Urogenital Schistosomiasis among Primary School Children in Rural Communities in Obudu, Southern Nigeria

1.1. Background of the Study

Urogenital schistosomiasis caused by infection with Schistosoma haematobium (S. haematobium) is widespread and causes morbidity on the African continent.1 The World Health Organization (WHO) regards the disease as a Neglected Tropical Disease (NTD) with an estimated 732 million persons being vulnerable to infection worldwide in renowned transmission areas.2 However, 85% of the cases reported annually occur in sub-Saharan Africa (SSA) and over 150,000 deaths are attributable to chronic infection with S. haematobium within regions.3 Within SSA, Nigeria has the highest prevalence of human schistosomiasis5 with about 29 million infected people.4 Other SSA countries such as Kenya6 and Ethiopia7 estimate that 6 million and over 5 million people are infected with 15 million and 37 million people at risk of infection, respectively.

Humans are infected with this disease when they come in contact with water bodies infested with skin penetrating cercariae. Adult S. haematobium inhabit the venules surrounding organs of the pelvis where they lay between 20 and 200 eggs daily.2 During infection, the parasites deposit terminal spine eggs which clog the venous plexus, impeding blood flow.8 The eggs of S. haematobium provoke granulomatous inflammation, ulceration and pseudo-polyposis of the vesical and ureteral walls. Hematuria is a very common sign of infection but other signs include dysuria, pollakisuria and proteinuria while the mortality caused by schistosomiasis is very low, subtle and indirect morbidities such as fatigue, physical or cognitive impairment are common in children.9

In Nigeria, urogenital schistosomiasis is widespread in both rural and urban communities.10,11 and the national policy on schistosomiasis control adopted praziquantel as the main drug of choice in the control strategy aimed at reducing morbidity. Dishearteningly, not much progress has been made in the control of urogenital schistosomiasis in the country. Presumably, the disease is more endemic in poor rural communities especially places where fishing and agricultural activities are dominant. There is a high level of the risk of becoming infected as a result of low literacy level, poverty, sub-standard hygiene and inadequate public infrastructure.12

Prior studies have reported the endemicity of urinary schistosomiasis in Southern Nigeria13,14 and specifically in Obudu.15 However, there is paucity of current scientific information on the endemicity of urinary schistosomiasis in many parts of the country especially in the rural areas where the high-risk population are school aged children. Therefore, there is need to provide updated information on the status of urinary schistosomiasis in Southern Nigeria. In addition, previous studies10,15,16 on urinary schistosomiasis from this region obtained their samples from one or two communities, but this study increased the geographical coverage to seven communities to provide larger and adequate information on the disease.

1.2. Objective of the Study

Despite considerable efforts to scale-up treatment activities in all states of Nigeria, coverage still remains poor in most rural and hard to reach communities. This study was designed with the aim of providing updated information on the extent of disease burden among primary school children of rural, communities at risk in Obudu Local Government Area (LGA), Cross River State, Nigeria. It is hoped that the result from this study will add to the existing baseline data on the endemicity of this disease in the country.

2.1. Study Area

This cross-sectional study was carried out in seven purposively selected communities’ in Obudu LGA. Obudu LGA is one out of the 18 LGAs of Cross River State, Nigeria with a population of 215,800 people in 2016. In each of the selected community, a simple random sampling was used to select the school using the lottery method. The communities are; Udigie (Lat. 6.6667°N, Long. 9.1679°E); Utugwang (Lat.5.6208°N, Long. 9.0336°E); Ibong (Lat. 6.5794°N, Long. 9.1273°E); Ukwortong (Lat. 6.5942°N, Long. 9.0721°E); Betukwel (Lat. 6.6054°N, Long. 9.1060°E); Ugboro (Lat. 6.6621°N, Long. 8.8419°E); and Ohong (Lat. 6.5963°N, Long. 9.1172°E). Cross River state is situated within the tropical rainforest belt of Nigeria. It lies within latitudes 4.4500°N to 5.5333°N and longitude 7.8333°E and 9.4666°E. The coastal area has an annual rainfall of about 350 mm while rainfall in the hinterland is between 120 and 200 mm annually with maximum precipitation occurring from July to September. Most of the communities depend on streams, rivers, rapids and shallow wells as their domestic water supply. These water bodies are frequently visited for water contact activities like bathing, swimming, washing and other domestic activities. Agriculture especially swamp-rice cultivation, cocoyam cultivation and fishing are the major occupations of the inhabitants of these communities.

