Susceptibility of Avian Polyomavirus to Inactivation

Abstract

Eight commercially available disinfectants, representing several major classes of chemical disinfectants, were evaluated for their ability to inactivate avian polyomavirus (Budgerigar fledgling disease virus). These disinfectants and their sources are listed in Table 1. Avian polyomavirus was considered to be a good test pathogen for a disinfectant because this nonenveloped virus is a frequently encountered pathogen that is considered to be relatively stable in the environment. Disinfectants were diluted according to the manufacturer's recommendations. Infectious virus preparations were placed in con tact with each diluted disinfectant for one minute or for five minutes at room temperature. After removal of the disinfectant by gel filtration, each sample was then placed on cultured cells to determine whether the virus was inactivated. Of the eight disinfectants tested, 0.525% sodium hypochlorite (Clorox) was considered the most economical. A stabilized chlorine dioxide (Dent-A-Gene) was effective and would be expected to be the safest. Chlorohexadine (Nolvasan) reduced but did not eliminate the infectivity of avian polyomavirus, which may explain why aviaries that use this disinfectant in the nursery frequently experience polyomavirus outbreaks. Heating the virus to 60°C for 5 minutes or 30 minutes reduced the titer of the virus, but did not eliminate infectivity. An Overview of Avian Polyomavirns The first acute, generalized infection associated with a polyomavirus was described in young psittacine birds and was called Budgerigar fledgling disease (BFD). 1•5 A virus that is similar to the one that causes Budgerigar fledgling disease has been shown to be associated with high levels of sickness, and in some cases death, in finches and a number of different genera of psittacine birds. It should be noted that while the polyomaviruses that infect Budgerigars, finches and larger psittacine birds have similarities, the clinical presentation, distribution of lesions and problems that the viruses cause within a flock are dramatically different among susceptible species."!' Infected Budgerigar neonates typically develop abdominal distention, subcutaneous hemorrhage, tremors of the head and neck and ataxia. Survivors may exhibit symmetrical feather abnormalities characterized by abnor- ma 11 y formed primary and tail feathers, lack of down feathers on the back and abdomen and lack of filo- plumes on the head and neck. When feather lesions are present, the disease is often referred to as French Molt. In larger psittacine birds, polyomavirus infections may cause a peracute death with no premonitory signs or death 24 to 48 hours after developing clinical signs including depression and anorexia, delayed crop emptying, regurgitation, weight loss, subcutaneous hemorrhages and diarrhea. Infections may occur in both parent and handraised babies and clinical signs are most common at the time of weaning.v" 12-14 The feather abnormalities that are relatively common with polyomavirus infections in Budgerigars are described less frequently in other psittacine species. In addition to clinical changes in neonates, polyomavirus infections have also been documented in an eight-month-old Splendid Parakeet Neopbema splendida and as the cause of sporadic, acute deaths in fully fledged lovebirds less than one year old.13.is An adult Moluccan Cockatoo Cacatua moluccensis with neurologic signs was diagnosed as having polyornavirus." An outbreak of polyomavirus in an aviary with numerous psittacine species resulted in the deaths of an adult Eclectus Parrot Eclectus roratus, a Painted Conure Pyrrhura picta and three of eleven adult White-bellied Caiques Pionites leucogaster in the collection. The affected birds were two to two and a half years old and had lesions similar to those seen with polyomavirus infections in psittacine fledglings.16 Avian polyomavirus infections have been described throughout the world. Characteristic lesions associated with the virus have been demonstrated in companion birds from the United States+" Canada,17·18 japan,'? Italy," Hungary,21 Germany22 and Australia.13·15 Avian polyomavirus has been associated with disease in a number of different species of companion and aviary birds including Budgerigars, caiques, macaws, Amazon parrots, conures, cockatoos, lovebirds, Splendid Parakeets, Pionus Parrots, African Grey Parrots, Eclectus Parrots, Cockatiels, Crimson Seed-crackers, finches and lories.l+ s-e, 12-15, 23, 24 The factors involved in polyomavirus infections are not fully understood. One of the formidable problems that occurs with polyomavirus is that normal adults and neonates from infected parents are thought to act as polyomavirus carriers.