Molecular Characterization of Streptococcus Pneumoniae Causing Disease Among Children in Nigeria During the Introduction of PCV10 (GSK)

Streptococcus pneumoniae (pneumococcus) is a leading vaccine-preventable cause of childhood invasive disease. Nigeria has the second highest pneumococcal disease burden globally, with an estimated ~49 000 child deaths caused by pneumococcal infections each year. Ten-valent pneumococcal conjugate vaccine (GSK; PCV10) was introduced in December 2014 in a phased approach. However, few studies have characterized the disease-causing pneumococci from Nigeria. This study assessed the prevalence of serotypes, antibiotic susceptibility and genomic lineages using whole genome sequencing and identified lineages that could potentially escape PCV10 (GSK). We also investigated the potential differences in pneumococcal lineage features between children with and without sickle cell disease. A collection of 192 disease-causing pneumococcal isolates was obtained from Kano (n=189) and Abuja (n=3) states, Nigeria, between 1 January 2014 and 31 May 2018. The majority (99 %, 190/192) of specimens were recovered from children aged 5 years or under. Among them, 37 children had confirmed or traits of sickle cell disease. Our findings identified 25 serotypes expressed by 43 Global Pneumococcal Sequence Clusters (GPSCs) and 85 sequence types (STs). The most common serotypes were 14 (18 %, n=35), 6B (16 %, n=31), 1 (9 %, n=17), 5 (9 %, n=17) and 6A (9 %, n=17); all except serotype 6A are included in PCV10 (GSK). PCV10 (SII; PNEUMOSIL) and PCV13 formulations include serotypes 6A and 19A which would increase the overall coverage from 67 % by PCV10 (GSK) to 78 and 82 %, respectively. The pneumococcal lineages were a mix of globally spreading and unique local lineages. Following the use of PCV10 (GSK), GPSC5 expressing serotype 6A, GPSC10 (19A), GPSC26 (12F and 46) and GPSC627 (9L) are non-vaccine type lineages that could persist and potentially expand under vaccine-selective pressure. Approximately half (52 %, 99/192) of the pneumococcal isolates were resistant to the first-line antibiotic penicillin and 44 % (85/192) were multidrug-resistant. Erythromycin resistance was very low (2 %, 3/192). There was no significant difference in clinical manifestation, serotype prevalence or antibiotic resistance between children with and without traits of or confirmed sickle cell disease. In summary, our findings show that a high percentage of the pneumococcal disease were caused by the serotypes that are covered by currently available vaccines. Given the low prevalence of resistance, macrolide antibiotics, such as erythromycin, should be considered as an option to treat pneumococcal disease in Nigeria. However, appropriate use of macrolide antibiotics should be vigilantly monitored to prevent the potential increase in macrolide resistance

Poliovirus seroprevalence before and after interruption of poliovirus transmission in Kano State, Nigeria.

INTRODUCTION: In September 2015, Nigeria was removed from the list of polio-endemic countries after more than 12months had passed since the detection of last wild poliovirus case in the country on 24 July 2014. We are presenting here a report of two polio seroprevalence surveys conducted in September 2013 and October 2014, respectively, in the Kano state of northern Nigeria. METHODS: Health facility based seroprevalence surveys were undertaken at Murtala Mohammad Specialist Hospital, Kano. Parents or guardians of children aged 6-9months, 36-47months, 5-9years and 10-14years in 2013 and 6-9months and 19-22months (corresponding to 6-9months range at the time of 2013 survey) in 2014 presenting to the outpatient department, were approached for participation, screened for eligibility and asked to provide informed consent. A questionnaire was administered and a blood sample collected for polio neutralization assay. RESULTS: Among subjects aged 6-9months in the 2013 survey, seroprevalence was 58% (95% confidence interval [CI] 51-66%) to poliovirus type 1, 42% (95% CI 34-50%) to poliovirus type 2, and 52% (95% CI 44-60%) to poliovirus type 3. Among children 36-47months and older, seroprevalence was 85% or higher for all three serotypes. In 2014, seroprevalence in 6-9month infants was 72% (95% CI 65-79%) for type 1, 59% (95% CI 52-66%) for type 2, and 65% (95% CI 57-72%) for type 3 and in 19-22months, 80% (95% CI 74-85%), 57% (49-63%) and 78% (71-83%) respectively. Seroprevalence was positively associated with history of increasing oral poliovirus vaccine doses. CONCLUSIONS: There was significant improvement in seroprevalence in 2014 over the 2013 levels indicating a positive impact of recent programmatic interventions. However the continued low seroprevalence in 6-9month age is a concern and calls for improved immunization efforts to sustain the polio-free Nigeria

