outbreak! portrait of an epidemic
TRANSCRIPT
OUTBREAK!
Portrait of an Epidemic
http://phil.cdc.gov/Phil/details.asp
THE BLACK DEATH
• 25 million dead over 5 years
• One-third of Europe’s population
• “Victims often had lunch with their friends and dinner with their departed ancestors”
WHAT CAUSES DISEASE
• Basically, 4 causes:– Bacteria– Viruses– Parasites– Prions
http://phil.cdc.gov/Phil/details.asp
BACTERIA
• Not all cause disease• Koch’s Postulates
– Show the bacterium is present in every case of the disease– Isolate the bacterium from the infected individual and grow it
outside the individual– Infect a healthy individual with the bacterium and have it produce
the same symptoms– Recover the bacterium from the newly sick individual
http://phil.cdc.gov/Phil/details.asp
E. coli
Salmonella
http://www.lbl.gov/
commtechlab.msu.edu
www.nasa.gov www.geocities.com/avinash_abhyankar/
StreptococcusCauses strep throatRound
BorreliaCauses Lyme diseaseSpiral-shaped
phil.cdc.gov/Phil/
phil.cdc.gov/Phil/
www.uiowa.edu/~cemrf/
www.life.umd.edu/classroom/bsci424
Bacillus anthracis
phil.cdc.gov/Phil/details.asp
Viruses
• Not really alive?• Require host to
reproduce
www.nsf.gov/od/lpa/
Influenza Virus
Avian Influenza
phil.cdc.gov/Phil/
www.cdc.gov/ncidod www.aids-info.ch/bilder/schule_aids
phil.cdc.gov/Phil/details.asp
PARASITES
• Protists– Malaria– African sleeping
sickness
• Other parasites– Hookworms– Wuchereria bancroftii
phil.cdc.gov/Phil/
PRIONS
• Bits of self-replicating protein
• Mad cow disease• Creutzfeldt-Jakob• Spongiform
encephalitis
phil.cdc.gov/Phil
picasso.ucsf.edu/~ulyanov/Structures/prion.html
INVESTIGATING AN OUTBREAKCenter for Disease Control (CDC)
1) Prepare for field work2) Establish the existence of an outbreak3) Verify the diagnosis4) Define and identify the cases5) Describe and orient the data in terms of time, place,
and person6) Develop hypotheses7) Evaluate hypotheses8) Refine hypotheses and carry out additional studies9) Implement control and prevention measures10) Communicate findings
INVESTIGATING AN OUTBREAKCenter for Disease Control (CDC)
1) Prepare for field work2) Establish the existence of an outbreak3) Verify the diagnosis4) Define and identify the cases5) Describe and orient the data in terms of time, place,
and person6) Develop hypotheses7) Evaluate hypotheses8) Refine hypotheses and carry out additional studies9) Implement control and prevention measures10) Communicate findings
• Is the incidence of the disease greater than what is normal for the area and time?
INVESTIGATING AN OUTBREAKCenter for Disease Control (CDC)
1) Prepare for field work2) Establish the existence of an outbreak3) Verify the diagnosis4) Define and identify the cases5) Describe and orient the data in terms of time, place,
and person6) Develop hypotheses7) Evaluate hypotheses8) Refine hypotheses and carry out additional studies9) Implement control and prevention measures10) Communicate findings
Places Gone Foods Eaten Activities
INITIALS: CASE #:_______ SEX: ILL? (YES/NO)
INVESTIGATING AN OUTBREAKCenter for Disease Control (CDC)
1) Prepare for field work2) Establish the existence of an outbreak3) Verify the diagnosis4) Define and identify the cases5) Describe and orient the data in terms of time, place,
and person6) Develop hypotheses7) Evaluate hypotheses8) Refine hypotheses and carry out additional studies9) Implement control and prevention measures10) Communicate findings
SGOT AltSGOT Diagnostic Lab
Signs and Symptoms
Case# InitialsDate of Report
Date of Onset
Physician Diagnosis
N V A F DU J HAIgM Other Age Sex
1 JG 10/12 10/6 Hep A + + + + + + + 37 M
2 BC 10/12 10/5 Hep A + - + + + + + 62 F
3 HP 10/13 10/4 Hep A + - + + +S*
+ 30 F
4 MC 10/15 10/4 Hep A - - + + ? - +Hbs/ Ag-
17 F
5 NG 10/15 10/9 NA - - + - + + NA NA 32 F
6 RD 10/15 10/8 Hep A + + + + + + + 38 M
7 KR 10/16 10/13 Hep A + - + + + + +SGOT = 240
43 M
S*=Sclera;, N=Nausea; V=Vomiting; A=Anorexia; F=Fever; DU=Dark urine; J=Jaundice; HAIgm=Hepatitis AIgM antibody test
INVESTIGATING AN OUTBREAKCenter for Disease Control (CDC)
1) Prepare for field work2) Establish the existence of an outbreak3) Verify the diagnosis4) Define and identify the cases5) Describe and orient the data in terms of time, place,
and person6) Develop hypotheses7) Evaluate hypotheses8) Refine hypotheses and carry out additional studies9) Implement control and prevention measures10) Communicate findings
LEGIONELLOSIS
• What Is It? A type of pneumonia caused by the bacterium Legionella pneumophila.
