Pneumococcal carriage in sub-Saharan Africa--a systematic review.

BACKGROUND: Pneumococcal epidemiology varies geographically and few data are available from the African continent. We assess pneumococcal carriage from studies conducted in sub-Saharan Africa (sSA) before and after the pneumococcal conjugate vaccine (PCV) era. METHODS: A search for pneumococcal carriage studies published before 2012 was conducted to describe carriage in sSA. The review also describes pneumococcal serotypes and assesses the impact of vaccination on carriage in this region. RESULTS: Fifty-seven studies were included in this review with the majority (40.3%) from South Africa. There was considerable variability in the prevalence of carriage between studies (I-squared statistic = 99%). Carriage was higher in children and decreased with increasing age, 63.2% (95% CI: 55.6-70.8) in children less than 5 years, 42.6% (95% CI: 29.9-55.4) in children 5-15 years and 28.0% (95% CI: 19.0-37.0) in adults older than 15 years. There was no difference in the prevalence of carriage between males and females in 9/11 studies. Serotypes 19F, 6B, 6A, 14 and 23F were the five most common isolates. A meta-analysis of four randomized trials of PCV vaccination in children aged 9-24 months showed that carriage of vaccine type (VT) serotypes decreased with PCV vaccination; however, overall carriage remained the same because of a concomitant increase in non-vaccine type (NVT) serotypes. CONCLUSION: Pneumococcal carriage is generally high in the African continent, particularly in young children. The five most common serotypes in sSA are among the top seven serotypes that cause invasive pneumococcal disease in children globally. These serotypes are covered by the two PCVs recommended for routine childhood immunization by the WHO. The distribution of serotypes found in the nasopharynx is altered by PCV vaccination

Rapid Evolution of Pandemic Noroviruses of the GII.4 Lineage

Over the last fifteen years there have been five pandemics of norovirus (NoV) associated gastroenteritis, and the period of stasis between each pandemic has been progressively shortening. NoV is classified into five genogroups, which can be further classified into 25 or more different human NoV genotypes; however, only one, genogroup II genotype 4 (GII.4), is associated with pandemics. Hence, GII.4 viruses have both a higher frequency in the host population and greater epidemiological fitness. The aim of this study was to investigate if the accuracy and rate of replication are contributing to the increased epidemiological fitness of the GII.4 strains. The replication and mutation rates were determined using in vitro RNA dependent RNA polymerase (RdRp) assays, and rates of evolution were determined by bioinformatics. GII.4 strains were compared to the second most reported genotype, recombinant GII.b/GII.3, the rarely detected GII.3 and GII.7 and as a control, hepatitis C virus (HCV). The predominant GII.4 strains had a higher mutation rate and rate of evolution compared to the less frequently detected GII.b, GII.3 and GII.7 strains. Furthermore, the GII.4 lineage had on average a 1.7-fold higher rate of evolution within the capsid sequence and a greater number of non-synonymous changes compared to other NoVs, supporting the theory that it is undergoing antigenic drift at a faster rate. Interestingly, the non-synonymous mutations for all three NoV genotypes were localised to common structural residues in the capsid, indicating that these sites are likely to be under immune selection. This study supports the hypothesis that the ability of the virus to generate genetic diversity is vital for viral fitness

Mentoring Faculty in Academic Medicine: A New Paradigm?

In this paper, we discuss an alternative structure and a broader vision for mentoring of medical faculty. While there is recognition of the need for mentoring for professional advancement in academic medicine, there is a dearth of research on the process and outcomes of mentoring medical faculty. Supported by the literature and our experience with both formal dyadic and group peer mentoring programs as part of our federally funded National Center of Leadership in Academic Medicine, we assert that a group peer, collaborative mentoring model founded on principles of adult education is one that is likely to be an effective and predictably reliable form of mentoring for both women and men in academic medicine

Systematic review of clinical trials comparing open and endovascular treatment of abdominal aortic aneurysm

Objective: Endovascular repair (EVAR) using stent-graft device is a new treatment for abdominal aortic aneurysm (AAA) that is gaining more and more popularity. This systematic review compares the new minimally invasive endovascular treatment with the conventional open repair aiming to provide more evidence for clinical decision on choice of treatment for aneurysm patients. Methods: Electronic search on MEDLINE, EMBASE and Cochrane Library and manual search on bibliographies was performed to identify studies published from 1991 to 2004 comparing clinical outcomes of patients who underwent EVAR and open repair. Quality of clinical studies was assessed by modified Evans and Pollok score and those scores below 50 were excluded. Systematic analysis was performed for short-, mid- and long-term clinical outcomes. The effect size of the clinical parameters was estimated by relative risk, weighted mean difference and standard mean difference. Results: 27 clinical studies and 7226 patients were included in this systematic review. Three studies were randomized control studies and the rest were comparative studies. Systematic review showed patients after EVAR had significantly lower 30-day mortality, shorter hospital and intensive care unit stay, less blood loss or blood transfusion, fewer cardiac and respiratory complications, less colonic ischaemia, and fewer overall operative morbidities. But EVAR carried a significant higher frequency of early secondary procedures and graft-related complications. The 1-5-year mortality between the two groups was similar. Patients receiving EVAR required more late secondary procedures and the cost related to EVAR was higher. Systematic review on quality of life could not be performed as there was a large variation on method of measurement. Conclusion: EVAR offers significant benefit to aneurysm patients in the early postoperative period. However, it does not show an advantage over open repair in mid- and long-term outcome. Furthermore, EVAR might carry more morbidity and higher cost in the long term. Prospective randomized control studies focusing on long-term outcome of EVAR and open repair aneurysm patients as well as on studies on newer generation devices are needed to provide more information for clinical decisions. © 2006 Blackwell Publishing Asia Pty Ltd.link_to_subscribed_fulltex