes of the throat, upper airways, and esophagus. The third and most severe form occurs with a rapid onset of generalized signs of illness, including depression, bluish discoloration of the skin, loss of appetite, and rapid death.

Veterinarians often recommend treatment with vitamin A and antibiotics, ointments for the eyes, heat, humidity, daily cleansing of the affected areas, and attention to diet. Poxvirus infections are transmitted by insect (usually mosquito) bites or through breaks in the skin. Therefore, mosquito control and indoor housing are vital to prevent outbreaks. Vaccines for canarypox and pigeonpox are available, but are protective only for their host species.

                                           Mycobacteriosis (Avian Tuberculosis)

Mycobacteriosis is a bacterial infection that is sometimes called avian tuberculosis, although it differs from tuberculosis in mammals. Three species of Mycobacterium bacteria are most frequently linked with mycobacteriosis in pet birds.

Mycobacteriosis is seen most frequently in pet birds of the parrot family, in which it usually affects the intestinal tract. This bacterial infection can also occur in toucans, finches, and pigeons. Most birds that are infected are adults. For many birds, infection is fatal.

Signs of infection may include weight loss (in spite of having a good appetite), diarrhea, increased thirst, difficulty breathing, and masses in the skin, eyes, and internal organs such as the liver, spleen, and lungs.

Treatment can be difficult and may take up to a year. In addition, the disease can potentially be transmitted from birds to humans, so great care must be taken to avoid infection by thoroughly washing hands with soap and water after contact with a sick bird, wearing gloves, and practicing other good hygiene. Although some evidence suggests that the risk of transmission from pet birds to people is low, people who are elderly, very young, or have weakened immune systems (such as individuals infected with the HIV virus) should avoid any contact with infected birds.