Septicaemia means blood poisoning. This can be caused by bacteria or their toxins going through the blood stream. Infection can occur at the same stages as with yolk sac infection. Birds will be depressed and huddling with increased mortality. The livers will be discoloured, spleens enlarged and there may be obvious pus present.
Bacteriology and sensitivity should be carried out to determine a suitable antibiotic therapy. However, antibiotics are usually too late for affected birds. As with yolk sac infection, prevention is key.