EFFECTS OF VITAMIN A SUPPLEMENTATION ON INTESTINAL
PARASITIC REINFECTIONS, GROWTH, IRON STATUS AND
EDUCATIONAL ACHIEVEMENT AMONG ORANG ASLI
SCHOOLCHILDREN IN POS BETAU,
PAHANG, MALAYSIA
HESHAM MAHYOUB S. AL-MEKHLAFI
FACULTY OF MEDICINE
UNIVERSITY OF MALAYA
KUALA LUMPUR
AUGUST 2008
2
EFFECTS OF VITAMIN A SUPPLEMENTATION ON INTESTINAL
PARASITIC REINFECTIONS, GROWTH, IRON STATUS AND
EDUCATIONAL ACHIEVEMENT AMONG ORANG ASLI
SCHOOLCHILDREN IN POS BETAU,
PAHANG, MALAYSIA
HESHAM MAHYOUB S. AL-MEKHLAFI
THESIS SUBMITTED IN FULFILMENT OF THE
REQUIREMENTS FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY
FACULTY OF MEDICINE
UNIVERSITY OF MALAYA
KUALA LUMPUR
AUGUST 2008
i
ABSTRACT
Intestinal parasitic infections, malnutrition and iron deficiency anaemia (IDA) are
still considered as public health problems in rural Malaysia especially among Orang
Asli children. Despite intermittent control programmes, the prevalence of these
problems is still high suggesting the need of other control and interventions
measures. This randomized double-blind, placebo-controlled trial was carried out
among Orang Asli schoolchildren from Sekolah Kebangsaan Betau in Pos Betau,
Pahang (200 km northeast Kuala Lumpur) to investigate the effects of vitamin A
supplementation on intestinal parasitic reinfections, growth, iron status and
educational achievement. Two hundred and ninety two children (145 males and 147
females) aged 7-12 years were screened for intestinal parasitic infections using Kato
Katz and Harada Mori techniques and trichrome staining technique. Demographic
and socioeconomic data were collected using pre-tested questionnaires. Almost all
children (98.6%) were found to be infected with one or more soil-transmitted
helminthes (STH). The overall prevalence of ascariasis, trichuriasis and hookworm
infections were 67.8%, 95.5% and 13.4% respectively. Almost one third of the
children had heavy trichuriasis, 22.3% had heavy ascariasis whereas all hookworm
infections were light infections. The prevalence of giardiasis was 17.8%. Nutritional
status of these children were assessed and the results showed that the overall
prevalence of mild and significant underweight was 52.3% and 37.3% respectively
and the prevalence of mild stunting and wasting was 43.6% and 43.1% respectively
while the prevalence of significant stunting and wasting was 43.6% and 5.6%
respectively. Blood samples were collected from 241 children to study the serum iron
and vitamin A status. Overall, 48.5% of the children were anaemic (Hb <12 g/dL).
The prevalence of IDA (Hb<12 g/dL, SI<10.74 µmol/L, TIBC>73.39 µmol/L and/or
%TS<16) was 34%, which accounted for 70.1% of the anaemic cases. Moreover, 66
(27.4%) children had serum retinol <0.70 µmol/L. Cognitive function and
educational achievement of these children were assessed and found to be poor. All
these assessments for intestinal parasitic infections, nutritional status, serum iron and
vitamin A status, cognitive function and educational achievement were considered as
the baseline data. Two hundred and fifty children were randomly assigned to receive
either vitamin A capsule or its identical placebo. The effects of vitamin A
supplementation were investigated over periods of 3 and 6 months after receiving the
capsules. All children received anthelmintics treatments for three days and complete
ii
deworming was achieved. The vitamin A supplementation showed no significant
effect on the STH reinfection among these children. However, prevalence of
giardiasis among vitamin A supplemented-children was significantly lower than
children in placebo group. Vitamin A supplementation showed significant positive
impacts on the growth (weight and height) of the children after 3 and 6 months.
Similarly, vitamin A supplementation significantly improved the iron and vitamin A
status compared with children who received placebo. The IQ increments in vitamin
A supplemented-children were significantly higher than in control children. The
positive effects of vitamin A supplementation could be attributed to its effects on the
immunity status of the children. In conclusion, although the positive effect of vitamin
A supplementation on intestinal parasitic reinfections was limited and parasite-
specific, but distribution of vitamin A to Orang Asli children is important to control
malnutrition and IDA; as it has significant positive effects on growth and serum iron
status. Public health personnel need to re-look at the current control measures and
identify innovative and integrated ways in order to reduce these health problems
significantly in the Orang Asli communities. Periodic distribution of anthelmintic
and vitamin A supplementation appeared to have promising effects on the health
status of the children that can help in the efforts to improve the quality of life of
Orang Asli children.
