Bulgy-eye is a growing problem it seems on grouse moors in the north of England (see here, here and here). We hear that one grouse moor in the Peak District has cancelled all its grouse shooting days for this year because of an outbreak.
It’s not totally surprising is it? When you are engineering unnaturally high densities of one species, Red Grouse, at the expense of all others, disease is likely to be a problem. Medicated grit has enabled many grouse moors to get on top of the problem of strongylosis but you can’t cheat nature for ever.
Of course, in a natural situation, without extreme predator control, the foxes and stoats might take out more of the diseased birds and cut down on transmission to healthy birds. But the state of affairs on grouse moors is far, far from natural. There are two cracking quotes from a grouse moor manager about this subject towards the end of Chapter 2 of Inglorious (pp79-80).
Bulge eye is caused by the protozoan Cryptospordium baileyi (which affects poultry but to which humans are not susceptible).