Introduction to Epidemiology and Surveillance

An Introduction to Epidemiology pt 01 Dr Alex Keenan, Epidemiology and Surveillance Analyst, Cheshire & Merseyside HPU 27 th April 2010

Learning Outcomes ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Aims of Session 1 ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Definitions of Epidemiology ,[object Object],[object Object]

Surveillance – functions WHO recommended surveillance standards, Second edition http://www.who.int/csr/resources/publications/surveillance/WHO_CDS_CSR_ISR_99_2_EN/en/ ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Case definition Agreed system/process A means to follow up cases Effective (secure) storage and skills to analyse Political will to act – perceived importance Requires…

Surveillance Systems Database Policy makers PCTs / LAs / SHAs Health Practitioners Dissemination Laboratory / clinic Data Analysis Specialist Laboratory Supplementary data

Data Quality ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Campylobacter – Weekly Surveillance (1)

Data Interpretation ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Exercise (1) - ~15 mins ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Exercise (2) ~ 15 mins ,[object Object],[object Object],[object Object],[object Object],[object Object]

Hospital Utilisation Data ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

General Practice Data ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

NHS Direct ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Other sources of Routine Data ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Routine Environmental Data ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Congenital Abnormalities ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Merseyside and Cheshire Congenital Anomaly Survey ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

[object Object],[object Object],[object Object],[object Object],[object Object]

Aims of Session 2 ,[object Object],[object Object],[object Object]

What is an outbreak? ,[object Object],[object Object],[object Object]

How do clusters arise? ,[object Object],[object Object],[object Object]

Clusters can be… In Time e.g. cases of legionella In Place e.g. meningococcal cases in same school class In Person e.g. cases of breast cancer in a family The term cluster denotes the suspicion of an increased frequency of some event occurring, not that any increase has been demonstrated

How do outbreaks come to light? ,[object Object],[object Object],[object Object],[object Object]

Types of outbreak ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Figure. Measles cases by date of onset of rash. Region of Madrid, March 2006. (Cases reported until 16th March, 2006) Example of propagated outbreak (see www.eurosurveillance.org/ew/2006/060330.asp)

Example of Point Source Outbreak

Why investigate outbreaks? ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

How to use epidemiology in outbreaks ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Examples of Types of Outbreak Investigation ,[object Object],[object Object],[object Object],[object Object],[object Object]

Risk Factors – some examples ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Odds Ratios (I) ,[object Object],[object Object],Ate / Exposed Didn’t Eat / Not Exposed Ill / Disease a b Not ill / No Disease c d

Odds Ratios Example ,[object Object],[object Object],Egg Salad Ate Didn’t Eat Ill 8 1 Not ill 1 4

Exercise (3) ~ 30 mins ,[object Object],[object Object],[object Object],[object Object],[object Object]

Outbreak at an event in Liverpool July 2009 ,[object Object],[object Object],[object Object],[object Object],[object Object]

Investigation ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Risk Factors Identified ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Single Variable Analysis <0.01 6.45 – 32.47 15.70 Rice <0.01 6.99 – 31.84 15.40 Chicken Curry <0.01 1.99 – 7.22 3.61 Vegetable Samosa <0.01 3.12 – 12.56 6.21 Beef Cutlet <0.01 2.80 – 10.52 6.05 Chicken Lollipop <0.01 2.60 – 9.77 4.87 Spring Roll 0.34 0.71 – 2.67 1.30 Sex 0.056 0.99 – 1.04 1.02 Age p – value Confidence Interval Odds Ratio

Further Analysis ,[object Object],[object Object],[object Object]

Multivariate Analysis <0.0001 4.34 – 36.88 12.63 Rice 0.003 1.54 – 8.51 3.63 Chicken Curry p- value Confidence Interval Odds Ratio

Summary of Epidemiological Findings ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

A Selection of Useful Reference Books ,[object Object],[object Object],[object Object],[object Object],[object Object]

[object Object],[object Object]

Introduction to Epidemiology and Surveillance

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Introduction to Epidemiology and Surveillance