PMV ALERT February 2015
Dr Colin Walker B.Sc. B.V.Sc. M.A.C.V.S. (Avian health )
Melbourne Bird Veterinary Clinic
Over the last 2 months but particularly the last 2 weeks a significant number of cases of PMV have been diagnosed at the Melbourne Bird Veterinary Clinic. Lofts containing infected birds have been located near Nagambie, Gippsland, Frankston and throughout the Melbourne metropolitan area
The usual sequence of events has been that concerned fanciers have contacted the clinic with either multiple sick or dying youngsters, an unwell bird has been selected and euthanized, multiple tissue samples have been collected during an autopsy and then forwarded to an avian pathologist ( Professor David Phalen ) for histopathology examination. This is a very thorough means of diagnosis. Apart from PMV, multiple cases of Circo virus and also Herpes virus as well as some cases of Adeno virus have been diagnosed. The number of viral cases prompted the following email from Professor Phalen last week. Professor Phalen is professor of avian medicine at the University of Sydney
With this and the other pigeon cases that you have sent me , particularly , in the past 2 weeks, a pattern is developing,
1, While less common or less obvious in past years, the pigeon Circovirus, this year, appears to be impacting multiple lofts and is likely to be resulting in immune suppression which may be making every infectious agent out there worse.
2, PPMV is obviously also circulating within many lofts. Either because of the change in the nature of the virus or concurrent infection with pigeon Circovirus, the nature of the PPMV lesions is changing. Splenic lesions are now much more severe, pancreatic lesions are also more consistently present and in this instance of this bird are extremely severe, and it appears that lymphoid tissue is more likely to be targeted including Kupffer cells, intestinal lymphoid tissue and bursa.
From what you have you have sent me, it might be a bit of a bad time for your pigeon folks in the coming weeks.
Fanciers need to be aware that the character of PMV has changed. This is due to the factors mentioned by Dr Phalen above but also because many of the birds that are now exposed to PMV virus have some partial immunity. Partial immunity is most commonly seen in unvaccinated youngsters which have passively acquired some immunity through the egg or crop milk from their vaccinated parents and also in youngsters which have received only one vaccination. This partial immunity modifies the symptoms displayed by infected birds. Most infected birds simply become quiet and develop wet droppings. Some birds will develop twisted necks and have poor co-ordination. In most infected lofts less than 10% of birds will die and in one recently diagnosed loft no birds died. We now rarely see the high mortality rates, extreme thirst and profuse wet droppings of several years ago. In fact many of the fanciers who contact the clinic with birds that subsequently were diagnosed with PMV initially thought their birds had a Salmonella infection.
As the vaccine is cheap, safe, effective and readily available there is little reason for fanciers not to vaccinate their birds. Not vaccinating not only puts their own birds at risk but also those of fellow fanciers. All Victorian fanciers are strongly urged not to become complacent about PMV and to ensure that their birds are vaccinated. Not only because of the risk of PMV, but also because of the risk of introduction of other viruses fanciers should obviously only introduce youngsters from reliably healthy sources