susceptible host

someone vulnerable to infection by an infectious agent

reservoir

wherever the agent previously resided

chain of infection

the transmission of an agent from its reservoir to a susceptible host

portals of exit / entry

skin, respiratory tract, gastrointestinal tract, urogenital, conjunctiva

direct mode of transmission

touches an infected individual or is exposed to their body fluids, close contact needed

indirect mode of transmission

inhales infected particles, touches an infected object or is bitten by an infected insect, air particles or animal intermediaries

infectious dose

the number of organisms it takes to cause illness following exposure

most dangerous doses in order from most to least

ebola, mycobacterium TB, influenza, E. coli

breaking chain of infection

stop from spreading from reservoir, block exit from host, stop transmission

immune system

defense mechanism that resists infection by destroying pathogens

innate immunity

nonspecific immune defense mechanisms we are born with, keep anything outside from coming in

acquired immunity

specific immune defense mechanisms acquired over a lifetime, use antibodies to respond to specific antigens

active immunity

acquired following an infection and recovery or from a vaccine, body makes its own antibodies

passive immunity

acquired from mother, antibodies given to child through placenta or breast feeding

lupus

autoimmune disease that leads immune system to destroy the individual, meds can suppress

tears

innate defense mechanism, contains enzymes that kill invading organisms, wash out invaders

nasal mucosa and cilia

innate defense mechanism, mucus and cilia (small hairs) in nose trap invaders

cilia in trachea and lungs

innate defense mechanism, wave upwards, invaders trapped in mucus and passed up and out

digestive enzymes

innate defense mechanism, oral enzymes help kill invaders

phagocytes

innate defense mechanism, cells that patrol lungs and eat and digest invaders

stomach acid

innate defense mechanism, pH of 2, kills invaders

normal flora

innate defense mechanism, live on skin, intestines, take up space and secrete chemicals to keep foreign invaders out and prevent them from attaching

secretions

innate defense mechanism, urine, female vaginal discharge, defecation flush out organisms

inflammation

innate defense mechanism, localized conditions, small blood vessels in tissue dilate to increase blood flow to injured tissue

fever

innate defense mechanism, elevation of temperature above normal range to stimulate WBC release

hypothalamus

structure in brain that regulates body temperature

acquired immunity

antigen (foreign invader like a pathogen) enters = T-cells cent to site of infection

T-cells

kill infected cells by secreting toxins, remember pathogens

B-cells

produces antibodies to block pathogens from entering cells, prevent bacteria from ingesting nutrients, and bind toxins released by pathogens to prevent them from harm

naturally acquired immunity

gained when an individual becomes ill following exposure to a pathogen and their immune system helps them recover

artificially acquired immunity

occurs when receive a vaccine

vaccine

contains weakened / dead form of pathogen

herd immunity

artificially acquired immunity that occurs when the majority of a population has been given a vaccine → resistant to infection

R-naught (R0)

used to measure how infectious an agent of disease is, quantifies ease of contracting infection

R0 < 1

one sick individual will, on average, infect fewer than one other individual

R0 = 1

One sick individual will, on average, infect one other individual.

R0 > 1

One sick individual will, on average, infect the number of individuals indicated.