Description of the study area
This study was conducted in Kinondoni municipality, one of the five municipalities of the Dar es Salaam region. According to the census of 2012, the municipality has a total population of 1,775,049 (914,247 females and 860,802 males) with more than 446,504 household.[12] The Municipality is boarded to the east by the Indian Ocean, to the north and west by the Coast Region. The area of Kinondoni has favorable climatic and ecological conditions that influence the survival of the Bulinus snail intermediate host of S.haematobium parasite. Kinondoni Municipality was selected because it’s one of the few urban endemic areas for urogenital schistosomiasis in Tanzania, with the ongoing praziquantel treatment program for more than ten years.[10]
Study design
A school-based cross-sectional study involving a quantitative method of data collection was conducted between June and August 2020 to investigate the prevalence of urogenital schistosomiasis and WASH risk factors for transmission among primary school children in an urban endemic area of Kinondoni Municipality in Dar es Salaam, Tanzania.
Study population, inclusion and exclusion criteria
The study population was primary school children from class four to six and aged seven to 15 years. All primary school children resident of Kinondoni municipality, aged seven to 15 from class four to six whose parents/guardian signed written informed consent form were eligible to participate. The students who were sick apart from urogenital schistosomiasis and whose parents/ guardians did not sign the written informed consent were excluded from participating in this study.
Sample size determination and sampling procedure
The sample size for this study was calculated from a formula for estimating sample size in a single cross-sectional survey.
n = sample size
z = level of confidence according to the standard normal distribution (for a level of confidence of 95%, z = 1.96)
p = proportion of S. haematobium (p =19.3%) found in previous study.[10]
d = tolerated margin of error
The calculated sample size was 263 primary school children. Kigogo ward was purposively selected because of the history of urogenital schistosomiasis endemicity for three and a half decades.[10] Simple random selection was employed to select the representative school for sample collection, whereby Kigogo primary school was selected. Students from class four to six were sampled according to the total number of students in each class, meaning the class with a higher number of students contributed to higher sample size. A total of 100,120 and 30 students were sampled from classes four, five, and six respectively.
Urine collection and laboratory analysis
All of the sampled students were provided with labelled wide mouth dry plastic containers for the collection of the urine samples and were instructed on how to collect terminal urine. The collected urine samples were transferred to the Parasitology and Medical Entomology Laboratory of Muhimbili University of Health and Allied Sciences on the same day for the laboratory analysis.
In the laboratory; microhaematuria analysis was done using a chemical reagent strip (Cybow 10 Urinalysis Test Strip). For each sample, the reagent strip was dipped into the mixed urine for three minutes then removed and read. The change of strip colour was compared to the colour chart on the container of the strips to estimate the amount of blood in the urine. The results of microhaematuria were recorded as negative or positive.
Microscopic examination was done for each urine sample for detection of S.haematobium ova. The nuclepore membrane filtration technique was performed whereby 10mls of each urine sample was drawn using a 10ml plastic syringe and passed through a polycarbonate filter with a pore size of 12um to recover the eggs. All urine filters were carefully removed from filter holders and placed on the microscope slides then stained with Lugols iodine, and examined under the microscope with the magnification X10 and X40. The S.haematobium eggs were counted and reported as the number of eggs per 10 ml of urine. The intensity of S.haematobium infection was differentiated according to WHO categories of 1-49 eggs/10 ml as light infection and >50 eggs/10 ml as heavy infection.[13]
Questionnaire survey
A structured questionnaire was prepared and used to collect information from primary school children. The questionnaire had three sections; the first section collected information on social-demographic characteristics of school children, the second section collected information on the uptake of praziquantel for prevention of urogenital schistosomiasis, and the third section collected information on WASH risk factors associated with the ongoing transmission of urogenital schistosomiasis among school children. Interviews were carried out after the collection of urine samples.
Data analysis
Data were checked for completeness, coded, entered, and cleaned using Statistical Package for the Social Sciences (SPSS) version 22. Descriptive statistics were computed to describe the prevalence of microhaematuria, prevalence, and intensity of S.haematobium ova according to social-demographic characteristics. The chi-square test (x2) or Fisher's exact test and their related p-values at a significance level of 0.05 were used to measure the association between the dependent variable (prevalence of urogenital schistosomiasis), and independent variables including social-demographic characteristics (age, sex, and class), uptake of praziquantel and WASH factors.
Ethical considerations
The ethical clearance was requested and obtained from the Muhimbili University of Health and Allied Sciences Institutional Review Board before the commencement of the study. Permission to conduct the study in Kinondoni Municipality was sought from the regional to district and school authorities. The written consent forms describing the objectives of the study, benefits and harms of participating in this study, and withdrawing rights from participation were distributed to eligible children to be given to their parents to read and sign if they consent their child to participate in this study. The children who were found positive for microhaematuria and S.haematobium were referred to a nearby dispensary for a further check-up, and treatment respectively.