Week 63 – 01 October 2017:
The Parakeet Fights Back
Birds can be endlessly attractive and engaging. Regrettably, being cute doesn’t protect birds from the bacteria, viruses, fungi and protists that infect members of all animal groups. Fortunately, when living at reasonably low densities in the wild, an otherwise-healthy bird is likely to be able to fight off most pathogens.
Once birds are taken from the wild and into captivity, and held in closer quarters, the story can change. The risk of transmission of communicable diseases can become much greater, not just to the birds themselves, but also to the humans that share their living spaces. Consequently it is necessary that zookeepers, pet store staff, poultry producers, quarantine staff, and pigeon fanciers monitor the birds in their care, watching for signs of ill-health.
As with other animals, an individual bird can serve as a host to viral and bacterial agents long before it shows any pathological signs of disease. An apparently healthy bird might be infective to those around it. It will, in some situations, be prudent to routinely screen for pathogens in a captive flock whose members all look healthy if later outbreaks are to be avoided. Swabs can be taken from the bird’s throat or its cloaca (the shared opening of the bird’s digestive, urinary and reproductive systems). Whatever was collected on the swab could then be cultured on a nutrient medium, or subjected to diagnostic genetic analysis. The difficulty is that sampling of this sort is invasive, time consuming, and potentially stressful on the animals being tested.
Alenka Dovč of the University of Ljubljana in Slovenia and thirteen of her colleagues investigated the possibility of utilizing noninvasive sampling techniques to monitor the health of captive birds. In particular, they studied the diagnostic value of filtering large samples of the air in bird enclosures.
In particular Dovč and her group studied the presence of airborne pathogens in four holding facilities for parrots. Although their paper did not say so specifically, contextual clues suggest that these were large-scale facilities that supplied parrots for the pet industry. Among the birds in these holding were Blue-throated Macaws (critically-endangered in the wild), Eclectus Parrots, Rose-billed Cockatoos, Orange-winged Amazons, and Great Green Macaws (endangered in the wild). In addition, Dovčet al. sampled the air from fifteen racing pigeon facilities. There are, presumably, a lot of pigeon enthusiasts in Slovenia. For comparative purposes, the research team also performed more traditional sampling.
The list of diseases that might be spread from one bird to another was, quite frankly, rather frightening. It included such diseases as psittacine beak and feather disease, and proventricular dilation wasting disease. Not all of the diseases would be restricted to bird hosts. Among the infections that have a high or moderate risk for humans are avian influenza virus, Chlamydia psittaci, Candida parapsilosis, giardiasis, salmonella, West Nile virus, cryptosporidiosis and cryptococcosis. Yikes!
Air sampling proved to be valuable in revealing infections of PDDV and CP, but less successful in the case of other infections such as psittacine beak and feather disease virus, adenoviruses and Mycobacterium avium complex. It seems that in avian health, as in human health, a comprehensive approach to diagnostics is likely to provide the best results.
How is your pet parakeet looking?
Dovč, A., et al. 2016. Occurrence of bacterial and viral pathogens in common and noninvasive diagnostic sampling from parrots and racing pigeons in Slovenia. Avian Diseases 60:487-492.
Photo credits: Blue-throated macaw artwork – www.pinterist.com; Rose-billed cockatoo (galah) artwork – www.redbubble.com