Population Attributable Risk of Wheeze in 2-<6-Year-old Children, Following a Respiratory Syncytial Virus Lower Respiratory Tract Infection in The First 2 Years of Life.

BACKGROUND: There is limited evidence regarding the proportion of wheeze in young children attributable to respiratory syncytial virus lower respiratory tract infections (RSV-LRTI) occurring early in life. This cohort study prospectively determined the population attributable risk (PAR) and risk percent (PAR%) of wheeze in 2-<6-year-old children previously surveilled in a primary study for RSV-LRTI from birth to their second birthday (RSV-LRTI<2Y). METHODS: From 2013 to 2021, 2-year-old children from 8 countries were enrolled in this extension study (NCT01995175) and were followed through quarterly surveillance contacts until their sixth birthday for the occurrence of parent-reported wheeze, medically-attended wheeze or recurrent wheeze episodes (≥4 episodes/year). PAR% was calculated as PAR divided by the cumulative incidence of wheeze in all participants. RESULTS: Of 1395 children included in the analyses, 126 had documented RSV-LRTI<2Y. Cumulative incidences were higher for reported (38.1% vs. 13.6%), medically-attended (30.2% vs. 11.8%) and recurrent wheeze outcomes (4.0% vs. 0.6%) in participants with RSV-LRTI<2Y than those without RSV-LRTI<2Y. The PARs for all episodes of reported, medically-attended and recurrent wheeze were 22.2, 16.6 and 3.1 per 1000 children, corresponding to PAR% of 14.1%, 12.3% and 35.9%. In univariate analyses, all 3 wheeze outcomes were strongly associated with RSV-LRTI<2Y (all global P < 0.01). Multivariable modeling for medically-attended wheeze showed a strong association with RSV-LRTI after adjustment for covariates (global P < 0.0001). CONCLUSIONS: A substantial amount of wheeze from the second to sixth birthday is potentially attributable to RSV-LRTI<2Y. Prevention of RSV-LRTI<2Y could potentially reduce wheezing episodes in 2-<6-year-old children.

Unveiling the contributions of immunization for progressing towards Universal Health Coverage.

The aim of the United Nations' Sustainable Development Goal (SDG)3 is to ensure healthy lives and promote well-being for all, at all ages; including reducing maternal and child mortality, combating communicable and non-communicable diseases, and achieving Universal Health Coverage (UHC). UHC aims to provide everyone with equal access to quality essential and comprehensive healthcare services including preventions, interventions, and treatments, without exposing them to financial hardship. Making progress toward UHC requires significant investment in technical and financial resources and countries are pursuing the implementation of cost-saving measures within health systems to help them achieve UHC. Whilst many countries are far from attaining UHC, all countries, particularly low- and middle-income countries, can take steps toward achieving UHC. This paper discusses key data showing how immunization is a fundamental, cost-effective tool for reducing morbidity and mortality associated with infectious disease in all populations, creating more productive communities, reducing treatment costs, and consequently, facilitating social and economic advancement. Immunization is key to advancing toward UHC by relieving the burden that diseases place on the healthcare services, freeing essential resources to use elsewhere within the healthcare system. Immunization is an essential, readily available strategy that countries can deploy to achieve UHC and the SDG3 agenda.

Impact of COVID-19 pandemic on routine immunization.

The current COVID-19 global pandemic continues to impact healthcare services beyond those directly related to the management of SARS-CoV-2 transmission and disease. We reviewed the published literature to assess the pandemic impact on existing global immunization activities and how the impact may be addressed. Widespread global disruption in routine childhood immunization has impacted a majority of regions and countries, especially in the initial pandemic phases. While data indicate subsequent recovery in immunization rates, a substantial number of vulnerable people remain unvaccinated. The downstream impact may be even greater in resource-limited settings and economically poorer populations, and consequently there are growing concerns around the resurgence of vaccine-preventable diseases, particularly measles. Guidance on how to address immunization deficits are available and continue to evolve, emphasizing the importance of maintaining and restoring routine immunization and necessary mass vaccination campaigns during and after pandemics. In this, collaboration between a broad range of stakeholders (governments, industry, healthcare decision-makers and frontline healthcare professionals) and clear communication and engagement with the public can help achieve these goals.Key messagesThe COVID-19 pandemic has a substantial impact on essential immunization activities.Disruption to mass vaccination campaigns increase risk of VPD resurgence.Catch-up campaigns are necessary to limit existing shortfalls in vaccine uptake.Guidance to mitigate these effects continues to evolve.