2.2. Study Design and Population

A school based cross-sectional study was conducted between June to December 2016. School- aged children aged 4-14 years were enrolled from 7 primary schools in each of the seven communities. Participants were selected by first stratifying the children according to the different classes (1-6) and then randomly selecting equal proportion of children in the different grades. This was done for all the seven schools.

2.3. Exclusion Criteria

Primary school children given chemotherapy for schistosomiasis during the national deworming program by WHO through the state ministry of health three weeks prior to and during the data collection at home were excluded during the study. The deworming status was verified while seeking their consent to participate in the study.

2.4. Sample Size Determination

This was estimated using the sample size formula17 as calculated below:

Z = 1.96 (95%)

P = prevalence of urogenital schistosomiasis = 50%

e = error rate 0.05 (5%)

n ~ = 384 + 20% non-respondent value = 384 + 77 = 461.

The minimum sample size is 461 pupils.

A total of 1113 individuals, comprising of 587 males and 526 females were selected randomly from the surveyed schools.

2.5. Ethical Consideration

This study was performed under a protocol that was reviewed and approved by the Research Ethics Committee of Cross River State Ministry of Health (CRSMoH), Calabar. Ethical approval was also obtained from the Local Government Education Authority Consent was verbally obtained from parents and Head teachers of children of the various schools. The village heads and opinion leaders were briefed on the objectives and purpose of the study. The respondents were interviewed in their classrooms with the assistance of their teachers.

2.6. Sample Collection

Each consenting child was provided with a 50 ml capacity autoclaved wide-mouthed screw capped container for collection of a mid-day urine sample. Samples were obtained between 10.00 hours and 14.00 hours, when egg excretion is usually maximal.10 Samples with visible hematuria were noted. The specimens were approximately labelled with identification numbers and placed in cold box with 16 packs immediately after collection. They were processed 1-2 hours from collection. In situations where delay in transportation of specimen to laboratory was inevitable, 0.2 ml of 37% formalin was added to urine sample as a preservative.

2.7. Parasitological Examination

Sedimentation quantitative technique was employed for the detection of S. haematobium eggs in the urine samples as previously described.18 Briefly, 10ml of each thoroughly mixed urine sample was put in a centrifuge tube. The centrifuge was spun for 5 minutes at 1500 rpm. The supernatant was decanted leaving about 0.5ml of the fluid with the sediment at the bottom of the tube undisturbed. The remaining fluid and sediment were mixed, then a drop of the mixture was transferred to a microscope slide and covered with a cover slip. The slide was meticulously examined for S. haematobium using x10 objectives. The eggs seen were counted and the intensity of infection per 10ml of urine accordingly determined. The intensity of S. haematobium was classified as light infection: 1-49 egg/10ml of urine; and heavy infection: ≥50 egg/10ml of urine.19

2.8. Examination of Urine for Hematuria and Proteinuria

Within 2 hours of urine sample collection, hematuria and proteinuria were detected in the field using dipsticks (Medi-Test Combi-9 manufactured by Machery-Hagel Duren, Germany). The reagent end of the test strip was dipped into fresh, well-mixed uncentrifuged urine for 40 seconds. Upon removal, the test area was compared with a standard color as described by the manufacturer.10

2.9. Statistical Analysis

Data obtained were entered into Microsoft Excel for Windows, version 2013 (Microsoft Corporation, Redmond, Washington, USA). Descriptive statistics and chi-square tests were performed on data at 95% Confidence Interval (C.I.) and Level of significance (P) set at p≤0.05 using the Statistical Package for Social Sciences (SPSS) for Windows, version 20.0 (SPSS Inc. Chicago, IL, USA).

