Human Intestinal Parasitic Infections: Prevalence and Associated Risk Factors among Elementary School Children in Merawi Town, Northwest Ethiopia

Background Intestinal parasitic infection is still common in Ethiopia. Periodic evaluation of the current status of human intestinal parasitic infections (HIPIs) is a prerequisite to controlling these health threats. This study is aimed at assessing the prevalence and determinant factors of HIPIs among elementary school-age children in Merawi town. Methods A school-based cross-sectional study design was used among 403 children. The direct wet mount method was used to diagnose the stool samples. The sociodemographic and behavioral characteristics of the respondents were collected using structured questionnaires. The data were analyzed using the chi-square test and logistic regression. Results Out of the 403 students, the overall prevalence of HIPIs was 173 (42.9%). The magnitudes of single and double infections were 39.7% and 3.2%, respectively. Seventy-two (17.9%) were positive for Entamoeba histolytica, 63 (15.4%) for Giardia lamblia, 28 (9.6%) for Ascaris lumbricoides, 22 (6.9%) for hookworm, and 1 (0.2%) for Schistosoma mansoni. The prevalence of intestinal parasites was high in the age group of 6–11 years compared to other age groups. The following were the risk factors associated with HIPIs: groups aging 6 to 11 (AOR = 9.581; 95% CI: 0.531-17.498; P = 0.008), aging 12 to 18 (AOR = 3.047; 95% CI: 0.055-1.828; P = 0.008), not washing of hands after defecation (AOR = 3.683; 95% CI; 1.577-8.598; P = 0.003), not regularly washing of hands after defecation (AOR = 2.417; 95% CI; 1.224-4.774; P = 0.003), dirty fingernails (AOR = 2.639; 95% CI: 1.388-5.020; P = 0.003), not wearing shoes (AOR = 2.779; 95% CI: 1.267-6.096; P = 0.011), rural residence (AOR = 6.6; 95% CI; 0.06-0.351; P < 0.0001), and a family size greater than or equal to five (AOR = 2.160; 95% CI: 1.179-3.956; P = 0.013). Conclusion The prevalence of HIPIs among elementary school children in Merawi town was very high. Thus, there is a need for intensive health education for behavioral changes related to personal hygiene and mass treatment for effective control of HIPIs in the study area.


Introduction
Human intestinal parasitic infections (HIPIs) have been a worldwide public health threat [1]. Such infectious diseases are already identified as neglected tropical diseases (NTDs) [2][3][4][5] and received attention very recently. Total control of the transmission of HIPIs and the reduction of possible aggravating factors are among the components of the sustainable development goals of the United Nations (2030 Agenda; Goal 3.3). Despite the efforts, intestinal parasites remain to be public health burdens, specifically in the tropical and subtropical regions [2,3,5].
Several risk factors for HIPIs in poor communities have been well documented [6]. Among others, poverty-related factors (poor sanitation, scarcity of potable water, unsafe human waste disposal systems, and open-field defecation), conducive environmental conditions for the parasites, lack of adequate health services, and low level of awareness are the contributing factors for the high rate of HIPIs [7][8][9].
School and preschool children are highly venerable to HIPIs due to exposure to the parasites as the result of their behaviors. Thus, urgent treatment and preventive interventions are required [4]. Young children have a less developed immune system, poor personal hygiene, and the habit of playing on contaminated soil. HIPIs cause health problems such as the increased risk of protein energy malnutrition, iron deficiency anemia, growth retardation, faulty cognitive development, and predisposition to other infections in young children [4,10,11].
There is a high global burden of protozoan intestinal parasites. For instance, E. histolytica infected some 48 million individuals. In the same way, there was a high global prevalence of giardiasis [4]. Besides, parasitic worms such as roundworm, hookworm, and whipworm have been among the common parasites affecting communities in low-income countries [3][4][5]12]. Thus, protozoan parasites and soiltransmitted helminths have been resulting in high morbidities and mortality of children in sub-Saharan African countries [4]. Previous reports show a high frequency of HIPIs in this African region, affecting nearly all people once or several times during their life spans.
The Federal Ministry of Health of Ethiopia has been trying to halt HIPIs and several other diseases by training thousands of health extension workers and assigning them to every village. Despite the efforts, Ethiopia is still under the high burden of HIPIs [8,13]. In Ethiopia, high prevalence rates of HIPIs (as high as 84%) were reported among primary school children [13][14][15][16][17].
Based on information obtained from health offices and clinics, people of Merawi town visit health centers mainly as the result of HIPIs. However, there was no study conducted on the prevalence of HIPIs and associated risk factors in Merawi town. Therefore, this study is aimed at scientifically documenting the prevalence and associated risk factors of HIPIs among elementary school children in Merawi town.

