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The most important poxviruses of pet birds are canarypox,
parrotpox, agapornis pox (lovebirds), and pigeonpox.


Clinical Findings:

Signs depend on host susceptibility and virulence of the virus.


There are three clinical forms:

1 Cutaneous—discrete papules, pustules, or crusty scabs (depending
on stage of infection) develop on unfeathered parts of the body.
Mortality is low, and the infection usually is self-limiting.

2 Diphtheritic or “wet” form—extensive fibrinonecrotic lesions
develop on mucous membranes of the oropharynx, upper respiratory
tract, esophagus, and occasionally conjunctivae. Mortality is
high.


3 Acute or also called “wet” form—onset of general signs,
including depression, cyanosis, anorexia, and rapid death, is
sudden. Transmission is by direct contact with infected birds or
fomites, and insects may act as mechanical vectors.


Canarypox may occur in an acute form with respiratory signs and
death in 1-3 days or in a chronic form with proliferative dermal
lesions around the eyes, mouth, nostrils, or feet. The virus
causes eosinophilic, intracytoplasmic inclusion bodies
(Bollinger's bodies).

Parrotpox is common among Amazon parrots (especially
blue-fronted), Pionus spp , lovebirds, Australian parakeets, and
rosellas. Lovebirds are apparently susceptible to both parrotpox
and agapornis pox. Poxvirus may cause high mortality in
lovebirds.

Most signs involve the periocular tissues. Early in the course of
disease, unilateral blepharitis and conjunctivitis usually are
present and lead to palpebral edema, which causes the affected
eye to close; ulcers and scabs at the medial or lateral canthus
follow. The serous ocular discharge becomes mucoid, and ocular
lesions may develop (keratitis, ulcerative keratitis, anterior
uveitis, possibly endophthalmitis). Scarring of eyelids and small
opacifications of the cornea are common sequelae, although
permanent damage is relatively minor compared with the original
lesions. Dermal lesions include scaly papules at the commissures
of the mouth, margins of the cere, and around or within the
external nares. Superficial, raised plaques in the choanal area,
at the base of the tongue, in the posterior pharynx, and within
the esophagus also are seen. Anorexia, sneezing, dyspnea, and
occlusion of nostrils may result. Death sometimes occurs and can
be related to septicemia, pneumonia, or starvation. Secondary
fungal infections are not uncommon.


Diagnosis

Diagnosis is by virus isolation and typical histologic
findings of epidermal hyperplasia with ballooning degeneration,
intraepithelial vesicles, and eosinophilic intracytoplasmic
inclusion bodies.


Treatment and Control

Parenteral vitamin A, ophthalmic ointments, heat, humidity, parenteral antibiotics, daily cleansing of the affected eye, and attention to diet is
recommended. A vaccine for parrotpox has been released under
conditional license in the USA. Domestic psittacine birds are
less likely to be exposed because “carrier” birds do not exist,
although the virus itself may be persistent in a contaminated
environment for some time. Canarypox vaccine has been used for
many years in Europe, and infections are common in North American
canaries although vaccination is not. Commercial pigeonpox and
fowlpox vaccines are not effective in psittacines.