The problems confronted by international health workers can be considered in two main groups: those related to the control of illnesses, injuries, and other threats to individual health; and those related to the provision of medical care services to individuals, and public health services to communities and nations. The major diseases include the widely distributed respiratory and intestinal infections, particularly in the very young; AIDS (acquired immunodeficiency syndrome) and other sexually transmitted diseases; as well as malaria, schistosomiasis, river blindness, and others caused by parasites that are prevalent in tropical regions. Non-communicable and chronic conditions are also of global concern. These include endocrine and metabolic conditions such as diabetes; mental illnesses; disabilities resulting from occupational and environmental hazards; and diseases of the circulatory system, malignancies, dementias, and other conditions that are found mainly in the elderly. Many of these health problems have origins in underlying factors such as poverty, culture and behavior, and the aging of individuals and populations. Regions ravaged by war, civil disturbance, or economic downturn often have outbreaks of diseases such as typhus, diphtheria, or tuberculosis, as well as manifestations of psychological stresses.
In populations throughout the world, patterns of high fertility and high mortality rates have been or are being replaced by low fertility and low mortality rates, a situation known as the "demographic transition." In the typical pattern, economic development and medical interventions generally lead to a rapid reduction in deaths, particularly in infants and children, and a decline in births follows after some time. In the interim, the excess of births over deaths results in a rapid rise in population numbers, a situation now occurring in many developing countries. Improved health further increases fertility by reducing the stresses of pregnancy and by lengthening the reproductive span of both parents. Voluntary family planning programs have been introduced widely to help limit this population increase.
As economic conditions improve and people are living longer, the median age of populations increases and the global burden of ill health is shifting slowly from infectious to chronic diseases. This change in the proportional causes of illness and death is known as the "epidemiologic transition."
In all countries, medical and health care systems are being re-examined. The World Bank's influential World Development Report for 1993, titled "Investing in Health," identified four major problems of health and medical care systems in most countries: misallocation of funds to less cost effective interventions; inefficient use of funds; inequities in access to medical care; and the explosion of health care costs. In 1990 the world spent about $1.7 trillion on health. High-income countries spent about $1,500 per person, or 90 percent of total spending. Low-income countries, with roughly three times the population, spent an average of $41 per person, or 10 percent of the global total. Approximately 1.3 billion people live in absolute poverty, living on less than the equivalent of one U.S. dollar per day.
PAUL F. BASCH, The Gale Group Inc., Macmillan Reference USA, New York,