Rotavirus vaccines performance: dynamic interdependence of host, pathogen and environment.

INTRODUCTION: As of January 2021, rotavirus vaccination programs have been implemented in 109 countries and their use has resulted in a positive impact on rotavirus-related diarrheal hospitalizations and mortality in children below 5 years of age. Despite these successes, several countries in Africa and Asia where disease burden is high have not yet implemented rotavirus vaccination at all or at a scale sufficient enough to demonstrate impact. This could be, among other reasons, due to poor vaccine coverage and the modest levels of efficacy and effectiveness of the vaccines in these resource-limited settings. AREAS COVERED: We review various factors related to the human host (malnutrition, maternally derived antibodies and breastfeeding, genetic factors, blood group, and co-administration with oral polio vaccine), rotavirus pathogen (force of infection, strain diversity and coinfections), and the environment (related to the human microbiome) which reflect complex and interconnected processes leading to diminished vaccine performance in resource-limited settings. EXPERT OPINION: Addressing the limiting factors for vaccine efficacy is needed but likely to take a long time to be resolved. An immediate solution is to increase the immunization coverage to higher values generating an overall effect of adequate proportion of protected population to reduce the prevalence of rotavirus disease.

PLAIN LANGUAGE SUMMARYWhat is the context?Rotavirus is contagious and causes severe diarrhea in children below 5 years of age. It caused 128,500 deaths and 258 million episodes of diarrhea in 2016.Vaccines protecting children from rotavirus are given orally and have been implemented in 109 countries and used for more than a decade. They considerably decreased the number of hospitalizations and deaths.Several Asian and African countries experience rotavirus infections in large numbers and lag behind in implementing rotavirus vaccination programs.In these countries, rotavirus vaccines only prevent a smaller percentage of severe cases. The reasons for this reduction in vaccination impact are not widely known.What is new?We reviewed the literature to identify the reasons that could explain the differences in vaccination impact worldwide.Factors that might influence the impact of vaccination include Infected children (malnutrition, breastfeeding, blood group, and co-administration with oral polio vaccine);Circulating virus(es) (force of infection, number of new strains, and coinfections with other pathogens) Environment: human microbiome (microorganisms at the surface and in the body; that could be altered by diet, method of childbirth, or hygiene).Why is this important?In summary, rotavirus vaccination has reduced rotavirus-associated hospitalizations and deaths; however, more research is needed to understand the factors influencing the impact of vaccination in order to optimize them. (see Figure 1 ­ Graphical PLS).

Measles, mumps, rubella prevention: how can we do better?

INTRODUCTION: Measles, mumps, and rubella incidence decreased drastically following vaccination programs' implementation. However, measles and mumps' resurgence was recently reported, outbreaks still occur, and challenges remain to control these diseases. AREAS COVERED: This qualitative narrative review provides an objective appraisal of the literature regarding current challenges in controlling measles, mumps, rubella infections, and interventions to address them. EXPERT OPINION: While vaccines against measles, mumps, and rubella (including trivalent vaccines) are widely used and effective, challenges to control these diseases are mainly related to insufficient immunization coverage and changing vaccination needs owing to new global environment (e.g. traveling, migration, population density). By understanding disease transmission peculiarities by setting, initiatives are needed to optimize vaccination policies and increase vaccination coverage, which was further negatively impacted by COVID-19 pandemic. Also, awareness of the potential severity of infections and the role of vaccines should increase. Reminder systems, vaccination of disadvantaged, high-risk and difficult-to-reach populations, accessibility of vaccination, healthcare infrastructure, and vaccination services management should improve. Outbreak preparedness should be strengthened, including implementation of high-quality surveillance systems to monitor epidemiology. While the main focus should be on these public health initiatives to increase vaccination coverage, slightly more benefits could come from evolution of current vaccines.

