Aspergillosis in pigeons
This disease is caused in pigeons by the fungus Aspergillus fumigatus and in rare cases by Aspergillus flavus and Aspergillus niger.
The fungus spreads by forming threads and can spread over a surface. Multiplication takes place by forming spores. These are tiny particles that spread through the air. It is a fungus that occurs almost everywhere in nature. Birds can become infected by breathing in these spores.
Whether an infection with the spores causes disease is largely due to the condition of the pigeon. A healthy pigeon that gets a good feed without deficiencies, will, in most cases, be able to tackle the inhaled spores itself and no disease will occur. Vitamin A deficiencies often play an important role in the development of fungal infections. In cases of infection with large numbers of spores, a healthy bird can also develop the disease.
If Aspergillus is not eliminated by the body itself, it will multiply and cause illness. The biggest problems with pigeons are often seen in the airways.
Acute or chronic
Aspergillus can have an acute or chronic course. With an acute form, the fungal spores attack different places and cause a large infection throughout the body. In addition to the airways, the liver and kidneys can also be affected. The pigeon will soon become ill, will not want to eat and will have difficulty breathing. They often drink a lot and droppings may be green coloured. They can even die suddenly without obvious symptoms.
The chronic form is more common. The fungi grow slowly, from one or more places in the body (often starting in the airways). They form plaques and granulomas (lumpy masses) of mould.
The fungus can attack at different places in the body. For example, fungal plaques can be in the nose or in the throat slit, and they often settle in the air pockets. Here they cover the wall and can even close the connection to the lungs. Spores that are formed spread slowly through the body. This can be a very insidious process. The birds are not acutely ill, but do lose condition, can be a bit slow and sleep a bit more. Shortness of breath is often present, especially after exertion.
The disease is more common in parrot varieties than in our racing pigeons, where this fungal disease is rather rare. However, I would like to write an article about it, because the symptoms are often reminiscent of other diseases.
Due to the tightness of the chest, we often first think of the ornithosis complex of the deeper airways, such as lungs and air pockets! If the usual antibiotic treatment(s) don’t work quickly, you have to look further to arrive at the correct diagnosis. In our pigeon clinic in Colchester near London, we were consulted by a pigeon fancier who had critically ill pigeons who died after a short time with symptoms of severe tightness of the chest, but also PMV-like symptoms, like twisted weak necks just before they died. Also, they were drinking more than usual and had dirty green slimy droppings. At first, it reminded me of Adeno type II. In this rapidly fatal disease, however, the droppings are bright yellow (due to the severe destructive liver infection). The mortality is acute within 20 hours!
Adeno Type II
I had the dubious honour of being the first to ‘see’ this disease. That was in 1991 in West-Brabant where many thousands of racing pigeons abruptly died in perfect condition. The University of Ghent only made the diagnosis much later: Adeno type II. And the first scientific articles followed on from the so-called Conference of the German Veterinary Society, the Specialist group for Bird Diseases (Poultry Diseases) in Munich, more than half a year later. I had already devoted a popular scientific article to it in the pigeon magazine, six months previously!
This doubtful honour to be the first (in the world) to discover and describe new diseases is one we also had with Herpes type II (in youngsters) in 1973. Also, a deadly disease once it appears among the members. During the first quarter of 2017, I was consulted by colleagues from Australia about an ‘alleged’ Rotavirus outbreak, which also showed Adeno II-type symptoms. Rapid mortality, pumping breathing, but no yellow droppings!
Back to the Aspergillosis outbreak in England. It was strange that the owner had similar problems at the same time the previous year. Which makes you quickly think about plants that bloom at the same time and may be poisonous. But first we also had to exclude PMV based on its vaccination schemes and symptoms! We got some sick, uncomfortable pigeons from England over to Breda and did the research here in collaboration with a good laboratory that also has the PCR method in house.
Through autopsy, we had already found the typical lesions in all organs, from lungs and air pockets to liver, spleen and kidneys!
After treatment with Amphotericin B, the not too sick pigeons recovered quickly and the problem was solved. We advised the owner to disinfect his lofts with steam! Advice for next year is: ensure optimal health with dry pens and good nutrition and sufficient minerals and vitamin A. Disinfect the pens with steam before you start breeding!
We only see aspergillosis as a problem once a year, fortunately. Some types of straw can also contain fungal spores, especially if damp!
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