Project – Prevalence and Genotype Distribution of Sickle Cell Disease among Students in Selected Secondary Schools in Ikorodu Local Government Area, Lagos State

CHAPTER ONE

INTRODUCTION

1.1 Background of the Study

Sickle Cell Disease (SCD) is one of the most common inherited haemoglobin disorders globally, characterized by the presence of abnormal haemoglobin S (HbS) that causes red blood cells to assume a sickle or crescent shape under low oxygen conditions. This abnormality leads to chronic haemolytic anaemia, vaso-occlusion, recurrent pain episodes, organ damage, and increased susceptibility to infections. The disease is inherited in an autosomal recessive pattern, meaning that an individual must inherit two abnormal HbS genes (one from each parent) to manifest the disease, while carriers possess one normal and one abnormal gene (heterozygous state) (Piel et al., 2017).

Globally, SCD remains a major public health concern, particularly in sub-Saharan Africa, which accounts for more than 75% of the global burden. Nigeria is recognized as the country with the highest burden of SCD worldwide, with an estimated 150,000 children born annually with sickle cell anaemia and about 25% of the population carrying the sickle cell trait (Adewoyin, 2015). The high prevalence in Nigeria is strongly associated with the protective advantage of the sickle cell trait against malaria, which has contributed to the persistence of the gene in malaria-endemic regions (Makani et al., 2011).

Among adolescents and young adults, especially secondary school students, SCD represents a significant health and educational challenge. Many affected individuals experience recurrent illness episodes, absenteeism from school, reduced academic performance, and psychosocial stress. Furthermore, a large proportion of adolescents remain unaware of their haemoglobin genotype, thereby increasing the risk of genetic transmission through future marriages. Studies conducted in Lagos and other parts of Nigeria have shown that while awareness of SCD may be relatively high among students, knowledge of genotype status and its implications for reproduction remains inadequate (Kanma-Okafor et al., 2022; Oluwole et al., 2018).

The distribution of haemoglobin genotypes in Nigeria typically includes HbAA (normal), HbAS (carrier state), HbSS (sickle cell disease), HbSC, and other rare variants. However, the frequency of these genotypes varies across regions and populations due to genetic, ethnic, and environmental factors. Studies in Lagos have reported significant proportions of carriers (HbAS), which reinforces the importance of early screening among adolescents in secondary schools (Taiwo et al., 2011).

Secondary school students in Ikorodu Local Government Area (LGA), Lagos State, represent a critical population for SCD screening and genetic awareness due to their stage of development, where health education can influence future reproductive decisions. Despite ongoing health education programs, many students still lack access to genotype testing, and misconceptions about SCD persist. This gap highlights the need for comprehensive epidemiological data on the prevalence and genotype distribution of SCD among this population.

Therefore, understanding the prevalence and genotype distribution of SCD among secondary school students in Ikorodu LGA is essential for guiding public health interventions, genetic counseling programs, and school-based screening initiatives aimed at reducing the burden of SCD in future generations.

1.2 Statement of the Problem

Sickle Cell Disease remains one of the most prevalent genetic disorders in Nigeria, contributing significantly to morbidity and mortality among children, adolescents, and young adults. Despite increased awareness campaigns and school-based health education programs, the disease continues to persist due to inadequate knowledge of genotype status and poor uptake of genetic screening services among secondary school students.

In Ikorodu Local Government Area, Lagos State, a large number of students are believed to be either carriers (HbAS) or unaware of their haemoglobin genotype status. This lack of awareness poses a serious public health challenge, as many adolescents may enter relationships and eventually marriage without knowledge of their genetic compatibility, thereby increasing the risk of giving birth to children with SCD. Previous studies in Lagos have shown that although awareness of SCD is relatively high, actual genotype testing and knowledge of personal genotype remain low among students (Kanma-Okafor et al., 2022).

Furthermore, there is limited localized data on the prevalence and genotype distribution of SCD specifically among secondary school students in Ikorodu LGA. Most available studies have been conducted in other parts of Lagos or among tertiary institution students, leaving a gap in evidence regarding adolescents in this locality. This lack of data makes it difficult for policymakers, educators, and healthcare providers to design targeted interventions such as school-based screening programs and genetic counseling services.

The persistence of SCD in Nigeria suggests that preventive strategies, including early genotype screening and genetic counseling, are not adequately reaching adolescents in secondary schools. Without proper data on prevalence and genotype distribution, efforts to reduce the burden of SCD through preventive education and premarital screening may remain ineffective.

Therefore, this study seeks to address this gap by determining the prevalence and genotype distribution of sickle cell disease among students in selected secondary schools in Ikorodu Local Government Area, Lagos State.

1.3 Objectives of the Study

The main objective of this study is to determine the prevalence and genotype distribution of Sickle Cell Disease among students in selected secondary schools in Ikorodu Local Government Area, Lagos State.

Specific objectives are to:

1. Determine the prevalence of SCD among secondary school students in Ikorodu LGA.
2. Identify the distribution of haemoglobin genotypes (HbAA, HbAS, HbSS, HbSC) among the students.
3. Assess the proportion of students who are aware of their genotype status.
4. Examine the relationship between awareness of genotype and prevalence of SCD among students.

1.4 Research Questions

1. What is the prevalence of SCD among secondary school students in Ikorodu LGA?
2. What is the distribution of haemoglobin genotypes among the students?
3. How many students are aware of their genotype status?
4. What is the relationship between genotype awareness and SCD prevalence among students?

1.5 Research Hypothesis

H₀: There is no significant relationship between students’ awareness of haemoglobin genotype status and the prevalence of Sickle Cell Disease among secondary school students in Ikorodu Local Government Area, Lagos State.

H₁: There is a significant relationship between students’ awareness of haemoglobin genotype status and the prevalence of Sickle Cell Disease among secondary school students in Ikorodu Local Government Area, Lagos State.

1.6 Significance of the Study

This study will be beneficial to several stakeholders. To students, it will increase awareness of haemoglobin genotype status and the importance of genetic screening. To school health authorities and educators, it will provide evidence for strengthening health education programs on SCD prevention.

To healthcare professionals and genetic counselors, the findings will assist in planning targeted screening and counseling services for adolescents. Policymakers and public health planners will also benefit from the data in designing effective interventions aimed at reducing the burden of SCD in Lagos State and Nigeria as a whole. Additionally, the study will contribute to existing academic literature on sickle cell epidemiology among adolescents.

1.7 Scope of the Study

This study is limited to students in selected secondary schools in Ikorodu Local Government Area, Lagos State. It focuses on the prevalence of SCD and the distribution of haemoglobin genotypes (HbAA, HbAS, HbSS, HbSC) among students. It also considers awareness of genotype status among respondents.

1.8 Operational Definition of Terms

• Sickle Cell Disease (SCD): A hereditary blood disorder caused by abnormal haemoglobin S leading to sickling of red blood cells.
• Haemoglobin Genotype: The genetic composition of haemoglobin in an individual (e.g., HbAA, HbAS, HbSS).
• Prevalence: The proportion of individuals in a population who have a specific condition at a given time.
• Carrier (HbAS): A person who inherits one normal gene and one sickle gene.
• Secondary School Students: Adolescents enrolled in junior or senior secondary education.

Project – Prevalence and Genotype Distribution of Sickle Cell Disease among Students in Selected Secondary Schools in Ikorodu Local Government Area, Lagos State