The study was carried out in Mkuranga district, Pwani region; the district boarders with Dar es Salaam region, Indian Ocean, Rufiji district, and Kisarawe district to the north, east, south and west respectively (Figure 1). The district is divided into 4 divisions, 18 wards and 121 villages and 463 hamlets. According to population and housing census of 2012 the district has a total population of 222,921 of which males were 108,024 and females were 114,897 (18). It has a total of 50 health facilities (public and private) which offer health services including RCH clinics. The district has favorable ecological condition for STH; it is one of the worst districts in Tanzania in terms of access to piped or protected water sources. As for 2002, 93% and 76% of rural and urban household respectively were using unprotected water source for drinking (19). The most common toilet facility (2002) is the traditional pit latrine owned by 89 per cent of house hold and 10.82% (2007/08) had no toilet (19)
Figure 1: Map of Tanzania showing the location of Mkuranga district (20).
Study design, sample size and enrollment of participants
A quantitative community based cross-sectional study was conducted between April and June 2019 to examine the prevalence and intensity of STHs among PSAC and the associated WASH factors. Two study populations were recruited: 525 PSAC for establishing the prevalence and intensity of STHs and 525 parents/caregivers for interview on their socio-demographic characteristics and WASH practices.
The sample size, 525 PSAC was determined using the formula for single population proportion (21) and considering 30% Prevalence of STH in the population (22), normal deviate of 1.96, 95% Confidence interval, 5% Margin of error, 10% non-response rate and design effect of 1.5.
Sampling was done in four stage clusters:
In the first stage two wards of Vikindu and Mwalusambe were randomly selected from eighteen wards using lottery system.
At the second stage, using lottery methods, two villages namely Kazole and Mwalusambe were randomly selected from Vikindu and Mwalusambe respectively.
In the third stage, the hamlets of Kilongoni and Mwalusambe Mjini were randomly selected from Kazole and Mwalusembe village respectively.
In the fourth stage, 525 PSAC and their corresponding mothers/caretakers were selected from each hamlet. Allocation of sample sizes was done by proportionate sampling based on the number of household found in each hamlet. We obtained the number of household in each hamlet from the hamlet chairman and the contribution of household to sample size was calculated by using the formula of probability proportional to size (Equation 1). Kilongoni hamlet had a total of 429 households while Mwalusembe Mjini hamlet had a total of 401 households.
Using the formula of probability proportion to sampling: number of house hold per hamlet =
Total households from the hamlet x Sample size required for the study (1) Grand total number of households in the two hamlets
Thus, a total of 271 and 254 household were selected to represent Kilongoni and Mwalusambe Mjini hamlets respectively
To obtain households, the office of the hamlet chairman was used as a central location and starting point. A bottle was spun to determine direction; the household closest to the office in the direction of the bottle was selected as the initial household. The next nearest household was selected until the estimated sample was obtained. Whenever more than one eligible child was found in the same household, one of them was chosen using a lottery method.
Inclusion and exclusion criteria
PSAC (12-59 months) living in the study area in the past six month and whose parents or legal guardians provided written consent were eligible to participate. Excluded were those who received anti-helminthic drug in the preceding one month, having diarrhea and those whose parents / care givers refused to sign a written consent.
Stool samples collection, processing and examination
To establish prevalence and intensity of STH, stool samples were collected, processed and examined for presence of STH eggs. Number of eggs found in sample was used to establish intensity of infection. Children were allowed to defecate on a piece of paper; using an applicator a portion of the feacal matter was transferred to a pre-labeled clean, dry and wide mouthed stool container. Samples were preserved in 10% formalin and transferred to the MUHAS Parasitology laboratory for further processing and examination. Presence of parasites was established by direct wet mount iodine preparations and formol-ether concentration techniques, while parasite intensity was established by the Kato-Katz technique as described by WHO (23).
Prevalence of STH was calculated as the ratio of number of children found positive for any STH species to the total number of children who provided complete data (Equation 2).
Prevalence = Number of subjects testing positive x 100 (2)
Number of subjects investigated
To determine the intensity, number of eggs of each species were recorded and converted into the number of eggs per gram of feces (EPG). EPG was calculated by multiplying egg count by conversion factor (24). Intensities were categorized (light/moderate/heavy infection) based on WHO categories (24). To ensure validity and reliability, standard operating procedures were followed during stool collection, processing, examination and analysis as described in the WHO bench mark aid for diagnosis of parasitic infections.
Socio-demographic characteristics and WASH practices:
Data were obtained through questionnaire interview with mothers/caretakers of PSAC. An observation check list was used to gather environmental WASH practices. For sanitation, we asked caretakers to show the households latrine facilities and then we categories them into improved non shared latrine vs. other types of latrines based on WHO, UNICEF definitions (25). On child sanitation, mothers/caretakers were asked on what they do when the child want to defacate and what is done to dispose the child faeces. We performed on spot observation to check for signs of open defecation around the house compound, outside latrine, on the latrine wall and around drop hole. Disposal of child faeces was categorized into hygienic/safe vs. unhygienic/not safe based on WHO, UNICEF definition (25).
To obtain data on drinking water, we asked respondents to mention the main source of drinking water. To determine quality of water sources, water sources were categorized into improved vs. unimproved according to WHO, UNICEF definition (25). We also investigated the habit regarding treatment of drinking water by asking the respondents to explain procedures taken to prepare drinking water at the household. Concerning hand hygiene, respondent were asked to explain their hand washing habit at critical times such as before preparing food, before feeding a child, after defecation and after cleaning a defecated child. We also investigated the presence of hand washing facilities. We investigated finger nails hygiene by observing mother/caretaker and the child finger nails and recorded them trimmed or untrimmed if the finger nails were cut short or kept long respectively.
Data were cleaned, coded and entered into Statistical Package for Social Sciences (SPSS) version 23. The data were summarized using frequency and proportion. Chi-square tests (Pearson chi square test and Fishers exact test) whenever applicable were performed to determine association between STH prevalence and WASH variables. A P value < 0.05 was considered significant.
Ethical clearance was obtained from the MUHAS Ethical Review Board. Permission was obtained at all administrative units involved in this study. A written consent was obtained from parent or legal guardian of each participant. Any information obtained during the study was kept confidential. At the end of the study, a brief report was prepared and sent to the District health officers so that infected children would receive treatment.