10. The chief channels of personal infection or the spread of the disease amongst a community are two: (a) dried tubercular sputum (or other tubercular discharges); (b) infected milk or meat. So long as the former remains wet or moist, infection cannot take place. It is, of course, better to destroy it completely. As for milk and meat, boiling the former and thoroughly cooking the latter will remove all danger.
11. The expectoration is infective. This is one of the commonest modes of infection, and to it is held to be due the large amount of respiratory tuberculosis (consumption, phthisis). The expectoration from the lungs must contain, from the nature of the case, a very large number of bacilli. As a matter of fact, a single consumptive individual can cough up in a day millions of tubercle bacilli. When expectoration becomes dry, the least current of air will disseminate the infective dust, which can by that means be readily reinspired. Expectoration on pavements and floors, as well as on handkerchiefs, may thus become, on drying, a source of great danger to others. The discharges from the bowels of infants suffering from the disease also contain the infective material.
12. Milk, though a much more likely channel for conveyance of tubercle than meat, is only or chiefly virulent when the udder is the seat of tuberculous lesions. The consumption of such milk is only dangerous when it contains a great number of bacilli and is ingested in considerable quantity. Practically the danger from using raw milk exists only for those persons who use it as their sole or principal food, e. g., young children. All danger is avoided by boiling or pasteurising the milk.
At the same time there is an increasing amount of evidence forthcoming at the present time which goes to prove that milk is not infrequently tainted with tubercle (see p. 195). The tuberculin test should be applied to all milch cows, and the infected ones isolated from the herd. Milk supplies should be more strictly inspected even than cowsheds.
13. There are several methods by which meat infection can be prevented. In the first place, herds should be kept healthy, and tubercular animals isolated. Cowsheds and byres should be under sanitary supervision, especially as regards overcrowding, dampness, lack of light, and uncleanliness. Public slaughter-houses under a sanitary authority would undoubtedly be most advantageous. Meat inspection should also be more strictly attended to; efficient cooking, and avoidance of "roll" meat which has not been thoroughly cooked in the middle.
14. Consumptive patients may diminish their disease. Dr. Arthur Ransome[95a] has laid down five axioms of hygiene for phthisical patients which, if followed, would materially improve the condition of such persons. At Davos, St. Moritz, Nordrach and other places where they have been practised, the beneficial change has been in many cases extraordinary:
(1) Abundance of light, nutritious, easily digested food, which must comprise a large allowance of fat; small meals, but frequent;
(2) An almost entirely open-air life, with as much sunshine as can be obtained;
(3) Suitable clothing, mostly wool;
(4) Cleanliness and bracing cold-water treatment;