iii
KESAN TAMBAHAN VITAMIN A TERHADAP RE-INFEKSI PARASIT USUS, PERTUMBUHAN, SERUM ZAT BESI, FUNGSI PEMBELAJARAN PADA
KANAK-KANAK ORANG ASLI DI POS BETAU, PAHANG, MALAYSIA
ABSTRAK
Infeksi parasit usus, malnutrisi dan anemia kekurangan zat besi (IDA) merupakan
masalah kesihatan awam dan adalah tinggi di perkampungan luar bandar di
Malaysia khususnya di kalangan kanak-kanak Orang Asli. Walaupun wujud
program-program tidak berterusan untuk pencegahan tapi prevalens infeksi ini
masih tinggi. Kajian intervensi ini ialah ujian perbandingan placebo kabur rawak-
rambang telah dilakukan ke atas kanak-kanak Orang Asli di Sekolah Kebangsaan
Betau, Pos Betau, Pahang, Malaysia untuk menentukan kesan tambahan vitamin A
terhadap reinfeksi parasit usus, pertumbuhan, zat besi dan fungsi kognitif dan
pembelajaran. Dua ratus sembilan puluh dua orang kanak-kanak (145 lelaki dan
147 perempuan) berumur antara 7 hingga 12 tahun telah diperiksa untuk infeksi
parasit usus dengan teknik Kato Katz, Harada Mori dan diwarnakan dengan
trikrom. Demografi dan sosioekonomi data dikutip dengan soal selidik. Hasil
kajian mendapati semua 288 (98.6%) kanak-kanak terinfeksi dengan helmin
tularan tanah (HTT). Prevalens askariasis, trikuriasis dan infeksi cacing kait
masing-masing adalah 67.8%, 95.5% dan 13.4% dengan 30% dan 22.3% kanak-
kanak masing-masing mengalami infeksi berat Ascaris dan Trichuris. Semua
infeksi cacing kait adalah rendah. Prevalens giardiasis adalah 17.8%. Status
nutriasi kanak-kanak ini dinilai dan hasil penilaian menunjukkan bahawa
keseluruhan prevalens kekurangan berat badan yang ringan dan yang signifikan
masing-masing adalah 52.3% dan 37.3%. Prevalens kebantutan yang ringan adalah
43.6% sementara kebantutan yang signifikan adalah 43.6%. Kekekekan ringan dan
signifikan masing-masing didapati pada 43.1% dan 5.6% kanak-kanak ini. Sampel
darah dikutip daripada 241 orang kanak-kanak dan 34% daripada kanak-kanak ini
mengalami IDA yang bertanggung jawab ke atas 70.1% anemia pada kanak-kanak
ini. 27.4% daripada kanak-kanak ini mempunyai paras serum retinol kurang
daripada <0.70 µmol/L. Fungsi kognitif dan pembelajaran pada kanak-kanak ini
adalah lemah. Dua ratus lima puluh orang kanak-kanak telah secara rambang
ditetapkan menerima kapsul vitamin A atau plasebo yang serupa dan kesan
tambahan vitamin A telah menentukan pada 3 dan 6 bulan selepas diberi capsul.
Semua kanak-kanak diterima ubat Albendazole untuk cacing selama tiga hari.
iv
Kajian ini mendapati tidak terdapat perbezaan yang signifikan antara prevalens
infeksi helmin tularan tanah antara kanak-kanak yang diberi tambahan vitamin A
dengan mereka yang diberi plasebo. Terdapat perbezaan prevalens giardiasis yang
signifikan rendah antara kanak-kanak yang diterima tambahan vitamin A.
Tambahan vitamin A ada kesan positif terhadap pertumbuhan (berat badan dan
tinggi) pada tempoh 3 dan 6 bulan. Serum zat besi dan serum retinol memberi
pembahan baik dan signifikan antara kanak-kanak yang diberi tambahan vitamin A
bersanding dengan mereka yang diberi plasebo. Kenaikan IQ antara kanak-kanak
yang diberi tambahan vitamin A adalah lebuh tinggi daripada mereka yang diberi
plasebo. Sebab oleh kesan positif ini mungkin merujukkan kesan vitamin A atas
immuniti kanak-kanak ini. Pada kesimpulannya, walaupun kesan tambahan
vitamin A yang positif adalah spesifik parasit tetapi pemberian vitamin A kepada
kanak-kanak Orang Asli adalah penting untuk kawalan dan pencegahan malnutrisi
tenaga-protein, anaemia khususnya IDA dan kekurangan vitamin A dalam
masyarakat Orang Asli ini. Pagawai kesihatan awam perlu mengkaji semula
langkah pengawalan dan kenal pasti cara-cara inovatif dan berintegrasi untuk
mengurangkan masaalah kesihatan di kalangan Orang Asli. Pangagihan ubat anti
helmin yang berkala dan tambahan vitamin A kelihatan mempunyai kesan baik
kepada status kesihatan kanak-kanak yang boleh membantu dalam usaha untuk
mempertingkatkan qualiti hidup kanak-kanak Orang Asli.