• Source: Contaminated water sources, such as showers, fountains, cooling systems, humidifiers, hot tubs and spas
• Cause of Spread: Spray from contaminated sources
• Normal Incidence: For Virginia, a 5-year average of 20 cases per year (about 2/month).
• Historical Relevance: 1996 outbreak in the Lynchburg, VA, region. 23 confirmed cases with 2 deaths.
phil.cdc.gov/Phil
INVESTIGATING AN OUTBREAKCenter for Disease Control (CDC)
1) Prepare for field work2) Establish the existence of an outbreak3) Verify the diagnosis4) Define and identify the cases5) Describe and orient the data in terms of time, place,
and person6) Develop hypothesis7) Evaluate hypothesis8) Refine hypothesis and carry out additional studies9) Implement control and prevention measures10) Communicate findings
CALCULATE AN ODDS RATIO
Case Patients
Controls Total
Ate at Restaurant A?
Yes a = 30 b = 36 66
No c = 10 d = 70 80
Total: 40 106 146
(a)(d)/(b)(c) = 5.8
Location
Visited the
Location?Cases (ill)
Controls (not ill)
Odds Ratio
HOMECOYes a = 9 b = 2
No c = 1 d = 8
COFFEE JUNCTION
Yes a = 5 b = 3
No c = 5 d = 7
VALUE WORLD Yes a = 5 b = 6
No c = 5 d = 4
Number of people whoate specified item
Number of people who did not eat specified item
Food Ill Well TotalAttack
Rate %
Ill Well TotalAttack
Rate %
Baked Ham
29 17 46 63 17 12 29 59
Spinach 26 17 43 60 20 12 32 62
Mashed potatoes*
23 14 37 62 23 14 37 62
Cabbage salad
18 10 28 64 28 19 47 60
Jell-O 16 7 23 70 30 22 52 58
Rolls 21 16 37 57 25 13 38 66
Brown bread
18 9 27 67 28 20 48 58
Milk 2 2 4 50 44 27 71 62
Coffee 19 12 31 61 27 17 44 61
Water 13 11 24 54 33 18 51 65
Cakes 27 13 40 67 19 16 35 54
Ice Cream (van)
43 11 54 80 3 18 21 14
Ice Cream (choc )*
25 22 47 53 20 7 27 74
Fruit Salad 4 2 6 67 42 27 69 61
Attack Rates by Items Served at a Church Supper,Oswego, New York, April 1940
INVESTIGATING AN OUTBREAKCenter for Disease Control (CDC)
1) Prepare for field work2) Establish the existence of an outbreak3) Verify the diagnosis4) Define and identify the cases5) Describe and orient the data in terms of time, place,
and person6) Develop hypothesis7) Evaluate hypothesis8) Refine hypothesis9) Implement control measures10) Communicate findings
OUTBREAK AT MIDDLIN HIGH
• Students are getting sick …. Why?
• 15 sick, so far
• Began getting sick Sunday.
• It’s now Wednesday… is the epidemic over?
Activity Summary Data Table
ACTIVITY # ILL STUDENTS INVOLVED IN
ACTIVITY
# ILL STUDENTS NOT INVOLVED
# WELL STUDENTS INVOLVED IN
ACTIVITY
# WELL STUDENTS NOT INVOLVED
Football 8 7 6 4
Café 12 3 8 2
Fair 9 4 5 5
Swimming 8 7 6 4
Cookout 13 2 4 6
FoodNumber of Students Who Ate the Item Number of Students Who Did Not Eat the
Item
Ill Well Total Attack Rate % Ill Well Total Attack Rate %
Chicken 5 3 8 10 7 17
Hamburger 6 3 9 9 7 16
HomemadeIce Cream
13 0 13 2 10 12
Celery 7 3 10 8 7 15
Milk 7 3 10 8 7 15
Hotdog 5 2 7 10 8 18
YOU ARE A CDC INVESTIGATOR
• Your group is a CDC team
• Your assignment is to investigate the illness, determine its source, and recommend action
• You must follow the proper CDC steps as previously discussed
TREATMENTS
• Antibiotics– Only for bacteria– Resistance becoming a problem
• Innoculations