54 DISEASES OF DOMESTICATED BIRDS 
sanguinarium. Also, the duration of symptoms is apt to be much 
shorter in the case of cholera. . 
Fowl typhoid is differentiated from fowl pest by the absence of 
severe intestinal congestion, failure to find petechiz in the mucosa 
of the proventriculus and by the fact that fowl pest is caused by 
a filterable virus and no organisms can be detected in the blood 
stream, or isolated on artificial culture media. 
Infectious leukemia has somewhat similar lesions and also shows 
a greatly changed condition of the blood. However, in this disease 
the loss of red cells and increase of white cells is much more marked 
than in fowl typhoid. Also, it is the mononuclear cells, instead 
of the polymorphonuclears, which show the principal increase in 
numbers in infectious leukemia. Unlike fowl typhoid, infectious 
leukemia is caused by a filterable virus and no microorganism can 
be grown, from the blood or organs on artificial culture media. 
Fowl typhoid and acute Bacterium pullorum infection of grown 
fowls have symptoms and lesions which are somewhat similar. The 
causative organisms also closely resemble each other both morpho- 
logically and in their cultural characteristics. In B. pullorum in- 
fection, however, the ovary is congested and nearly always presents 
several hard irregular ova. It is the principal seat of predilection 
for the pullorum bacterium. 
PSITTACOSIS OF PARROTS 
Synonyms. Septic fever of the parrot, parrot septicemia, (Eng- 
lish) ; septicemie des perruches, mycose des perroquets, (French) ; 
Psittacosis, (German). 
Characterization. The disease is a contagious septicemia in- 
volving parrots and parrakeets and causing fever, weakness, stupor 
and diarrhea. 
Transmission to man, The disease has received considerable 
attention because suspicion has been aroused that the infection may 
be transmitted to man. A number of outbreaks of infectious pneu- 
monia in man have been observed to occur simultaneously with the 
bird disease. 
Leichtenstern sums up the question of the transmission of the dis- 
ease to man as follows: 
_ “4, Epidemiological, clinical and especially bacteriological evidence is 
not disclosed to prove that the infection of house epidemics of pneumonia 
suspected of being psittacosis, did originate from sick parrots. 
“9, It is proven that bacterial diseases, especially enteritis, occur fre- 
