ROUTES OF INFECTION

Te Ao Hou, October 1956, Page 53

ROUTES OF INFECTION Tubercle bacilli may enter the animal's body in different ways, the most important being Positions of lymph nodes (swellings in these show tuberculosis). A, B, C and D are superficial but those marked G are inside the chest and when enlarged may press on the gullet, causing recurring bloat. Cows in the last stages of tuberculosis become weak and emaciated. through the nose in breathing. An animal affected with tuberculosis of the lungs may cough frequently and discharge into the air millions of bacilli. These are readily inhaled by animals close to the affected one. Tubercle bacilli may also be taken in through the mouth with food and water. In a tuberculosis infected herd, a lick to which all stock have access is very undesirable. Tubercle bacilli can survive for a long time on pastures. As infected cattle may pass out large numbers of bacilli in their dung, the pastures may become heavily contaminated. Lick or feed boxes or communal water troughs are other possible sources of infection. Tubercle bacilli may also enter the body through wounds, scratches, or abrasions.