Material and Methods
2.1. The Study Area and Period. This study was conducted from March to April 2017 among students from three selected primary schools in Merawi town, Mecha district, Amhara Regional State, Northwest Ethiopia. All the elementary schools had toilet and water facilities, although not proportional to the number of students. Mecha district lies on 156,027 hectares of land. It is located at an elevation of 1,800-2,500 m above sea level.
The study area lies at 523 km Northwest of Addis Ababa (the capital of Ethiopia) and 35 km southwest to Bahir Dar (the capital of the Amhara Regional State). According to the 2007 population census, the total population of the district was 292,250 (147,700 males, 144,550 females) [18]. Close to a quarter (21%) (63,627) (30,606 males and 33,021 females) of the district's population is from Merawi town. Mecha district has 13 health centers, 46 health posts, and one hospital and 103 primary schools, seven secondary schools, and one preparatory school. Merawi town has five health facilities (one health center, three health posts, and one hospital) and five schools (three elementary, one secondary, and one preparatory). The majority of the population of the district is engaged in mixed agricultural activities. The residents earn their living as farmers, merchants, daily laborers, and government employees. The dominant crops grown are maize, millet, and, "teff", and the animals reared were cattle, goats, sheep, and poultry. The inhabitants of the district use water sources from streams, rivers, wells or pools, and tap water. 2.3.2. Independent Variables. Gender, age, the habit of handwashing before and after meals, the habit of handwashing after defecation, fingernail cleanliness, shoe wearing habit, residence, latrine facility, latrine usage, source of drinking water, treatment of water before drinking, family size per household, parental education, and parental occupation are the independent variables.

Inclusion and Exclusion Criteria
2.4.1. Inclusion Criteria. Those volunteers who/whose guardians signed informed consent and delivered stool specimens and those who did not receive any antiparasitic treatments in the days before sampling are included.

Exclusion Criteria.
Students who did not have signed informed consent, those who did not properly collect their stool sample, students who did not answer the questions on the form for sample collection, and subjects who had taken antiparasitic drugs in the last three weeks or during data collection were excluded.
2.5. The Study Design and Sampling Technique. A crosssectional study was conducted among students of three primary schools (Merawi 01 Kebele, Merawi Junior, and Merawi 02 Kebele) in Merawi town in 2017. Out of the 112 sections comprising of 6,619 students (3,311 males and 3,308 females), 14 sections were selected using the lottery system. Students' names from the attendances of the 14 sections were ordered alphabetically, from which the participants were selected by a simple random sampling technique.

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Journal of Parasitology Research 2.6. Sample Size Determination. The sample size was estimated using the following statistical formula [18]: where n = the minimum required sample size, z = 1:96 at 95% confidence interval, p = prevalence of intestinal parasites, and d = margin of the sampling error assumed to be 0.05. Since the overall prevalence rate (p) of intestinal parasites was not known in the study area, it was taken as 50% and this gave a minimum sample size of 384.
To lessen errors arising from the likelihood of noncompliance or possible dropout, 5% of the sample size (19 children) was added to the normal sample size. Consequently, 403 total school children were selected. Age-wise, the respondents were grouped as middle childhood (6 to 11 years), early adolescence (12 to 18 years), and late adolescence (19 to 21 years) [19].
2.7. Questionnaire Data Collection. Pretested standardized questionnaires were developed based on known potential risk factors. These questionnaires were constructed in English and translated into Amharic. Then, children were interviewed in their mother tongue. For those students who were not able to respond to questionnaires properly, their parents/guardians were contacted through school principals and gave interviews on behalf of their children. During the interview, the fingernails, the general hygienic conditions, and the footwear of students were inspected by the interviewers. Coded questionnaires were used to gather information on the demographic and socioeconomic characteristics of the participants.

Stool Sample Collection and Examination.
The subjects were instructed to provide stool samples (10-20 g) and were provided labeled clean cartons, toilet tissue papers, and pieces of applicator sticks. The stool samples were labeled and microscopically examined using the direct wet mount method for protozoa, helminths, and intestinal parasites.
A direct wet mount was conducted as follows. A drop of normal saline (0.85% NaCl solution) was added at the center of a labeled slide. A small amount of fecal specimen was added in the saline solution and thoroughly emulsified using an applicator stick. After homogeneous thin films were prepared on each slide, coverslips were placed on each preparation and examined for parasites under a light microscope of 10× and 40× objectives.
2.9. Data Analysis. After the row data were collected through interviews and parasitological examinations, results were initially fed into Microsoft Excel 2007 software and then copied to Statistical Package for Social Sciences (SPSS) software version 20. Descriptive logistic regression was used to quantify the degree of association of HIPIs with socioeconomic and potential risk factors. The levels of significant differences of proportions were compared using the Pearson chi-square test. Logistic regression analysis was expressed as an odds ratio to evaluate the prevalence and associated with HIPIs. The 95% CI was used to show the accuracy of data analysis, and probabilities less than 5% (P < 0:05) were considered statistically significant.

