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Pacheco's disease is an acute and often lethal infectious disease in psittacine birds.[1] The disease is caused by a species of herpesvirus, Psittacid alphaherpesvirus 1 (PsHV-1), which consists of four genotypes.[2] Birds which do not succumb to Pacheco's disease after infection with the virus become asymptomatic carriers that act as reservoirs of the infection.[3] These persistently infected birds, often Macaws, Amazon parrots and some species of conures, shed the virus in feces[2] and in respiratory and oral secretions.[3] Outbreaks can occur when stress causes healthy birds who carry the virus to shed it.[4] Birds generally become infected after ingesting the virus in contaminated material, and show signs of the disease within several weeks.[3]

Psittacid alphaherpesvirus 1
Virus classification e
(unranked): Virus
Phylum: incertae sedis
Class: incertae sedis
Order: Herpesvirales
Family: Herpesviridae
Genus: Iltovirus
Psittacid alphaherpesvirus 1

The main sign of Pacheco's disease is sudden death, sometimes preceded by a short, severe illness.[2] If a bird survives Pacheco's disease following infection with PsHV-1 genotypes 1, 2 or 3, it may later develop internal papilloma disease in the gastrointestinal tract.[3]

Susceptible parrot species include the grey parrot,[4] and cockatoo.[1] Native Australian birds, such as the eclectus parrot, Bourke's parrot, and budgerigar are susceptible to Pacheco's disease, although the disease itself has not been found in Australia.[5]


Pacheco's disease is an eponymously named disease; it is named after the Brazilian veterinarian, Genesio Pacheco,[6] who first came across the disease in 1929,[7] in an outbreak affecting the turquoise-fronted amazon parrot, Amazona aestiva.[8] Initially, Pacheco's disease was thought to be a manifestation of avian psittacosis.[8] The causative agent of the disease, a herpesvirus, was not identified until 1975.[7]


  1. ^ a b Thureen, DR; Keeler, CL Jr. (August 2006). "Psittacid herpesvirus 1 and infectious laryngotracheitis virus: Comparative genome sequence analysis of two avian alphaherpesviruses". Journal of Virology. 80 (16): 7863–72. doi:10.1128/JVI.00134-06. PMC 1563825. PMID 16873243.
  2. ^ a b c Schmidt, RE; Reavill, DR; Phalen, DN (2015). "Chapter 4: Liver". Pathology of Pet and Aviary Birds (2nd ed.). John Wiley & Sons. pp. 95–126. ISBN 9781118828113.
  3. ^ a b c d Doneley, Bob (2016). "Chapter 17: Disorders of the Liver". Avian Medicine and Surgery in Practice: Companion and Aviary Birds (2nd ed.). CRC Press. pp. 251–264. ISBN 9781482260199.
  4. ^ a b Graham, JE, ed. (2016). "Herpesviruses". Blackwell's Five-Minute Veterinary Consult: Avian. John Wiley & Sons. pp. 140–142. ISBN 9781118934609.
  5. ^ Ladds, P, ed. (2009). "Pacheco's disease". Pathology of Australian Native Wildlife. Csiro Publishing. ISBN 9780643099401.
  6. ^ Gravendyck, M; Balks, E; Schroder-Gravendyck, AS; Eskens, U; Frank, H; Marschang, RE; Kaleta, EF (1998). "Quantification of the Herpesvirus content in various tissues and organs, and associated post mortem lesions of psittacine birds which died during an epornithic of Pacheco's parrot disease (PPD)". Avian Pathology. 27 (5): 478–89. doi:10.1080/03079459808419372. PMID 18484032. 
  7. ^ a b Katoh, H; Ogawa, H; Ohya, K; Fukushi, H (September 2010). "A review of DNA viral infections in psittacine birds". The Journal of Veterinary Medical Science. 72 (9): 1099–106. doi:10.1292/jvms.10-0022. PMID 20424393. 
  8. ^ a b Randall, CJ; Dagless, MD; Jones, HG; Macdonald, JW; Smith, W (July 1979). "Herpesvirus infection resembling Pacheco's disease in Amazon parrots". Avian Pathology. 8 (3): 229–38. doi:10.1080/03079457908418348. PMID 18770448.