Basic Field Epidemiology

AUSTRALIA INDONESIA PARTNERSHIP FOR EMERGING INFECTIOUS DISEASES

Basic Field Epidemiology

Session 9 – Collecting data and counting cases



In this session we will talk about:

• How to collect data and count cases of disease


Activity

Task for everyone to do:Now we understand what a case definition is –

1. How might you go about collecting information about cases and non-cases?


Video

• Show recorded PowerPoint file for Session 9


After watching the recorded PowerPoint

In this video we learnt about – How to collect data on cases and non-cases

Task for everyone to do:1. Revisit your ideas to questions prior to the

video. • Have your views changed?


Group activity – Investigation of FMD in a Thai villageBackground information

Village in Lampang Province with 91 households owning cattle (beef cattle and buffalo).Outbreak reported to authorities on 29 January. Investigation team visited and collected detailed information on the progression of the outbreak (typed as Asia 1). There has been some vaccine use in the past (type O vaccine) but only few cattle were vaccinated.


Group activity –FMD in a Thai villageusing case & non-case data

We can use case & non-case data to produce % estimates

1. How can we use these estimates to assess disease occurrence and severity in different groups of animals?

%=𝑛𝑢𝑚𝑒𝑟𝑎𝑡𝑜𝑟𝑑𝑒𝑛𝑜𝑚𝑖𝑛𝑎𝑡𝑜𝑟 ×100=

𝑐𝑎𝑠𝑒𝑠𝑐𝑎𝑠𝑒𝑠+𝑛𝑜𝑛−𝑐𝑎𝑠𝑒𝑠 ×100

In a defined outbreak where the denominator is all animals at risk of getting the disease, the estimates are called attack rates (AR)


Never sick

FMD cases

Total animals

Total casesAnimal type Age Mild Severe Died

Beef cattle < 1 y old 15 4 9 2 30 15

Adults 90 21 23 0 134 44

Buffalo < 1 y old 13 8 0 0 21 8

Adults 124 33 1 0 158 34 FMD cases Beef BuffaloWeek 1 1 0Week 2 15 9Week 3 20 22Week 4 15 11Week 5 5 0Week 6 2 0Week 7 1 0


Group activity – FMD in a Thai village

2. Are young animals more likely to get FMD than older animals?

Breed Age Cases TotalBeef <1 yr 15 30

Adult 44 134Buffalo <1 yr 8 21

Adult 34 158Combined <1 yr 23 51 Adult 78 292


Group activity – FMD in a Thai village

2. Are young animals more likely to get FMD than older animals?

Breed Age Cases Total % (AR) Ratio (RR)Beef <1 yr 15 30 50.0 1.52

Adult 44 134 32.8 1Buffalo <1 yr 8 21 38.1 1.77

Adult 34 158 21.5 1Combined <1 yr 23 51 45.1 1.69 Adult 78 292 26.7 1


In this session we talked about:

• Ideas on how to collect data and count cases of disease


Learn new skills

Have funImprove your job satisfaction

Better animal healthfor Indonesia

Key concepts of session 9

• Data on cases and non-cases comes from– Asking the farmer questions– Direct observation of signs of disease from the

animal– Laboratory results

Documents

Basic Field Epidemiology