Gondar town is located in Northwest Ethiopia with 12°35′N latitude and 37°28′E longitude at an altitude of around 2200 meters above sea level. It has a total population of 207,044 (98,120 men and 108,924 women) based on 2007 national population census . The ranges of mean maximum and minimum temperature in 2015 were 22.70C - 29.70C and 17.60C - 22 0C respectively with the annual rainfall of 1151 mm. The highest rainfall was registered in July (328 mm) and August (307 mm) compared to the driest January (4 mm) and February (6 mm) in the same year . This study was conducted in the Azezo-Teda sub-city. The Azezo-Teda sub-city administration is located south of the central part of Gondar. Compared to the other sub-cities, the Azezo-Teda sub-city contains urban and rural populations. The Gondar town is expanding mostly in Azezo-Teda area. The rivers that cross Azezo-Teda sub-city are Angereb, Kaha, Shenta, Demaza and Magech rivers. The Gondar Town Administration Health Bureau regularly conducts deworming in school children in around May and June. The last date for the last deworming was June, 2017. Almost 1 year has passed since the last deworming program in the study school. Infrastructure such as piped borne water, good roads and electricity are lacking in the rural areas. Inhabitants, therefore, obtain ground water for drinking and domestic purposes. By occupation, majority are farmers, with few other working in thread mills or as laborers in central Gondar town.
This study was a cross-sectional survey, involving systematic random sampling of school aged children in Azezo-Teda sub-city, Gondar town between February and May, 2018. Azezo elementary school was seIected due to high prevalence rate of intestinal helminth infections in school age children during previous study in the Azezo area. Grade level stratified random sampling by rotary mthod was used to select the study participants. Pre-tested questionnaires were used to obtain demographic data and data about food shortage in the family and other possible risk factors which could be the source of malnutrition or intestinal helminth infections. Using anthropometric measures, school children were grouped as stunted, wasted, obese and Normal. Kato-Katz technique was used to determine intestinal helminth infections while automated hematological and biochemical machines were used to measure haematological and biochemical values. Appropriate statistics were used to see if intestinal helminth infections is associated with malnutrition.
Sample size determination technique
The prevalence of intestinal helminth and Schistosoma mansoni infections (72.9%)  during previous study in Azezo primary school was used to calculate sample size of school-age students participated in the study. A single population proportion formula at 95% confidence interval [n = (Z α/2)2p (1-p)]/(0.05)2] was used to calculate the minimum 303 sample size by using the probability of intestinal helminth and Schistosoma mansoni infections during previous study. Including 30% contingency (91) for possible discarded samples and drop out study participants, a total of 404 sample size was planned to include in the study. At the end of the sampling, 20 participants were excluded due to incomplete data which made the overall sample to be 384.
Following ethical approval by research ethical review board of University of Gondar and permission letter obtained from Azezo – Teda sub-city administration to conduct this research in Azezo government elementary school, study participants were recruited for the study. This elementary school was selected purposefully as it has students coming from both urban and rural areas and high prevalence rate of helminth infections. A stratified random sampling method was used to select the study participants based on their grade level. A rotary method was used to select the total number sample required for the study from all students attending from grade 1 up to grade 8. The students were participated in the study after the purpose and a benefit of the research explained to their parents or guardians and written consent was obtained. Only students willing to participate in the research were included. The students could also withdraw from the study at any time during the execution of the sampling process.
After pre-tested structured questionnaire prepared in English was translated exactly to Amharic
Version (National language), one of the investigators interviewed the parents or guardians to obtain data about socio-demography and risk factors for possible malnutrition and intestinal helminth infections. Then, anthropometric measures, stool and blood samples were obtained from all study participants by senior laboratory science personnels. The questionnaire contained questions related to socio-demographic factors (first part) and possible risk factors for malnutrition and intestinal helminth infections. Data about residences, accessibility of food, swimming and/or washing in rivers in the study areas, possession of shoes and proper wearing habits and hand washing habits were collected from the study participants to address possible risk factors for malnutrition and intestinal infections. Family without known income or no or low (<1500 birr/month) salary and very low annual harvest, no television, serious problem in getting enough food and clothing was grouped as family with low accessible food. The other families with no problem of food accessibility grouped as family with accessible food. Mothers who could at least read and write were grouped as literate and those who could not read and write were grouped as illiterate. Based on residence, respondents living in Gondar town were grouped as urban inhabitants, and those in surrounding rural area were grouped as rural inhabitants.
