Polyoma

Polyoma Virus Virus

AVIAN POLYOMA VIRUS IN PSITTACINES AND PASSERINES

By Susan Horton, DVM

History

First described as Budgerigar fledgling disease in 1981, was called papovavirus

It is a nonencapsulated DNA particle

Avian polyoma viruses are apparently worldwide, but presentation of the disease is different between species

Effects Budgerigars, nonbudgerigar psittacines, finches and gallinaceous species

Clinical Features

Budgerigars

	Feather abnormalities: reduced formation of down (Head and neck), contour feathers, and flight feathers; these birds are older then 15 days (runners, French molt)
	Develop normally for 10-15 days, then die
	Abdominal distension, hemorrhage under the skin, neurologic signs: ataxia, tremors of head and neck
	Mortality rates vary dependent on age of bird at time of exposure to virus
	Embryonic death

Nonbudgerigar psittacine birds

Peracute death with no signs (most common in young birds)

	Acute infections: 12 to 24 hour period of clinical changes such as depression, anorexia, weight loss, delayed crop emptying, regurgitation, dehydration, diarrhea, polyuria, difficulty breathing, bleeding under the skin followed by death
	Subcutaneous hemorrhage over the crop and across the cranium-common in larger psittacines (any disease causing vasculitis, clotting disorders or damage to the liver)
	Yellowish urates
	Increased LDH, AST, AlkPhos
	Eclectus parrots may also exhibit gastrointestinal stasis, melena, hematuria, and abdominal pain
	Chronic form (Europe ): Weight loss, intermittent anorexia, polyuria, poor feather formation, and recurrent bacterial or fungal infections. Renal failure may follow

Passeriformes

Acute death (fledglings, adults)

Beak abnormalities (fledglings)

Epizoology

All species should be considered susceptible to polyomavirus.

Most commonly effected species include young budgerigars, macaws, conures, Eclectus parrots, lovebirds, ring-necked parakeets, and caiques.

Birds considered naturally susceptible to avian polyomavirus

Psittaciformes

African Grey Parrots     Amazon Parrots        Bourke’s Parrots

Budgerigars                 Cockatiels                 Cockatoos

Conures           Grey-cheeked parakeets      Eclectus Parrots

Hawk-headed Parrot          Kakariki                   Lories

Lorikeets                       Lovebirds                  Macaws

Meyer’s Parrot               Parrotlets               Pionus Parrots

Quaker Parakeets Rose-ringed Parakeets Scarlet-chested Parrot

Senegal Parrot      Splendid Parrot

Passeriformes

Canaries                     Blue Bills                         Finches

Seedcrackers

Others

Chickens                  Brown Pigeon               Golden Pheasants

Lady Amhurst Pheasant     Turkeys                  Ostriches

Peaceful Dove

Age susceptibility/Mortality

Mortality rate with budgerigars less than 15 days may be as high as 100%, older birds range from 30-80%

Nonbudgerigar neonates are highly susceptible (parent or hand-raised)- usually signs show up at time of weaning; mortality rates from 31-41%

Older psittacine birds

Can seroconvert and may be clinically normal (budgies over one month, and over five months of age in others)

Exceptions seem to be Eclectus, caiques, grass parakeets and cockatoos

Persistent infections

These are individuals (budgies) that develop latent infections and shed virus periodically throughout their lives

They are responsible for the persistence, transmission and spread of virus through budgie flocks as well as exposure to others

Polyoma virus inclusion bodies can be detected in feathers, feather follicles and renal tissue in and may be protected in these areas from the neutralizing effects of antibodies

Persistent (latent) infection has not been proven in other nonbudgie species

Incubation

Budgerigars naturally exposed have peak mortality rates between day 15 and day 19

Incubation period in nonbudgie species has not been determined but is estimated to be as long as 14 days and as short as 2 days.

Transmission

Horizontal transmission- virus-contaminated feather dust, feces, urine, urates, respiratory secretions, crop secretions… Aerosolized virus: intranasal route of infection, ingestion

Vertically – Parent to offspring (infected embryos, Budgies only)

In Budgerigars- horizontally and vertically; ie both among members of the flock and between parent and offspring.

