Quarantine
From time immemorial, wars have always presented epidemiological problems, and the prevention of infection has been a source of anxiety to the commanders in the field.
In the early centuries, the Crusaders spread leprosy widely along their paths to England and north-west Europe from Palestine, and in the sixth and seventh centuries, there were a number of leper houses in France and Lombardy.
From the earliest days leprosy appears to have been regarded as contagious and the isolation of persons suffering from this disease was carried out with the utmost severity.
Quarantine as such, however, appears to have been first enforced against the plague in Ragusa, Italy, in 1377 when ships from Levantine and Egyptian ports were required to be isolated in special positions for a period of thirty days, later extended to forty. The word quarantine originally means isolation for a period of forty days, but now is used to describe the conditions in which a patient, ship, and so on, is isolated for any period.
SEWAGE
The water-carried discharges of the human body together with the liquid waste from household and factory are called sewage. The discharges themselves consist chiefly of feces and urine, but they also include washings and secretions from the skin, mouth and nose. Civilization requires that the wastes of the human body be removed from habitations promptly and safely; in urban communities they are usually removed by means of water-carriage system of sewage.
Hygienic considerations governing the disposal of human excreta are chiefly concerned with the fate of pathogenic organisms that may be contained in human wastes. The microorganisms of typhoid fever, cholera, the dysenteries, and other intestinal worm diseases, as well as infectious hepatitis and certain other intestinal diseases, have their ultimate source in the discharges of man and are conveyed from host to host through many channels; by water, soil, food, or contact; sometimes by human agencies, sometimes by animals, often by flies.
Water supplies and purification
Water is essential to human life. Extensive and intricate systems of water transportations, purification plants, and distribution systems must be supplied wherever humans live.
The physician is primarily interested in the water supply because it may be an important factor in the transmission of disease. Water-borne infection practically always results from pollution of the water supply with human wastes, particularly with the urine and feces or individuals with active intestinal disease, or perhaps by the carriers of infective agents.
Many etiologic agents of disease survive for a long period of time in water, though they do not multiply or increase there. The intensity of water-borne infection in any community is in direct proportion to the degree and duration of water pollution by human wastes.
Common human infections that are transmitted through water are:
Typhoid fever Acute diarrhea
Cholera Infectious jaundice
Bacillary dysentery Tularemia
Metallic poisoning, particularly lead poisoning should also be included as a disease agent that may be transmitted through the water supply.
Water supplies from deep-driven wells may be considered the safest and best source of water. However, most cities must rely upon surface water from rivers. This form of supply is a potential source of danger. Various methods of water filtration and purification have been devised. These methods rely basically upon natural methods of water purification supplemented by chemical and mechanical procedures.
Two important methods are used for determination of the purity of water: supervision of the source of water supply; laboratory analysis of the water.