v
To my parents, wife and daughters who have been
endless source of strength, encouragement and
happiness throughout my life. May Almighty ALLAH
bless and protect them
vi
AKNOWLEDGMENTS
IN THE NAME OF ALLAH, THE MOST GRACIOUS, THE MOST MERCIFUL
All praise to Allah (SWT) who, alone, brings forgiveness and light and new life to
those who call upon Him; and to Him is the dedication of this thesis.
First and foremost, I would like to express my deepest sense of gratitude to my
supervisor Professor Dr. Johari Surin for taking the initiative to the present work, for
excellent counseling, and for continuous support and encouragement. I also appreciated
his generosity, warmth and sense of humour which were instrumental in making me
confident and making this report possible.
I also would like to thank my co-supervisor Professor Dr. Atiya Abd Sallam for
sharing his tremendous experience within statistics and clinical trials, for expert
guidance, and for his great belief in me. A very special thanks and appreciation goes to
my co-supervisor Professor Dr. Wan Ariffin Abdullah for his valuable guidance and
continuous support and encouragement. I am really grateful to them.
The present work was carried out at the Department of Medical Parasitology,
Faculty of Medicine, University of Malaya. I came into contact with this department
when I was looking for an admission as a PhD student. The friendly, enthusiastic and
scientifically highly qualified milieu at the department made it easy to go on as a PhD
student. It has been a privilege to be part of this department. I thank the head of the
department, Prof. Dr. Rohela Mahmud, staff and all my colleagues.
I acknowledge the financial support for this study by University of Malaya
(Fundamental grant, Vote F grant and PPP grant). I wish to thank the Director and staff
of Institute of Research Management and Consultancy (IPPP) for their cooperation in
managing the research grants. I also wish to extend my thanks to Datuk Rafiah Salim
(Vice-Chancellor of UM), Prof. Dato’ Dr. Mohd Amin Jalaludin (Deputy VC), Prof.
Datin Dr. Norhanom Abdul Wahab (Dean of IPS), Assoc. Prof. Dr. Siti Aisha Hashim
(Deputy Dean IPS), Assoc. Prof. Dr. Md Yusoff (Deputy Dean IPS) and Assoc. Prof.
Dr. Kamila Ghazali (ICR) for their encouragement and motivation during my study.
This research could not have been completed without attentive support of many
persons and organizations. I am very grateful to all of them. I acknowledge my
gratitude to Dr Che Abdullah Hassan from the Ministry of Health for his generous
cooperation in providing the albendazole tablets. I also wish to acknowledge the
vii
cooperation from Tablets (India) Limited, India for manufactured and provided the
vitamin A and placebo capsules.
I am also very thankful to Dr. Yvonne Lim for her valuable guidance and
comments. I would like to thank Prof. Dr. Kamaruddin Mohd Yusoff for his generous
help in retinol analysis using his HPLC machine. I also wish to convey my thanks to
Mr. Mustafa Kassim Abdulazez for his fruitful training on HPLC and his generous
cooperation in retinol analysis. I owe a lot to my colleague Mr. Mohammed A. Mahdy
who helped me during my study especially within the fieldwork. I also wish to convey
my thanks to Mr. Wan Hafiz from UM, Mr. Adel Amran, Mr. Abdulsalam Al-
Mekhlafi, and Mr. Ismail M. Gauth from UKM.
I would like to thank the director of Gombak Hospital, Dr. Sa’iah Abdullah for
her logistic support and Mr. Kim Tai of being the administrative regional coordinator. I
am also grateful to Mr. Mohd Pairol, Mrs. Norainon, Ms. Marina, Ms. Zarifah and Ms.
Maziaty from Clinic Pos Betau for their diligent and fruitful help during the study. My
sincere thanks to the headmaster of Sekolah Kebangsaan Betau, Mr. Nik Hassan Nik
Mat, Mr. Mahadi Talib and all teachers for their fruitful help and of being patient and
generous during the visits and samples collection. I also would like to convey special
thanks to the head of the villages, children and their families for their participation and
cooperation in this study.
