Emerging and Re-emerging Infectious Diseases
by Irma S. Jarcho
Dean Harvey V. Fineberg of the Harvard School of Public Health moderated a panel presentation on "Emerging and Re-emerging Infectious Diseases: Challenges to Health Care Systems" at the Harvard Club in New York City on 20 May 1997. Comprising the panel of distinguished experts in the field were Stephen S. Morse, Director of the Program in Emerging Diseases at Columbia University; Robert Pinner, Special Assistant for Surveillance in the Office of the Director for the National Center for Infectious Diseases of CDC; and Margaret Hamburg, New York City's 33rd Health Commissioner, now at the Department of Health and Human Services under Secretary Donna Shalala.
Dr. Morse reminded his listeners of the changing relationships between humans and the environment. Infectious diseases are the leading cause of death worldwide. Viral emerging diseases undergo a two-stage process. In the first, virus meets human and there are many factors responsible for its appearance and dissemination. The viruses come from nature and, in the process, we are sampling nature's diversity. In the second stage the virus becomes both established and disseminated. Morse characterized the Boeing 747 as the vector of HIV. Human intervention is a factor in the emergence of viruses, and he gave as an example the effect of agricultural practices in the development of new strains of the influenza virus, which seem to travel from ducks to pigs to humans. Another example was the influence of climate, illustrated by the appearance of Hantavirus in the southwest following an explosive increase in the number of the deer mouse vectors. The virus probably had been in the area for at least decades; it had been identified as early as 1959.
Dr. Pinner listed some of the factors in the emergence of infectious diseases: ecological changes; changes in human demographics; international travel and commerce; technology and industry (he cited the changes in food processing techniques), microbial adaptations and changes; and, lastly, breakdown in public health measures, which he saw as largely responsible for the re-emergence of diseases such as tuberculosis.
Infectious diseases had been on the decline in the United States, but now there is a recent, and troubling, upturn. Among recent outbreaks noted was the contamination of Schwann's ice cream with Salmonella enteritidis, which caused a nationwide outbreak with 225,000 cases. Much in the news now is the contamination of imported strawberries with Cyclospora. The strawberries were used in school lunches and their importation has now been banned. Another emerging disease was monkeypox, a virus closely related to that of smallpox. The latter has been eliminated, but the monkey variety continues to infect. Reference was also made to the outbreak of caccidiodomycosis in Ventura County, California, following the Northridge earthquake. The clouds of dust which covered the area served to disseminate the organism.
Dr. Hamburg spoke of these emerging and re-emerging diseases as a real public health problem, both as foci of attention and as part of the burden of disease. For example, New York City alone has 3% of the U.S. population but 19% of AIDS cases. The resurgent epidemic of tuberculosis, especially cases caused by multiply drug resistant (MDR) strains, posed a severe strain on health care facilities.
The trend towards urbanization increases the opportunities for disease transmission. In addition, we are an increasingly transient society and these changes in behavior have affected disease patterns. International trade and commerce, mentioned several times, pose a threat of imported disease. There was an outbreak of pneumonic plague in India and the 31 daily flights from India to New York had to be monitored. The recirculation of air in planes can also be a menace. There was one case of a multiply drug resistant tuberculosis being spread to fellow passengers fro Asia=2E Dr. Hamburg emphasized, as, indeed, did all the speakers, that if we want to control infectious diseases nowadays, we must think nationally and globally.
The panel was hosted by the Harvard Public Health Alumni Association of Metro New York as part of the School's celebration of its 75th anniversary.
Home Spring 97 Full Screen
The TEACHERS CLEARINGHOUSE FOR SCIENCE AND SOCIETY EDUCATION