2.2. Liderazgo Educacional 1 Concepto
2.4.1. Valores universales Los mismos que son los siguientes:
The concentration of helminth eggs can be done by means of sedimentation and floatation techniques.59 For helminth egg counts, the floatation techniques has been the most frequently used because it gives more efficient results than the sedimentation techniques.59
a. Ferreira’s Method
This method is based on the concentration of the sample through the floatation technique.59 As a floatation solution, it uses 35 percent zinc sulphate with a density of 1.192g/ml. The sample is placed in a tube and a funnel is
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adapted to it, both are centrifuged and the floating material is placed on a glass slide and a 22 x 40mm coverslip is applied.59 The result of the count is then multiplied by a factor of 5 to obtain the total number of eggs per gram. Its advantage is that in sample with light parasite load, a greater probability of positive results is achieved.59
b. Modified Zinc Sulphate Method
This method involves a previous screening with a volume of water similar to that of the sample, it is centrifuged and extractions are done with mixtures of ethanol – formaldehyde, formaldehyde saline and diethyl-ether.60 Finally, it is re-suspended in the zinc sulphate saturated solution with a density of 1.40, centrifuged again and from the upper part of the tube the sample for analysis is taken.60
The main disadvantage is that it consumes several solutions and much time is spent for processing and analysis of the sample (2-3 hours).61
The ova of intestinal helminths are quite characteristic60 as described subsequently and as shown in Figure 3.
Ascaris lumbricoides – the egg is broadly oval, has thick rough shell with an outer mamillated covering. Each egg contains unsegmented cells with rough granules and measures 45-70m x 35–45m.
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Hookworm – the eggs are ovoid and thin – shelled and each measures 64-80m x 36-40m.
Strongyloides stercoralis – the eggs are thin with smooth shell; each measures 50-76m x 35 - 47m.
Enterobius vermicularis – the egg has thick shell, smooth, and asymmetrical.
The shell consists of 4 layers and each ovum measures 50-60m x 20 - 32m.
Trichuris trichiura – has clearly protruding plugs at each end and each measures 49-65m x 20-30m.
lv Fig 3. Microscopic appearance of ova of gut nematodes.
Source: Brooks G F, Butel J S, Morse S A. Intestinal helminths. In: Jawetz, Melnick and Adelberg’s Medical Microbiology, 21st Edition: 646.
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For less heavy infection and for the detection of helminths which produce low numbers of ova, concentration methods (like the formalin-ether concentration method) are required to improve the sensitivity of the smear examination. Quantitative method may be used to give estimates of worm load eg kato-katz method.61
The finding of nematode larvae in fresh stool is diagnostic of Strongyloides stercoralis. Where the suspicion of Strongyloides stercoralis infection is high but careful stool examination fails to detect larvae, duodenal juice may be sampled for microscopy – where both larvae and ova may be detected.7
Definitive diagnosis of Strongyloides stercoralis can be elusive in an immunocompetent host.62 Diagnosis requires the finding of rhabditiform larvae in samples of stool or duodenal fluid. Because of scanty and irregular egg output by Strongyloides stercoralis, even examination of multiple concentrated stool specimens has a sensitivity of only about 25%.62 Faecal culture is necessary in clinically suspected cases.
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Serum IgE value is often elevated. A sensitive Enzyme-linked immuno sorbent assay (ELISA) serologic test for Strongyloides stercoralis exists but is not generally available.7
The ova of Enterobius vermicularis are most easily demonstrated by the ‘cellotape’ method whereby sticky tape is placed on the perianal folds and then stuck on to a microscope slide.62 The adherent ova are readily seen through the transparent tape by microscope examination.
Fewer than 5% of persons infected with Enterobius vermicularis have eggs in the stools.63 In suspected cases, at least 5 adhesive tape preparations should be taken from the perianal skin on awakening on successive mornings to rule out pinworm infection.63 Eggs are occasionally seen on vaginal pap smear examination. Adult pinworms which resemble small pieces of thread, may be seen with the naked eye on the normal skin or in the stool. 62
Differentiating between the types of hookworm infection is usually important and that can be done by culturing the various larvae using Harada-mori culture technique.61
The presence of eosinophilia (>600 eosinophils/mm3) in a blood film is very suggestive of worm infection.7 Very high levels may be found in conditions
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with invasive larval stages of Ascaris lumbricoides, hookworm and Strongyloides stercoralis. High levels are, however, not diagnostic of a specific infection.7
Since recent advances are being made in the use of real-time quantitative polymerase chain reaction (PCR) 64,65 in parasitology, there is hope that in near future it will be available for use in helminthic diagnosis in the tropics.