To Professor Dr. Norhayati Moktar (UKM), I would like to convey my sincere
gratitude for her continuous support, encouragement and show the scientific way. Prof.
Dr. Norhayati was my supervisor during Master programme and her wise style in
supervision was instrumental in my achievements. To my beloved country, I send my
sincere gratitude to Prof. Dr. Ahmed A. Azazy (Head of Parasitology Department,
Sana’a University), Assoc. Prof. Dr. Yahya Raja’a, Prof. Dr. Mohammed Sarhan
Khalid, Assoc. Prof. Dr. Abdullah Mohammed Ali and Dr. Mohammed Nagi Al-Doais
for their continuous guidance and support. I am also grateful to Sana’a University,
Yemen for awarding me the scholarship to pursue my postgraduate study.
Last but not least, my heartfelt appreciation and gratefulness are dedicated to
my parents Mr. Mahyoub Sarhan and Mrs. Molk Ahmed, my beloved wife Taghreed,
daughters: Halah, Sama’a and Nor Al-Qamar, and my uncle Dr. Mohammed Sarhan for
their constant prayers, love, encouragement and moral support rendered to me during
all the period toward this substantial achievement.
viii
CONTENTS
Page ABSTRACT i ABSTRAK iii DEDICATION v ACKNOWLEDGEMENTS vi CONTENTS viii LIST OF FIGURES xv LIST OF TABLES xvi LIST OF SYMBOLS AND ABBREVIATIONS xx
CHAPTER I INTRODUCTION 1
1.1 1.2
Objectives of the study Hypotheses
5 6
CHAPTER II LITERATURE REVIEW
2.1 Intestinal parasitic infections 8 2.1.1 Global prevalence of intestinal parasitic infections 8 2.1.2 Prevalence of intestinal parasitic infections in
Malaysia 12
2.1.3 Risk factors of intestinal parasitic infections 14 2.1.4 Reinfection with intestinal parasites 18 2.2 Vitamin A 19 2.2.1 Definition and importance 19 2.2.2 Sources and metabolism 19 2.2.3 Vitamin A deficiency (VAD) 20 2.2.4 Definition of VAD 20 2.2.5. Assessment of VAD 21 2.2.6 Risk factors of VAD 22 2.2.7 Global prevalence of VAD 24 2.2.8 Prevalence of VAD in Malaysia 27 2.2.9 Control of VAD 28 2.3 Protein-energy malnutrition (PEM) 33 2.3.1 Definition of PEM 33 2.3.2 Assessments of PEM 33 2.3.3 Risk factors of PEM 34 2.3.4 Global prevalence of PEM 37 2.3.5 Prevalence of PEM in Malaysia 39 2.4 Iron 41 2.4.1 Definition and importance 41 2.4.2 Sources 41 2.4.3 Anaemia and iron deficiency anaemia (IDA) 42 2.4.3.1 Definition of anaemia and IDA 42 2.4.3.2 Development and classification of IDA 43 2.4.3.3 Assessment of anaemia and IDA 43 2.4.3.4 Risk factors of anaemia and IDA 44 2.4.3.5 Global prevalence of anaemia and IDA 47
ix
Page 2.4.3.6 Prevalence of anaemia and IDA in Malaysia 48 2.5 Vitamin A and parasitic infections 50
2.5.1 Relationship between vitamin A and parasitic infections
50
2.5.2 Effects of vitamin A supplementations on parasitic infections
53
2.6 Vitamin A and growth 61 2.7 Vitamin A and iron status 67 2.8 Vitamin A, cognitive functions and educational achievement 71
2.8.1 Definition of cognitive functions and educational achievement
71
2.8.2 Assessment of cognitive functions and educational achievement
71
2.8.3 Risk factors of poor cognitive functions and educational achievement
71
2.8.4 Effects of vitamin A on cognitive function and educational achievement
73
CHAPTER III METHODOLOGY
3.1 An overview and the country profile 77
3.2 Orang Asli population 78
3.2.1 Demographic overview 78
3.2.2 Health profile 82
3.2.3 Education profile 83
3.3 Study area 84 3.3.1 Selection of the study area 86
3.4 Study population 86
3.4.1 Selection of subjects 86
3.4.2 Sample size 87
3.5 Study design and randomization 89
3.6 Pre-testing of study instruments 91
3.7 Description of study design and data collection 91
3.8 Data collection 94
3.8.1 Field work strategy 94
3.8.2 Preliminary data 95
x
Page 3.8.3 Anthropometric measurements 95 3.8.4 Laboratory examination and interpretation of
results 96
3.8.4.1 Faecal examination 96 A Examination of faecal samples (Baseline
screening) 96
B Re-examination after deworming with albendazole 98 C Cure and reinfection rates 98
3.8.4.2 Blood examination 98 A Hematological studies 99 B Biochemical studies. 99 3.9 Cognitive functions assessment 101 3.9.1 Description of TONI-3 102 3.9.2 Testing procedures of TONI-3 102 3.10 Educational achievement assessment 104 3.11 Nutrient intakes 104 3.12 Deworming 106 3.12.1 Description of anthelmintic treatment 106 3.12.2 Distribution and provision of anthelmintic
