Abstract:
Background: Sickle cell disease (SCD) is a genetic disorder inherited in autosomal
recessive fashion and affects the haemoglobin (Hb) molecule. The homozygous state
(HbSS) is the severest form of SCD and the heterozygous state(HbAS) is the Sickle
cell trait or carrier state (SCT). Health education, genetic counseling, testing and
identifying persons with the sickle cell gene and advising them on how to prevent
birth of children with SCD are important primary intervention strategies for control of
SCD.
Objectives: To determine the prevalence of sickle cell trait among adolescents
attending mixed day secondary schools in Bungoma County. To determine the
haemoglobin variants among adolescents attending mixed day secondary schools in
Bungoma County. To test the association between the demographic characteristics
and sickle cell trait among adolescents attending mixed day secondary schools in
Bungoma County.
Methods cross-sectional study was done on adolescents attending mixed day
secondary schools in Bungoma County of Western Kenya between January 2017 and
July 2017. Stratified random sampling was applied; the county was stratified into 9
constituencies; a mixed day secondary school was selected randomly from each
constituency. Public health education on SCD control was offered to 2389 students in
9 schools, 2248 met eligibility criteria. A total of 225 eligible participants were
selected randomly from the school registers and consented. Pretest counseling was
done followed by testing for sickle cell gene status using a point of care (POC) device
(The Sickle scan™). Post test counseling was offered. Demographics and test results
were documented. Proportions and Percentages was used to describe categorical data;
Mean and Median for continuous data. Logistic regression was done and risk ratios
(RR) generated, Pearson chi square was used to test for associations. Level of
significance was set at p-value <0.05 with Confidence interval at 95%.
Results: All 225 participants consented for testing; Males: 116/225(51.6%), Females:
109/225(48.4%). The median age was 17 years. HbAS prevalence was 18.7%
(42/225) (CI 0.14-0.24). Proportion of males with HbAS was 24/116(20.7%);
proportion of females with HbAS was 18/109(16.5%). Proportion of HbAS among
students with known family history of SCD was 6/12 (50%);proportion of HbAS
among those with no known family history of SCD was 36/213 (16.9%).Of those with
family history of SCD; 1/12(8.3%)reported a sibling,9/12(75%) reported a cousin and
2/12(16.6%)reported other relatives. Hb variants were HbAA (183/225,81.3%) and
HbAS (42/225,18.7%), there were no other Hb variants. There was no invalid result.
Those with Family History of SCD were three times more likely to have HbAS(RR-
2.958, p-value= 0.004,CI:1.561-5.607).
Conclusion: Prevalence of HbAS among adolescents is high. Hb variants found were
HbAA and HbAS, there was no HbSS or HbC variants found. Having a Known
Family History of SCD was significantly associated with having HbAS.
Recommendations: Public Health Education on SCD and SCT to Bungoma County
residents. Setting up of genetic counseling and testing centers for SCD and SCT in
Bungoma County.