Copyright is owned by the Author of the thesis. Permission is given for
a copy to be downloaded by an individual for the purpose of research and
private study only. The thesis may not be reproduced elsewhere without
the permission of the Author.
Copyright is owned by the Author of the thesis. Permission is given for
a copy to be downloaded by an individual for the purpose of research and
private study only. The thesis may not be reproduced elsewhere without
the permission of the Author.
AN EVALUATION OF ABATTOI R DATA FOR DISEASE SURVE ILLANCE.
This thesis rep re sents 70% of the as ses sment requirements for the degree of Mas ter of Philosophy at Mas sey Unive rs ity.
RI CARDO FERRE MARERO 1980
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AB STRACT
Data from abattoirs were evaluated to determine their use fulnes s for disease surve illance . Self-acquire d data from three surveys
conducted at abat toirs and routine ly gene rated dis eas e s tatis tics from meat export s laughterhous es we re analys e d .
Three techniq ues were emp loyed in the analysis o f these availab le data from New Zealand abat toirs . Re turns from a large scale survey of bovine ocular s quamous ce ll carcinoma were indexed on print ed cards as a filing system and t hose from the s e ro logical surveys of two separate groups of abattoir workers were conve rted into computer system files . The "pencil and paper"-calculator me tho d was used for t he recorded disease s tatis tics.
Convers ion of survey re turns into system files facilitat ed t he handling of data . Manual sorting in a card index sys t em provide d new information on the epidemiology and e conomic imp ort ance of s quamous
ce ll carcinoma o f the bovine eye in New Zealand. The rate o f " cance r eye "
in Herefords and He reford crosses was 403/100,000 compared to 8/100,000 in other b ree ds . Further investigat ions indicated that these dif ferences were associated wit h pigmentation of t he ocular structures .
The data from the sero logical surveys among abat toir workers we re convenient ly manipulated in the comput er and provided information of t he risk factors involve d in three potential zoonoses at t he works . Both leptos pirosis and bruce llos-is were s hown to b e occupational hazards . In t he cas e of leptospiros·is, direct pig contact app eared to cons t itute
the great e s t risk, while in b ruce l losis, one of the more important
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corre lations was in re lat ion to time emp loye d in the Meat Indus try . Toxop lasmos is did no t appear to be an occupational disease .
The information derived on these files were dependent on the manne r o f organisation (e.g. e s t ablishing variab les from meas urements , coding value s ) of the data originally ob taine d from the disease surveys carried out by others .
Routine ly gene rat ed vital s t atis tics o f the p revalence of ''Diseases and Defects" recorded by the Me at Division of the Ministry o f Agriculture and Fisheries we re examine d and analysed . Analysis o f variance t es ts we re applied to s elected conditions to determine re gional variat ions . The app lication o f s tatis tical tes ts uncove re d the s ubtle ties of each group of data and reveale d information on diseas e prevalences. True geo graphical variations in the prevalence of sarcocys ts , cas eous lymphade nitis and
p le urisy o f sheep we re demons trate d .
Th rough these techniques us e ful information was derived from data generated by these three disease surveys carrie d out at the abat toir and from routinely recorde d meat ins pection s tatis tics . Information ob taine d f rom the surveys is discus s e d in re lat ion to previous s tudies on the same topics. Routinely recorded vital s tatis tics we re app raise d f o r accuracy and their use fulne s s i n s tudying variations in d isease
prevalence . The evaluation o f data and information ob tained during these inve s tigat ions manifests the potential of the abat t oir as a s ource of use ful information for diseas e su rveillance .
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ACKNOWLEDGEMENTS
I am grate ful to the New Zealand government and her Ministry o f Foreign Af fairs for giving me this opp ortunity , as a grante e o f the Philippine government , of having s tudied at the Department of
Ve terinary Pathology and Public Health at Mas sey University .
Many thanks are extended to my supervisors : Profe ssor D . K . Blackmore for his continuous and untiring guidance throughout my work , to Mr . G . V . Petersen for his inspiring patience and tutorship and his arrangements for Meat Divis ion materials and visits at the local works , and to the late Dr . R.E . Harris whose ins tructions in computer analysis and kindness will be remembe red .
The cons tructive advice and timely help prof fered by Dr . Linda Schollum and the e xpert typing of the thesis by Mrs . Allain Scott are warmly app reciated .
Many acquaintances and friends have directly and indirectly helped
me in my work : thos e from the dif ferent departments of the Faculty of Ve terinary Science who were keenly recep tive to my e nquiries and
requests; t he t houghtful and genial peop le of the Animal Health Division of Palmers ton North; the able ve terinarians , skillful me at inspectors , chee rful meat workers and accommodating memb��s of the managerial s taffs at Longburn, Fe ilding and Gisborne meat works; the honest p eople casually met , and new friends who have made my soj ourn worthwhile . I e xt end to them my s inceres t gratitude .
And to my great folks at home who have always believed in me , to my wife who has endured this all and to my kids who wondered why I had to
s t udy in New Zealand , this work is dedicated.
