Pacheco's disease ("psittacine herpes")
Etiologic agent: psittacid herpesviruses (PsHVs)

Test code: S0090 - Qualitative detection of Pacheco's disease viruses (psittacid herpesviruses - PsHVs) by polymerase chain reaction. This assay detects but does not differentiate psittacid herpesvirus genotypes 1, 2, 3 and 4 (serotypes 1, 2 and 3).

Pacheco's disease is caused by psittacid herpesviruses (PsHVs) which are a heterogeneous group of viruses divided into four genotypes (Tomaszewski et al., 2003). PsHV is an enveloped double-stranded DNA virus belonging to the family alphaherpesvirus. At least three serotypes of PsHV are recognized. Genotypic and serologic correlation has indicated that genotypes 1 and 4 correspond to serotype 1 isolates; genotype 2 corresponds to serotype 2 isolates; genotype 3 corresponds to serotype 3 isolates. Viruses representing all four genotypes can be found in both the United States and Europe. In United States, PsHV genotype 1 represents the predominant type.

Infection of psittacine birds with Pacheco's disease virus can result in an acute fatal disease. Many parrot species, originating from multiple geographic regions, are susceptible to Pacheco's disease. However, Amazon parrots (Amazona spp.) account for the majority of cases, followed by African grey parrots (Psittacus erithacus), macaws (Ara spp.), cockatoos (Cacatua spp.), and conures (Aratinga spp. and Pyrrhura spp.). Although some infected birds may survive this fatal disease, they may become latently infected. Some infected birds may develop no symptoms whatsoever, and these birds become chronic carriers of the virus.

Whenever birds die suddenly or show nonspecific signs such as lethargy, anorexia, ruffled feathers, sinusitis and intermittent diarrhea, Pacheco’s disease should be included in the differential diagnosis. The first sign of a problem often occurs when a seemingly healthy carrier bird is introduced into a collection and birds start to die suddenly. Any type of stress (eg breeding) can activate the virus and result in its being shed in large numbers in the feces. The incubation period is thought to be as short as a few days in some of the smaller parrots.

Molecular detection of Pacheco’s disease by PCR is highly sensitive and specific for this virus. Genotypes 1, 2, 3 and 4 (corresponding to serotypes 1, 2 and 3) are detected but not differentiated by PCR.

Utilities:

• Confirm the disease causing agent
• Environmental monitoring
• Ensure that bird populations are free of PsHV
• Early prevention of spread of the virus among bird populations
• Minimize human exposure to the virus
• Safety monitoring of biological products and vaccines that derive from birds

References:
Tomaszewski, E.K., Kaleta, E.F. and Phalen, D.N. (2003) Molecular phylogeny of the psittacid herpesviruses causing Pacheco's disease: correlation of genotype with phenotypic expression. J Virol. 77:11260-11267.

Specimen requirements: 0.2 ml whole blood in EDTA (purple top) or ACD (yellow top) tube, or cloacal swab, or swab of the outer surface of liver, spleen or kidney, or 0.2 ml fresh or paraffin-embedded tissue, shipped overnight at room temperature; or frozen tissue shipped frozen.

For specimen types other than those listed here, please call to confirm specimen acceptability and shipping instructions.

For all specimen types, if there will be a delay in shipping, or during very warm weather, refrigerate specimens until shipped and ship with a cold pack unless more stringent shipping requirements are specified. Frozen specimens should be shipped so as to remain frozen in transit. See shipping instructions for more information.

Turnaround time: 2 business days

Methodology: Qualitative PCR

Normal range: Nondetected