CHAPTER XXXI

INFECTIOUS DISEASES OF POULTRY


FOWL CHOLERA.--This is a highly infectious disease of all species of
poultry, that is characterized by weakness, depression and yellowish
colored excrement.

The _specific cause_ of fowl cholera is the _Bacillus avisepticus_ (Fig.
123). This microorganism is transmitted to the healthy birds by the feed,
or water becoming contaminated with the discharges from the diseased birds.
According to Salmon, the period of incubating varies from four to twenty
days.

_The early symptoms_ are a falling off in appetite, high fever, dulness,
diarrhoea and weakness. The affected bird becomes drowsy, the head is drawn
toward the body, and it may remain asleep for long periods at a time.
Salmon states that the general outline of the sick bird becomes spherical
or ball-shaped.

[Illustration: FIG. 123.--_Bacillus avisepticus_.]

The disease is usually highly fatal. In the acute form the larger portion
of the flock may die off within a week. In the subacute and chronic forms,
the birds become greatly emaciated, and a few die off weekly through a