"We may say, therefore, that to prevent infection of the individual it is necessary for him only to avoid being bitten by the louse. In theory this may readily be done, for we know that the body louse infests and attaches itself almost entirely to the body linen, and that boiling kills this insect and its eggs. Individual prophylaxis is based essentially, therefore, on the avoidance of contact with individuals likely to harbor lice. Practically, however, this is not always as easy as it may seem, especially under the conditions of such intimate association as is imposed by urban life. Particularly is this the case in places such as some of the large Mexican cities, where a large proportion of the population harbors this vermin. Under such circumstances it is well to avoid crowds or crowded places, such as public markets, crowded streets, or public assemblies at which the 'peon' gathers." "Community prophylaxis efficiently and intelligently carried out is, from a certain point of view, probably easier and more effective in protecting the individual than is the individual's own effort to guard himself. Typhus emphasizes, perhaps better than any other disease, the fact that fundamentally, sanitation and health are economic problems. In proportion as the economic condition of the masses has improved--that is, in proportion as they could afford to keep clean--the notorious filth disease has decreased or disappeared. In localities where it still prevails, its further reduction or complete eradication waits on a further improvement in, or extension of, the improved economic status of those afflicted. Economic evolution is very slow process, and, while doing what we can to hasten it, we must take such precautions as existing conditions permit, looking to a reduction in or complete eradication of the disease." "When possible, public bath houses and public wash houses, where the poor may bathe and do their washings at a minimum or without cost, should be provided. Similar provision should be made in military and construction camps. Troops in the field should be given the opportunity as frequently as possible to wash and _scald_ or _boil_ their body linen." "Lodging houses, cheap boarding houses, night shelters, hospitals, jails and prisons, are important factors in the spread and frequently constitute foci of the disease. They should receive rigid sanitary supervision, including the enforcement of measures to free all inmates of such institutions of lice on admission." "So far as individual foci of the disease are concerned these should be dealt with by segregating and keeping under observation all exposed individuals for 14 days--the period of incubation--from the last exposure, by disinfecting (boiling or steaming) the suspected bedding, body linen, and clothes, for the destruction of any possible vermin that they may harbor, and by fumigating (with sulphur) the quarters that they may have occupied."