quietness and extreme depression;
– sudden drop in production of eggs, many of which are soft-shelled or shell-less;
– wattles and combs become swollen and congested;
– swelling of the skin under the eyes;
– coughing, sneezing and nervous signs;
– diarrhoea; – haemorrhages on the hock;
– a few deaths may occur over several days, followed by rapid spread and a mortality rate that can then approach 100% within 48 hours.