treatment 106
3.13 Vitamin A supplementation 107 3.13.1 Description of vitamin A supplements and
placebos 107
3.13.2 Distribution and provision of interventions 107 3.14 Why vitamin A supplements? 108 3.15 Description of follow-up and drop out 110 3.16 Definition of variables 113 3.17 Data management and statistical analysis 115 3.18 Ethical consideration 119 3.19 Limitations 120
CHAPTER IV RESULTS
4.1 General characteristics of study population 121 4.2 General baseline of study subjects involved in the trial 122 4.3 Intestinal parasitic infections 124 4.3.1 Prevalence and distribution of STH 124 4.3.2 Intensity of STH 126 4.3.3 Correlation of means epg of STH according to
gender and age 128
4.3.4 Risk factors associated with STH 129
xi
Page A Potential risk factors associated with prevalence of
A. lumbricoides – univariate analysis 129
B Potential risk factors associated with prevalence of A. lumbricoides – multivariate analysis
131
C Potential risk factors associated with intensity of A. lumbricoides - univariate and multiple linear regression analysis
132
4.3.5 Prevalence of giardiasis 134 4.4 Efficacy of albendazole on the prevalence and intensity of
intestinal parasitic infections 135
4.5 Pattern and predictors of soil-transmitted helminth reinfections
137
4.5.1 Potential predictors associated with STH reinfections - univariate and multivariate analysis
139
4.6 Effects of vitamin A supplementation on intestinal parasitic reinfections
141
4.6.1 Effects of vitamin A supplementation on the reinfection rates of intestinal parasitic infections 3 months after interventions
141
4.6.2 Effects of vitamin A supplementation on the reinfection rates of intestinal parasitic infections 6 months after interventions
141
4.6.3 Effects of vitamin A supplementation on the reinfection intensities of STH 3 months after interventions
144
4.6.4 Effects of vitamin A supplementation on the reinfection intensities of STH 6 months after interventions
144
4.6.5 Mixed between-within subjects analysis of variance (Repeated measures ANOVA)
146
4.7 Nutritional status 148 4.7.1 Anthropometric characteristics of subjects 148 4.7.2 Prevalence of protein-energy malnutrition 150 4.7.3 Predictors of PEM – univariate analysis 150 4.7.4 Predictors of PEM–multivariate analysis 154 4.8 Effects of vitamin A supplementation on growth 156 4.8.1 Baseline anthropometric characteristics of vitamin
A and placebo groups 156
4.8.2 Correlation between serum retinol and growth parameters
157
4.8.3 Effects of vitamin A supplementation on growth 158 4.8.4 Effects of vitamin A supplementation on growth 3
months after intervention 158
4.8.5 Effects of vitamin A supplementation on growth 6 months after intervention
159
xii
Page 4.9 Iron status 165 4.9.1 Characteristics of subjects 165
4.9.2 Prevalence of anaemia and IDA 165 4.9.3 Correlations between serum iron indices 166
4.9.4 Predictors of low concentrations of serum iron indices– univariate and multivariate analyses
168
4.9.5 Predictors of IDA – univariate analyses 171
4.9.6 Predictors of IDA – multivariate analyses 171 4.10 Effects of vitamin A supplementation on iron status 173 4.10.1 Baseline characteristics of the intervention groups 173 4.10.2 Relationship between serum retinol and serum
iron indices 175
4.10.3 Effects of vitamin A supplementation on iron status after three months
177
4.11 Cognitive functions and educational achievement 182
4.11.1 Characteristics of subjects 182 4.11.2 Correlation between variables used to assess the
cognitive functions and educational achievement of children
184
4.11.3 Predictors of low cognitive functions and low educational achievement of Orang Asli schoolchildren - univariate and multivariate analyses
185
4.12 Effects of vitamin A supplementation on cognitive functions and educational achievement
187
4.12.1 Baseline characteristics of the subjects in vitamin A and placebo groups
187
4.12.2 Effects of vitamin A supplementation on cognitive functions and educational achievement 3 months after intervention
188