Molecular Characterization of Streptococcus pneumoniae Causing Disease Among Children in Nigeria During the Introduction of PCV10 (GSK)

Streptococcus pneumoniae (pneumococcus) is a leading vaccine-preventable cause of childhood invasive disease. Nigeria has the second highest pneumococcal disease burden globally, with an estimated ~49 000 child deaths caused by pneumococcal infections each year. Ten-valent pneumococcal conjugate vaccine (GSK; PCV10) was introduced in December 2014 in a phased approach. However, few studies have characterized the disease-causing pneumococci from Nigeria. This study assessed the prevalence of serotypes, antibiotic susceptibility and genomic lineages using whole genome sequencing and identified lineages that could potentially escape PCV10 (GSK). We also investigated the potential differences in pneumococcal lineage features between children with and without sickle cell disease. A collection of 192 disease-causing pneumococcal isolates was obtained from Kano (n=189) and Abuja (n=3) states, Nigeria, between 1 January 2014 and 31 May 2018. The majority (99 %, 190/192) of specimens were recovered from children aged 5 years or under. Among them, 37 children had confirmed or traits of sickle cell disease. Our findings identified 25 serotypes expressed by 43 Global Pneumococcal Sequence Clusters (GPSCs) and 85 sequence types (STs). The most common serotypes were 14 (18 %, n=35), 6B (16 %, n=31), 1 (9 %, n=17), 5 (9 %, n=17) and 6A (9 %, n=17); all except serotype 6A are included in PCV10 (GSK). PCV10 (SII; PNEUMOSIL) and PCV13 formulations include serotypes 6A and 19A which would increase the overall coverage from 67 % by PCV10 (GSK) to 78 and 82 %, respectively. The pneumococcal lineages were a mix of globally spreading and unique local lineages. Following the use of PCV10 (GSK), GPSC5 expressing serotype 6A, GPSC10 (19A), GPSC26 (12F and 46) and GPSC627 (9L) are non-vaccine type lineages that could persist and potentially expand under vaccine-selective pressure. Approximately half (52 %, 99/192) of the pneumococcal isolates were resistant to the first-line antibiotic penicillin and 44 % (85/192) were multidrug-resistant. Erythromycin resistance was very low (2 %, 3/192). There was no significant difference in clinical manifestation, serotype prevalence or antibiotic resistance between children with and without traits of or confirmed sickle cell disease. In summary, our findings show that a high percentage of the pneumococcal disease were caused by the serotypes that are covered by currently available vaccines. Given the low prevalence of resistance, macrolide antibiotics, such as erythromycin, should be considered as an option to treat pneumococcal disease in Nigeria. However, appropriate use of macrolide antibiotics should be vigilantly monitored to prevent the potential increase in macrolide resistance

World Health Organization’s Growth Reference Overestimates the Prevalence of Severe Malnutrition in Children with Sickle Cell Anemia in Africa

Anthropometric indices are widely used to assess the health and nutritional status of children. We tested the hypothesis that the 2007 World Health Organization (WHO) reference for assessment of malnutrition in children with sickle cell anemia (SCA) overestimates the prevalence of severe malnutrition when compared to a previously constructed SCA-specific reference. We applied the WHO and SCA-specific references to children with SCA aged 5–12 years living in northern Nigeria (Primary Prevention of Stroke in Children with SCA in sub-Saharan Africa (SPRING) trial) to determine the difference in prevalence of severe malnutrition defined as body mass index (BMI) Z-score <−3 and whether severe malnutrition was associated with lower mean hemoglobin levels or abnormal transcranial Doppler measurements (>200 cm/s). A total of 799 children were included in the final analysis (median age 8.2 years (interquartile range (IQR) 6.4–10.4)). The application of the WHO reference resulted in lower mean BMI than the SCA-specific reference (−2.3 versus −1.2; p < 0.001, respectively). The use of the WHO reference when compared to the SCA-specific reference population also resulted in a higher prevalence of severe malnutrition (28.6% vs. 6.4%; p < 0.001). The WHO reference significantly overestimates the prevalence of severe malnutrition in children with SCA when compared to an SCA-specific reference. Regardless of the reference population, severe malnutrition was not associated with lower mean hemoglobin levels or abnormal transcranial Doppler (TCD) measurements