Management of intestinal helminthiasis
In an ideal situation, individuals with helminthic disease should be investigated and treated on the basis of the particular parasite or parasites present.62 In such circumstances, treatment can be tailor–made to cure a particular infection.62 When it is not possible to make an individual diagnosis as may be obtainable in some parts of the tropics, it is important to choose a treatment regimen which is most likely to be effective against the parasites which the child is most likely to harbour.7
Albendazole, a benzimidazole, is reasonably an ideal broad spectrum anti helminthics and has some larvicidal and ovicidal effects in addition to its primary vermicidal action.7 It is being used increasingly in many countries at single dose of 400 mg (200 mg in small children) and, if available, is the drug of
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choice.7 A three-day (six-doses) course of mebendazole (100 mg twice a day) is likely to be highly effective. Also a three-day course of pyrantel (10 mg/kg per day) and oxantel may be used.62 In situations where only single-dose regimens are practicable , and where albendazole is not available, single doses of mebendazole (400, and 200 mg in small children under 2 years), levamisole (3 mg/kg), or pyrantel (10 mg/kg with or without oxantel 10-15 mg/kg) may be used.7
The action of the benzimidazoles depends on the disruption of helminth metabolism, especially, inhibition of tubulin polymerases,66 which causes a cascade of other effects such as inhibition of fumarate reductase and glycogen depletion in the helminth. This effect extends beyond the lumen-dwelling adult worm to include helminth eggs in the gut67 and even the migrating larvae. Of all the gut helminth infections, strongylodiasis is the most difficult to treat in individuals because of auto-infection and benzimidazoles have to be given for 3-7 days.7 Recently, however ivermectin has been approved for Strongyloides stercoralis treatment and is effective at a single dose of 200g per kg.68
Thiabendazole is largely restricted to use in stronglylodiasis, because of its relatively high incidence of side-effects.68 However, since it is absorbed and
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achieves relatively high serum levels, it is the drug of choice in tissue helminthiasis such as visceral and cutaneous larvae migrans.68
It should be stressed that worm infection cannot be dealt with in isolation.
It must be viewed in the context of the child’s overall health and social background. Thus, treatment of worm infection forms a part of the management of anaemia and of malnutrition and proper attention must be focused on these and other problems in each child.7
Prevention and control of intestinal helminthiasis
Measures to prevent and control helminthiasis include chemotherapy, hygienic and sanitary practices, health education and integrated worm control.6
Chemotherapy schemes for control in the community will include mass chemotherapy for everybody who comes for treatment, selective chemotherapy for patients predisposed to large worm burdens and targeted chemotherapy for preschool and school-aged children6
Good hygienic and sanitary practices will help in the prevention and control of helminthiasis such as hand-washing before eating or handling of food, washing of vegetables and fruits before eating and efficient sewage disposal and proper disposal of human waste.7 Also, wearing of footwear to avoid direct contact of the feet with soil will prevent hookworm infection.6,7
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Furthermore, health education and integration of worm control into the already established health care programmes will be very useful in the prevention of helminthiasis.
AIMS AND OBJECTIVES
(A) GENERAL OBJECTIVE
The general objective of the study was to determine the pattern of intestinal helminthiasis in children aged 1-10 years in Enugu
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(B) SPECIFIC OBJECTIVES
(1) To determine the prevalence of intestinal helminthic infections in children aged 1-10 years in Enugu.
(2) To determine the various species of helminths infecting these children.
(3) To determine the age and gender specific prevalence of intestinal helminthiasis.
(4) To measure the weights and heights (growth status) of the affected children and assess the socio economic
status of their parents
(5) To identify the risk factors for intestinal helminthiasis in children aged 1-10 years in Enugu.
SUBJECTS AND METHODS Study area
The study was conducted in Enugu, the capital of Enugu state which is one of the states in Nigeria (see Appendix 1). Enugu is located in the South Eastern region of the country. Enugu city is made up of three local government
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areas which include the Enugu North, Enugu South and Enugu East (see Appendix II and III). Each of these local government areas consists of Urban, semi-urban and slums within urban areas (urban- slum areas).
The urban-slum areas are densely populated, with overcrowded houses, poor toilet facilities and dirty environment. The slum areas also do not have pipe-borne water. The sources of drinking water are mainly wells and streams.
Refuse disposal is indiscriminate.
The semi-urban areas are moderate population density areas with fairly-planned houses and streets; and stipulated sites for waste disposal. Some live in flats while others live in communal yards with common pit latrines. There is no functional pipe-borne water system and their sources of drinking water are well, stream and water supplied by water tankers.
The urban areas are low-density population areas with spaciously-designed and well-planned houses. The urban areas also have definite sites for waste disposal and most inhabitants are top civil servants, professionals and high class politicians.
Study Population.
