You can also call one of the big Veterinary colleges or Universities such a s Texas A&M University that has done years of research and teaching about Psitticines and their diseases. Most of our pet birds are raised in clean and healthy conditions these days have been vetted and have not come in from the wild so are never exposed to much of anything communicable to humans. The biggest health issues seem to be from breathing feather dust and you can avoid most of that by having a good air purifier running near your birds cage and not sleeping in the same room as your bird. You poor panicked wife should have more concerns about what our fruits & veggies have been sprayed with, what our meats have been treated with and all the pollutants in our homes and environments. Insecticides, mildew and mold PVC's can make us all sick and can kill your Grey. There are some bad breeders out there who sell birds who have exposures to diseases but those kill the birds not the humans, just heartbreak rather than risk of ill health.
"I think any viral brain infection would be an encephalitis that is transmitted through a mosquito bite from bird to bird an occasionally to humans. These are not from Parrots but our Native birds such as Blue Jays, Crows and Grackles who are subject to this disease.
Eastern equine encephalitis (EEE) is a rare but serious viral disease spread by mosquitoes that can affect people and horses. EEE can also cause disease in captive birds such as the ring-necked pheasant, emu, ostriches, quail and ducks. EEE infection and disease can occasionally occur in other livestock, deer, dogs, other mammals, reptiles and amphibians.
EEE is transmitted by the bite of an infected mosquito. Mosquitoes become infected by feeding on infected birds. Infected mosquitoes will then occasionally feed on horses, humans and other mammals. Several species of mosquitoes can become infected with the EEE virus (EEEV). EEE is not spread person-to-person, from people to animals or from animals (other than mosquitoes) to people. "
Encephalitis Definition - Diseases and Conditions - Mayo Clinic
http://www.mayoclinic.org/diseases.../encephalitis/.../con-200219...Mayo Clinic
Encephalitis — Comprehensive overview covers symptoms, causes, treatment of this potentially life-threatening condition.