In the early 1600s, the development of cities and the spread of poverty in feudal Europe produced the necessary environmental changes to set off the first tuberculosis (TB) epidemic in humans. Dubbed “the Great White Plague,” TB ran rampant in the crowded, unsanitary slums of early industrial cities (1). At its apex in the 17th and 18th Centuries, tuberculosis took the lives of one in five adults (2).
Contrary to the belief that tuberculosis is a disease of the past, nearly 3 million people died of TB in 1995 (3). Although the disease appears to have leveled off in 1996 as the result of concerted government action, and a control program launched by the World Health Organization (WHO), the TB epidemic is expected to continue to pose a serious threat to human health, especially in developing countries. Global implementation of WHO’s strategy could reduce these numbers dramatically, but without interventions, as many as 90 million people could contract TB in the next 10 years (4).
The global emergence of HIV/AIDS has been an important factor driving the prevalence of TB, especially in Africa and Asia. The HIV virus damages the immune system and accelerates the speed at which tuberculosis progresses from a harmless infection to a life-threatening condition. About one third of the estimated 1 million AIDS-related deaths in 1995 were the result of a secondary infection with TB (5).
Increasing poverty and homelessness in cities also seems to be linked with the reemergence of TB (6). Associations among tuberculosis, urbanization, and poverty have been noted in studies from countries as diverse as Denmark and Puerto Rico (7). It is clear that growing numbers of poor, malnourished people living in unhygienic, overcrowded conditions can facilitate the transmission of TB. In poor neighborhoods, the combination of overcrowding and poor ventilation often means that one person with TB, if not properly treated, will transmit the infection to between 10 to 15 other people each year (8).
In the United States, the number of tuberculosis cases increased by 20 percent between 1985 and 1992, with most of these cases concentrated in inner cities (9). Since then, the numbers have dropped, but rates in cities such as Washington, D.C., and New York remain high (10). In Russia, the number of TB cases climbed 42 percent between 1991 and 1994, and the death rate soared 87 percent in the same 3-year period. After experiencing nearly 40 years of a steady decline of TB, Eastern Europe now shows an increase in TB deaths, which is linked to the impact of recent political, social, and economic changes that have dramatically reduced living standards and incomes (11).
Multidrug resistance has become an important factor, impeding the effort to control and prevent TB in large urban centers. New York, London, Milan, Paris, Atlanta, Chicago, as well as cities throughout the developing world especially in Asia have reported increasing numbers of multidrug-resistant TB cases (12). In some countries of the developing world where resources are limited, it is estimated that drug-resistant rates exceed 30 percent (13). The implications are profound: for individuals infected with multidrug-resistant strains of TB, the fatality rate is greater than 50 percent. In addition, the average cost of treating an antibiotic-susceptible case of TB in New York City is around US$2,000, but for a multidrug-resistant case, the number soars to around US$250,000, placing effective treatment well beyond the reach of impoverished nations and people (14).
The social and economic costs of TB are enormous, particularly because the incidence of TB is concentrated in adults between the ages of 15 and 54, who are the primary producers and wage earners. Of avoidable adult deaths globally, 26 percent may be due to TB (15). One estimate projects that the Thai economy will lose the equivalent of US$7 billion by the year 2015, solely to TB sickness and death. In India, the estimated loss of economic output due to TB deaths reaches more than US$370 million every year (16). Overall, the death or disability of an adult wage earner can severely affect the ability of a household to survive, especially because TB tends to strike households least able to cope without those earnings. Studies have shown that in households where one parent suffers from a serious debilitating disease, such as TB, children are 2.5 times more likely to be severely malnourished (17). The combination of the enormous burden of TB as well as the inconsistent availability of cost-effective interventions, such as chemotherapy and immunization, make TB one of the highest priorities for action in international health (18).
References and notes
1. Joseph H. Bates and William W. Stead, “The History of Tuberculosis as a Global Epidemic,” Medical Clinics of North America, Vol. 77, No. 6 (November 1993), p. 1207.
2. Michael D. Iseman, “Evolution of Drug-Resistant Tuberculosis: A Tale of Two Species,” Proceedings of the National Academy of Sciences, Vol. 91 (March 1994), p. 2428.
3. World Health Organization (WHO), “TB Deaths Reach Historic Levels,” March 21, 1996 (WHO press release no. 22).
4. World Health Organization (WHO), Groups at Risk: WHO Report on the Tuberculosis Epidemic 1996, (WHO, Geneva, 1996), p. 1.
5. Ibid., pp. 2-3, 12.
6. Carolyn Stephens, “Healthy Cities or Unhealthy Island? The Health and Social Implications of Urban Inequality,” Environment and Urbanization, Vol. 8, No. 2 (October 1996), p. 23.
7. Donald Enarson, Jie-Siu Wang, and John M. Dirks, “The Incidence of Active Tuberculosis in a Large Urban Area,” The American Journal of Epidemiology, Vol. 129, No. 6 (June 1989), p. 1274.
8. Op. cit. 4.
9. World Health Organization (WHO), TB: A Global Emergency, WHO Report on the TB Epidemic (WHO, Geneva, 1994), p. 2.
10. Tuberculosis “Morbidity United States, 1996,” Morbidity and Mortality Weekly Report, Vol. 46, No. 30 (1997), p. 695.
11. Mary E. Wilson, “Disease in Evolution: Introduction,” Disease in Evolution: Global Changes and Emergence of Infectious Diseases, Annals of the New York Academy of Sciences, Vol. 740, Mary E. Wilson, Richard Levins, and Andrew Spielman, eds. (New York Academy of Sciences, New York, 1994), p. 8.
12. Op. cit. 3.
13. Op. cit. 2.
14. World Health Organization (WHO), The TB Epidemic is Getting Worse, (WHO, Geneva, 1995), available online at: http://www.who.ch/gtb/publications/tbrep_95/worse.htm (December 11, 1997).
15. Christopher Murray, Karel Styblo, and Annik Rouillon, “Tuberculosis,” in Disease Control Priorities in Developing Countries, Dean T. Jamison et al., eds. (Oxford University Press, Oxford and New York, 1993), p. 245.
16. Op. cit. 4, p. 14.
17. Op. cit. 15, p. 245.
18. Op. cit. 15, p. 256.
