A few more answers on the cormorants

11 03 2009
One of the Double-crested cormorants tested for Newcastle Disease

One of the Double-crested cormorants tested for Newcastle Disease

Follow-up on yesterday’s post:

After speaking with a veterinarian at the Cornell Diagnostic Laboratory, and consulting a few other trusted sources, SEANET has gleaned a bit more information on Newcastle Disease. It turns out that it is indeed possible that birds that were once infected with Paramyxovirus generally, or Newcastle Disease specifically, could recover and clear the virus from their systems entirely. This would mean that a bird could test negative for the disease, but might have had it some time in the past. And certainly, the wing paralysis seen in our cormorants could be the result of permanent nerve damage caused by a virus that is no longer present in the body.

However, Paramyxoviruses (Newcastle among them) are capable of persisting in the body for a long time. In cormorants, the virus can be detected in feces for over a month after initial infection, and pigeons can shed the virus for six months, long after all signs of disease have diappeared! What this means for our set of cormorants is that it is probably unlikely that the birds were recently infected by the virus, if they ever were. If the wing paralysis seen was indeed due to Newcastle infection, it is more likely that the birds were infected months prior to their presentation.

Of course, the most unsatisfying possibility of all is that the birds never had the virus at all, leaving us with no explanation for the wing paralysis whatsoever. This sort of uncertainty is both the frustration and the beauty of pathology and SEANET wouldn’t have it any other way. Well, maybe a few more definite answers would be nice…

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