PLAIN LANGUAGE SUMMARYWhat is the context?Measles, mumps, and rubella are highly contagious diseases associated with significant medical and societal burden. Effective vaccines against these diseases are available, and the implementation of vaccination programs drastically reduced disease incidence globally. However, reports of measles and mumps outbreaks in the last few years highlight remaining challenges to eliminate these diseases.What does the review highlight?We conducted a literature review to identify challenges associated with controlling measles, mumps, and rubella infections, and interventions needed to address them. We identified 11 challenges mainly related to low immunization coverage and vaccine characteristics. Societal challenges could be addressed by increasing awareness of disease severity and vaccines impact, targeting high-risk, unvaccinated, and under-vaccinated populations, improving vaccination access, setting up clear outbreak preparedness plans, and implementing country-specific vaccination policies. System weaknesses could be addressed through improving vaccination services and health infrastructure, implementing high-quality surveillance, patient invite, and reminder systems, ensuring vaccine implementation and long-term supply. Interventions related to vaccine characteristic challenges could include adaptation of vaccination schedules (shorter interval between doses, administration of a third dose) and development of vaccines against emerging strains.What is the take-home message?Policymakers should support the following strategies to increase vaccination coverage and reach elimination of measles, mumps, and rubella: strengthening health systems and vaccination access; raising awareness of disease severity and vaccination impact; limiting disease propagation owing to global changing environment and population dynamics (traveling, migration); improving surveillance systems to rapidly address the immunity gaps against disease resurgence.

Long-Term Persistence of Antibody Response with Two Doses of Inactivated Hepatitis A Vaccine in Children.

INTRODUCTION: Hepatitis A virus infection is more severe in adults than children. Although vaccination can protect adults, current childhood programs cover a large population more successfully. Childhood vaccination is, therefore, a solution to protecting adults if it induces lasting immunity. Fifteen-year protection has been demonstrated in children, but longer-term data are only available for adults. We aimed to predict long term persistence of antibody in children beyond 15 years and assess if immunological mechanisms triggered by vaccination support longer-term protection. METHODS: Long-term clinical studies using hepatitis A (HAV) or A/B vaccines (HAB) containing 720 or 1440 Enzyme-linked immunosorbent assay Units (EU) of hepatitis A virus antigen were identified. Duration of persistence of antibodies and possible protection was determined by descriptively comparing antibody geometric mean concentration (GMC) kinetics, as well as GMC (95% confidence interval) at 15 years post-vaccination across studies. Immunological mechanism studies describing hepatitis A vaccination were identified. RESULTS: One study in children 12-15 years (2-dose HAB 720) and four in adults (2-dose HAV 1440 and 3-dose HAB 720) showed comparable GMC kinetics and per year rates of change up to 15 years. At 15 years, the GMC in children [414.7 mEU/ml (336.9; 510.5)] was in the same range as in adults [range 282.6 (217.6; 367.0) to 550.1 (416.0; 727.4)]. Based on these data, mathematical model predictions from adult studies (showing > 85% protected at 50 years) were deemed likely to also apply to children. Studies identified, both humoral and cell-mediated responses are induced following vaccination. CONCLUSION: Based on comparable antibody data in adults and children up to 15 years, similar longer-term antibody persistence is expected in children with 2-dose inactivated hepatitis A 720 containing vaccine at least up to 50 years. Accordingly, improving routine childhood hepatitis A vaccination coverage could protect against more severe disease in adulthood. Fig. 1 Plain language summary TRIAL REGISTRATION: ClinicalTrials.gov identifiers, NCT00875485, NCT01000324, NCT01037114, NCT00289757, NCT00291876.

Development of new genetic resources for faba bean (Vicia faba L.) breeding through the discovery of gene-based SNP markers and the construction of a high-density consensus map.

Faba bean (Vicia faba L.) is a pulse crop of high nutritional value and high importance for sustainable agriculture and soil protection. With the objective of identifying gene-based SNPs, transcriptome sequencing was performed in order to reduce faba bean genome complexity. A set of 1,819 gene-based SNP markers polymorphic in three recombinant line populations was selected to enable the construction of a high-density consensus genetic map encompassing 1,728 markers well distributed in six linkage groups and spanning 1,547.71 cM with an average inter-marker distance of 0.89 cM. Orthology-based comparison of the faba bean consensus map with legume genome assemblies highlighted synteny patterns that partly reflected the phylogenetic relationships among species. Solid blocks of macrosynteny were observed between faba bean and the most closely-related sequenced legume species such as pea, barrel medic or chickpea. Numerous blocks could also be identified in more divergent species such as common bean or cowpea. The genetic tools developed in this work can be used in association mapping, genetic diversity, linkage disequilibrium or comparative genomics and provide a backbone for map-based cloning. This will make the identification of candidate genes of interest more efficient and will accelerate marker-assisted selection (MAS) and genomic-assisted breeding (GAB) in faba bean.

