Lecture 2 EMERGING AND REEMERGING INFECTIOUS DISEASES

Reading Assignments: (1) Text: Chapter 54, (2) ON THE MIC 361 WEBSITE: Centers fo Disease Control and Prevention. 1998. Introduction, p. 1-14. In Preventing Emerging Infectious Diseases – A Strategy for the 21^st Century. Department of Health and Human Services, Atlanta, GA.

(3) OPTIONAL HANDOUT: Berkelman, R. 1997. Introduction, p. 1-6. In C.R. Horsburgh, Jr. and A.M. Nelson (ed.) Pathology of Emerging Infections, American Society for Microbiology, Washington, D.C.

I. HISTORY AND INTRODUCTION

A. 1992 - Institute of Medicine Report: Emerging Infections: Microbial Threats to Health in the United States (Chaired by Nobel Laureate Joshua Lederberg)

B. 1994 - CDC's answer: Addressing Emerging Infectious Disease Threats: A Prevention Strategy For The United States

C. Implementation of the CDC Plan

D. 1998 - CDC's plan for the next five years: Preventing Emerging Infectious Diseases – A Strategy for the 21^st Century

II. DEFINITIONS

A. Disease – a change in the normal structure or function of any part of the body that is manifested by a characteristic set of symptoms and signs.

B. Infectious Disease – a change from a state of health to disease because of the presence of an infectious agent (microorganism), or its products (toxins, enzymes, or other microbial products.)

C. Emerging Infectious Disease – (As defined in the 1992 IOM Report)- those disease that have increased in incidence in the past 20 years or threaten to increase in the near future. Includes:

1. Infectious diseases caused by new agents

2. Infectious diseases caused by reemerging pathogens (those pathogens whose incidence had previously declined)

3. Pathogens that are developing drug resistance

4. Established (chronic) diseases with a newly discovered infectious origin

III. SIX FACTORS THAT PROMOTE THE EMERGENCE OF NEW OR PREVIOUSLY EXISTING PATHOGENS:

A. Changes in human demographics and behavior

1. The Developing World

2. The Developed World

B. Lapses in public health systems

C. Increased international travel and trade

D. Ecologic and environmental changes (includes changes in land use and/or climate)

1. Economic development places people in contact with pathogens not previously encountered.

2. Ecologic changes can result in conditions that increase the size of a microbial population (thereby increasing the chances that man will be infected).

a. Due to natural changes in ecology or climate

i. Hantavirus pulmonary syndrome

ii. Lyme disease

iii. Disease outbreaks linked to El Nino

iv. The potential threat caused by global warming??

b. Due to man-made changes: Pfiesteria piscicida – “the cell from hell”

E. Microbial adaptation and change

1. The overuse of antibiotics has selected for widespread antibiotic resistance

2. Pathogens with increased virulence for man:

a. Influenza A

i. Genetic reassortment (antigenic shift) of Influenza A virus strains

ii. “Jumping Species” – The Hong Kong Flu

b. Other viruses that can “jump species” from animal to man

c. Invasive Group A Streptococci

IV. CDC RECOMMENDATIONS FOR ADDRESSING DOMESTIC AND GLOBAL INFECTIOUS DISEASE THREATS

A. Four goals

1. Strengthen surveillance and response capacity

2. Address research priorities

3. Strengthen prevention and control programs at the local, state, and federal levels (education).

4. Rebuild the public health infrastructure

B. Target areas (See reading Assignment (2), above)

a. Emerging Disease Issues

b. Populations of Special Concern