During the tour of the viruses, which we started at the beginning of the year, I want to direct your attention to the Paramyxovirus in the next couple of newsletters.
The Variola- and Herpesviruses were discussed in earlier newsletters. Just as these viruses, I want to start by giving some scientific information and talk in the next newsletter about the practical consequences.
Paramyxovirus (part 1)
This disease among pigeons is caused by
the paramyxovirus serotype 1. It consists of a variation of the NCD virus which causes Newcastle among chicken. This disease occurred massively for the first time in Holland and Belgium around 1983. Typical were in the first years, the watery feces and serious nerves problems. Now a day, we distinguish aggressive and less aggressive strains, which could cause nerves problems. The prevention of these virulent strains, made sure that the symptoms are not that recognizable and the diagnosis can be missed. Even through required vaccination before flights makes it hard to control this virus. We could say that this virus is fixed in Europe, so-called endemic.
The paramyxovirus infection frequently appears in the fall, from August/September through November. The incubation period (the time between infection and the first symptoms) depends on the strength of the virus and can vary from three days to five weeks. In the first years of this virus, the first symptom showed within one week till ten days. The pigeons can carry the virus for a long period without the pigeon lover's knowledge.
The pigeons can get infected through contact with sick pigeons or by inhaling the virus. But even eating infected grains or drinking from an infected drinking trough could be the cause of the infection.
On not-vaccinated lofts, all pigeons will be infected, but the death ratio can vary, now a day, it usually is five per cent. Death thanks to a paramyxovirus outbreak, is common among nestlings.
In case of classical symptoms during a paramyxovirus outbreak, death can occur through the inability to drink or eat from nerves problems.
Traditionally, the paramyxovirus causes lesions in the brains and kidneys. In the kidneys, there is interstitial nephritis which means that the kidneys are unable to reabsorb enough fluid and the feces become watery. This has nothing to do with intestinal problems. Thanks to the fluid loss, the pigeons will drink quite a lot and results in the so-called poly-urie poly-dipsie (Pu/Pd). The water intake could increase up to two to three times the normal size.
The watery feces can remain up to two months. The feces will slowly become more firm. But for a part of the infected pigeons, the watery feces will remain.
Clearly, there's a distinction in the fecal matter between diarrhea and Pu/Pd. In the latter, the fecal matter is almost normal, but there's a small puddle of moister surrounding the feces. The pigeons could remain in a good state, but only if they keep eating.
From the moment when there is brain damages, the pigeons are unable to eat properly (turning heads, vibrations of the head; leaning heads) and this will lead to a decline of the condition. In case of paralysis of the feet and wings, due to brain damages, recovery is out of the question.
The light cerebral symptoms will fade away eventually. Still, in case of stress, some symptoms, like a light leaning head or vibration, could appear. A typical symptom of paramyxo infection is pecking next to the food.
The real classical signs of paramyxo are less present now a day. This leads to pigeon lovers who contribute watery feces to diarrhea and threat this with antibiotic, in vain.
In case of the classical symptoms of a paramyxo infection, the diagnosis is made on basis of the symptoms and the disease progression. To confirm this diagnosis, there has to be a serologic test. Obviously, this is only wise when the pigeons are not vaccinated. If this has already happened, the antibodies could originate through the vaccination instead of the infection. If you want to do this properly, after a while, you have to repeat the test to see if the titer has increased due to the virus infection.
During an outbreak, for several years, we perform in our clinic a Quicktest which shows if the virus is present in the cloaca or during necropsy of the brain. Through these Quicktests, it is possible to prove if the virus is present in pigeons who you wouldn't think to check on the paramyxo virus.
Through necropsy, it is possible to prove a paramyxo virus infection. Often the kidneys are swollen. And supporting histology can confirm the diagnosis.
In case of turning heads, you can think of a Salmonella infection as an alternative diagnosis. Also, the brain symptoms could be signs of an overdose of an imidazole compound, which is used to treat Trichomoniasis.
Watery feces in the nest could come from the change from crop milk to fast food during breeding.
In principle, you have to isolate the infected pigeons with moderate symptoms from the couple. Also, you have to avoid stress and direct the treatment on supporting the pigeons. This means that you can't feed them too much, you can't limit the water intake and give out vitamin and trace element preparations. A treatment focused on raising the resistance is useful. Even an emergency vaccination during an outbreak could be useful, because the protection from the vaccination becomes available after one week. In Belgium, you have to report a paramyxo infection. After mentioning this, there are appropriate measures to be taken.
In the next newsletter, I will discuss the practical approach.