S. TUBERCULOSIS

Tuberculosis is a disease of truly worldwide proportions occurring in both temperate and tropical countries and for centuries one of the chief causes of death in practically all areas of the globe. Since 1947, however, there has been a dramatic decline in tuberculosis mortality owing to the use of new types of chemotherapy first introduced in that year. The comparative data shown here are for the years 1950-54 and only for those countries where good statistics are available. The decline would be even greater if calculated from 1947.

Despite this progress, tuberculosis remains one of the main targets in the international disease control. The mortality rates in certain areas of many countries are still extremely high. Furthermore, the decline in mortality, as such, does not indicate that the prevalence of the disease has decreased in the same measure. In some countries where morbidity statistics are available the number of known infectious cases has actually increased, even though the mortality rate has been lowered. The growing urbanization of population in many countries serves to accentuate the danger of the disease.

Reliable data in most of the underdeveloped countries are not obtainable, and it is in these countries that the incidence of tuberculosis is probably the heaviest. Recent surveys incident to BCG immunization programs show the prevalence of previous tuberculosis exposure for age group 15 of 77 percent in Bombay, India; 72 percent in Tangier; 66 percent in the urban communities of Taiwan; 59 percent in Yugoslavia; 52 percent in Egypt, and 49 percent in Ecuador. These ratios may be compared with a figure of 9 percent in one underprivileged section of New York City.

The management of tuberculosis is rapidly changing from a clinical to a public health approach through the use of immunizing agents and prophylactic and therapeutic drugs.

Source: "WHO Epidemiological and Vital Statistics Reports," vol. 10, Nos. 2 and 4, 1957.

1950

1954

T. THE CONTROL OF INFECTIOUS DISEASES

There are four chief methods by which the spread of infectious diseases can be controlled.

Immunization, or vaccination, is an essential in any attempt to control smallpox, typhus, whooping cough, poliomyelitis, typhoid fever, tuberculosis, influenza, cholera, plague, and yellow fever. Nearly all the vaccines in use today are highly effective. The main problem is to make sure that all the people who may be exposed to any of these diseases are properly vaccinated.

Prophylaxis and/or clinical treatment of the disease, is indicated for yaws, malaria, leprosy, tuberculosis, syphilis, bejel, pinta, and trachoma. Effectiveness depends on the number of clinical centers and medical personnel available and the utilization of these services. Control or eradication of the disease-carrying insect, through mass spraying campaigns or other methods is fundamental in the attack on malaria, trypanosomiasis, plague, typhus, encephalitis, onchocerciasis, and filariasis. Though sometimes expensive to carry out, these control campaigns have, generally speaking, proved highly

effective.

Control of human waste disposal is primarily a public health service sanitation operation, and is basic in any attempt to control schistosomiasis, hookworm, roundworm, cholera, amebiasis, and dysentery.

THE SPREAD OF INFECTIOUS DISEASES CAN BE CONTROLLED BY THESE ACTIONS

U. HEART DISEASE

Degenerative heart disease is now the most frequent cause of death in North America, in most of Europe, and among the more prosperous segments of the population in many other parts of the world. It affects chiefly middle-aged and older people, and its incidence and resulting mortality rates in particular countries are, therefore, affected to a considerable degree by the age distribution of the population.

Generally speaking, those countries having a high life expectancy rate, and consequently a larger proportion of older people in the population, will have a higher rate of cardiovascular mortality. However, there is evidence to suggest that the richer diet and more intensively paced life of the industrially advanced and higher income areas are in part responsible for the heavy prevalence of these diseases. The United States, for instance, with an average life expectancy of 70 years has one of the highest reported cardiovascular mortality rates-460 per 100,000 of population-whereas, Ceylon with the very respectable life expectancy rate of 60 has a rate roughly one-seventh as high (about 68).