The study population consisted of children attending nursery and primary schools in Enugu. The documented population of Enugu State as at 2000 is
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2,751,192 out of which 1,294,517 were males and 1,456,675 were females.69 The population of Enugu metropolis is 601,135 with 298,764 males and 302,370 females. Thirty percent of the population is under the age of 10 years.69
There are 73 approved nursery schools and 139 approved primary schools in Enugu.. Samples were drawn from schools in urban, semi urban and urban slum areas in the three local government areas in Enugu as shown in Tables II and III. Many of the parents of children in Enugu are civil servants while some are traders and farmers. Most parents living in the urban-slum areas are mainly of the lower social class consisting of farmers, petty traders, artisans and junior civil servants. Those living in the urban areas are mainly senior civil servants, well-to-do business men and professionals. Most adults living in the semi urban areas comprise of those from the various social strata.
Study duration
The study was done in the months of August and September 2003.
Inclusion criteria
(1) Apparently healthy nursery and primary school pupils in selected schools in Enugu metropolis.
(2) Only children aged between 1 and 10 years were included.
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Exclusion criteria
(1) Pupils whose ages fell outside the range of one and ten years.
(2) Pupils whose parents did not give consent.
Minimum sample size
The sample size was calculated using the formula.70 n =z2 p(100-p)
Where n = minimum sample size.
Z = confidence interval (1.96).
p = maximum prevalence for a comparable study population inferred from a previous study (33.7%).4
d = standard error (5%).
Substitutions in the above formula gave a minimum sample size of 343 pupils.
Final sample size based on Araoye’s method71
The final sample size was calculated based on the chosen attrition rate of 31.4%. This presupposes that the response rate will be 100 minus the attrition rate. i.e. 100% – 31.4% = 68.6%.
Using Araoye’s method, the final sample size was calculated as follows ns = n
x
where ns = final sample size d2
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n = initial sample size
x = expected response rate in percentage (100 – chosen attrition rate).
Substitutions in the above formula
ns = 343 where 68.6% = 68.6 = 0.686
68.6% 100
ns = 343 0.686 ns = 500
Ethical approval and consent.
The study was reviewed and approved by the Ethical committee of the University of Nigeria Teaching Hospital (UNTH) Enugu (Appendix iv). Informed written consent was obtained from each parent (see Appendix v) who was duly educated on the need for the study and its possible benefit. Some of the parents were addressed during their quarterly Parents Teachers Association meeting and others as they brought their children to school. Also a letter was written to all parents informing them about the study and asking for their consent. A copy of the letter is shown in appendix v. Verbal consent was also obtained from some of the children.
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Questionnaire development
Questionnaires were first administered to 30 students drawn from 3 different schools. The interview guide covered the name, age, residential address, parents’ occupation and educational level and risk factors for helminthiasis. The result of the pretest showed that some vital information were missing in the options provided for the questions on boiling and source of drinking water. These aspects were eventually modified in the final questionnaire that was used. A sample of the questionnaire is shown in appendix vi.
Methodology
This research was a cross sectional study. Samples were drawn from three nursery and three primary schools within Enugu. These schools had children who were representatives of the various socioeconomic families and located in urban, semi-urban and urban – slum areas of Enugu. A multi-staged sampling technique was used.
Selection of nursery and primary schools representing different socio economic areas.
The nursery and primary schools in Enugu were grouped into those from the urban, semi-urban, and urban slum areas as shown in Tables II and III. The
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nursery schools in the urban area were assigned numbers and these numbers were written on pieces of paper cut into equal sizes. These pieces of paper were put in a bag and shaken together with the bag covered. Same was done for the nursery schools in the semi-urban and urban slum areas and for the primary schools in the urban, semi-urban and urban slum areas. A piece of paper was picked at random from inside each of the six bags (three representing primary and three representing nursery schools) without looking into the bags. The schools that were represented by the number on the pieces of paper were used for the study. This represented the balloting - a form of simple random sampling.72
Determination of number of pupils studied from each of the chosen schools.
The total population of nursery school pupils in Enugu was 12,736, and the total population of primary school pupils in Enugu was 43,397, giving a nursery: primary school population ratio of 1: 3.4. Since five hundred was the minimum sample size, this ratio when extrapolated represents 114 to 386 (nursery to primary school pupils)
as shown below.
(14.4) x 500 x 1 = 114 for nursery schools
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and
(14.4) x 500 x 3.4 = 386 for primary schools
From table II, the population of nursery school pupils in urban, semi-urban, and urban-slum areas were 6416, 5120 and 1200 respectively. This gave a proportion (population of pupils in each of the areas divided by total number of nursery school pupils in Enugu) of 0.50, 0.40, 0.10, for the urban, semi-urban and urban slum respectively. To obtain the exact number of pupils studied from each school, the proportion was multiplied by the sample size (114) to get 57, 46 , and 11 pupils from the schools representing the urban, semi-urban, and urban- slum areas.
