Dave J. Rupiper DVM, Dipl. ABVP East Petaluma Animal Hospital 1420-B South McDowell Blvd., Petaluma, CA 94954 Phone: (707) 765-9098 Fax: (707) 765-2984 Web: EPAH.net Psittacine Herpes Virus (Pacheco's Disease) History Pacheco's Disease is caused by a Herpes virus and has been reported in South America, North America and Austral-asia. Many species are susceptible to the infection, particularly Amazons, cockatoos and macaws. Other species such as conures may be infected yet not show any clinical signs and thus can be carriers. Nanday conures and Patagonian conures seem to be more resistant to the disease and can carry it without showing signs. Thus, they are often incriminated in outbreaks. Signs Signs of Psittacine Herpes Virus are usually present only immediately prior to death. Birds are usually in good condition, in breeding form and eating well. Fluffing, lethargy and watery feces are some of the signs exhibited by infected birds. In a few hours to a couple days they succumb to the disease, with or without treatment. The prognosis for birds showing clinical signs in an outbreak is extremely poor. The birds usually die from the severe liver damage caused by the virus. Death is fairly rapid once they become infected. Diagnosis Diagnosis of Pacheco's Disease must be made quickly in order to prevent further spread of the infection to the remainder of the flock. The virus leaves a very characteristic "footprint" in the liver tissues of affected birds which can be seen microscopically. Therefore, dead birds should be immediately necropsied (autopsied) to check for this disease. Other tests such as virus isolation are available but are not usually necessary. Transmission The virus is transmitted by birds carrying the disease but these birds may not show any signs. When these carrier birds are stressed with environmental changes, other disease problems, breeding, crowding, transportation, etc., the virus may become active and is shed in the feces. Nearby birds obtain the infection by ingesting the virus in contaminated food and water and by preening contaminated plumage. Treatment Treatment for Psittacine Herpes is often unrewarding. A drug called acyclovir (Zorivax) has been used to prevent virus shedding and reduce mortality but it is very expensive and difficult to administer. Acyclovir can be used in the water but tends to settle out so it is best given by tube feeding. Tube feeding a large flock of birds is labor intensive and usually unrewarding since birds may relapse when the medication is discontinued. A vaccine is available which will help reduce mortality, but it does not protect the birds from infection. Vaccinated birds may still become infected and develop a carrier state yet will not develop clinical signs. The best cure is prevention. Maintain a "closed" aviary, one that does not allow birds to be admitted unless they test negative to various diseases and separate conures from the primary breeding flock since conures may be silent carriers. Vaccinate all birds if psittacines are being moved through the aviary on a regular basis or if there is a history of Psittacine Herpes in the aviary. Vaccination consists of two injections given intramuscularly three to four weeks apart.