6 Conclusions and recommendations
6.1 Conclusions
6.1.1 Market structure
A multistage sampling technique was used. From the F.C.T Education Secretariat, the list of all the schools in AMAC was obtained. Ten schools (representing 10 percent of the entire junior secondary schools registered with F.C.T UBE) were selected from the four major districts (Wuse, Garki, Maitaima and Asokoro) by balloting - a form of simple random sampling.114 The schools were unevenly distributed (Wuse district having 36 schools, Garki districts having 31 schools, Maitiama and Asokoro districts having 27 and 20 schools respectively). Three schools were selected from each of the districts with more schools (i.e. Wuse and Garki districts) and two from districts with fewer schools (i.e Maitama and Asokoro districts). Numbers were assigned to the junior secondary schools. These numbers were written on pieces of papers cut into equal sizes. These papers were put into four black bags (representing the districts) and shaken together with the bags covered. Three pieces of paper were picked at random one after the other from the bags (representing Wuse and Garki districts) while two pieces were picked from the bags (representing Maitama and Asokoro districts). Each piece of paper picked was marked and replaced in the bag before the next piece of
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paper was picked to allow equal chances. If the same paper was picked twice, the process was repeated until another paper was picked. The schools that were represented by the numbers on the pieces of papers were used. Thus, 10 junior secondary schools in AMAC were used.
Secondly, the number of students in each of the schools selected was obtained from the school registers, and added to get the total number of students in the sample frame (7,173).
A sample fraction was then calculated as: calculated sample size (N) / total number of students in the sample frame. (1180/7173 = 0.165)
This fraction was multiplied with the total number of students within each school to obtain proportionate sample size (SN) from each school according to the population across each group of selected schools.
Table 1. The number of students required from each selected school for the study School Total population of student Sample size required from each school
(Total student x 0.165)
I 308 51
II 560 92
III 978 161
IV 458 76
V 563 93
VI 1009 166
VII 1172 194
VIII 1156 191
IX 365 61
X 604 100
Thirdly, to have adequate representation of each class group (Class JSS1 to Class JSS3), the sample size for each school was divided by the number of students in the school to obtain a sample fraction that was multiplied with the number of students in each arm. This gave the number of students
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selected from each arm. (Example: in School A, students from each arm was calculated by determining the sample fraction for the school; 51/308=0.167. this fraction was multiplied with total number of students in each arm to determine the number required from each arm).
Lastly, the students were selected from the various classes in each arm according to their sitting position by a random sampling method using a random number table. The first seat by the door was labelled seat one and the others accordingly.
Data collection: This was done by the author and 2 trained field assistants (Medical Doctors- Post internship) who were fluent in English language and “pidgin” English (a language commonly spoken by the students).
Stages of activities in each school:
The researcher had multiple contacts with the subjects during the course of the research;
First contact: Activities included permission from the principal, familiarity with the school teachers, and inspection of the classrooms.
Second contact: Activities included introduction to the students, brief introduction of the study to the students, issuance of consent forms to the students to take home to their parents for approval of their child or ward to participate in the study.
Third contact: Activities included retrieval of consent forms and issuance of assent form to the subjects. Administration of the video questionnaire (AVQ 3.0) and the written questionnaire (for additional information) to the subjects in the class. Education of the students on the proper method of stool collection and issuances of the stool sample collection bottle with spatula to the students.
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Fourth contact: Activities included collection of stool sample bottle and issuance of anti-helminthic medication to the participants.
Determination of Asthma symptoms in the School population
The Video questionnaire was chosen to ensure a uniform understanding of the symptoms and avoid the various misinterpretation of the term “Wheeze” and “Asthma” by the students. A pre-test conducted to validate the video questionnaire for this study involved twenty children aged 10 to 15 years with diagnosed asthma attending the respiratory clinic of National Hospital Abuja, and twenty non-asthmatic children who attended other clinics were recruited, The video questionnaire was administered to the children in the two groups. The sensitivity of the video questionnaire for asthma symptoms were for wheezing (70%) for night cough (75%) and for wheezing and breathlessness (60%). The specificity of the video questionnaire was for wheezing (90%) for night cough (65%) for wheezing and breathlessness (95%).
The subjects were interviewed through a directed validated international version of the Video questionnaire (AVQ 3.0) developed by the International Study on Asthma And Allergy in Childhood (ISAAC) to assess for asthma symptoms. The video showed five scenes with children of different ethnic groups with different manifestations of asthma. Each sequence was followed by two questions asking the respondent
if their breathing had ever been like the person‟s in the video ?
if "yes" "in the last 12 months?" (which implies a recent occurrence)
The first sequence showed a young person seated with clearly audible wheezing, but without breathlessness and no evidence of airway obstruction. Four further sequences are shown in the video: exercise-induced wheezing, waking at night with wheezing, night cough and a final
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sequence showing a young person with breathlessness and wheezing. The specific asthma symptom identified in the children was based on affirmative response to the respective video sequences of the ISAAC video questionnaire. This video was projected in the class after class sessions. The video session lasted seven minutes. The questionnaire attached to the activity projected in the video is attached as appendix 8.
