INTRODUCTION TO THE STUDY OF INFECTIOUS DISEASES

I. HISTORY

A. Girolamo Fracastoro (1478-1553) – suggested that disease was caused by invisible microorganisms

B. Anton Leuwenhoek – 1673 – first person to see bacteria and protozoa under the microscope

C. “The Golden Age of Microbiology” (1800's to 1950)

1. Germ theory of disease

2. Agostino Bassi (1835) – silkworm disease due to a fugus/ many diseases due to microbes

3. M.J. Berkley (1835)- Great Irish Potato blight was caused by a fungus

4. Louis Pasteur – disease of silkworms due to a protoza

5. Joseph Lister – 1867 antiseptic surgery

6. Robert Koch – bacteria (B. anthracis) caused the disease anthrax; techniques to grow bacteria on solid medium

7. Vaccines against anthrax and rabies (Pasteur) and antitoxins against diptheria (von Behring) and tetanus (Kitasato)

8. Viruses:

a. Charles Chamberland – porcelain filter

b. Walter Reed – Yellow fever

9. Infectious diseases are controlled by vaccines, antobiotics, impored sanitation and water quality

D. Following WW II, sense of optimism and control, attention is turned away from infectious diseases. Public Health infrastructure dismantled.

E. Optimism premature:

1. antibiotic resistance

2. emerging and reemerging infectious diseases

II. HOST- PATHOGEN/ HOST-PARASITE RELATIONS

A. SYMBIOSIS- associations in which one species live in or on the body of another

1. Commensalism – one species uses the body of a larger species as its physical environment and may make use of that

environment to acquire nutrients

2. Mutualism – a relationship where there is benefit for both organisms

3. Parasitism – relationship which is one sided and benefits the parasite but harms the host

B. THE HOST : What are some host factors that explain differences in susceptibility to disease

C. THE PATHOGEN: What is a pathogen?

1. Steps that pathogens must go through to cause disease.

a. Attachment and entry into the body.

b. Local or general spread in the body.

c. Multiplication

d. Evasion of host defenses.

e. Shedding (exit from the body)

f. Cause damage to the host.

 

D. COEVOLUTION OF PATHOGEN AND HOST TOWARDS BALACED PATHOGENICITY