Immunogenicity of pneumococcal conjugate vaccine formulations containing pneumococcal proteins, and immunogenicity and reactogenicity of co-administered routine vaccines - A phase II, randomised, observer-blind study in Gambian infants.

BACKGROUND: Two conserved pneumococcal proteins, pneumolysin toxoid (dPly) and pneumococcal histidine triad protein D (PhtD), combined with 10 polysaccharide conjugates from the pneumococcal non-typeable Haemophilus influenzae protein D-conjugate vaccine (PHiD-CV) in two investigational pneumococcal vaccine (PHiD-CV/dPly/PhtD) formulations were immunogenic and well-tolerated when administered to Gambian children. Here, we report immunogenicity of the polysaccharide conjugates, and immunogenicity and reactogenicity of co-administered routine vaccines. METHODS: In this phase II, controlled, observer-blind, single-centre study, healthy infants aged 8-10 weeks were randomised (1:1:1:1:1:1) to six groups. Four groups received 3+0 schedule (2-3-4 months [M]) of PHiD-CV/dPly/PhtD (10 or 30 µg of each protein), PHiD-CV, or 13-valent pneumococcal conjugate vaccine; and two groups received 2+1 schedule (2-4-9 M) of PHiD-CV/dPly/PhtD (30 µg of each protein) or PHiD-CV. All infants received diphtheria-tetanus-whole cell pertussis-hepatitis B-Haemophilus influenzae type b (DTPw-HBV/Hib) and oral trivalent polio vaccines (OPV) at 2-3-4 M, and measles, yellow fever, and OPV vaccines at 9 M. We evaluated immune responses at 2-5-9-12 M; and reactogenicity 0-3 days post-vaccination. RESULTS: 1200 infants were enrolled between June 2011 and May 2012; 1152 completed the study. 1 M post-primary vaccination, for each PHiD-CV serotype except 6B and 23F, ≥97.4% (3+0 schedule) and ≥96.4% (2+1 schedule) of infants had antibody concentrations ≥0.2 µg/mL. Immune responses were comparable between groups within the same vaccination schedules. Observed antibody geometric mean concentrations (GMCs) increased by 1 M post-primary vaccination compared to pre-vaccination. In the following months, GMCs and opsonophagocytic activity titres waned, with an increase post-booster for the 2+1 schedule. Immune responses to protein D and, DTPw-HBV/Hib, OPV, measles, and yellow fever vaccines were not altered by co-administration with pneumococcal proteins. Reactogenicity of co-administered vaccines was comparable between groups and did not raise concerns. CONCLUSION: Immune responses to the 10 PHiD-CV polysaccharide conjugates and co-administered vaccines were not altered by addition of dPly and PhtD. ClinicalTrials.gov identifier NCT01262872.

Four-Gene Pan-African Blood Signature Predicts Progression to Tuberculosis.

Rationale: Contacts of patients with tuberculosis (TB) constitute an important target population for preventive measures because they are at high risk of infection with Mycobacterium tuberculosis and progression to disease.Objectives: We investigated biosignatures with predictive ability for incident TB.Methods: In a case-control study nested within the Grand Challenges 6-74 longitudinal HIV-negative African cohort of exposed household contacts, we employed RNA sequencing, PCR, and the pair ratio algorithm in a training/test set approach. Overall, 79 progressors who developed TB between 3 and 24 months after diagnosis of index case and 328 matched nonprogressors who remained healthy during 24 months of follow-up were investigated.Measurements and Main Results: A four-transcript signature derived from samples in a South African and Gambian training set predicted progression up to two years before onset of disease in blinded test set samples from South Africa, the Gambia, and Ethiopia with little population-associated variability, and it was also validated in an external cohort of South African adolescents with latent M. tuberculosis infection. By contrast, published diagnostic or prognostic TB signatures were predicted in samples from some but not all three countries, indicating site-specific variability. Post hoc meta-analysis identified a single gene pair, C1QC/TRAV27 (complement C1q C-chain / T-cell receptor-α variable gene 27) that would consistently predict TB progression in household contacts from multiple African sites but not in infected adolescents without known recent exposure events.Conclusions: Collectively, we developed a simple whole blood-based PCR test to predict TB in recently exposed household contacts from diverse African populations. This test has potential for implementation in national TB contact investigation programs.

