Biology 216 - Lect 37 - Epidemiology)
I. Basics of Epidemiology - integrates all we've talked about. 
	Etiology and control (transmission/vaccination).
A. Epidemiology ("beyond people") - 
	Study of medically important occurrences in human population 
		(Goal: cause and effect)
	(auto deaths/seatbelts; asbestos/lung cancer; smoking/lung cancer; 
		honey/infant botulism; Rely and TSS)
	Focus on community or populations rather than specific patient 
		- public health concern.
	Infectious disease: Acquisition/spread ----> 
		prevention and control; Documented in MMWR.
	Epizootiology - same in animals (ex. fowl botulism)
B. Epidemic - occurrence in excess of normal expected incidence.
	Graph: cases/100,000 vs time show expected, 
		epidemic threshold, observed (epidemic)
	Ex. Kaposi sarcoma - 1981 observed surpass threshold.
	Endemic - habitual presence at acceptable level. 
		Historically defined; Ex. Smpox 2, GC 100K.
	Epidemic dies out when susceptible and shedder decrease
		 to level where encounter approaches zero.
C. Definition of population important in evaluating causes: 
	Age (Hib); Sex (TSS); Genetics (Native TB);
	Season (Legionella, Lyme);
	Geography (Coccidioidomycosis, ETEC)
D. Additional terms: Morbidity (rate of disease/pop); 
	Mortality (rate of death/population)
	Pandemic (global outbreak); Epizootic (non-human outbreak)
II. Most important principles (Transmission, Control) 
	- Less emphasis on pathogenesis.
A. Transmission - Communicab le - focus control on transmission
	 (Graph - cases/time skewed) Ex TB
	Non-communicable - no secondary spread; 
		often single source (food, Legionaires)	
	1. Mechanisms of tranmission: Mother -> fetus (syphilis)
		- identify infected mothers.
		Respiratory (size of droplets: 100 um diameter drop out; 
			10 um airborne 20 min; <6 um lower resp)  Time
		Fecal/oral; Direct skin contact; Blood (AIDS,CMV); 
		Vectors (Lyme); STD.
B. Control - Recognize and block transmission,
	 treat communicable, induce immunity.
III. Molecular epidemiology to trace outbreaks
	Biotype (cholera), serotypes (cholera), 
	antibiotypes (hospital surveilance), plasmid (staph), phage (staph, Ps)
IV. Journals and Agencies
A. Amer J. Public Health (epidemiol);
	 MMWR (reportable diseases of public health concern)
B. CDC - Monitor occurrences in US (worked out Legionaires); 
	Atlanta, GA
C. State and County Public Health Departments
	 (State divided into groups)
V. Careers - not wide open
A. Hospital ID officer/nurse - RN (Enloe full time) - 
	surveilance of nosocomial, communication to personnel,
	minimal environmental surveilance, policy writing, 
	national certification; data collection -> recommendation
B. Public Health Micro - State and county: Water, rabies, TB, 
	AIDS, plague, influenza, controllable diseases. 
VI. Examples:
A. 1981 - epidemic of Kaposi sarcoma; 
	pneumocycstis carinii pneumonia (PCP)
	decreased CMI; TH/TS lowered; Normally healthy young men.
	Population: 70 % homosexual/bi men; 
		17 % iv drug; 5 % Haitians; 1 % hemophiliacs
	Common practice (Boulean logic overlaps) - blood mixing
	HTLV III = HIVI (from central Africa -> Haiti --> US)
	Drugs - selectively toxic for viral replication (AZT) - side effects
	Control - Education to control transmission; 
		C. Everett Koop mailing; Vaccine development; 
		Screen blood suppy
B. Mothers in Lyme Co CT report several children w/ arthritis.
	Are these related; other cases; infectious?; 
		Any known infectious arthritis (ARF)?
	Established case definition: Sudden onset, chronic, 
		Knee, Recall large skin rash
	Time, place, personal characteristics: Spring, rural...
	Is it epidemic or artifact of surveilance (nagging mothers) - 
		Ask in other area for increase? No.
	Transmission: wooded area (suggest viral arthropod source); 
		antibiotics help (bacterial)
	Search for agent: Ticks to Rocky Mtn NIK; 
		Spirochetes found; Feed on rabbits -> arthritis
		Culture, check patient sera.