Contagious and destructive nature of the disease. Mode of extension
from the mouth and pharynx. Causes: bacillus diphtheriæ columbarum;
its characters: pathogenesis to birds, mice, rabbits, Guinea pigs;
dogs, rats, and cattle immune; diagnosis from bacillus diphtheriæ.
American disease. Incubation. Symptoms: prostration; wheezing
breathing; sneezing; difficult deglutition; false membrane on fauces;
necrotic changes in mucosa; perforations; lesions of internal organs;
blood infection; nostrils stuffed; bill gapes; lesions on eye, tongue,
gullet, crop, intestine; diarrhœa; vomiting. Skin lesions. Course,
acute, chronic. Paralysis. Mortality. Prognosis. Diagnosis from
coccidiosis, from croupous angina of Rivolta, from aspergillus
disease. Treatment: isolation; destruction of carcasses; hatching;
destruction of dead wild birds and rabbits; exclusion of living;
quarantine of new birds; disinfection; locally, antiseptics by
inhalation, swabbing, and internally, iron in water.
This affection prevails in certain countries and causes heavy losses
among young pigeons, so that it might with great propriety be included
among animal plagues, which should be dealt with by the State. The
malady is a local inflammation leading to the formation of false
membranes and its usual course is to progress from the mouth and
pharynx, to the nasal passages, lachrymal ducts and sacs, the larynx,
trachea, bronchia, intestines and skin.
_Causes._ The essential cause of the disease is held by Löeffler to be
the _bacillus dipththeriæ columbarum_, which is a short bacillus with
rounded ends, a little longer than the bacillus of fowl cholera and not
quite so broad. It is usually found in irregular clusters, especially in
the interior of the hepatic capillaries. It is ærobic, non-motile,
non-liquifying, and grows on nutrient gelatine, blood serum or potato.
In gelatine it forms a white surface layer, and spherical colonies along
the line of puncture, which show a yellowish brown tint under the
microscope. On blood serum and potato it forms a grayish white layer.
_Pathogenesis._ The bacillus is inoculable on other =pigeons= and as it
usually appears in the young birds in the nest, still fed by the parent
bird, it is probable that no inflammation nor abrasion is necessary to
make it take. Pure cultures inoculated in the mouth gave rise to the
usual local type of the disease. When inoculated subcutem it caused a
local necrotic inflammation.
In =mice= subcutaneous injections proved fatal in five days with general
dissemination of the bacillus. There are congested and hemorrhagic spots
on the lungs, enlarged spleen, and the liver is marbled by numerous
necrotic white masses, in the centre of which the capillaries are found
to be blocked with the bacilli. This is so pathognomonic that Löffler
looks on the inoculation of mice as the best means of diagnosis.
Inoculated =rabbits= showed inflammation in the seat of inoculation and
sometimes fibrinous peritonitis and enlarged spleen. Inoculation on the
cornea produced a false membrane.
In =Guinea pigs= induration and ulceration occurred in the seat of
inoculation but recovery followed in 14 days.
=Sparrows= inoculated in the pectoral muscles died in three days with
yellowish necrotic tissue highly charged with bacilli.
Inoculation of the =chicken= by Löffler and Megnin produced a
circumscribed redness which soon disappeared. On the other hand
Krajewski, Colin, Loir and Ducloux seem to have inoculated chickens
successfully, and Cadeac says that the cultures are infecting for
=sparrows=, =pigeons=, =turkeys=, =chickens= and =ducks=. It rests
uncertain therefore whether the pseudomembranous pharyngitis of hens is
a distinct disease as alleged by Löffler and Megnin or if the chickens
used by these observers were not already immune by reason of a prior
attack.
Löffler’s experiments showed that _dogs_ and _rats_ were immune. Loir
and Ducloux failed to infect cattle.
In infected dove-cots a comparative immunity is attained by the older
pigeons, which continue to harbor the germ, but do not suffer materially
from its presence. They however communicate it to the susceptible young
in the milky secretion produced in the crop and with which they feed
them, and these accordingly perish in large numbers. Thus pigeons that
are themselves in fine condition become the propagators of the bacillus
to the more impressible.
_Sparrows_ and other _small birds_ are also held to be common
propagators of the germ, and if they too can secure an individual
immunity and yet harbor the bacillus, their passage from yard to yard
may be attended with great danger. The grains soiled by their bills and
not swallowed are common media of transmission.
Loir and Ducloux found the affection transmissible between man and
pigeon. The identity of the bacillus with that of genuine diphtheria in
man appears to have been thoroughly disproved by the observations of
Roux and Yersin.
The following differential characters have been noted:
_Bacillus Diphtheriæ _Bacillus Diphtheriæ Columbarum_
(Klebs-Löffler)._
1. In gelatine cultures grows only 1. In gelatine cultures grows at
above 23°C. 15–17°C.
2. Kills Guinea-pig and dog. 2. Guinea-pig and dog nearly
immune.
3. Mice immune. 3. Mice usually die with hepatic
necrosis.