Responses to auxin signals: an operating principle for dynamical sensitivity yet high resilience.

Plants depend on the signalling of the phytohormone auxin for their development and for responding to environmental perturbations. The associated biomolecular signalling network involves a negative feedback on Aux/IAA proteins which mediate the influence of auxin (the signal) on the auxin response factor (ARF) transcription factors (the drivers of the response). To probe the role of this feedback, we consider alternative in silico signalling networks implementing different operating principles. By a comparative analysis, we find that the presence of a negative feedback allows the system to have a far larger sensitivity in its dynamical response to auxin and that this sensitivity does not prevent the system from being highly resilient. Given this insight, we build a new biomolecular signalling model for quantitatively describing such Aux/IAA and ARF responses.

Kinetics of antibodies against pneumococcal proteins and their relationship to nasopharyngeal carriage in the first two months of life.

INTRODUCTION: The currently used Streptococcus pneumoniae vaccines have had a significant impact on the pneumococcal diseases caused by the serotypes they cover. Their limitations have stimulated a search for alternate vaccines that will cover all serotypes, be affordable and effective in young children. Pneumococcal protein antigens are potential vaccine candidates that may meet some of the shortfalls of the current vaccines. Thus, this study aimed to determine the relationship between antibodies against pneumococcal protein antigens and nasopharyngeal carriage in infants. METHODS: One hundred and twenty mother-infant pairs were enrolled into the study. They had nasopharyngeal swabs(NPS) taken at birth and every two weeks for the first eight weeks after delivery, and blood samples were obtained at birth and every four weeks for the first eight weeks after delivery. Nasopharyngeal carriage of S. pneumoniae was determined from the NPS and antibodies against the pneumococcal proteins CbpA, PspA and rPly were measured in the blood samples. RESULTS: The S. pneumoniae carriage rate in infants increased to that of mothers by eight weeks of age. The odds of carriage in infants was 6.2 times (95% CI: 2.0-18.9) higher when their mothers were also carriers. Bacterial density in infants was lower at birth compared to their mothers (p = 0.004), but increased with age and became higher than that of their mothers at weeks 4 (p = 0.009), 6 (p = 0.002) and 8 (p<0.0001). At birth, the infants' antibodies against CbpA, and rPly pneumococcal protein antigens were similar, but that of PspA was lower (p<0.0001), compared to their mothers. Higher antibody concentrations to CbpA [OR (95% CI): 0.49 (0.26-0.92, p = 0.03)], but not PspA and rPly, were associated with protection against carriage in the infants. CONCLUSION: Naturally induced antibodies against the three pneumococcal protein antigens were transferred from mother to child. The proportion of infants with nasopharyngeal carriage and the bacterial density of S. pneumoniae increased with age within the first eight weeks of life. Higher concentrations of antibodies against CbpA, but not PspA and rPly, were associated with reduced risk of nasopharyngeal carriage of S. pneumoniae in infants.

Mycobacterium tuberculosis Infection in Close Childhood Contacts of Adults with Pulmonary Tuberculosis is Increased by Secondhand Exposure to Tobacco.