From Table III, the population of primary school pupils in urban, semi-urban and semi-urban-slum areas were 18731, 17793, and 6873 respectively with a proportion of 0.43, 0.41 and 0.16 respectively. Therefore, the number of pupils studied from each of the chosen schools (proportion multiplied by sample size of 386) was 166, 158 and 62 representing urban, semi-urban and urban slum- areas respectively.
Table II - Distribution of nursery school pupils In Enugu Urban
Semi-urban
Urban-slum
Total
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Number of nursery schools Population of nursery pupils
Proportion of nursery school population
Number of nursery school pupils studied (proportion
x 114)
32 6,416 0.50 57
26 5,120 0.40 46
15 1,200 0.10 11
73 12,736 1
114
Table III - Distribution of primary school pupils In Enugu
Urban Semi-urban
Urban-slum
Total
Number of primary schools 57 54 28 139
Population of primary school
pupils 18,731 17,793 6,873 43,397
Proportion of primary school
population 0.43 0.41 0.16 1
Number of primary school Pupils studied (proportion x
386) 166 158 62 386
Selection of nursery school pupils to be studied.
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Each of the nursery schools was stratified into nursery 1,2 and 3. The proportion of the students from each of the strata was obtained. Example, taking the urban nursery school; the total number of pupils in nursery one was divided by the total number of pupils in the same nursery school (i.e 50/186 = 0.27). This was also done for the other two strata giving 0.32, and 0.41. The ratio then of stratum 1: stratum 2: stratum 3 was obtained as 0.27: 0.32: 0.41 respectively. Bearing in mind that 57 pupils were needed for the study in the nursery school representing the urban area, this 57 was divided accordingly into the different strata viz:
0.27 x 57 = 15, 0. 32 x 57 = 18, 0. 41 x 57 = 24.
All the pupils in nursery one that met the inclusion criteria were given numbers which were also written down on equal-sized pieces of paper. These pieces of paper where shaken in a bag and 15 numbers were picked without looking into the bag. The 15 pupils were used for the study. The same method was used to obtain the 18 and 24 pupils required from nursery 2 and 3. Thus the 57 pupils representing the urban areas were obtained.
This same method described above was used to obtain the 46 and 11 pupils required from the semi-urban and urban-slum areas.
Selection of primary school pupils to be studied
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Each of the primary schools was stratified into six: primary one, two, three, four, five and six. The proportion of the students from each of the strata was obtained and this was used to calculate the number of pupils to be studied from each stratum.
A class from each stratum was chosen by simple random sampling (using the ballot method).72 All the children in each of the chosen classes that met the inclusion criteria were given numbers which were also written down on equal-sized pieces of paper. These pieces of paper were shaken together in a bag and the desired number of samples were picked without looking into the bag. The children that were represented by the picked numbers were used for the study.
Questionnaire administration
The questionnaire was administered directly by the researcher to the children. Data was obtained from the children who were able to answer the questions. For the children who were not able to answer, information was obtained from their parents as they brought their children to school in the mornings. The parents who were not seen in school were visited and interviewed at home. The ages of some of the children (where in doubt) were confirmed from their birth certificates.
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Social class of the parents of the subjects
Social class of the parents of the subjects was determined employing the method of Olusanya et al73 which uses the father’s occupation and mother’s educational attainment. This enabled their classification as follows:
A Scores Father’s occupation
1 Professionals, Top Civil Servants, Business executives and Politicians.
2 Middle level Bureaucrats, Technicians, Skilled Artisans and well-to-do traders.
3 Unskilled workers and those in general whose income is at or below the national minimum wage.
B Scores Mother’s level of education 0 Education up to University level.
1 Secondary or Tertiary below University (e.g College of Education, School of Nursing) 2 No schooling or up to primary level only.
Adding scores from A and B above gave the social class.
Social class 1 or upper class: Score 1 or 2 Social class 2 or middle class: Score 3
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Social class 3 or lower class: Score 4 or 5
Anthropometric Measurement Height / Length Measurement
The length of children less than 2 years were measured by the researcher with the aid of an infantometer (locally constructed with table and steel meter rule). The subject was placed, faced upward with head towards, the fixed end and the body parallel to the long axis of the board. One assistant ensured that the crown of the child’s head was in contact with the fixed headboard. The researcher held the subjects’ feet, without shoes, toes pointing directly upwards and kept the subject’s knees straights. The moveable footboard was then brought to rest firmly against the heels. The reading was then taken to the nearest millimeter.
For children over two years of age, their heights were measured by the researcher in a standing position, using a stadiometer (England model of 17 Camp den Street, London). The subject stood straight with the feet together, knees straight and heels, buttocks and shoulder blades in contact with the vertical surface of the stadiometer. The moveable headboard was then gently