4.12.3 Effects of vitamin A supplementation on cognitive functions and educational achievement after controlling for baseline status
191
4.13 Vitamin A status 193
4.13.1 Prevalence and distribution of low serum retinol 193 4.13.2 Predictors of low serum retinol–univariate and
multivariate analyses 195
4.14 Effects of vitamin A supplementation on serum retinol status 197 4.14.1 Effects of vitamin A supplementation on serum
retinol level 3 months after intervention 197
4.15 Nutrient intakes 200
xiii
Page
CHAPTER V DISCUSSION
5.1 Intestinal parasitic infections 206 5.1.1 Prevalence and distribution of STH 207 5.1.2 Risk factors associated with STH 210 5.1.3 Prevalence of giardiasis 213 5.2 Effects of a 3-day course albendazole 214 5.3 Intestinal parasitic reinfections - pattern and predictors 216 5.4 Effects of vitamin A supplementation on intestinal parasitic
reinfections 218
5.5 Nutritional status 228 5.5.1 Prevalence of PEM 228 5.5.2 Risk factors associated with PEM 229 5.6 Effects of vitamin A supplementation on growth 233 5.7 Serum iron status 241 5.7.1 Prevalence of anaemia and iron deficiency anaemia 241 5.7.2 Predictors of anaemia and IDA 244 5.8 Effects of vitamin A supplementation on serum iron status 248 5.9 Cognitive function and educational chievement 256 5.9.1 Cognitive function and educational achievement
among Orang Asli schoolchildren 256
5.9.2 Determinants of cognitive function and educational achievement
258
5.10 Effects of vitamin A supplementation on cognitive function and educational achievement
262
5.11 Vitamin A status 269 5.11.1 Prevalence of low serum retinol (VAD) 270 5.11.2 Predictors of low serum retinol 272 5.12 Effect of vitamin A supplementation on vitamin A status 277 5.13 Nutrient intakes 283
CHAPTER VI CONCLUSION AND RECOMMENDATIONS
6.1 Conclusion 286 6.2 Recommendations 291 REFERENCES 294 APPENDIX A PHOTOGRAPHS OF POS BETAU SCHOOL (STUDY
AREA) AND CLINIC POS BETAU 328
APPENDIX B PHOTOGRAPHS OF ORANG ASLI CHILDREN CTIVITIES 329
xiv
Page APPENDIX C PHOTOGRAPHS OF FIELD WORK ACTIVITIES 330 APPENDIX D QUESTIONNAIRE 333 APPENDIX E PHOTOGRAPHS OF DIAGNOSTIC TECHNIQUES FOR
INTESTINAL PARASITES 336
APPENDIX F PHOTOGRAPHS OF EGGS OF SOIL-TRANSMITTED HELMINTHS
337
APPENDIX G PHOTOGRAPHS OF DIFFERENT DIAGNOSTIC STAGES OF Giardia duodenalis
339
APPENDIX H SERUM RETINOL MEASURMENT– HPLC 340 APPENDIX I TONI 3 KIT 341 APPENDIX J NUTRIENT INTAKE ASSESSMENT 342 APPENDIX K INTERVENTIONS ( ANTHELMINTIC, VITAMIN A AND
PLACEBO) 343
APPENDIX L PHOTOGRAPHS OF ORANG ASLI VILLAGES AND HOUSES
344
APPENDIX M PUBLICATIONS AND PRESENTATIONS 346
xv
LIST OF FIGURES
Figure No
Title Page
2.1 Priority countries for vitamin A supplementation 29
2.2 Country-level coverage of vitamin A supplementation, 2004 30
2.3 Effects of parasitic infections on the host which may impair
nutritional status
36
3.1 Map of Malaysia 77
3.2 Distribution of various Orang Asli subgroups in Peninsular Malaysia 80
3.3 Map of Pos Betau showing the location of the school and villages
involved in the study (Study area)
85
3.4 Flow chart of the study 90
3.5 Flow chart of data collection and follow up 112
4.1 Prevalence of ascariasis, trichuriasis and hookworm infections
according to type of infections (n=292)
125
4.2 The frequency of eggs/gm of A. lumbricoides among Orang Asli
schoolchildren in Pos Betau, Pahang (n=292)
126
4.3 The frequency of eggs/gm of T. trichiura among Orang Asli school
children in Pos Betau, Pahang (n=292)
127
4.4 The frequency of eggs/gm of hookworm among Orang Asli school
children in Pos Betau, Pahang (n=292)
127
4.5 Effects of interventions (vitamin A and placebo) and time on intensity
of reinfection with STH at 3 and 6 months post-intervention using
mixed between-within repeated-measures ANOVA
147
4.6 Three months weight and height increments of Orang Asli school
children by initial serum retinol concentrations and treatment groups
164
4.7 Six months weight and height increments of Orang Asli school
children by initial serum retinol concentrations and treatment groups
164
4.8 Intelligence quotient (IQ) of Orang Asli schoolchildren in Pos Betau,
Pahang (n=241)
183
4.9 Effects of vitamin A supplementation on cognitive functions (IQ