Tobacco use is a major risk factor for tuberculosis (TB). Secondhand smoke (SHS) is also a risk factor for TB and to a lesser extent, Mycobacterium tuberculosis infection without disease. We investigated the added risk of M. tuberculosis infection due to SHS exposure in childhood contacts of TB cases in The Gambia. Participants were childhood household contacts aged ≤ 14 years of newly diagnosed pulmonary TB (PTB) cases. The intensity of exposure to the case was categorized according to whether contacts slept in the same room, same house, or a different house as the case. Contacts were tested with an enzyme-linked immunospot interferon gamma release assay. In multivariate regression models, M. tuberculosis infection was associated with increasing exposure to a case (odds ratios [OR]: 3.9, 95% confidence interval [CI]: 2.11-71.4, P < 0.001]) and with male gender (OR: 1.5 [95% CI: 1.12-2.11], P = 0.008). Tobacco use caused a 3-fold increase in the odds of M. tuberculosis infection in children who slept closest to a case who smoked within the same home compared with a nonsmoking case (OR: 8.0 [95% CI: 2.74-23.29] versus 2.4 [95% CI: 1.17-4.92], P < 0.001). SHS exposure as an effect modifier appears to greatly increase the risk of M. tuberculosis infection in children exposed to PTB cases. Smoking cessation campaigns may be important for reducing transmission of M. tuberculosis to children within households.

Efficacy of a novel, protein-based pneumococcal vaccine against nasopharyngeal carriage of Streptococcus pneumoniae in infants: A phase 2, randomized, controlled, observer-blind study.

BACKGROUND: Conserved pneumococcal proteins are potential candidates for inclusion in vaccines against pneumococcal diseases. In the first part of a two-part study, an investigational vaccine (PHiD-CV/dPly/PhtD-30) containing 10 pneumococcal serotype-specific polysaccharide conjugates (10VT) combined with pneumolysin toxoid and pneumococcal histidine triad protein D (30µg each) was well tolerated by Gambian children. Part two, presented here, assessed the efficacy of two PHiD-CV/dPly/PhtD formulations against pneumococcal nasopharyngeal carriage (NPC) prevalence in infants. METHODS: In this phase 2, randomized, controlled, observer-blind trial, healthy infants aged 8-10weeks, recruited from a peri-urban health center, were randomized (1:1:1:1:1:1) into six groups. Four groups received PHiD-CV/dPly/PhtD (10 or 30µg of each protein), PHiD-CV, or 13-valent pneumococcal conjugate vaccine at ages 2-3-4months (3+0 infant schedule) and two groups PHiD-CV/dPly/PhtD-30 or PHiD-CV at 2-4-9months (2+1 infant schedule). The primary objective was impact on non-10VT NPC at ages 5-9-12months. Secondary objectives included confirmatory analysis of protein dose superiority and safety/reactogenicity. Impact on pneumococcal NPC acquisition, bacterial load, and ply and phtD gene sequencing were explored. RESULTS: 1200 infants were enrolled between June 2011 and May 2012. Prevalences of pneumococcal (60-67%) and non-10VT (55-61%) NPC were high at baseline. Across all post-vaccination time points, efficacy of PHiD-CV/dPly/PhtD-10 and PHiD-CV/dPly/PhtD-30 against non-10VT NPC (3+0 schedule) was 1.1% (95% CI -21.5, 19.5) and 2.1% (-20.3, 20.3), respectively; efficacy of PHiD-CV/dPly/PhtD-30 (2+1 schedule) was 0.5% (-22.1, 18.9) versus PHiD-CV. No differences were observed in pneumococcal NPC acquisition, clearance, or bacterial load. Both protein-based vaccines elicited immune responses to pneumococcal proteins. CONCLUSIONS: In this high carriage prevalence setting, inclusion of pneumococcal proteins in the PHiD-CV/dPly/PhtD investigational vaccine had no impact on pneumococcal NPC in infants, regardless of protein dose or schedule. Future evaluations will assess its impact against pneumococcal disease endpoints. FUNDING: PATH, GlaxoSmithKline Biologicals SA. ClinicalTrials.gov identifier NCT01262872.

Drivers of structural features in gene regulatory networks: From biophysical constraints to biological function.

Living cells can maintain their internal states, react to changing environments, grow, differentiate, divide, etc. All these processes are tightly controlled by what can be called a regulatory program. The logic of the underlying control can sometimes be guessed at by examining the network of influences amongst genetic components. Some associated gene regulatory networks have been studied in prokaryotes and eukaryotes, unveiling various structural features ranging from broad distributions of out-degrees to recurrent "motifs", that is small subgraphs having a specific pattern of interactions. To understand what factors may be driving such structuring, a number of groups have introduced frameworks to model the dynamics of gene regulatory networks. In that context, we review here such in silico approaches and show how selection for phenotypes, i.e., network function, can shape network structure.

