The Biology of The Biology of DiseaseDisease

Infectious AgentsInfectious AgentsModes of InfectionModes of Infection

Germ Theory of DiseaseGerm Theory of DiseaseDefense Against DiseaseDefense Against Disease

DiseaseAny change (other than Any change (other than an injury) that disrupts an injury) that disrupts normal body functionsnormal body functions– Inherited/geneticInherited/genetic– Environmental factorsEnvironmental factors– Infectious agents Infectious agents

(pathogens)(pathogens)• VirusesViruses• BacteriaBacteria• ProtistsProtists• FungiFungi• Large parasitesLarge parasites• Prions*Prions*

http://en.wikipedia.org/wiki/Dengue_fever. http://www.rcsb.org/pdb/101/motm.do?momID=103

Incubation period3-14 days

Incubation period3-14 days

Miasma, curses, and moreMiasma, curses, and more““As long as (individuals) believed that As long as (individuals) believed that

microorganisms could arise from microorganisms could arise from nonliving substances, scientists saw no nonliving substances, scientists saw no

purpose in considering how diseases purpose in considering how diseases were transmitted or how they could be were transmitted or how they could be

controlled.” controlled.” - Black, 1996- Black, 1996

http://upload.wikimedia.org/wikipedia/commons/9/92/Cholera_art.jpg

Germ ThGerm Theory of eory of DiseaseDisease• Refuted

theory of spontaneous generation

• Infectious disease is caused by germs (L. “to beget”) or pathogens.

http://jvi.asm.org/content/77/11.cover-expansion

Development of the

Germ Theory of

Disease

http://www.cdc.gov/features/handwashing/handwashing_a200px.jpg, http://www.accessexcellence.org/RC/AB/BC/images/lou_p.gif,

http://news.bbc.co.uk/2/shared/spl/hi/pop_ups/06/magazine_local_treasures/html/1.stm

, http://en.wikipedia.org/wiki/File:TB_Culture.jpg, http://www.extension.umn.edu/distribution/horticulture/dg1168.html

Pathogen What it is What it causes

Viruses Noncellular particles that invade living cells

AIDS, polio, smallpox, measles, colds, influenza, chicken pox,

SARS, bird flu

Bacteria Unicellular prokaryotes; from Domain Bacteria

gonorrhea, botulism, pneumonia, strep throat, boils/acne, tuberculosis,

meningitis, cholera, tetanus

ProtistsAny eukaryote that is

NOT a plant, an animal, or a fungus; from Kingdom Protista

malaria, amoebiasis/amoebic dysentery, African sleeping

sickness

Fungi Eukaryotic heterotrophs w/ chitinous CWs; from Kingdom Fungi

ringworm, athlete’s foot, San Joaquin Valley fever (lung disease), histoplasmosis

Worms Parasitic animals from the phyla Platyhelminthes & Nematoda

schistosomiasis, beef tapeworm

Prions*Misfolded proteins that cause other

normal proteins to misfold and cause widespread damage

Mad-cow disease, Creutzfeldt-Jakob disease,

scrapie

How do pathogens cause disease?

http://www.morning-earth.org/Graphic-E/BIOSPHERE/Bios-Microbe-Image/M-Dfission.jpg, http://www.bioprepwatch.com/wp-content/uploads/2012/02/botulinum-toxin.jpg, http://www.trichinella.org/images/synopsis/21.1.jpg

Koch’s Postulatesset of rules that is used to determine whether a specific pathogen is the cause of a specific disease

http://4.bp.blogspot.com/_xURh3pkJN6E/TOlmOYp_8FI/AAAAAAAAABA/IcD4KNRSt4k/s1600/Kochs%2BPostulate.jpg

Discovering the cause of Lyme diseaseAllen Steere (Yale University)Lyme, Connecticut

Observations•39 children, several adults•Pain, joint inflammation•Summer-early fall•Insect bite then expanding skin rash

ProblemWhat is causing Lyme disease?

http://upload.wikimedia.org/wikipedia/commons/0/01/Erythema_migrans_-_erythematous_rash_in_Lyme_disease_-_PHIL_9875.jpg

Using Koch’s Postulates

http://commons.wikimedia.org/wiki/File:Ixodes_scapularis.png, http://www.lawestvector.org/LymeDisease.htm

Modes of Infection

http://media.photobucket.com/image/vitruvian%20homer/austinheap/myspace/homer.gif?o=1

Two major types of defenses

INNATE (NONSPECIFIC)IMMUNITY

Rapid responses to a broad range of microbes

ACQUIRED (SPECIFIC) IMMUNITY

Slower responses to

specific microbesExternal defenses Internal defenses

Skin

Mucous membranes

Secretions

Phagocytic cells

Antimicrobial proteins

Inflammatory response

Natural killer cells

Humoral response(antibodies)Cell-mediated response(cytotoxic lymphocytes)

Invadingmicrobes

(pathogens)

Pathogen Awareness Project•3D model of a chosen pathogen that affects Filipinos (pref. recycled materials, NO STYRO!)•Include a write-up with the following information on an A3 sized sheet:– Characteristics of the

pathogen– Modes of transmission– Incubation period– Symptoms induced– Prevention/cure– Interesting

trivia/statistics•Due Oct 15th, 12NN

CAMIA1,2 – Virus

3,4 – Bacteria5,6 – Large parasite

7,8 – Virus9,10 - Bacteria

CHAMPACA1,2 – Virus

3,4 – Bacteria5,6 – Large parasite

7,8 – Virus9,10 – Large parasite