The Millennium in Infectious Diseases: Focus on the Last Century 1900-2000

Vincent A. Fulginiti, MD

Disclosures
In This Article

The Year 2000 and Beyond

In my view, the health of the world's citizens, in the instance of infectious diseases, is remarkably good, even though a number of diseases are not under adequate control. Malaria still is a major problem in some areas of the world; cholera rears its ugly head periodically; tuberculosis, especially infection with multidrug-resistant organisms, prevails in some populations of patients and in some areas of the world; and other diseases such as the expanded hepatitis virus-caused illnesses still defy control. New diseases continue to emerge, and older infections become more difficult to treat or control. However, in the developed world, good hygiene, excellent nutrition, effective public health policies and practices -- combined with effective vaccines and superb diagnosis and treatment of many of the previous scourges of mankind -- have resulted in excellent prospects for avoidance or control of infectious disease.

Some societal changes have contributed to new problems to be delineated later. The rapidity of air travel and greater facility in worldwide globe-trotting, both for business and tourism, has changed the paradigm of transmission. Introduction of infectious disease to a "clear" zone is made possible by such easy and massive travel. Population increases, crowding, refugees, wars, and many other "people problems" have resulted in emerging and re-emerging infections.[42,43,44] Such a seemingly simple act as the construction of a dam may be attended by unforeseen problems in vector control, as still waters behind the dam may prove to be fertile sites for insect replication. Natural disasters can exact their toll in emergence of infections as well. Global warming has also had an enhancing effect on transmission by vectors and replication of some species of infectious agents.

In some underdeveloped areas of the world, some of the "old" infectious diseases are still rampant, exacting their toll in morbidity and mortality. In addition, new diseases, such as AIDS, caused by infection with HIV, or the Nipah virus, newly isolated from encephalitis patients in Malaysia, have added to the burden of infectious diseases in these populations.

Despite the remarkable achievements of the last millennium, not all of the news in 2000 is good. We are seeing a rise in tuberculosis worldwide with some resurgence in the United States, especially among immune-deficient patients. Drug-resistant organisms have gained a foothold in many parts of the world, and with the ease of travel, refugee migrations, wars, and other natural disruptions of populations, transmission appears to have increased. This increase, in part, has been facilitated by the diminution of public health efforts and laboratories in the era of great reduction of this disease. Efforts are under way to reinvigorate these public health efforts.

Antimicrobial resistance is a major deterrent to effective treatment and control of many infectious diseases. As a result of excessive demand and use in humans, and the deployment of antibiotics in animal husbandry to increase growth and eliminate some bacteria, more organisms are demonstrating resistance. The problem is a major one in the United States at present, and the discovery and implementation of new antimicrobials has not stemmed the tide of these infections. This set of problems is a critical area for research in the near future. Organisms such as Mycobacterium tuberculosis, Escherichia coli, the enterococcus, Staphylococcus aureus, Streptococcus pneumoniae, among others, have demonstrated multidrug-resistant strains, requiring resourceful means of control and treatment; some of these strategies no longer are effective in some individual patients. Use of formerly infrequently used antimicrobials has been attended by increased resistance to these drugs, necessitating a rotating use of some antimicrobials in institutions or outright bans on their use for a period of time to enable restoration of sensitivity of the offending organisms.

Smallpox has been eliminated, but the debate continues over the disposition of stocks of smallpox vaccine believed to be limited to the United Kingdom and the United States, although some skeptics believe other countries such as Russia and Iraq may have stored some of the virus. Some are in favor of eliminating all smallpox viruses; others fear that the virus may be used by bioterrorists and insist on maintaining stores under tight security to enable future use in defense against deployment by bioterrorists. Others suggest that valuable research may be gained by study of the genome, and other characteristics and destruction would impede that effort. Still others feel that vaccine virus should be maintained both as a hedge against bioterrorism and as a potential vehicle for viral and genetic vaccines. The debate is unresolved as of this writing.[38,39,40]

Paralytic polio has been eliminated in the Western Hemisphere and markedly reduced worldwide. This phenomenon, combined with the persistent occurrence of live-virus vaccine (OPV) instances of paralytic diseases, resulted in a recommendation by the major advisory committees of the CDC and the American Academy of Pediatrics to use only inactivated polio vaccine (IPV) for routine immunization.

Although prevention of viral diseases by vaccines has been a major focus in the last millennium, these infections have also yielded to development and implementation of effective antiviral agents, such as the acyclovir family, the arabinosides, the fluorocytosines, interferons, and IV immune globulin. Some of the effects have been dramatic, some less so, and others just short of ineffectiveness. In addition, resistance has been a problem that is growing in concern as viruses, like many bacteria, adapt to the antiviral environment by overgrowth of resistant mutants in the population being treated. For the future, new agents will be developed, particularly as new information regarding viral attachment, replication, and pathogenesis evolves.[41] New vaccines are rapidly being developed, and one can anticipate control of some diseases that have resisted vaccine development, such as cytomegalovirus, respiratory syncytial virus, the parainfluenza group, and many others.

As the human genome is unraveled, many anticipate further control of infectious diseases by recognition of specific susceptibilities engendered by one's genetic constitution. The most optimistic suggest that genetic therapy will alter such susceptibility in any given individual. Skeptics believe some inroads may be made but elimination of susceptibility will not be possible.

The future is brighter because of the tapestry of intellectual scientific accomplishment begun in the last millennium and carried forward into the next.[15,26,28] Many problems remain, as have been outlined, but one must not lose sight of the remarkable improvement in the health of all of the world's citizens secondary to understanding of basic biologic and immunologic mechanisms and application of this information to the clinical arena. One can only wonder at what this article would look like in the year 3000.

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