Elevated serum 25-hydroxy (OH) vitamin D levels are associated with risk of TB progression in Gambian adults.

BACKGROUND: Vitamin D is essential in the host defence against tuberculosis (TB) as an immune modulator. The aim of this study was to determine the level of 25-hydroxyvitamin D (25 (OH) D) from adult TB index cases before and after treatment and their exposed household contacts (HHC) in The Gambia. METHODS: Serum from adult index TB cases and their TB-exposed household contacts (HHC) was analysed for 25(OH) D and Vitamin D binding protein (VDBP) concentrations. Tuberculin skin test (TST) status was used as a measure of Mycobacterium tuberculosis (Mtb) infectivity in the HHC. In addition, HHC who later progressed to active TB (incident cases) were assessed alongside non-progressors to determine the influence of 25 (OH) D levels on TB risk. RESULTS: Eighty-three TB cases, 46 TST+ and 52 TST- HHC were analysed. Generally levels of 25(OH) D were considered insufficient in all subjects. However, median levels of 25(OH) D and VDBP were significantly higher in TB cases compared to both TST+ and TST- HHC at recruitment and were significantly reduced after TB therapy (p < 0.0001 for all). In addition, levels of serum 25(OH) D at recruitment were significantly higher in TB progressors compared to non-progressors (median (IQR): 25.0(20.8-29.2) in progressors and 20.3 (16.3-24.6) ng/ml in non-progressors; p = 0.007). CONCLUSION: In The Gambia, an equatorial country, 25(OH) D levels are higher in serum of TB progressors and those with active disease compared to latently infected and uninfected subjects. These results contrast to findings in non-equatorial countries.

C-reactive protein, Neopterin and Beta2 microglobulin levels pre and post TB treatment in The Gambia.

BACKGROUND: Tuberculosis is one of the leading causes of morbidity and mortality in developing countries. Analysis of the host immune response may help with generating point-of-care tests for personalised monitoring. Thus, the aim of this study was to assess the relationship between immune activation markers: C-reactive protein (CRP), Beta2 microglobulin (B2M) and Neopterin, disease severity prior to treatment and response to therapy in adult pulmonary TB patients. METHODS: HIV negative adult pulmonary TB index cases (n = 91) were recruited from the TB clinic at MRC, The Gambia. Plasma samples were collected at enrolment and at 2 and 6 months following TB treatment initiation. An enzyme linked immunosorbent assay (ELISA) was performed for evaluation of CRP, B2M and Neopterin levels and correlated with clinical and microbiological parameters including strain of infection. Disease severity was determined using Chest X-ray (CXR), Body Mass Index (BMI) and sputum smear grade. RESULTS: Plasma levels of all three markers were highly elevated in patients at recruitment and declined significantly during TB therapy. No correlation with disease severity was seen at recruitment. CRP showed the most significant decrease by 2 months of treatment (p < 0.0001) whereas levels of B2M and Neopterin showed little change by 2 months but a significant decrease by 6 months of treatment (p = 0.0002 and p < 0.0001 respectively). At recruitment, B2M levels were significantly higher in subjects infected with Mycobacterium africanum (Maf) compared with those infected with Mycobacterium tuberculosis sensu stricto (Mtb) (p = 0.0075). In addition, while CRP and Neopterin showed a highly significant decline post-treatment regardless of strain (p < 0.0001 for all), B2M showed differential decline depending on strain (p = 0.0153 for Mtb and p = 0.0048 for Maf) and levels were still significantly higher at 6 months in Maf compared to Mtb infected subjects (p = 0.0051). CONCLUSION: Our findings suggest that activation markers, particularly CRP, may have a role in identifying good response to TB therapy regardless of the strain of infection and could be further developed as point-of-care tests. In addition, B2M levels may allow differentiation between Mtb and Maf-infected subjects.

A randomized controlled study comparing community based with health facility based direct observation of treatment models on patients' satisfaction and TB treatment outcome in Nigeria.