In Nonbudgerigars-Just horizontally

Pathology

In Budgerigars

Hydropericardium

Cardiomegally

Hepatomegally with multifocal yellow-white foci

Ascites

Splenomegally

Hemorrhage under the skin, of the intestines and heart

Feather dystrophy

Histologically there is atrophy of the lymphoid tissue in the spleen and cloacal bursa; inclusion bodies can be found in most tissues

In Nonbudgerigars

Clear fluid in the abdominal cavity

Small, pale spleen

Congested, hemorrhagic liver

Splenomegally

Pale, swollen kidneys

Pale cardiac and skeletal muscles

Feather dystrophy (rare)

Ascites

Hemorrhage under the skin and over any serosal surface

Histologically there is hepatic necrosis, lymphoid depletion of the cloacal bursa, and membranous glomerulopathy

Intranuclear inclusion bodies can be found in spleen and liver tissue most often

Immunity

Natural exposure to the virus can produce virus-neutralizing antibodies; titers usually decrease over a two to three month period

Diagnosis

Most accurate confirmation involves recovery of virus in cell culture from tissues of an infected bird

Electron microscopy

Four fold increase in antibody titer in paired samples

Specialized staining techniques of tissue sample

Detection of viral nucleic acid using polyoma-specific DNA probes (cloacal swabs)

DNA testing shows there is no correlation between active shedding of polyomavirus in feces and the titer of neutralizing antibodies… 98.2 % sensitivity, 100% specificity

Prevention and Control

Reduce exposure to virus

Sound hygienic practices

-Virus is shed in feces, urine, and feather dust

-Good disinfectants are Avinol-3 (Synthetic phenol), Clorox (Sodium hypochlorite), Dent-A-Gene (Stabilized Chlorine dioxide), and Alcohol (ethanol 70%)

-Nursery is cleaned and disinfected regularly

Closed Aviaries

-Limited visitors

Managed Aviaries

-Quarantine all new birds for 60-90 days

-Do not accept or ship unvaccinated birds

-Budgies are not in same airspace as other neonate psittacines

-Use biosecure shipping containers to prevent exposure

-Ship only weaned birds

-No Visitors in the Nursery

-Do not return neonates to nursery that have been exposed to other birds

-Separate feeding instruments for each bird

-Do not replace feeding utensil into common food container

Vaccination

-Vaccinate susceptible adults and neonates

-Do not ship unvaccinated birds

Disinfectants found to experimentally inactivate avian polyoma and their sources

Agent                     Active ingredient                       Dilution

Synphenol      Synthetic phenol                  1:256

Clorox             Sodium hypochlorite            1:10

Dent-A-Gene Stabilized chlorine dioxide 1:400

Alcohol             Ethanol 70%                    Undiluted

Treatment

To date, there is no effective treatment

Interferon, acyclovir and AZT have been tried, may show some promise.

Seriously effected birds need intensive supportive care

Vaccination

Adults (at risk breeding birds, birds going to shows)

Vaccinated during nonbreeding season

Series of 2 vaccinations, 2 to 3 weeks apart

During the vaccination process, it is expected that 2 to 4 % of the breeding population will also be found to have serious pre-existing medical problems (even in best managed aviaries)

Immature birds

In general, vaccination is started 4 weeks prior to weaning

Series of 2 vaccinations 2 to 3 weeks apart

Last vaccination 2 weeks before shipping

If aviary has a history of polyoma disease, start vaccination at 40 to 50 days of age

If having an outbreak, vaccine can safely be given at 20 days of age; these birds are boostered 2 additional times, 2 to 3 weeks apart

Original certificate of vaccination should be sent with bird

Companion birds

If kept in complete isolation, not necessary

Dr. Ritchie points out that if the bird or it’s keeper leaves the home to go to the groomer, veterinarian, club meetings or anywhere else where direct or indirect exposure might occur, vaccination is not a bad idea.

It is interesting to note that we protect our dogs and cats who are maintained in relative isolation with yearly boosters against common viruses

References

1.       Ritchie BW. Avian Viruses: Function and Control. Wingers Publishing, Inc., Lake Worth , Florida . 1995. Pp136-170

2.       Ritchie BW, Niagro FD, Latimer KS , et al: Avian Polyomavirus. An overview. J Assoc Avian Vet 5:147-153, 1991

3.                   Clubb SL, Davis RB: Outbreak of papova-like viral infection in a psittacine nursery-a retrospective view. Proc Assoc Avian Vet, 1984, pp 121-129.

4.                    Niagro FD, Ritchie BW, Lukert PD, et al: Avian Polyomavirus: Discordance between neutralizing antibody titers and viral shedding in an aviary. Proc Assoc Avian Vet, 1991, pp22-26.

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In This Section:

News and Info:

Polyoma Virus Virus

History

Clinical Features

Epizoology

Psittaciformes

Passeriformes

Others

Age susceptibility/Mortality

Persistent infections

Incubation

Transmission

Pathology

In Budgerigars

In Nonbudgerigars

Immunity

Diagnosis

Prevention and Control

Synphenol Synthetic phenol 1:256

Clorox Sodium hypochlorite 1:10

Dent-A-Gene Stabilized chlorine dioxide 1:400

Alcohol Ethanol 70% Undiluted

Treatment

Vaccination

Adults (at risk breeding birds, birds going to shows)

Immature birds

Companion birds

References