Preventing emerging infectious diseases: a strategy for the 21st century.

Societal, technological, and environmental factors continue to have a dramatic effect on infectious diseases worldwide, facilitating the emergence of new diseases and the re-emergence of old ones, sometimes in drug-resistant forms. Modern demographic and ecologic conditions that favor the spread of infectious diseases include rapid population growth; increasing poverty and urban migration; more frequent movement across international boundaries by tourists, workers, immigrants, and refugees; alterations in the habitats of animals and arthropods that transmit disease; increasing numbers of persons with impaired host defenses; and changes in the way that food is processed and distributed.

Several recent health events underscore the need for a public health system ready to address new disease problems as they arise. For example, in 1997, an avian strain of influenza that had never before infected human beings began to kill previously healthy people in Hong Kong. This crisis raised the specter of an influenza pandemic similar to the one that killed 20 million people in 1918. Also in 1997, strains of Staphylococcus aureus with diminished susceptibility to the antibiotic vancomycin were reported in Japan and the United States. If drugs like vancomycin cannot be replaced as they lose their effectiveness - or if the emergence and spread of drug resistance cannot be limited - some diseases might become untreatable, as they were in the preantibiotic era. In addition, researchers recently discovered that a strain of the virus that causes acquired immunodeficiency syndrome (AIDS) has been infecting human beings at least since 1959. Infectious agents can remain undetected for years before emerging as public health problems. Table 1, below, lists the annual costs and charges associated with several infectious diseases in the United States.

The Centers for Disease Control and Prevention (CDC) has published Preventing Emerging Infectious Diseases: A Strategy for the 21st Century, which represents the second phase of a plan to revitalize our ability to protect the public from infectious disease. The effort was launched in 1994 with the publication of Addressing Emerging Infectious Disease Threats: A Prevention Strategy for the United States. During the past four years, CDC has implemented the 1994 plan incrementally, with the help of many partners. By fiscal year 1997, funds were available to implement about one-third of the recommended programs and activities, which focused on improving surveillance, conducting applied research, rebuilding the public health infrastructure, and strengthening efforts to prevent emerging infectious diseases. CDC decided to update its plan in 1998 because of these achievements and because new discoveries and challenges have developed in the past four years. The updated plan focuses on four areas of effort:

1. surveillance and response,

2. applied research,

3. infrastructure and training, and

4. prevention and control.

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The aim is to build a stronger, more flexible U.S. public health system that is prepared to respond both to known disease problems and to unexpected events, whether pandemics, diseases caused by unknown organisms, or bioterrorist attacks. The implementation of this plan will require the dedicated efforts of many partners, including state and local health departments, other federal agencies, professional societies, universities, research institutes, health care providers, and the World Health Organization.

Copies of the plan are available from the Office of Health Communication, National Center for Infectious Diseases (NCID), Centers for Disease Control and Prevention, Mail Stop C-14, 1600 Clifton Road, Atlanta, GA 30333. The plan also can be accessed from the NCID home page at http://www.cdc.gov/ncidod/publicat.htm.

(Source: Morbidity and Mortality Weekly Report, Vol. 47, No. RR-15.)

Events Prompting CDC to Update Its 1994 Plan

The Centers for Disease Control and Prevention (CDC) decided to update its strategy for addressing emerging infectious diseases because of progress in implementing the highest priorities of the 1994 plan and because new challenges and discoveries have developed.

Emerging Threats

* A new variant of a fatal neurologic illness, Creutzfeld-Jakob disease, appeared in the United Kingdom and was possibly transmitted by ingestion of beef from animals afflicted with bovine spongiform encephalopathy, also known as "mad cow disease." This disease might be caused by a newly recognized type of transmissible agent called a prion.

* A new and virulent strain of influenza in Hong Kong raised fears of a global pandemic.

* The United States had several multistate foodborne outbreaks, including outbreaks caused by Cyclospora parasites on fresh raspberries; hepatitis A virus on frozen strawberries; and Escherichia coli 0157:H7 bacteria in apple cider, lettuce, alfalfa sprouts, and ground beef.

* Staphylococcus aureus with reduced susceptibility to vancomycin - the only antibiotic that remains effective against some strains of this bacterium - was reported for the first time in the United States and Japan.

* A new strain of tuberculosis (Strain W), which is multidrug-resistant and appears more frequently in persons with HIV infection, has become endemic in New York.

Scientific Findings

* Scientists have found increasing evidence that certain infectious microbes cause or contribute to the development of some chronic diseases.

* Many human genes have been discovered that influence susceptibility to infection, severity of infection, and responsiveness to vaccination or treatment.

Tools and Technologies

* Electronic communications are linking public health institutions in most areas of the world, providing a constant and enormous stream of information on infectious disease outbreaks and related health issues.

* Innovations in biotechnology are making it easier to identify and track strains of infectious microbes and to determine the causes and sources of outbreaks as well as the routes of disease transmission.

Changes in Health Care Delivery

* Large numbers of Americans have switched from fee-for-service medical insurance to various types of managed care. The shift to managed care has created new challenges and opportunities for disease prevention, surveillance, control, and research. Because of their structures, managed care organizations are in a good position to conduct surveillance, answer clinical research questions, and effect changes in medical practice (e.g., implementation of guidelines).

* Shortened hospital stays for some conditions have made it necessary to develop new ways to monitor certain patient outcomes, including hospital-acquired infections whose symptoms do not appear until after the patient has left the hospital.

* Home health care has become the fastest growing sector of the U.S. health care industry. New public health partnerships and new methods for assessment are needed to monitor the impact of treatments and to measure the occurrence of health care-related infections in home health care settings.

Public and Policy Issues

* Many Americans have learned about new diseases like Ebola hemorrhagic fever through media reports, films and television movies, and books. In addition, they might know somebody who has suffered from an emerging infectious disease or an antibiotic-resistant infection.

* In 1995, the Committee on International Science, Engineering, and Technology (CISET) of the National Science and Technology Council recommended government-wide action to combat emerging infectious diseases.

* In 1996, a Presidential Decision Directive on emerging infectious diseases established a new national policy to address the growing health and national security threat posed by infectious diseases, including the potential threat of bioterrorism.

Environmental Health-'Net

Public Health Officials Online

http://www.nlm.nih.gov/news/press_releases/pubhthpr.html

Helping public health officials hook up to the Internet and making it easier for them to access health information is the goal of "Partners in Information Access," a joint project of the National Library of Medicine, the National Network of Libraries of Medicine (NN/LM), CDC, the Health Resources and Services Administration (HRSA), the Association of State and Territorial Health Officials (ASTHO), and the National Association of County and City Health Officials (NACCHO). On October 1, 1998, NLM and NN/LM jointly announced the award of 13 contracts totaling $650,000 as an important step toward this goal. The 13 projects, which are scattered around the United States in rural and other underserved areas from Alaska to Vermont, provide information services for public health professionals who are addressing a variety of community health problems and special populations.

(Source: Public Health Initiatives Bulletin, Issue 20, October 20, 1998.)