Body weight and height of the school aged children were measured using digital weighing balance and tape ruler respectively. The students were weighed without shoes and the instruments were calibrated to measure weight with 0.1 gram scale while their heights were measured with vertical length measurement with 0.1 cm scales. Measurements were taken twice to use the average for each student. Height-for-age Z-score (for stunting) and body mass-index-for-age Z-score (for wasting and thinness) were calculated using the WHO AnthroPlus software version 1.04 (WHO, Geneva, Switzerland) (available http://www.who.int/ //en/). Weight for age (WAZ) was not been used as it is not recommended for age group above 10 years. The z-scores were classified based on WHO Child growth standards as stunting or wasting/thinness. Stunting is defined as insufficient height for age or when height-for-age Z score (HAZ) is less than - 2 SD (standard deviation). Underweight was defined as insufficient weight for age or when weight for age Z - scores (WAZ) is less than - 2 SD from standard median scores. Wasting or sever thinness is defined as insufficient mass for height (low body mass index (BMI) for age) or when body mass index for age Z - score is less than – 2 SD [22, 23].
Collection of stool samples and parasitological examination
Sterile sample bottles were distributed to consenting school-aged children. Collected specimens were analysed using the Kato-Katz technique to determine the presence of intestinal helminths ova [30, 31]. The Kato Katz technique was performed on the same date to determine infection and intensity of infections. Kato–Katz slides thick stool smears prepared from 40.7 milligram stool filtrate were examined microscopically within 30 to 60 minutes after preparation to count helminthes eggs and multiply by 24 .6 to get egg per gram stool (epg).
Collection of blood samples and haematological analysis
About 3 ml venous blood was collected from consenting school-aged children in a sterile tube containing anti-coagulant. The tube was transported quickly to the University of Gondar before the blood was analysed using fully-automated haematological cell counter (Mindray BC-3200). The parameters assessed include total white blood cells (WBC), red blood cells (RBC), hemoglobin concentration (Hgb), packed cell volume (PCV), hematocrit value; mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), lymphocytes and neutrophils. The haematological values were classified as normal, below normal and above normal according to standard normal range values . In addition, 2 mm of venous blood sample were collected using sterile syringe from the arm of the consenting school-aged children. The blood samples were placed in a separator test tube and centrifuged at 3000 rpm for 5 minutes. The separated serum was analysed for glucose and total protein concentrations by using Mindray BS-200E chemistry analyser to determine their normal concentration in the blood according to standard reference values.
Ethical approval was obtained from the University of Gondar ethical review committee. Written consent was obtained from study participant's parent/guardian after permission was obtained from Teda - Azezo district administration and school administration. Laboratory results were kept confidential and; children who were infected with helminth infections and with abnormal hematological test were linked to the Gondar district health centre for free treatment.
Data about socio-demography and the possible risk factors were collected using questionnaire before the results for malnutritional indices, intestinal helminth infection and haematological tests obtained. The datab collected was cleaned in an Excel spread sheet before transferred to statistical package for social sciences (SPSS) version 20 for statistical analysis. Descriptive statistics was used to analyze the prevalence of the different outcome variables. Mann whitnay test (non-parametric analysis of variance (ANOVA)) was used to determine the existence of gender or age group related statistically significant difference for intestinal helminth infection, intensity of infection, co-infections, infecting species, anaemia, stunting, wasting and haematological categories in the school children. Binary logistic regression test was used to see association between intestinal helminth infection, anemia, stunting,, wasting, age groups, malnutrition indices and haematological categories. Multiple logistic regression analysis was used to determine the likelihood of anemia or odd ratio (OR) in school children, when it was compared with uninfected, mono-infected, co-infected and species of intestinal helminth. For the statistical analysis, p-value < 0.05 was considered as significant different for 95% confidence interval.