pacheco's disease pacheco's disease pacheco's disease is a highly infectious and acute bird disease caused by a species of herpesvirus, psittacid alphaherpesvirus 1 (pshv-1). all psittacine species are susceptible to pacheco's disease, mainly those in zoological collections and aviaries in any geographic regions. specifically, pacheco's disease has a high occurrence rate in amazon parrots, followed by african grey parrots, parrots, macaws, cockatoos and conures. due to a very high mortality rate within these susceptible species, concerns are brought to companion bird markets and breeders. pacheco's disease virus classification (unranked): virus realm: duplodnaviria kingdom: heunggongvirae phylum: peploviricota class: herviviricetes order: herpesvirales family: herpesviridae genus: iltovirus species: psittacid alphaherpesvirus 1 synonyms herpes hepatosplenitis the main sign of pacheco's disease is a sudden and rapid death of birds. it is often preceded by short, severe illnesses, which includes diarrhoea, lethargy, anorexia and inactivity. the virus is transmitted between birds through ingestion, by contaminated food or water, as well as through inhalation and conjunctival exposure. the rate that the virus can spread is highly influenced by its environment and living conditions. birds can then develop signs and symptoms weeks after being in contact with the virus. if a bird survives pacheco's disease, it may later develop internal papilloma disease in its gastrointestinal tract. pacheco's disease is diagnosed through a dna probe or chemical and serological testings. no vaccine directly cures pacheco's disease. there are only treatments with acyclovir and formalin-inactivated vaccine that helps prevent the virus from replicating. the first case of pacheco's disease occurred in brazil in 1930. since then, there have been multiple outbreaks globally including in europe, japan, middle east and the u.s. the main source of these outbreaks is mainly due to the importation of birds. signs and symptoms an uninfected blue-fronted amazon parrot; one of the vulnerable species to carry and transmit pacheco's disease birds infected with pacheco's disease usually experience minor signs and symptoms that appear right before or after its death. birds can have a watery, yellowish to greenish discolouration of urates and faeces or have moist droppings. they can experience mucoid discharges from its nostrils, such as in blue-and-gold macaws and amazon parrots, or a regurgitation of clear sanguineous fluids. as the disease progresses, birds can become difficult to arouse, experience lethargy and somnolence as well as lose interest in eating and its normal daily activities. birds can also display signs of extreme depression only hours before its death. however, due to the short and lack of severe clinical signs indicating a presence of the herpesvirus, the birds that experience a rapid death are found in excellent bodily conditions with full crops. this means that birds often do not live long enough for the collection of its blood for testings or diagnoses. laboratory tests can also display the abnormalities of tissues, such as a liver with pale yellow to brown patches in necrotic areas. examinations mainly present lesions in the bird's liver and spleen, such as an enlargement of both organs with diffuse patches of necrosis and the bleeding of broken capillaries (petechial haemorrhage). there can also be minimal to no inflammatory response surrounding the necrotic areas. by comparing these signs and symptoms to a healthy liver that displays no signs of reactions, this indicates a presence of the herpesvirus infection. external factors surrounding the birds can also promote the spread of these signs and symptoms and infections. specifically, environmental changes, such as importing birds from a warm to cold environment as well as creating a stressful event for birds in crowded situations, often triggers a virus amplification and increased virulence. cause