BACKGROUND: Directly observed treatment short-course (DOTS) strategy is an effective mode of treating TB. We aimed to study the cost effectiveness and patients' satisfaction with home based direct observation of treatment (DOT), an innovative approach to community-based DOT (CBDOT) and hospital based DOT (HBDOT). METHODS: A randomized controlled trial involving 150 newly diagnosed pulmonary TB patients in four TB clinics in Ile Ife , Nigeria, was done. They were randomly assigned to receive treatment with anti TB drugs for the intensive phase administered at home by a TB worker (CBDOT) or at the hospital (HBDOT). Outcome measures were treatment completion/default rates, cost effectiveness and patients' satisfaction with care using a 13 item patients satisfaction questionnaire (PS-13) at 2 months. This trial was registered with pactr.org: number PACTR 201503001058381. RESULTS: At the end of intensive phase, 15/75 (20%) and 2/75 (3%) of patients in the HBDOT and CBDOT, respectively had defaulted from treatment, p= 0.01. Of those with pretreatment positive sputum smear, 97% (68/70) on CBDOT and 54/67 (81%) on HBDOT were sputum negative for AFB at the end of 2 months of treatment, p=0.01. The CBDOT method was associated with a higher patient satisfaction score compared with HBDOT (OR 3.1; 95% CI 1.25-7.70), p=0.001.The total cost for patients was higher in HBDOT (US$159.38) compared with the CBDOT (US$89.52). The incremental cost effectiveness ratio was US$410 per patient who completed the intensive phase treatment with CBDOT. CONCLUSIONS: CBDOT is a cost effective approach associated with better compliance to treatment and better patient satisfaction compared to HBDOT.

Antibiotic suppression of intestinal microbiota reduces heme-induced lipoperoxidation associated with colon carcinogenesis in rats.

Epidemiological studies show that heme iron from red meat is associated with increased colorectal cancer risk. In carcinogen-induced-rats, a heme iron-rich diet increases the number of precancerous lesions and raises associated fecal biomarkers. Heme-induced lipoperoxidation measured by fecal thiobarbituric acid reagents (TBARs) could explain the promotion of colon carcinogenesis by heme. Using a factorial design we studied if microbiota could be involved in heme-induced carcinogenesis, by modulating peroxidation. Rats treated or not with an antibiotic cocktail were given a control or a hemoglobin-diet. Fecal bacteria were counted on agar and TBARs concentration assayed in fecal water. The suppression of microbiota by antibiotics was associated with a reduction of crypt height and proliferation and with a cecum enlargement, which are characteristics of germ-free rats. Rats given hemoglobin diets had increased fecal TBARs, which were suppressed by the antibiotic treatment. A duplicate experiment in rats given dietary hemin yielded similar results. These data show that the intestinal microbiota is involved in enhancement of lipoperoxidation by heme iron. We thus suggest that microbiota could play a role in the heme-induced promotion of colorectal carcinogenesis.

Lessons in participant retention in the course of a randomized controlled clinical trial.

BACKGROUND: Clinical trials are increasingly being conducted as new products seek to enter the market. Deployment of such interventions is based on evidence obtained mainly from the gold standard of randomized controlled clinical trials (RCCT). A crucial factor in the ability of RCCTs to provide credible and generalisable data is sample size and retention of the required number of subjects at completion of the follow-up period. However, recruitment and retention in clinical trials are hindered by prevalent peculiar challenges in Africa that need to be circumvented. This article shares experiences from a phase II trial that recorded a high retention rate at 14 months follow-up at a new clinical trial site. METHODS: Mothers bringing children less than two months of age to the health facility were given information and invited to have their child enrolled if the inclusion criteria were fulfilled. Participants were enrolled over 8 months. Trial procedures, duration and risks/benefits were painstakingly and sequentially explained to the communities, parents and relevant relatives before and during the trial period. The proportions of participants that completed or did not complete the trial were analyzed including the reasons for failure to complete all trial procedures. RESULTS: 1044 individuals received information regarding the trial of which 371 returned for screening. 300 (81%) of them who fulfilled the inclusion criteria and did not meet any exclusion criteria were enrolled and 94% of these completed the trial. Consent withdrawal was the main reason for not completing the trial largely (75%) due to the father not being involved at the point of consenting or parents no longer being comfortable with blood sampling. CONCLUSIONS: Participant retention in clinical trials remains a crucial factor in ensuring generalisability of trial data. Appropriate measures to enhance retention should include continuous community involvement in the process, adequate explanation of trial procedures and risks/benefits; and innovative tracing of participants adapted for the setting.