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chapters 15-23

morbidity rate

number if people affected by a disease in a given period of time in relation to total population

notifiable disease

physicians required to report occurence of thesee diseases to u.s. public health service


number of microbes in a dose required to cause death in 50% of test animals


Centers of disease control


number of microbes in a dose required to cause infection in 50% test animals


Source of disease organisms Human-human disease
-Animal-disease spread from animals to humans (zoonotic)
-Nonliving-primarily soil and water


body returnes to pre-disease state


signs symptoms subside


period with most overt signs/symptoms of immune system is unable to resolve death


brief period following incubation characterized by general aches and pains


period between infection and appearence of first signs/ symptopms

Subclinical infections

infected individuals show no signs or symptoms i.e thyphoid mary: carrier for illness

Primary infections

may weaken the immune system and allow for a more serious secondary infection i.e HIV and pneumonia


pertaining to blood


infectious organisms are spread throughout the body (chikenpox)

Local infection

infectious orgainisms are limited to a small bodily area (pink eye)

Duration: Chronic

Develops slowly; likely to reccur last for long periods of time

Duration: Acute

Rapid development lasts a short-time and is resolved

specific immunity

defense response triggered by invasion of a foreign organism


molecule that reacts specifically with either an antibody or an antigen recepeter on a lymphocyte


mediated by b- cells and antibody response

cell-mediated immunity

immunity involving a T-cell response

Acquired immunity

immunity developed over time in response to exposure to antigens

Natural active

results from exposure to antigens in the course of daily life

natural passive

results from antibody transfer from mother-infant

artificial active "antigens"

recieving antigen from a vaccine

artificial passive

result from injection of antibodies into the body

humoral immunity

mediated by b-cells vaccination are geared towards these cells

Activation complement

by Fc region cross-linking enhance the efficiency of phagocytosis


antigen coated in antibodies to enhance phagocytosis


portion of antigen recognized by immune system. "b-cells only to recognize on epitope"


Viruse or toxin is prevented from binding to cell surface


originate from stem cells located in bone marrow. upon encounter with its specific antigen a b-cell will proliferate and convert to a plasma cell circle throughtout the body waiting for antigen. b-cells become memory cells

Plasma cell

antibody "factories" which produce "only" the antibody specific for the antigen that triggered its production

Humoral immunity

works to elimate extracelluar antigens bacteria, toxins viruses B cells are responsible for Humoral immunity

Cell-mediated immunity

Dependent on activity of T cells. T-cells mature in the thymus 2 types CD4 and CD8

CD4 t-cells

helper t-cells=Th

CD8 t-cells


3 types of APC

B cell dendritic cell, macophage MHC 1- presents antigen to CD8 T cells, MHC 11- presents antigen to CD4 and T cells expressed only on APC

Function of Tc Cells

MHC1 presents intracelluar antigens (derived from viruses, intracelluar bacteria) to CD8 and T cells. Any particualr CD8 T cell will only recognize one antigen Upon binding to its appropriate antigen. MHC 1 complex, CD8 T cells induce cell death in the target cell


Chemical messenger: Secreted cytokines may stimulate B-cells to develop into plasma cells or memory B cells (TH2) secreted cytokines may stimulate activation of macrophages and or stimulate CD8 T-cell activity (TH1)


study of disease patterns in populations


transmitted from one host to another (person to person)


diseases which can spread easily from host to host


unusually large numbers of cases in a population short period of time


when cases occur only from time to time


constantly present in a given population


worldwide epidemic


subjective changes resulting from diverse (general pain, discomfort, headache


measurable changes resulting from disease (inflammation, swelling, fever)


rapid development; lasts a short time and is resolved


develops slowly, likely to recur, last for long periods of time

Human reservoir

for most human diseases humans are the reservoir, and the disease is most easily controlled

Animal reservoir

diseases that are spread from animals to humans (zoonotic)

Nonliving reservoir

primarily in soil and water


an incident in which an infectious disease is transmitted

Direct transmission

person to person

indirect transmission

fomites. (counter tops, door handles)

Droplet transmission

only for short distances influenza and pneumonia


Transmission of a disease through a medium such as food, water, air


animals that carry disease from one host to another, Arthropods are most important

Portal of exit

how a microbe is shed from the host

Portal of entry

how a microbe gains access to the host, mucous membrane, skin,

Paternak route

position a organisms underneath damaged skin, mucouse membrane

preferred portal of entry

for many microbes, they must enter by their preferred portal in order to cause disease


acquired while at the hospital


produced by microbes to inhibit/kill other microbes

Selective toxicity

more toxic to microbes than humans

Paul Erlich

magic bullet, Chemotherapy, tried to find the "magic bullet" that could hunt down and destroy a pathogen without harming the infected host. Found salvarsan works on syphilis

Alexander Fleming

discovered penicillin in 1928

Selective toxicity

more toxic to microbes than humans

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