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A. E. Hamerton—Diseases of Aviary Birds



Ross, who demonstrated their development in the mosquito—a revela¬

tion that led directly to the discovery of the anophales mosquito as the

essential insect host of the parasite (Plasmodium) of human malaria.

Avian plasmodia infest the red-blood corpuscles of their vertebrate

hosts, and produce malarial fever, which is a fairly common cause of

death in recently imported tropical birds. Newly imported birds will

sometimes suddenly drop off their perches dead. Post-mortem

examination may show nothing visible to the naked eye : a micro¬

scopical examination of the blood, however, will reveal great destruction

of red blood cells, more than half of which may be occupied by a malarial

parasite.


Diseases of the Circulatory System .—Idiopathic anaemia of birds

can rarely be traced to the blood-forming organs. Leukaemia, however,

is a fairly common cause of avian mortality, and is manifested by an

enormous increase of the leucocytes and decrease in the number of

red cells ; associated with pale, watery appearance of the blood,

and a pallid anaemic aspect of all the internal organs. Pericarditis,

with serous or purulent effusion, or a dry form of the disease with

a white film or urate deposit on the opposing surfaces of the sac is

commonly found as a secondary complication of grave primary lesions

of the kidneys, or in general septicaemia. Birds will sometimes die,

however, with the pericardium distended with clear fluid, and a like

effusion in the peritoneum, and no other lesion. There is generally

a history of exposure in such cases. Myocarditis and fatty degeneration

of the heart in old birds is often associated with rupture of the auricles,

haemopericardium, and sudden death. Endocarditis, or valvular

disease of the heart, is quite a common cause of death, and is generally

acute, and often associated with an external septic lesion, such as

septic “ corns 53 of feet, or infection of the wound after pinioning,

or other injury. Chronic endocarditis resulting in sclerosis and dis¬

tortion of the mitral valves with incompetence and cardiac hypertrophy

occurs in old birds. Patty and calcareous atheromatous deposits in

the arterial system are sometimes so advanced as to seriously diminish

the flow of blood by narrowing of the calibre of the brachio-cephalic

and coronary arteries, a common disease in aged Parrots.


Diseases of the Urinary and Genital Systems, —Birds of all kinds