Hydroxyurea for primary stroke prevention in children with sickle cell anaemia in Nigeria (SPRING): a double-blind, multicentre, randomised, phase 3 trial

Background: In high-income countries, standard care for primary stroke prevention in children with sickle cell anaemia and abnormal transcranial Doppler velocities results in a 92% relative risk reduction of strokes but mandates initial monthly blood transfusion. In Africa, where regular blood transfusion is not feasible for most children, we tested the hypothesis that initial moderate-dose compared with low-dose hydroxyurea decreases the incidence of strokes for children with abnormal transcranial Doppler velocities.Methods: SPRING is a double-blind, parallel-group, randomised, controlled, phase 3 trial of children aged 5-12 years with sickle cell anaemia with abnormal transcranial Doppler velocities conducted at three teaching hospitals in Nigeria. For randomisation, we used a permuted block allocation scheme with block sizes of four, stratified by sex and site. Allocation was concealed from all but the pharmacists and statisticians. Participants were assigned in a 1:1 ratio to low-dose (10 mg/kg per day) or moderate-dose (20 mg/kg per day) oral hydroxyurea taken once daily with monthly clinical evaluation and laboratory monitoring. The primary outcome was initial stroke or transient ischaemic attack, centrally adjudicated. The secondary outcome was all-cause hospitalisation. We used the intention-to-treat population for data analysis. The trial was stopped early for futility after a planned minimum follow-up of 3·0 years to follow-up for participants. This trial was registered with ClinicalTrials.gov, number NCT02560935.FINDINGS: Between Aug 2, 2016, and June 14, 2018, 220 participants (median age 7·2 years [IQR 5·5-8·9]; 114 [52%] female) were randomly allocated and followed for a median of 2·4 years (IQR 2·0-2·8). All participants were Nigerian and were from the following ethnic groups: 179 (82%) people were Hausa, 25 (11%) were Fulani, and 16 (7%) identified as another ethnicity. In the low-dose hydroxyurea group, three (3%) of 109 participants had strokes, with an incidence rate of 1·19 per 100 person-years and in the moderate-dose hydroxyurea group five (5%) of 111 had strokes with an incidence rate of 1·92 per 100 person-years (incidence rate ratio 0·62 [95% CI 0·10-3·20], p=0·77). The incidence rate ratio of hospitalisation for any reason was 1·71 (95% CI 1·15-2·57, p=0·0071), with higher incidence rates per 100 person-years in the low-dose group versus the moderate-dose group (27·43 vs 16·08). No participant had hydroxyurea treatment stopped for myelosuppression.Interpretation: Compared with low-dose hydroxyurea therapy, participants treated with moderate-dose hydroxyurea had no difference in the stroke incidence rate. However, secondary analyses suggest that the moderate-dose group could lower incidence rates for all-cause hospitalisations. These findings provide an evidence-based guideline for the use of low-dose hydroxyurea therapy for children with sickle cell anaemia at risk of stroke.Funding: National Institute of Neurological Disorders and Stroke

Randomized controlled trial of fixed low-vs moderate-dose hydroxyurea for primary stroke prevention in Sub-Saharan Africa: Final results of the Spring Trial

