Spreading of Tubercle bacilli

   These disease may spread through three routes

i)                    Directly along continuous surface

ii)                  By the lymph system

iii)                By blood stream

1.. Spreading from continuous surface

(a)    When the lesions in the lung or bronchial glands are broken , there may be tuberculous broncho-pneumonia from where upper respiratory tract and face may be affected . Apex of right lung is commonly affected due to restricted movement of apical part and slowing of blood and lymphatic flow .

(b)    From the tuberculosis of epididymis , prostate and bladder may be affected due to ascending infection

2.. By the lymph stream

   The regional lymph glands draining the area are inflamed and caseous . It is found commonly in children . there may be lymphangitis of the lymphatics draining that area . There will be formation of primary complex which will consist of –

a)      the area of broncho-pneumonic patch in the lung

b)      Lymphangitis

c)      Glandular component like gland involvement .

In majority of the cases , it is arrested , being encapsulated by fibrous tissue and may even calcified . A few cases show other glandular group in volvement and enter into thoracic duct and then enter into blood stream .

3… By the blood stream

(a)    large number of organism when they enter into blood stream , cause generalized infection with production of military tuberculosis . Here small tubercle are present in many organs .

small number of organism when they enter into blood stream , localize themselves in various organs particularly the bones , joints and kidneys . this will produce chronic or subacute type of lesion .