Inhalation of dust containing the pathogen. Contaminated feed (insects, mice, rats). Dirty feed troughs and water bowls. Mating. Transmission from the hen to the egg. Feeding the nestling with infected crop milk and billing.
Many birds carry salmonella without becoming ill. New strains of salmonella more often will cause illness. Pigeons that appear healthy after surviving salmonella infection, but shed the pathogen at irregular intervals and sometimes pose a risk to the current flock and their young.
Upon appearance of the symptoms described, treatment with 4 in 1 should be started immediately. Treat the entire flock rather than individual birds.
It is unlikely that severely infected birds will be cured.