🔹 Key Concepts
Infection Control: Prevents the spread of disease.
Infectious Disease: Caused by pathogens (germs).
Epidemic: Widespread disease in one region.
Pandemic: Global outbreak.
🔹 Types of Infections
Generalized/Systemic: Whole body → fever, headache, vomiting,
fatigue, diarrhea, ↑ pulse/resp.
Localized: One area → red, swollen, warm, painful, pus/drainage.
🔹 Scope of the Problem
Health care settings = high germ risk.
HAI (Healthcare-Associated Infection): Occurs during medical care
(used to be called “nosocomial”).
Industrial Illness: Health workers catch infections at work.
Sharps injuries: Needlesticks & scalpels → leading cause of
occupational illness/death. Safety devices in use.
🔹 Regulatory Agencies
CDC – Studies disease causes/spread.
OSHA – Sets & enforces workplace safety standards.
FDA – Ensures safety of food, drugs, vaccines, devices, cosmetics,
radiation products.
🔹 Microorganisms & Host Relationship
Normal Flora – Good bacteria needed for body function.
, Aerobic – Needs oxygen.
Anaerobic – Lives without oxygen.
Immune Response – Antibodies fight pathogens.
Opportunistic Infection – Occurs when body is weakened.
Host relationships:
o Symbiosis (mutual benefit)
o Neutralism (no effect)
o Parasitic (organism harms host → parasites)
🔹 Types of Microbes
Bacteria – One-celled, some harmful; many make toxins.
Viruses – Smallest, need host cells, hard to treat, no antibiotics.
Fungi – Yeasts (1-cell), molds (multi-cell); cause chronic infections
(ringworm, athlete’s foot).
Rickettsia – Spread by insect vectors (fleas, ticks, mites).
Protozoa – 1-cell animals; cause malaria, dysentery, trichomoniasis.
Body’s Defense Mechanisms
Your body has two main lines of defense against infection:
1. Nonspecific defenses (general barriers):
o Skin – First physical barrier, blocks pathogen entry.
o Mucous membranes – Trap and filter microbes (nose, throat, GI
tract).
o Cilia – Tiny hairs in respiratory tract sweep pathogens out.
o Coughing & sneezing – Expel pathogens.
o Tears & saliva – Contain enzymes (lysozyme) that break down
bacteria.
o Hydrochloric acid in stomach – Kills swallowed microbes.