Introduction: In children with sickle cell anemia (SCA) without transcranial Doppler (TCD) screening, the incidence rates of ischemic strokes is approximately the same among children living in low- and high- low-resource settings (Pediatr Neurol. 2019;95:73-78.) with a prevalence of ~ 11%. However, in high-income settings, the standard use of TCD ultrasonography, coupled initially with monthly blood transfusion therapy has dropped the stroke prevalence to < 1%. In a low-income setting, such as Nigeria, where 50% of children in the world with SCA are born (150,000 per year), initial monthly blood transfusion therapy is not practical for most children.In the Stroke Prevention in Nigeria (SPIN) Feasibility Trial (NCT01801423), fixed moderate-dose hydroxyurea was associated with a decreased rate of strokes in children with SCA and abnormal time-averaged mean of the maximum velocity (TAMMV) TCD measurements (≥200cm/sec) when compared to no treatment in the STOP Trial, 0.76 and 10.7 strokes per 100 person-years, repsectively (Am J Hematol. 2020). Based on the success of the SPIN trial, plus the challenges of real-world implementation of a government-supported primary stroke prevention programs for estimated 40,0000 children with SCA in three states in Nigeria, we tested the hypothesis that fixed-moderate dose (~20 mg/kg/day) hydroxyurea therapy for primary stroke prevention results in a 66% relative risk reduction (9 to 3 events per 100 person-years) when compared to fixed low-dose hydroxyurea (~10 mg/kg/day) therapy in a randomized controlled trial (The SPRING Trial; NCT02560935).Methods: In this partial-blind controlled phase III trial, we randomly assigned children between 5 and 12 years of age with SCA and a TCD time-averaged mean of the maximum velocity (TAMMV) ≥ 200 cm/sec measured independently twice or TAMMV ≥220 cm/sec once at study screening to receive fixed low-dose or fixed moderate-dose hydroxyurea. The primary endpoint was a clinical stroke or a transient ischemic attack (TIA). Myelosuppression was assessed with monthly complete blood counts (CBCs). Adherence to hydroxyurea was primarily based on an increase in MCV from baseline and monthly pill count return as a percent of dispensed pills. Hemoglobin F levels were measured at baseline, annually and upon trial exit. To evaluate the safety of hydroxyurea in the trial, children attending the same SCA clinics with TCD (TAMMV) <200 cm/sec at study screening were prospectively followed with biweekly phone calls and annual research visits.Results: A total of 220 children (mean age: 7.5 years, 51.8% female) were randomly assigned to fixed low- (10 mg/kg/day) or moderate- (20 mg/kg/day) dose hydroxyurea, and were followed for a median of 2.4 years (IQR 2.0-2.8). NINDS Clinical Trials leaders stopped the trial early because of futility for the primary outcome. In the fixed low- and moderate-dose hydroxyurea groups, the incidence rates of strokes per 100 person-years were 1.19 and 1.92 respectively, with an incidence rate ratio of 1.60 (95% CI: 0.31-10.34), p = 0.768. The incidence rate ratio of mortality when comparing the children treated with low- and moderate- fixed-dose hydroxyurea to the non-elevated TCD group (no hydroxyurea therapy, n= 211) was 1.97 (95% CI: 0.64-6.02) and 0.47 (95% CI: 0.05-2.38), p = 0.265 and 0.545, respectively. Returned pills during the trial was 5.4% and 4.8% in the fixed low- and moderate-dose groups, respectively, p= 0.144. MCV from baseline to endpoint increased 1.5fl and 7.2 fl in the fixed low- and moderate-dose groups, respectively, p<0.001. Upon exit from the trial 29.4% and 66.7% of the fixed- low and moderate -dose groups, respectively, had either hemoglobin level ≥ 9.0 g/dl, or a fetal hemoglobin level ≥ 20%.Conclusions: For primary stroke prevention in children with SCA, fixed low-dose, when compared to fixed moderate-dose hydroxyurea therapy, demonstrated no difference in the incidence rate of strokes. Both fixed low- and moderate -dose hydroxyurea doses are superior to no treatment for primary stroke prevention with abnormal TCD values. In partnership with Katsina, Kano, and Kaduna health department's leaders in Nigeria, 9 distinct SCA and primary stroke prevention clinics have been established, with the provision of free fixed low-dose hydroxyurea therapy (Bond Chemical, Nigeria; $0.15 per 500 mg) for abnormal TCD values, and biannual CBCs as standard care ,for over 40,000 children with SCA