Results
3.1. General Characteristics of the Study Participants. The demographic and socioeconomic characteristics of the participants are shown in Table 1. A total of 403 participants (49.2% male and 50.6% female) aged between seven and 20 years with a mean age of 11.9 were involved in this study. One hundred seventy-three (42.9%) were from Merawi 01 Kebele Primary School, 143 (35.5%) from Merawi Junior School, and 87 (21.6%) from Merawi 02 Kebele Primary School. The distribution of participants in the three schools is displayed in Figure 1. Two hundred sixty-five (65.8%) of the respondents regularly washed their hands before and after meals, 175 (43.4%) of them did not wash their hands after defecation, 258 (64.0%) of the students had clean fingernails, and 335 (83.1%) of the participants had shoe wearing habits. The majority of the respondents, 327 (81.1%), used to drink tap water, 372 (92.3%) of them used untreated water, 212 (52.6%) came from rural areas, 392 (97.3%) had toilet facilities, 278 (69.0%) regularly used latrines, 221 (54.8%) were from family sizes less than five (<5), 150 (37.2%) of the fathers had an education level of secondary school and above, and 180 (44.7%) of the mothers were illiterate. The majority of the fathers 196 (48.6%) were farmers and the majority of their mothers 193 (47.9%) were housewives.

Risk Factors Associated with
HIPIs. The strength of the association of HIPIs with their risk factors is presented in   Table 3. The results from the univariate analysis showed that students in the age groups of 6 to 11 were five times (AOR = 4:455; 95% CI: 2.899-6846; P < 0:0001) more likely to be infected by HIPIs than students in the age group of 19 to 21. Students who irregularly washed their hands before and after meals were 4.111-fold (AOR = 4:111; 95% CI: 2.659-6.358; P < 0:0001) more likely to acquire HIPIs than those who regularly washed their hands.
Children who had dirty fingernails were three times (AOR = 2:639; 95% CI: 1.388-5.020; P = 0:003) at risk of HIPIs than children who had clean fingernails. Students who had no shoe wearing habit were close to three times more likely to be infected by HIPIs (AOR = 2:779; 95% CI: 1.267-6.096; P = 0:011) than students who wore shoes regularly. Students who were living in rural areas were seven times (AOR = 6:6; 95% CI; 0.06-0.351; P < 0:0001) more likely to be infected by HIPIs than those who used to live in the urban areas. Students who lived in family sizes greater than or equal to five were two times more likely to be infected (AOR = 2:160; 95% CI: 1.179-3.956; P = 0:013) than students who lived in family sizes of less than five.
According to this finding, males were more infected than females. This finding is similar to that of the studies conducted in Chilga (Northwest) [25] and Delgi [22]. In contrast, in a study from Adigrat, females were more infected than males [26].
A higher prevalence of HIPI has been recorded in Merawi 01 Kebele with 98 (24.3%) compared to 65 (16.1%) and 23 (5.7%) in Merawi Junior and Merawi 02 Kebele Primary School, respectively. The trend of HIPIs reduced with an increase in age. For instance, from 60.4% in the age group 6 to 11 years to 25.5% in the age group 12 to 18 years. The reason might be due to older children had better awareness of washing hands and personal hygiene compared to the younger ones [23].
The prevalence of hookworm in the present study (5.7%) was higher than that of the studies conducted by Abera [35] and Nibret in Tilili (0.5%) and Haftu et al. [37] in Arba Minch (2.2%). This difference might be due to the differences in awareness of wearing shoes and a large family size. The prevalence of hookworm was much lower than that from the reports from Dagi Primary School, Amhara National Regional State (23.6%) [21], in Dona Berber, Bahir Dar (22%) [15], and in Zegie Peninsula (43.4%) [14]. This difference might be due to the geographical location of the study areas. However, hookworm prevalence was comparable with that of the work of EL-Masry et al. [28] in Sohag Governorate (Egypt) (5.1%).
The prevalence of S. mansoni (0.2%) in the present study was very much lower than that in Delgi (North Gondar) (15.9%) [22], in Mek'ele city [38] (23.9%), and Zegie Peninsula [14] (29.9%). This difference might be due to differences in the residences of the study subjects and living and socioeconomic conditions.
The results in the present study showed that subjects had single and double infections. The mixed infections detected were E. histolytica and G. lamblia (1.48%), E. histolytica and hookworm (0.98%), A. lumbricoides and hookworm (0.49%), and E. histolytica and A. lumbricoides (0.25%). This result agrees with the works from Aksum town [24] and Dona Berber (Bahir Dar) [15].
