How to use epidemiology for trouble shooting the problems

1
How to use epidemiology for trouble shooting the
problems

• Investigation of an outbreak of neonatal
  diarrhoea in pigs

2
History

• ???????????????? 150 ??? ?????????????????????????
  ????????
• ?????? 12 ????????????? outbreak ????? ?? 7
  ??????????????????? ???????????????? 40

3
Immediate action taken by vet

• ?????????????? 3 ?????????????????
• ???? 1 ??? ?? E. coli serotype 08
• ????? bacteria or virus ????????? 2 ???
• ?????????? ?????????????? acute enteritis

4
Preweaning diarrhoea in pigs

• ????? endemic neonatal diarrhoea ????????????
  ???????????????????? ?? ???????? periodic
  outbreaks
• E. coli rota virus Salmonella spp.
  Campylobacter spp cryotosporidia coccidia TGE
  virus
• ??????????????? ?????????????????

5
Factors involved in neonatal colibacillosis in
pigs

• design of shed and crates
• temperature
• drainage/pen moisture
• bedding
• cleaning/disinfection
• all in- all out farrowing

• farrowing shed environment

• sow

• management

• E. coli levels, serotype virulence

• immunity - age, parity, vaccination
• cleanliness
• disease status - mastitis

• neonatal pig

• diarrhoea

• genetic resistance
• passive immunity - colostrum, milk

6
Verification of diagnosis

• necropsy ?????????????
• ????????????????????
• rectal swabs ????????????????????? ??????????????

7
Define a case

• ????????????????????????????? ???
• ????????? external ??? internal ????????????????
• ?? signs ??? dehydration
• intestinal contents abnormally fluid-like
• peri-anal region stained

8
Determination magnitude of problem

• 11 (42.3) of 26 litters affected
• ???????????????????????? 7 and 5 ????????????
  ??
• scours-specific mortality rate
• ??????????????????????????/???????????????????
  24/253 0.09
• proportional mortality rate for scours
• ?????????????????????????? /??????????????????????
  24/48 0.50

9
Define temporal pattern

• ?? epidemic curve ????????????????????????????????
  ?????
• ????????????? ????????????????????????

10
Spatial pattern
??????? (???????????)
???????????????????????????????
?????????????????????????????????
???????? (?????????)
11
Animal pattern
12
Analysis of data

• ????????????????????????? ??????????????,
  ????????, ?????????????????????????
  ????????????????
• ????? relative risks ?????? Chi-Square test

13
Parity distribution

• Chi-Square test ???????????????????????
  ??????????????????????????????????????????????????
  ??
• x2 7.9 7 df p 0.34

14

• 2 7.9 df 7 p 0.34

15
(No Transcript)
16

• RR 4/5 / 7/21 2.4
• 2 3.6 1 df p 0.06 (Fishers exact test
  (2-tailed) p 0.13)

17
Sick-sow data

• RR 2/2 / 9/24 2.67
• 2 3.0 1 df p 0.09 (Fishers exact test
  (2-tailed) p 0.17)

18
Litter size

• 2 6.0 3 df p 0.11

19
Pen-location data

• RR 9/14 / 2/12 3.86
• 2 6.0 1 df p 0.01 (Fishers exact test
  (2-tailed) p 0.02)

20
Problem multiple factors significant

• ??? multivariate analysis ?????
• identify ??????????????????????????
• identify confounding factors
• Logistic regression for multivariate analysis of
  binary outcome variables
• outcome variable E. coli diarrhoea in litter
  present or not present

21

• results
• ????????? ??????????????????????????
• ????????????????????????????? ????????????
• ????? interaction ???????????????????????????
  model
• ??????????????????????????????????????????????????
  ?????????

22

• ????????
• ??????????????????????????????????????????????????
  ?
• ??????????????????????????????????????????????????
  ??????????
• ??????????????????????????????????????????????????
  ????????????????

23
Interpretation of data analysis

• ??? 10 significance level ????? power
  ????????????????????? ??????????????????????????
  (26 ????)
• ??????????????
• ???????????????????????????????????
  ???????????????????????????????? --gt multivariate
  analysis ???????????? confounding
  ????????????????????????????????

24

• ?????????????????????????????????????????? ???
• ????????????????????????????????????
• ????????????
• ??????????????????
• ?????????????????? (?????????????????????)
• passive immunity ???????????
• disinfection ????????????????? ?????????

25
Testing hypotheses

• ?? clinical trial ???????????????????? (E. coli)
  ????????????????????????? ??????? passive
  immunity ????????

26
Economic evaluation

• preweaning mortality ???????? 19 ??????????
  11.5 --gt 7.5 ???????????????????????????????
• mortality ???????????? 7.5 ??????????????????????
  ????????? 253 ??? ??? 19 ??? ?????????????????
  1 ??? (5) ?????????????, ???????? 18
  ?????????????
• ????????? ?????????????????????????? 7 ????????
  --gt 1.8 ???? (7) ???????????????????????? 26
  ??????????????????????, ????????????????? 8 ????
  (31) ??? 26 ???? ???????????????????????

27

• opportunity costs ????????? 18 ??? 18 35
  630
• treatment cost ????????????? 6 ???? 6 10
  60
• total of 690 --gt 26.50/??????????????
• ????????????????????
• 5 for vaccine ????????? 0.30 5.30
• benefit/cost ratio 26.5/5.3 5

28
Control measures

• ?? clinical trial ????????????????? E. coli
  ?????????
• investigate spatial pattern (??? ?????????
  ????????????????????????????)
• ??????????????????????????????????????????????????
  ????????????????????????????????
  ???????????????????????????
• ????????????
• ??????????????????????????????????
• ???????????????????????

29

• ??????????????????????????????????????????????????
  ???????????? (MMA) --gt ?????????? impact
  ??????????????????????????????? (???????????? 2
  ??????????)
• surveillance ?????
• ??????????????????????????????????????????
• ???????????????