Schistosomiasis and Associated Risk Factors Among School-Aged Children in Northern Nigeria

Background of the Study

Schistosomiasis is the most prevalent neglected tropical disease (NTD) after malaria and intestinal helminthiases.¹ It is the third most devastating tropical disease in the world, being a major public health problem in many developing countries in Africa, South America and the Middle East. More than 207 million people are infected globally, 80% of these live in Africa and an estimated 700 million people are at risk of infection in 76 countries where the disease is considered endemic.² People in endemic areas were exposed to parasite-infested fresh water mainly through their agricultural work, domestic chores and recreational activities. Globally 200,000 deaths are attributed to schistosomiasis annually.³ Nigeria is having the greatest number of cases of schistosomiasis worldwide, with about 29 million people at risk of infection and an overall prevalence of 9.5%.^4,5

Schistosomiasis is a parasitic infection caused by blood trematodes of the genus Schistosoma and transmitted to humans by certain freshwater snails after skin contact with infected water.^6,7 The transmission occurs when the parasites deposit terminal spine eggs to the host during the infection, which block the venous plexus and prevent blood flow. This causes the veins to break, allowing blood and eggs to enter the urinary bladder.⁸ The five species of Schistosoma that cause the disease worldwide are S. haematobium, S. mansoni, S. japonicum, S. intercalatum and S. mekongi; S. haematobium, and S. japonicum account for the largest percentage (95%) of all human cases of schistosomiasis found in the world.⁶ In Nigeria, two species are pathogenic to man; S. haematobium and S. mansoni. The disease caused by S. haematobium is characterized by bloody urine, calcification of the bladder, kidney failure, and bladder cancer. It is also the major cause of female genital schistosomiasis (FGS).^9,10 On the other hand, intestinal schistosomiasis, which is caused by S. mansoni, can have symptoms such as abdominal pain and bloody diarrhea. In severe cases, liver enlargement that is often linked with a peritoneal fluid retention and abdominal blood vessel hypertension. In such cases there may also be enlargement of the spleen.¹¹

According to the data gathered from peer-reviewed journals and nationwide geographical information system database, schistosomiasis is endemic in 35 of Nigeria's 36 states.⁸ Schistosomiasis prevalence and morbidity is highest among school children, adolescent and young adult.¹² As a result, the negative effects on academic achievement and the infirmity caused by untreated disease demoralizes both social and economic progress in endemic areas.¹³

The global effort to eliminate schistosomiasis is enshrined in World Health Organization's (WHO) schistosomiasis plan with a vision of a “World Free of Schistosomiasis,” with its end goal to eliminate the disease as a public health problem by 2025, and to interrupt transmission in many areas by the same time.²To control schistosomiasis, it is recommended that people become more educated about the effect and transmission of the parasites, improve sanitation, have access to basic amenities such as safe drinking water, and limit water contact activities.¹⁴ In response to this global effort Nigeria came up with national program to eliminate schistosomiasis together with other NTDs. According to the Nigerian master plan for NTDs 2015 – 2020, all the 774 Local Government Areas (LGAs) in the country have been mapped; 603 are endemic for schistosomiasis and the provisional prevalence of the disease ranged between 0-84% nationwide.^15,16

Prior to the development of the master plan there was a national effort to control schistosomiasis mainly through the provision of an antihelminthic praziquantel and health education to school-aged children. For instance, in Jigawa State a pilot control effort was carried out by the state Ministry of Health in five primary schools in Dutse metropolis from 2009 to 2013.¹⁷ Based on WHO protocol for the control of schistosomiasis, all healthy children in the five schools were given the antihelminthic drug once a year to swallow under the supervision of their teachers and health officials from the ministry. The children were later observed for any side effects due to the administration of the antihelminthic. In addition, a health education campaign was undertaken on how the children could safeguard themselves from contracting the disease. Prior to the commencement of the control effort in these primary schools, the overall prevalence of schistosomiasis using the sedimentation and Kato- Katz methods was 22.9%.¹⁸ Unfortunately, there was no follow up on the progress made in such control efforts. The present work aims at conducting a post-intervention study on the prevalence and risk factors of schistosomiasis using the same methods on school-aged children in three primary schools in Dutse metropolis in order to determine the status of schistosomiasis following the intervention.

Objectives

To determine the prevalence of urinary and intestinal schistosomiasis among school aged children (6-15 years) in Dutse metropolis following preventive chemotherapy from 2009 to 2013. To determine the risk factors associated with prevalence of schistosomiasis among school aged children (6-15 years) in Dutse metropolis following chemotherapy from 2009 to 2013. Our specific aim was to conduct a post-intervention study of the prevalence of schistosomiasis and its associated risk factors among school aged children in Dutse metropolis, Dutse, Jigawa State, Northern Nigeria. We hypothesized that there is no significant difference in the prevalence of schistosomiasis among school aged children (6-15 years) between the pre and post-intervention periods in Dutse metropolis. The researchers hypothesize that there is no association between the prevalence of schistosomiasis and risk factors among school aged (6- 15 years) in Dutse metropolis.

Study Area

The study was carried out in Dutse metropolis, Dutse Local Government Area, Jigawa State, Nigeria. Dutse is a city located in Northern Nigeria and is the capital of Jigawa State. It is situated between latitude 11 42'8.46'N and longitude 9 20'2.46”E or 11.702351 and 9.334016 respectively. Dutse is currently the largest city in Jigawa State with an estimated population of 153,000.¹⁹ The population of Dutse is predominantly the Hausa and Fulani tribes practicing agriculture as the main source of livelihood.

