Eggs may be one of the means of spreading the disease, as they may become contaminated in the oviduct or the cloaca of birds affected with blackhead.
Treatment. No remedy or satisfactory method of prevention has been discovered. The difficulty of effecting a cure is obvious when the nature of the disease is considered. Drs. Cole and Hadley summarize measures of prevention as follows:
1. Protect the yards and flocks which may have the good fortune to be uninfected with the blackhead organism by a thorough examination of all new stock, whether turkeys, fowls, geese or other domestic birds.
2. Keep the turkeys on grounds which are as fresh as can be obtained, and above all, keep them isolated from fowls and other domestic birds.
3. Keep every turkey in the flock under close observation in order to separate and at once isolate any bird which gives evidence of the disease. To facilitate such observations it is helpful to leg-band each individual, and to record its weight from time to time. Such a course makes it possible to learn whether any birds are losing weight, and if this is the case, these birds must be regarded with suspicion, and separated from the rest of the flock.
4. If it is known that blackhead is present in any of the poultry, the yard should be kept free from English sparrows, and the poultry houses and grain boxes from rats and mice, which have been shown to carry the causative organism.
5. When it is desired to fatten birds for the market, begin to increase the rations gradually. Never attempt to fatten birds which, in successive weighings, show a loss of weight. Overfeeding does not cause blackhead, but frequently causes the sudden death of birds in which blackhead is present.
6. When birds have died of blackhead, their bodies should be promptly burned or buried in order to prevent the dissemination of the coccidia, either through the ravages of rats or skunks, or consequent to the natural processes of decay.
BREAKDOWN
Not often seen in the poultry yard
Symptoms. The abdomen becomes enlarged, hangs down at the back, and sometimes touches the ground.