http://www.jstor.org/pss/1589494

A must read abou tparasitic larva that migrated to the brain of Pigeons, which in trun created neurological symptom of walking in circles.

A must read indeed.

Thanks Chars.

It is creepy thing these parasites, but not only pigeons have them.
Brain worm and brain amoebas are common parasites in deer, moose and even free grazing domestic animals in wetland areas. These parasites are dangerous for humans too. Infection leads to the symptoms of craziness and walking in circles when vestibular system is affected. Unfortunately there is no cure and outcome is lethal.

I think it's so incredible the more research and investigation being done we are discovering just how many illnesses do have similar symptoms to PMV. This is so important for all of us to know.

All the more reason one can't assume a pigeon displaying an upside down head or walking in circles automatically has PMV.
There are just too many variables.

If at all possible, testing for PMV is a great tool when symptoms are questionable.

Thank you Charis for this link! It is good to know about this - on the other hand it is creepy and very demotivating to think about all the probabilities that could occur.

The problem with these deseases is that no vet would be able to diagnose this or mostly even refuse to test. I was told that PMV tests are complicated and extensive. This means that they are extremely costly. I have already spent more money on my sick birds as I can really afford without even getting any "fancy" tests possible.

My point is that many people who care for their pets and other animals simply cannot follow any recommendation because there is no relation any more between going broke, risking a split between 2 partners because of conflicting opinions and the potential (not guaranteed) recovery of a bird - as hard and inhuman this may sound.

We simply cannot cover anything and everything. But it is wise to increase knowledge. Yet it is also essential to use common sense and not get into panic about what could be.

Here is an excerpt...
A diagnostic case with a history of central nervous system signs in Tumbler pigeons was submitted to our laboratory on Sept. 6. 1974. The loft contained 60 pigeons, 15 of them introduced two months previously. Five to six weeks after the new birds were introduced, several birds of the orginal group were observed to walk in circles and evidenced loss of control of flight and equilibrium. Ten deaths were reported in this group. No clinical signs or deaths had been observed in the 15 new birds.

At necropsy of the first bird presented for examination, a few intestional parasites [Capilliaria and Davinea] were found.
An image is below of a cross-section of parasite in the brain.

I believe that Ivermectin treatment of birds may be helpful in the cases of Parasitic Encephalitis. They use it on sheep and catle:

http://old.cvm.msu.edu/extension/Rook/ROOKpdf/bwflukesfinal.PDF

and I use it on every new bird as initial treatment against worms, lice etc.

After the shock findings of parasites in internal organs in Velvet's necropsy I have asked myself whether Sammy's very long-lasting PMV-type symptoms might not be partly related to parasites too.
After so much time (5 months), I guess if he had parasitic encephalitis I would have lost him by now, but the truth is that his recovery has sped up considerably since I treated him with Ivermectin. His seizures are shorter and he can now fly a little, but in circles.
Mind you, having Pippin to spend time with has helped him a lot too.

It's pretty incredible to learn about the many different illnesses that display neurological symptoms.