Study Design, Sample Size and Population

A cross sectional study involving 150 school pupils, aged 6 -15 years old, was conducted in Dutse metropolis in July 2018. The sample size was determined using the formula for schistosomiasis.²⁰

Where, N= Sample size, Z= the normal standard de- viate (Z=1.96)

P= the frequency of occurrence of Schistosomes (P = 22.9%), Q= 1-p

D= degree of precision (0.05%).

Out of the five schools targeted for pilot schistosomiasis control in Dutse metropolis by the Jigawa State Ministry of Health in 2009 and 2013, three primary schools were selected for the post-intervention to study namely: Galadanchi, Dr. Nuhu Muhammad Sunusi and Kachi Special primary schools. A total of 150 pupils were randomly selected from classes 1-6, ages 6-15 years.

Questionnaire Administration

A validated structured questionnaire was used to obtain demographic and socioeconomic information such as water contact activity, source of drinking water, personal and environmental hygiene practices and contact with a fresh bodies of water.

Parasitological Examination

Three hundred (300) samples comprising 150 urine and 150 stool samples were collected by assignment of numbers to every randomly selected participant from the different classes. In appropriately labeled plastic screw cap urine and stool containers, the children were asked to collect 10mls of the urine sample and 5g of fresh stool samples at mid-day. The pupils were also instructed on how to collect the urine sample advising to include the first and last drops, for these drops often contain the highest number of the Schistosoma eggs.

Both stool and urine samples were taken in an ice container to the Biology Laboratory, Department of Biological Sciences, Federal University Dutse, Jigawa State, Nigeria for immediate processing. The urine samples were processed using sedimentation technique as described in previous studies.^21,22 The supernatant was discarded using syringe and needle, and the sediment was transferred to a plain slide with cover slip and the sediment was examined initially at ×10 and then × 40 magnifications under the light microscope. Eggs were detected and identified by the shape and terminal spine characteristic of S. haematobium. The stool samples were analyzed as outlined in prior studies^21,23 using Kato-Katz kit. Malachite green was added to each of the processed slide and was examined under the microscope initially under ×10 and later × 40 for the presence of egg or ova of S. mansoni. The eggs were detected and identified by the shape and lateral spine characteristics of S. mansoni. Positive samples for both S. haematobium and S. mansoni were counted and recorded.

Data Analysis

The data generated were analyzed using SPSS version 18.0 (IBM corporation, NY, USA). The demographic characteristics and socioeconomic variables of the research participants were presented in the form of frequencies and percentages. Chi-square was used to test the association between demographic, socioeconomic and behavioral variables with infection. A linear regression analysis was used to identify the risk factors that significantly (p < 0.05) associated with schistosomiasis infection.

Ethical Approval

Ethical clearance was obtained from Jigawa State Ministry of Health via a letter with a reference number MOH/SEC/3.5/620/1 dated 21^st April, 2018. Correspondingly the Jigawa State Universal Basic Education Board (JGSUBEB) consented to the study based on the MOH ethical clearance. The purpose of the study was explained to the Headmaster of the schools and informed consent and assent from the pupils, parent or guardian of the children was sought before the commencement of the work and kept confidential.

Demographic and Socioeconomic Characteristics of the Participants

The demographic and social characteristics of the participants are presented in Table 1. The majority of participants were males (62%), while 38% were females. Participation according to age groups showed that the 11 – 15 years age group had the highest number 72% followed by 6 – 10 years age group with 28%. The same trend is maintained with regard to participation based on class of the pupils, children in class 4 – 6 were more in number than those in class 1- 3. Many of the pupils' parents were civil servants 48%, while 28% were farmers.

Prevalence of Schistosomiasis among Primary School Pupils in Dutse Metropolis

Table 2 presents the prevalence of infection among the participants. The overall prevalence of schistosomiasis was 10% with S. haematobium 8%, S. mansoni 2.67% and co-infection 0.67%. Males had an overwhelming prevalence of 15.10% over females with 1.75%. The 11 - 15 years age group had higher prevalence of 10.10% than the 6 - 10 years age group with 9.68%. Kachi Primary School had the highest prevalence 14.00% followed by Galadanchi with 12.00% while Sir Muhammadu Sunusi had the lowest 4.00%. Almost all the infections occurred among pupils in classes 4 – 6 with 12.10% and an infection among the class 1 – 3 pupils. Children whose parental occupation was unskilled laborer had the highest prevalence of 16.67% followed by civil servants at 12.50%, farming at 4.76%, trading at 6.25% and butcher at 0.00%.

Risk Factors of Schistosomiasis among the Study Population

Table 3 shows the univariate analysis to determine the association between infection with schistosomiasis and demographic characteristics, socioeconomic status and behaviors of the research participants. Apart from gender, all the other variables (age, parents' occupation, water contact activities, water source usage and personal hygiene) were found to be not significantly associated with schistosomiasis infection among the school aged children in the three primary schools. Schistosomiasis prevalence was found to be significantly higher among males than females (14.1% vs 1.7%, p = 0.011). When gender was considered for logistic regression analysis in Table 3, the level of significance was retained at p = 0.033 indicating that males were at higher risk of becoming infected than their female counterparts. The odds of infection was more than nine times higher in males than in females (OR = 9.38; 95% CI = 1.19, 73.76).

Limitations

The major constrain was that the post-intervention study was done about five years after the index intervention. Therefore the reported reduction in prevalence may not be solely attributed to the index intervention, it could also be associated with government programs especially improved water supply and environmental sanitation. In addition among the risk factors considered only gender was controlled. There should be a more extensive study of schistosomiasis among both schooled and unschooled children covering the entire state in order to gather comprehensive data that could be used in planning and executing a more integrated schistosomiasis control program in the state.

Compliance with Ethical Standards