20
Infectious Disease Epidemiology, Module I Introduction

Infectious Disease Epidemiology, Module I Introduction

Embed Size (px)

Citation preview

Page 1: Infectious Disease Epidemiology, Module I Introduction

Infectious Disease Epidemiology, Module I

Introduction

Page 2: Infectious Disease Epidemiology, Module I Introduction

9/22/00 ANN JOLLY 2

Introduction Round table Your expectations of this day Your career goals Knowledge base Why is infectious disease epidemiology

important?

Page 3: Infectious Disease Epidemiology, Module I Introduction

9/22/00 ANN JOLLY 3

General goals Understand the infectious disease

process Identify transmission routes, modes,

media and reservoirs Understand public health law

Understand infectious disease surveillance Understand the process of outbreak

investigation

Page 4: Infectious Disease Epidemiology, Module I Introduction

9/22/00 ANN JOLLY 4

What causes disease?

AgentAgent HostHost

EnvironmentEnvironment

BacteriaBacteriaVirusesVirusesFungiFungiParasiteParasitessPrionsPrions

HousingHousing FoodFoodWater qualityWater quality Air qualityAir quality

AgeAgeGenderGenderEthnic groupEthnic groupLifestyleLifestyleSocioeconomicSocioeconomic

Page 5: Infectious Disease Epidemiology, Module I Introduction

9/22/00 ANN JOLLY 5

Expos

ureIn

fect

ion

Diseas

e, sy

mpto

mat

ic/

asym

ptom

atic

Carrie

r

Conva

lesce

nt

Sequela

e

Infectious disease process

Page 6: Infectious Disease Epidemiology, Module I Introduction

9/22/00 ANN JOLLY 6

What determines infection?

(other than exposure) The deposition, colonisation and

multiplication of an organism in a host, Usually accompanied by an immune

response May occur with or without clinical illness

Page 7: Infectious Disease Epidemiology, Module I Introduction

9/22/00 ANN JOLLY 7

Predictors of infectionAGENT

HOST ENVIRONMENT

ImmunityRaceAge

Gender

Socioeconomic

Living Conditions

Social

Climate

Dose

Genetics

Hardiness

Communicability

Page 8: Infectious Disease Epidemiology, Module I Introduction

9/22/00 ANN JOLLY 8

Infectious disease process - Source

Reservoirs human insect animal

Medium air borne water borne food borne blood borne genital

Page 9: Infectious Disease Epidemiology, Module I Introduction

9/22/00 ANN JOLLY 9

Infectious disease process- Transmission

Route direct

Oral, oral/faecal sexual respiratory - droplets or droplet nuclei 1-5m parenteral congenital

indirect vector vehicle

Page 10: Infectious Disease Epidemiology, Module I Introduction

9/22/00 ANN JOLLY 10

Infectious disease process -Infection & Incubation

Infection dose infectivity hardiness rate of replication

Incubation infectiousness immune response intervention

Page 11: Infectious Disease Epidemiology, Module I Introduction

9/22/00 ANN JOLLY 11

Infectious disease process- Disease

Disease signs, symptoms asymptomatic infectious

Outcome/Prognosis morbidity mortality sequelae recovery

infectious (chronic carrier)

Page 12: Infectious Disease Epidemiology, Module I Introduction

9/22/00 ANN JOLLY 12

Diagnosis Clinical

based on signs, symptoms Laboratory confirmed

microbiology detection isolation

serology parasitology virus

Page 13: Infectious Disease Epidemiology, Module I Introduction

9/22/00 ANN JOLLY 13

Diagnostic process

Patient presents due to symptoms case - finding

screening active investigation of contacts

Page 14: Infectious Disease Epidemiology, Module I Introduction

9/22/00 ANN JOLLY 14

Laboratory diagnosis

Lab tests ordered Method of collection, site, volume Right tests ordered

correct organisms antimicrobial sensitivity

Sent to the right place In the right media Transport conditions

Time Temperature

Page 15: Infectious Disease Epidemiology, Module I Introduction

9/22/00 ANN JOLLY 15

Laboratory diagnosis, (cont.) Routine identification of organisms causing

diarrhoea C & S

shigellae salmonellae yersinia aeromonas campylobacter

In children < 5 in the summer Vertoxigenic E. coli

Page 16: Infectious Disease Epidemiology, Module I Introduction

9/22/00 ANN JOLLY 16

Laboratory diagnosis, (cont.)

If food-borne is suspected and written on the requisition staph aureus bacillus cereus clostridium perfringens

Page 17: Infectious Disease Epidemiology, Module I Introduction

9/22/00 ANN JOLLY 17

Interpretation of tests, if positive

Test sensitivity % of people accurately diagnosed as ill of all

people tested Normal flora?

N. meningitidis Streptococcus pyogenes

Carrier state Contamination during collection Lab. Error Multiple infections

Page 18: Infectious Disease Epidemiology, Module I Introduction

9/22/00 ANN JOLLY 18

Interpretation of tests, if negative

Prior antibiotic therapy Problems in

collection timing site

storage transport media

Failure to incubate long enough

Page 19: Infectious Disease Epidemiology, Module I Introduction

9/22/00 ANN JOLLY 19

Summary

Infectious disease process reservoir - transmission - disease/death

Determinants of infection agent, host, environment interaction

Page 20: Infectious Disease Epidemiology, Module I Introduction

9/22/00 ANN JOLLY 20

Next Steps Future applied

disease in populations surveillance outbreaks