A strong association existed between HIPIs and the residence of students, fingernail cleaning, handwashing habit after defecation, shoe wearing habit, and family size (P < 0:05). This study was in agreement with the studies done in Dona Berber (Bahir Dar) [15] and Al-Ahsa (Saudi Arabia) [39].
Students from rural areas were almost seven times (AOR = 6:666; 95% CI: 0.06-0.351; P < 0:0001) more likely to get HIPIs compared with students from Merawi (town). This finding agreed with the findings of the studies conducted in Motta (Amhara Region) [27] and Adigrat [26]. However, it was different from the work in Delgi [22]. The possible reasons for more infections among students from rural areas might be the presence of relatively poor personal and environmental hygiene, poor handwashing habits, presence of unclean fingernails, and a large family size.
The risk of HIPIs among students who did not frequently wash their hands after defection was almost four times (AOR = 3:683; 95% CI: 1.577-8.598; P = 0:004) more than that of those who used to wash their hands regularly. Students who sometimes washed their hands after defecation were two times (AOR = 2:417; 95% CI: 1.224-4.774; P = 0:004) more at risk than students who used to wash their hands regularly. This was comparable with the studies conducted in Motta (Amhara Region) [27] and Dona Berber (Bahir Dar) [15].
Likewise, the likelihood of being infected by intestinal parasites among students who did not frequently wear shoes was three times more than that among students who regularly used to wear shoes (AOR = 2:776; 95% CI: 1.312-5.873; P = 0:008). Similar associations between HIPIs and shoe wearing habits of students were reported from Dagi Primary School, Amhara National Regional State [21], Dona Berber (Bahir Dar) [15]. The possible explanation may be that walking barefoot increases the chance of being infected with IPs, especially those which enter the body through skin penetration.
At the same time, the risks of being infected by IPs were increased almost three times (AOR = 2:639; 95% CI: 1.388-5.020; P = 0:003) more among students with unclean fingernails as compared to students who had clean fingernails. Similar associations of HIPIs with unclean fingernails were reported from Lumane [36] and Dona Berber (Bahir Dar) [15].
Furthermore, the family size was strongly associated with HIPIs. The likelihood of being infected by HIPs was increased by two times (AOR = 2:160; 95% CI: 1.179-3.956; P = 0:013) more among students belonging to the family size of five and above as compared to students in a family size of less than five. This agrees with studies conducted in Tilili [35] and Dona Berber (Bahir Dar) [15].

Conclusions
A relatively high prevalence of HIPIs (42.9%) was observed among students from primary schools in Merawi town. Single infections accounted for 39.7% of the infections followed by double infections (3.2%). HIPI was common among children of middle childhood (6 to 11 years) than early adolescent (12 to 18 years) and late adolescent (19 to 21 years) students. Male children were more prone to HIPI than 8 Journal of Parasitology Research female children. The age 6 to 11 years, poor handwashing habit after defecation, dirty fingernails, lack of shoe wearing habit, rural residence, and family size greater than or equal to five were risk factors associated with HIPIs.

Recommendation
Owing to the high prevalence of HIPIs in the present study, awareness creation to the children and their guardians, establishment of sanitary facilities in the school compounds, inspecting the sanitary situations of students especially in the age group of 6 to 11 years, monitoring the hand washing and finger trimming habits of students, and promoting shoe wearing and sanitary measures in the rural areas are recommended.

Limitations
Only the wet mount technique was used to identify the parasites. This may underestimate the prevalence of HIPs in the study area compared to the more efficient and specific techniques such as formal ether concentration and Kato Katz methods.
Abbreviations AOR: Adjusted odds ratio CI: Confidence interval COR: Crude odds ratio NTDs: Neglected tropical disease HIPIs: Intestinal parasitic infections SPSS: Statistical Package for Social Sciences.

Data Availability
All datasets generated and analyzed during the study are presented in the text.

Ethical Approval
The survey has been approved by the Research Ethics Committee of the Science College of Bahir Dar University.

Consent
Before the implementation of the questionnaire survey, agreements from participants and/or their relatives are necessary, and all of them signed informed consent.

Disclosure
The funding institutions played no role in the study design, analysis, decisions to publish, and manuscript writing.