Diagnostic Accuracy of HemotypeSC as a Point-of-Care Testing Device for Sickle Cell Disease: Findings from a Southwestern State in Nigeria and Implications for Patient Care in Resource-Poor Settings of sub-Saharan Africa.

This study aimed to determine the performance of a rapid, point-of-care testing device (HemotypeSC)™ for diagnosing sickle cell disease (SCD) relative to 2 commonly-used methods compared to DNA polymerase chain reaction (PCR) as the reference standard. The diagnostic performance of (HemotypeSC)™ in diagnosing SCD and determining various other Hb genotypes relative to high performance liquid chromatography (HPLC) and cellulose acetate Hb electrophoresis in alkaline buffer (CAE) was investigated among 156 participants aged 4 to 23 years in Ekiti, Southwest Nigeria. PCR was considered as the reference method/gold standard. The sensitivity and specificity for SS, SC, AS, AC, and AA genotypes by HemotypeSC and HPLC when compared with PCR, were each 100%. Similarly, their positive and negative predictive values were each 100%. However, sensitivity and specificity for identifying these Hb genotypes by CAE were 100, 100, 96.5, 0, 99.2%, and 99, 100, 92.9, 0, 91.7%. Also, CAE did not identify any of the 2 HbAC individuals that were correctly identified by PCR and both HemotypeSC, and HPLC, thus representing 100% HbAC misdiagnosis. In conclusion, this study shows that HemotypeSC has perfect concordance with PCR and 100% accuracy in diagnosing SCD in the population tested. Its ease of use, accuracy and other attributes make it suitable for use in sub-Saharan Africa for rapid determination of Hb genotypes.

Haematological indices of sickle cell patients with chronic leg ulcers on compression therapy.

BACKGROUND: Recurrent chronic leg ulcers and its are morbidities associated with sickle cell anaemia (SCA). Compression therapy increases the rate of healing of these ulcers and also decreases the rate of recurrence. OBJECTIVE: This study evaluated the haematological parameters of patients with SCA and chronic leg ulcers placed on high compression bandaging to provide data for improved ulcer management and prevention. METHODS: Eighteen patients with SCA and chronic leg ulcers were recruited for treatment by compression therapy in Ibadan, Nigeria, from March to June 2015. Eighteen SCA patients with no history of chronic leg ulcers were age and sex matched and recruited as controls. Blood samples, wound biopsies and swabs were collected at different time points for full blood count, microbiology, culture and antimicrobial susceptibility tests. Haemoglobin variants were quantified by high performance liquid chromatography. Fasting blood sugar was tested for leg ulcer patients to determine diabetic status. RESULTS: Ulcers ranged from 0.5 cm2 to 416 cm2 (median: 38.4 cm2). Post-intervention ulcer size ranged from 0.0 cm2 to 272 cm2 (median: 18.6 cm2, p < 0.001); four ulcers completely healed. Compared to the control group, haematological indices at commencement of treatment were more severe in leg ulcer patients (p = 0.02). No patients with chronic leg ulcer was diabetic. Microorganisms isolated from the leg ulcers include Pseudomonas aeruginosa, Staphylococcus aureus, Proteus sp., Escherichia coli and Klebsiella oxytoca. CONCLUSION: Measures to improve haematological parameters during leg ulcer treatment in SCA patients should be taken to aid wound healing.

Acquisition, maintenance and adaptation of invasion inhibitory antibodies against Plasmodium falciparum invasion ligands involved in immune evasion.

Erythrocyte-binding antigens (EBAs) and P. falciparum reticulocyte-binding homologue proteins (PfRhs) are two important protein families that can vary in expression and utilization by P. falciparum to evade inhibitory antibodies. We evaluated antibodies at repeated time-points among individuals living in an endemic region in Nigeria over almost one year against these vaccine candidates. Antibody levels against EBA140, EBA175, EBA181, PfRh2, PfRh4, and MSP2, were measured by ELISA. We also used parasites with disrupted EBA140, EBA175 and EBA181 genes to show that all these were targets of invasion inhibitory antibodies. However, antigenic targets of inhibitory antibodies were not stable and changed substantially over time in most individuals, independent of age. Antibodies levels measured by ELISA also varied within and between individuals over time and the antibodies against EBA181, PfRh2 and MSP2 declined more rapidly in younger individuals (≤15 years) compared with older (>15). The breadth of high antibody responses over time was more influenced by age than by the frequency of infection. High antibody levels were associated with a more stable invasion inhibitory response, which could indicate that during the long process of formation of immunity, many changes not only in levels but also in functional responses are needed. This is an important finding in understanding natural immunity against malaria, which is essential for making an efficacious vaccine.