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CONTENTS
ABSTRACT
ACKNOWLEDGEMENTS LIST OF FIGURES LIST OF TABLES
EXAMPLES OF PROGRAMS , PRINTOUTS AND COMPUTATIONS GENERAL INTRODUCTION
CHAPTER I : ANALYSIS OF MEAT WORKS " CANCER EYE "
SURVEY IN NEW ZEALAND Introduction
Materials and Methods Results
Discuss ion
A. S igni ficance of f indings 1 . Breed
2 . Sex
3 . Pigmentation 4. Age
5 . Site of origin
6 . Evidence of malignancy B . An evaluation of the survey
Page ii iv vii viii ix 1
7 7 8 1 3 25 25 25 26 26 28 28 28 29 CHAPTER II : APPLYING THE COMPUTER IN DATA ANALYSIS 33
Introduction 33
A brief background and general aims of the
serological surveys 35
Preparing survey data for SPSS input 3 6
The data base 36
Estab lishing variab les from the files 3 6 Determining values o f variables 36 As s igning variables' code names and
numeric values 37
Constructing the codebooks 3 7
Data coding 3 7
Copying the data f iles onto the input medium 39 Storing the data f iles as SPSS system files 39
Converting the INSPECTOR data f ile into
an SPSS system file 40
Converting the MEATWORKER data file into
an SPSS system file 44
Acces s ing the system files 45
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Page
Types of analysis performed 4 6
1 . Disp laying frequency distribution of variables 4 6 2 . Measur ing association through cros stabulation 48
Summary of results 5 1
Discuss ion 5 8
Lep tospirosis 58
Bruce llosis 58
Toxop lasmosis 60
An assessment of the use of the computer 6 1 CHAPTER Ill : VITAL STATISTICS FROM MEAT WORKS 6 3
Introduction 6 3
Part A : An assessment of a recorded vital statistic at a local works - sheep arthritis 68
Mater ials and methods 69
Results and dis cussion 70
Part B : An evaluation of the 1 9 78-9 Meat Division
vital sbatistics from meat works 74
Mater ials and metho ds 75
Results 82
Discuss ion 82
Ovine arthritis 85
Cysticercus avis 88
Caseous lymphadenitis o f sheep and lamb s 89 Pleuri sy of sheep , lamb s and cattle 90
Sarcocysts of sheep 9 1
Actinoform lesions 9 3
Conclus ion 94
GENERAL DISCUSS ION 9 6
REFERENCES 101
APPENDICES 107
Figure 1 2
3
4
5
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LIST OF FIGURES
An AZ6 4 printed card with data entered
Distribution o f "cancer eye " cases by county from three meat works in the North Is land
Dis tribution of " cancer eye" cases by county from three meat works in the South Is land
Distribution o f 42 meat works , indicated as M . E . numbers , according to regions in the North and South Is lands of New Zealand
Minis try o f Agriculture and Fisheries of control
lines
6 Format of the Diseases and De fects prevalence report
7 Reg ional p ercent prevalence o f some d iseases of sheep , lamb s and cat t le
Page
10
23
24
64
6 6
7 6
87
Tab le 1 2 3 4
5
6
7
8 9 1 0 11 1 2
- v i i i - LIST OF TABLES
"Cancer eye " survey tally sheet
"Cancer eye " attack rates Adjusted breed specific rates Eye p i gmentation of cattle at Feild ing and Longburn meat works Pigmentat ion of the eyelid of catt le at Gisborne meat works
Pigmentat ion of the third eyelid of cat t le at Gisborne meat works
Pigmentation of the sclera of cat t le at Gisborne meat works Stock s laughtered at the works
Number of variables in the data f iles
Summary o f analysis performed on the data files Distribut ion of external vis ib le and palpable abnormalities of 1 18 joint s
Distribut ion of internal vis ible les ions of 1 18 jo int s
13 Meat works 19 78-79 Vital Statist ics Mean , minimum and maximum percent prevalence of Diseases and Defects 14
15
1 6
Regional means and their standard errors of p ercent prevalence of arthrit is , Cys t icercus ovis , caseous lymphadenit is , p leurisy and sarcocys ts o f sheep
Reg ional means and their s tandard errors of p ercent preva lence of arthri t is , Cys t i cercus ovis , caseous lymphadenitis , and p leurisy of lambs
Regional means and the ir standard errors of percent p revalence of act inoform les ions and pleurisy of cat t le
Page 14 15 1 7 18
20
2 1
2 1 38 5 6 5 6 7 1 7 3
78
83
84
86
Examp le 1
2 3
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EXAMPLES OF PROGRAMS , PRINTOUTS AND COMPUTATIONS
Program to generat e an SPSS sys tem file for INSPECTOR data
Saving file RLLEM Saving file MEATWORKER
4 Frequency dist ribut ion of cases for variables WOCONP ( contact wi th p igs at the works ) and WOCONG ( contact wi th goats at the works ) in INSPECTOR file
5-A Program segment request ing frequency distribut ion o f variable BRSAT ( Brucella standard agglut ination tes t ) , opt ions and statist ics , and frequency distribut ion o f BRSAT i n INSPECTOR file
5-B Succeeding page to Examp le 5-A showing his togram of BRSAT ' s values and the summary statis t i c s reques ted for BRSAT
6 Cross tabulat ion o f variables LEPPOM (pomona t itre s ) and PCON (pig contac t in and outside
Page
4 1 42 42
47
4 9
5 0
the works ) i n INSPECTOR file 52
7 Cross tabulat ion o f var iables WOCONG ( contact with p igs at the wo rks ) and BRSAT (Brucella
standard agglut inat ion tes t ) after reclassifying the var iable s ' values in INSPECTOR file
8 Printout port ion o f a program run relat ing var iables WOCONG ( contact with goats at the works ) , BRSAT ( Brucella standard agglut inat ion
t e s t ) and WORKEMP (works of emp loyment ) in
5 3
INSPECTOR file 55
9 Analysis o f var iance computations o f percent
p revalence o f arthritis o f sheep 80