3.1. Demographic Characteristics

A total of 1,113 school children were examined for urogenital schistosomiasis comprising of 587 males (52.7%) and 526 females (47.3%). The age group of 10-14 years were the highest respondents with 830 (74.6%) children followed by 5-9 year-olds with 269 (24.6%) (Table 1).

3.2. Prevalence of Urogenital Schistosomiasis

Among the 1,113 school children examined, 153 were observed shedding eggs of S. haematobium in their urine giving an overall prevalence of 13.7% (95% C.I. = 6.207 – 21.193 %). Prevalence in schools ranged from 7.8% to 28.9% and 42.9% (3/7) of the schools had infection prevalence of >10%. Significant difference (p<0.001) was observed in the prevalence of the parasites among the selected schools (Table 2). Males (86 (14.7%) (95% C.I. = 6.871 – 22.329%): were more infected than females (67 (12.7%) (95% C.I. = 4.442 – 20.615%)). There was no significant difference (p=0.355) in the prevalence between male and female pupils (Table 2).

Children age 5 to 9 years old (46 pupils or 17.1%) had the highest prevalence compared to those in the age groups of 15-19 years (16.7%), 10- 14 years (12.7%) and 0-4 years (12.5%) (Fig. 1). There was no significant difference in prevalence among the age groups (χ² = 3.446, df = 3, p=0.328) (Table 3).

Close

Figure 1

Prevalence of Urogenital Schistosomiasis in Relation to Age and School in the Study Area

Export to PPT

3.3. Prevalence of Hematuria and Proteinuria

Hematuria is the presence of blood in urine while proteinuria is the presence of protein in urine. The total prevalence of hematuria was 152 (13.7%) (95% C.I. = 10.649 – 18.751). The 5-9 years age group had the highest hematuria rate of 46 (17.1%) (Fig. 2). The prevalence of proteinuria was 172 (15.5%) (95% C.I. = 5.102 – 38.712.), with the 15-19 age group having the highest prevalence of 2 (33.3%) (Fig. 3). Proteinuria was not observed in the age group of 0-4 years, significant difference (χ² = 7.818, df = 3, p=0.050) was observed in the prevalence of proteinuria among the age groups (Table 3).

Close

Figure 2

Prevalence of Hematuria in Relation to Age and School in the Study Area

Export to PPT

Close

Figure 3

Prevalence of Proteinuria in Relation to Age and School in the Study Area

Export to PPT

3.4. Mean Intensity

Mean intensity represents the arithmetic mean of the number of individual S. haematobium parasites per infected host in a sample. The overall ova intensity (eggs/10ml of urine) among the infected children was 13.30 eggs/10ml urine (range 2.0 eggs/10ml urine to 63 eggs/10ml urine). Females had a higher intensity of 13.69 eggs/10ml urine than males of 12.91 eggs/10ml urine (pp=0.236). Community-level intensity varied among schools from 10.0 eggs/10ml urine in Ibong to 26.2 eggs/10ml urine in Ohong, while the age group 15-19 years had the highest intensity (34.0 eggs/10ml of urine) when compared to other age groups (Table 4).

4.1. Limitations

This study has some limitations. The geographic distribution of schistosomiasis species is closely dependent on the presence of appropriate freshwater snails (Bulinus and Biomphalaria) that serve as obligatory molluscan host. In this study a detailed malacological studies of the community streams was not carried out. However, on-the-spot check of the streams revealed the presence of Bulinus snail vectors of Schistosoma haematobium. Additionally, cases of high-risk infection were not recorded, however, those of moderate to low-risk infection were quite high and could transform to high-risk if they remain untreated. Our study results should therefore be interpreted within the context of these limitations.

4.2. Recommendations for Further Studies

Given the presence of urogenital schistosomiasis in Obudu LGA, there is need to initiate control programs so as to arrest the progression of the disease to an alarming rate. The national schistosomiasis control program should consider targeted treatment every two years in schools and surrounding communities with prevalence of between 10% but less than 50%. In addition, potable water should be provided in the schools and communities to reduce human-vector contact. Adequate snail vector control program should also be implemented to check intermediate snail host population expansion in the study area.