scores) 3 months after intervention (n=241)
189
4.10 Effects of vitamin A supplementation on educational achievement (TS
scores) 3 months after intervention (n=250)
190
xvi
LIST OF TABLES
Table No. Title Page
2.1 Different stages of iron deficiency anaemia (IDA) 43
2.2 Studies on the effects of micronutrients on parasitic infections and
reinfections
59
2.3 Studies on the effects of micronutrients on growth (weight and
height) of children
64
2.4 Studies on the effects of micronutrients on haemoglobin and serum
iron status of children
69
2.5 Studies on the effects of micronutrients and deworming on
cognitive functions and educational achievement of children
74
3.1 Orang Asli population breakdown as of December 2003 79
3.2 Geographical distribution of Orang Asli villages as of December
2003
81
3.3 Severity of soil-transmitted helminthiases according to eggs per
gram faeces
97
3.4 Serum iron status classification 101
4.1 Age distribution of schoolchildren participated in this study 122
4.2 Baseline characteristics of the intervention groups 123
4.3 Prevalence of ascariasis, trichuriasis and hookworm infections
according to intensity of infections and gender (n=292)
125
4.4 Correlation of mean epg of A. lumbricoides, T. trichiura and
hookworm according to gender and age (n=292)
129
4.5 Odds ratios for potential risk factors associated with ascariasis
among Orang Asli schoolchildren in Pos Betau, Pahang (n=292)
130
4.6 Logistic regression analysis for the potential risk factors associated
with ascariasis among Orang Asli schoolchildren in Pos Betau,
Pahang (n=292)
131
4.7 Univariate analysis for the potential risk factors associated with
intensity of A. lumbricoides among Orang Asli schoolchildren in
Pos Betau (n=292)
133
4.8 Multiple linear regression analysis for the potential risk factors
associated with intensity of A. lumbricoides among Orang Asli
schoolchildren in Pos Betau, Pahang (n=292)
134
xvii
Table No. Title Page
4.9 Prevalence of giardiasis among Orang Asli primary schoolchildren
in Pos Betau, Pahang according to age and gender (n=292)
135
4.10 Effects of a 3-day course of 400mg albendazole daily on the
prevalence and intensity of intestinal parasitic infections among
Orang Asli schoolchildren in Pos Betau, Pahang (n=292)
136
4.11 Reinfection rates and reinfection intensities of STH 6 months after
deworming among Orang Asli schoolchildren in Pos Betau, Pahang
(n=120)
138
4.12 Predictors associated with STH reinfections among Orang Asli
schoolchildren in Pos Betau, Pahang (n=292)
140
4.13 Effects of vitamin A supplementation on reinfection rates of STH
and Giardia after 3 months among Orang Asli schoolchildren in
Pos Betau, Pahang
142
4.14 Effects of vitamin A supplementation on reinfection rates of STH
and Giardia after 6 months among Orang Asli schoolchildren in
Pos Betau, Pahang
143
4.15 Effects of vitamin A supplementation on STH reinfection
intensities 3 and 6 months after interventions among Orang Asli
schoolchildren in Pos Betau
145
4.16 Anthropometric characteristics of Orang Asli schoolchildren in Pos
Betau, Pahang (n=241)
149
4.17 Prevalence of malnutrition among Orang Asli schoolchildren in Pos
Betau, Pahang (n=241)
151
4.18 Univariate analysis for predictors associated with underweight
among Orang Asli schoolchildren in Pos Betau, Pahang (n=241)
152
4.19 Univariate analysis for potential predictors associated with stunting
among Orang Asli schoolchildren in Pos Betau, Pahang (n=241)
153
4.20 Multivariate analysis for predictors of underweight among Orang
Asli schoolchildren in Pos Betau, Pahang (n=241)
154
4.21 Multivariate analysis for predictors of stunting among Orang Asli
schoolchildren in Pos Betau, Pahang (n=241)
155
4.22 Baseline anthropometric characteristics of schoolchildren in the
interventions groups (vitamin A and placebo)
156
xviii
Table No. Title Page
4.23 Correlation between serum retinol and growth parameters at
baseline according to age and gender
157
4.24 Mean changes in anthropometric measurements after 3 months in
vitamin A and placebo groups
159
4.25 Mean changes in anthropometric measurements after 6 months in
vitamin A and placebo groups
160
4.26 Adjusted mean weight increments of schoolchildren in vitamin A