At the end of the video session, the following symptoms of asthma were identified 1. Wheezing (in three different situations)
i) Wheezing at rest
ii) Wheezing after exercise
iii) Waking up at night with wheezing 2. Night cough
3. Wheeze and breathlessness
Additional Information on the bio-data of the students, socioeconomic data of their parents and risk factors for asthma (allergic rhinitis, food allergy, parental smoking, exposure to smoke and ownership of animal pets, flexural skin lesion suggestive of eczema etc.) and intestinal helminthiasis was obtained using a written questionnaire which was self-administered with guidance from the researcher (Appendix 9).
Allergic rhinitis was defined as nasal symptoms (sneezing, runny nose and congestion) accompanied by itchy-watery eyes in the last 12 months not associated with colds.115 Eczema was defined as the presence of itchy red or excessively dry rash at any time affecting any of the following places: the folds of the elbows, behind the knees, in front of the ankles, under the
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buttocks, or around the neck, ears or eyes in the last 12 months.115 Food allergy was defined as sudden occurrence of any of these symptoms following ingestion of a particular food in the past 12 months (hives or itching and swellings of the lips, mouth/skin or repetitive coughing, vomiting, diarrhoea or stomach pains). Parental socio-economic classification was described using the highest educational qualification and occupation of the parents or guardians as described by the method developed by Oyedeji116 illustrated in appendix 10.
Diagnosis of intestinal helminthiasis
All students eligible for the study had their stool tested for intestinal worms. The students were taught how to collect the stool sample themselves at home into a small sized, clean, dry, and leak-proof plastic container with a wide rim and pre-labelled with the subject‟s identification number assigned at recruitment (Picture 1). An early morning stool sample was preferred. A spatula attached to the cover of the stool container was used to collect an aliquot of a freshly passed formed stool by the students. The stool sample was brought in the morning as the child was coming to school, and the researcher with the trained assistants were available in the various schools to collect the stool sample from each student that same morning for analysis in the laboratory.
The modified Kato-Katz technique for stool analysis for helminths, was used for the stool analysis at the Laboratory of the National Hospital Abuja. The stool slide was prepared according to the modified Kato-Katz methods (Appendix 3). The slides were read by the researcher under the microscope within six to twenty four hours after collection of sample and another reading done after twenty four hours. However thirty percent of the slides read were double checked by the medical microbiologist (a senior registrar in medical microbiology) for quality assurance. The laboratory findings were recorded in a Pro-forma for the laboratory result (Appendix 11).
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Assessing the species and intensity of the intestinal helminths
The different species and intensity of Intestinal helminths in all the subjects were determined by viewing the slides under the microscope using ×10 and ×40 objectives of the compound microscope to identify the eggs of the various helminths as well as counting the eggs in each slide. Several criteria were employed in recognizing the worms:
Ascaris lumbricoides eggs were recognized on the basis of the ova being round or elliptical with rough membrane (fertilized) or a bit elongated with rough membrane (unfertilized).
(Picture 2)
Trichuris trichiura ova were identified on the basis of their dark brown colour and smooth shell, oval shape, “plug-like” prominences at each pole and a single-cell ovum. (Picture 3)
Schistosoma mansoni eggs were recognized on the basis of their large size, relatively thin shell with a conspicuous lateral spine. (Picture 4)
Hookworm ova were recognized on the basis of their clear, thin shells and the ovum which is usually in the 4 or 8 cell stage. (Picture 5)
The degree of intensity was obtained in eggs per gram of faeces by counting helminths eggs systematically under the microscope using x40 lens moving the slide from one corner of the cover slip back and forth across and noting the number of eggs found. The figure obtained after counting the eggs was multiplied by a factor of 24 according to the Kato- Katz protocol.99,103 Helminth infection intensities were grouped into
1. light ; A. lumbricoides, 1-4,999 epg; T. trichiura, 1-999 epg, S. mansoni 1-99 epg, Hookworm, 1-1999epg
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2. moderate; A. lumbricoides, 5, 000-49, 999epg; T.trichiura, 1, 000- 9, 999 epg; S.
mansoni 100-399 epg, Hookworm, 2000-3999 epg)
3. Heavy; A. lumbricoides, ≥50, 000 epg; T. trichiura, ≥10,000 epg, S. mansoni >400 epg, hookworm > 4000 epg).
Assessing the
association of helminthic infestation to asthma symptom prevalence
Two groups of subjects – student with asthma symptoms (wheezing, night cough and wheeze and breathlessness) and those without asthma symptoms were identified and compared for the different species of worms and intensity of infestation. Chi square was obtained for the two groups and the values compared. A p-value less than 0.05 was considered to be statistically significant.Multivariate logistic regression analysis on the variables that were found significant was used to determine the strength and direction of the association.