Speckled Sussex, approx 1 year old. Symptoms: Head-shaking, loss of balance, sitting back on "haunches"; after handling, unable to get up for a while, lies on side but head up and looking around. Bird is clear-eyed, alert and eating well; comb and wattles red and undamaged. No discharges, nasal or otherwise; feathers are clean with no loss: no mites or ticks found. Birds receive vitamins and have been wormed. Diet is cereal (wheat, corn), whatever they forage and occasional treats. No other birds (another roo, four hens) affected.