and placebo groups
161
4.27 Adjusted mean height increments of schoolchildren in vitamin A
and placebo groups
162
4.28 Levels of serum iron indices, prevalence of anaemia, ID and IDA
among Orang Asli schoolchildren according to age and gender
(n=241)
167
4.29 Correlation between serum iron indices among Orang Asli
schoolchildren according to age and gender (n=241)
168
4.30 Odds ratios and 95%CI for predictors of low serum iron indices among Orang Asli schoolchildren in Pos Betau (n=241)
170
4.31 Univariate analysis for predictors of IDA among Orang Asli
schoolchildren in Pos Betau, Pahang (n=241)
172
4.32 Multivariate analysis for predictors of IDA among Orang Asli
schoolchildren in Pos Betau, Pahang (n=241)
173
4.33 Baseline iron status of the children in both interventions groups (n=241)
174
4.34 Serum retinol levels at baseline among Orang Asli schoolchildren in Pos Betau, Pahang according to anaemic status
175
4.35 Correlation between serum retinol and serum iron indices at baseline according to age and gender (n=241)
176
4.36 Mean changes in Hb and serum iron indices from baseline 3 months
after intervention in vitamin A and placebo groups
178
4.37 Effects of vitamin A supplementation on prevalence of anaemia and
IDA after 3 months
178
4.38 Adjusted mean changes in Hb and SF among schoolchildren in
vitamin A and placebo groups
180
4.39 Adjusted mean changes in serum iron indices among schoolchildren
in vitamin A and placebo groups
181
xix
Table No. Title Page
4.40 Baseline educational achievement test scores (TS) among Orang
Asli schoolchildren in Pos Betau, Pahang
183
4.41 Correlation between variables used to assess cognitive function and
educational achievement among Orang Asli schoolchildren in Pos
Betau, Pahang
184
4.42 Mean scores of intelligence quotient (IQ) and total educational
achievement (TS) by socioeconomic and health determinants
among Orang Asli schoolchildren in Pos Betau, Pahang
186
4.43 Baseline cognitive performance and educational achievement of
both groups
188
4.44 Analysis of covariance (ANCOVA) of cognitive functions (IQ
scores) after 3 months by type of supplement after controlling for
IQ scores at baseline
191
4.45 Analysis of covariance (ANCOVA) of educational achievement
total score (TS) after 3 months by type of supplement after
controlling for TS scores at baseline
192
4.46 Serum retinol level by age and gender among Orang Asli
schoolchildren in Pos Betau, Pahang, (n=241)
194
4.47 Univariate analysis for predictors of low serum retinol among
Orang Asli schoolchildren in Pos Betau, Pahang (n=241)
196
4.48 Multivariate analysis for predictors of low serum retinol among
Orang Asli schoolchildren in Pos Betau, Pahang (n=241)
197
4.49 Effects of vitamin A supplementation on serum retinol level of
children in the both groups after 3 months
199
4.50 Nutrient intakes by age among Orang Asli schoolchildren in Pos
Betau, Pahang (n=241)
201
4.51 Mean daily nutrient intakes of Orang Asli schoolchildren by gender
(n=241)
202
4.52 Percentage (%) of Orang Asli schoolchildren consuming nutrients
below two-third RDA by age and gender (n=241)
203
4.53 Mean daily nutrient intakes of Orang Asli schoolchildren in vitamin
A and placebo groups at the baseline (n=241)
204
4.54 Mean daily nutrient intakes of Orang Asli schoolchildren in vitamin
A and placebo groups 6 months after interventions (n=241)
205
xx
LIST OF SYMBOLS AND ABBREVIATIONS
cm
χ2
CI
ºC
≥
≤
g/dL
Hb
IQ
IU
IDA
kg
>
P
µg/L
µmol/L
mg
OR
%
%TS
PEM
RDI
SF
SI
SR
<
STH
SD
TIBC
VAD
WHZ
HAZ
WAZ
Centimeter
Chi-square
Confidence interval
Degree centigrade
Equals or larger than
Equals or smaller than
Gram per deciliter
Haemoglobin
Intelligence quotient
International unit
Iron deficiency anaemia
Kilogram
Larger than
Level of significance
Microgram per liter
Micromole per liter
Milligram
Odd ratio
Percent
Percent transferrin saturation
Protein-energy malnutrition
Recommended daily intake
Serum ferritin
Serum iron
Serum retinol
Smaller than
Soil-transmitted helminth
Standard deviation
Total iron binding capacity
Vitamin A deficiency
Z-score for Weight-for-height
Z-scores for height-for-age
Z-scores for weight-for-age
