Epidemiology (Schneider) Effect of Temperature in Salmonella Growth Number of Salmonella per gram...

Epidemiology (Schneider)

Effect of Temperature in Salmonella Growth

Nu

mb

er

of S

alm

one

lla p

er

gra

m

Days21 4 53

95oF (35o C)

50oF (10o C)

44oF (6.7o C)

42oF (5.5o C)

Incubation Periods

Contaminated by carrier, not foodborneShigella*24-48 hours

Raw fish, shellfishVibrio parahemolyticus*12 hours

Canned foods, smoked fish

Clostridium botulinum12-36 hours

Meat, poultry, eggsSalmonella*12-36 hours

Cooked meats, gravy Clostridium perfringens12 hours

Cooked ham, meat,

eggs, sauces and graviesStaphylococcus

aureus2-4 hours

* Fever

National Data on Etiology of Foodborne Illness

7.3%Chemicals (28 agents)

12.3%Fish (28 agents)

-Plants (36 agents)1.8% Fungal (16 agents)

0.5%Parasites (31 agents)9.4%Viral (11 agents)9.5% Clostridium botulinum

10.0% Clostridium perfringens12.7% Staph. aureus25.0% Salmonella68.7%Bacteria (40 agents)

Agent

On April 19, 1940, the local health officer in the village of Lycoming, Oswego County, New York, reported the occurrence of an outbreak of acute gastrointestinal illness to the District Health Officer in Syracuse. Dr. A. M. Rubin, epidemiologist-in-training, was assigned to conduct an investigation.

When Dr. Rubin arrived in the field, he learned from the health officer that all persons known to be ill had attended a church supper the previous evening, April 18. Family members who had not attended the church supper had not become ill. Accordingly, the investigation was focused on the circumstances related to the supper.

Investigating an Epidemic: Oswego, NY


Interviews regarding the presence of symptoms,

including the day and hour of onset, and the food

consumed at the church supper, were completed on 75

of the 80 persons known to have been present. A total

of 46 persons who had experienced gastrointestinal

illness were identified.

Q: Is this an Epidemic?

Endemic for the region?

Due to seasonal variation?

Due to random variation?

Select the correct case definition and find the error in the others:

1. All participants in the Oswego church supper held in the basement of the church in Lycoming, Oswego County, New York, on April 18, 1940, between 6:00 PM and 11:00 PM; whether they attended church or not; whether they participated in food preparation, transport, or distribution or not; whether they ate or not.

2. Persons who developed acute gastrointestinal symptoms within 72 hours of eating supper on April 18, 1940, and who were among attendees of the Lycoming, Oswego Church supper.

3. Church members who developed acute gastrointestinal symptoms within 72 hours of the church supper held in Lycoming, Oswego on April 18, 1940.

Select the correct case definition and find the error in the others:

1. All participants in the Oswego church supper held in the basement of the church in Lycoming, Oswego County, New York, on April 18, 1940, between 6:00 PM and 11:00 PM; whether they attended church or not; whether they participated in food preparation, transport, or distribution or not; whether they ate or not. Missing definition of sickness

2. Persons who developed acute gastrointestinal symptoms within 72 hours of eating supper on April 18, 1940, and who were among attendees of the Lycoming, Oswego Church supper. CORRECT

3. Church members who developed acute gastrointestinal symptoms within 72 hours of the church supper held in Lycoming, Oswego on April 18, 1940. Did not specify that they went to the dinner

Incidence of Cases of Diarrhea Among People Attending Lycoming,Oswego Church Supper, June 1940


The supper was held in the basement of

the village church. Foods were contributed

by numerous members of the

congregation. The supper began at 6:00

PM and continued until 11:00 PM. Food

was spread out upon a table and

consumed over a period of several hours.


Main Dishes • Baked ham• Spinach• Mashed potatoes• Cabbage salad• Fruit Salad

Side Dishes • Jello• Rolls• Brown Bread

Desserts • Cakes• Vanilla Ice Cream• Chocolate Ice Cream

Beverages • Milk• Coffee• Water

Church Supper Menu


Which menu item(s) is the

potential culprit?

To find out, calculate attack rates.

The foods that have the greatest difference in

attack rates may be the foods that were

responsible for the illness.

Attack Rates by Items Served: Church Supper, Oswego, New York; April 1940

692742624Fruit salad27720472225Ice cream (choc)21183541143Ice cream (van)351619401327Cakes511833241113Water441727311219Coffee712744422Milk48202827918Brown bread381325371621Rolls52223023716Jello471928281018Cabbage salad371423371423Mashed potato321220431726Spinach291217461729Baked ham

Attack rate %

TotalWellIllAttack rate (%)

TotalWellIll

Number of persons who did not eat specified item

Number of persons who

ate specified item



Attack rate %TotalWellIllAttack rate (%)TotalWellIll


Number of persons who ate

specified item

Attack Rate by Consumption of Vanilla Ice Cream, Oswego, New York; April 1940

61.3752946Total

14.321183No

79.6541143YesAte vanilla ice cream?

Attack Rate (%)

TotalWellIll

• The relative risk is calculated as 79.6/14.3 or 5.6

• The relative risk indicates that persons who ate vanilla ice cream were 5.6 times more likely to become ill than those who did not eat vanilla ice cream


Conclusion

An attack of gastroenteritis occurred following a church supper at Lycoming

The cause of the outbreak was most likely contaminated vanilla ice cream


Surveillance

Ongoing systematic collection, collation,

analysis and interpretation of data; and the

dissemination of information to those who

need to know in order that action may be

taken.

World Health Organization


Purposes of Public Health Surveillance Estimate magnitude of the problem Determine geographic distribution of illnesses Portraying the natural history of disease Detect epidemic / Define a problem Generate hypotheses and stimulate research Evaluate control measures Monitor changes in infectious agents Detect changes in health practice Facilitate planning

CDC


Passive Surveillance Physicians, laboratories, and hospitals are given forms to

complete and submit with the expectation that they will report all of the cases of reportable disease that come to their attention

Advantages: Inexpensive

Disadvantages: Data are provided by busy health professionals. Thus, the data are more likely to be incomplete and underestimate the presence of disease in the population


Active Surveillance Involves regular periodic collection of case

reports by telephone or personal visits to the reporting individuals to obtain the data

Advantages: More accurate because it is conducted by individuals specifically employed to carry out the responsibility

Disadvantages: Expensive


Sentinel Surveillance Monitoring of key health events, through sentinel

sites, events, providers, vectors/animals

Case report indicates a failure of the health care system or indicates that special problems are emerging

Advantages: Very inexpensive

Disadvantages: Applicable only for a select group of diseases


Some Surveillance Programs National Notifiable Diseases Surveillance System

http://www.cdc.gov/epo/dphsi/nndsshis.htm

Morbidity and Mortality Weekly Report (MMWR)

http://www.cdc.gov

Cancer Surveillance, Epidemiology and End Result (SEER)

http://www.seer.cancer.gov/


“Good surveillance does not necessarily ensure

the making of right decisions, but it reduces the

chances of wrong ones.”

Alexander D. Langmuir

NEJM 1963;268:182-191

Epidemiology (Schneider) Effect of Temperature in Salmonella Growth Number of Salmonella per gram...

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