Swaziland National Health Research Agenda: The Formulation Process

Background: The objectives of this article are to describe the process followed in development of the Swaziland’s national health research agenda (NHRA); and to provide an overview of the health research priorities that emerged from that process.Discussion: Swaziland followed a fourteen step process to develop it’s NHRA, namely: search and review of the existing health research priority setting guidelines; situation analysis included review of Swaziland’s socio-economic indicators; identification of research stakeholders; identification of the preliminary main broad research themes; development of questionnaire on ranking of main research themes; workshops with each of the eight stakeholders; ranking of major health themes and identification of sub-themes; identification of research gaps under each sub-theme and main research areas; scoring of research areas; research areas were grouped by sub-themes and ranked; collating research areas ranked as number one in each sub-theme; providing content to the agenda; preparation of the zero NHRA draft report; preparation of the first NHRA draft report taking into account critical inputs from stakeholders; and stakeholder’s final validation of the NHRA draft report. The paper provides an overview of communicable diseases, non-communicable diseases, sexual and reproductive health, injuries and health system research gaps under four categories of research: situation (burden and determinants); improvement of existing interventions; effectiveness of interventions; and feasibility of developing new capacities (tools and products).Conclusion: The National Health Research Department, with the support of the National Health Research Review Board, will be responsible for dissemination, preparation of rolling annual action plans to secure government funds for implementation of NHRA, promoting adherence among stakeholders, establishing a registry of R4H, establishing a knowledge translation platform, building of public-private-partnerships for research, mobilization of external resources, coordination and monitoring of the implementation of the NHRA. KeywordsSwaziland, National Health Research Agenda, Health Research Priorities, Research Stakeholders, Research Gaps

A population-based national estimate of the prevalence and risk factors associated with hypertension in Rwanda: implications for prevention and control

BACKGROUND

Hypertension is a leading cause of cardiovascular diseases and a growing public health problem in many developed and developing countries. However, population-based data to inform policy development are scarce in Rwanda. This nationally representative study aimed to determine population-based estimates of the prevalence and risk factors associated with hypertension in Rwanda.

METHODS

We conducted secondary epidemiological analysis of data collected from a cross-sectional population-based study to assess the risk factors for NCDs using the WHO STEPwise approach to Surveillance of non-communicable diseases (STEPS). Adjusted odds ratios at 95% confidence interval were used to establish association between hypertension, socio-demographic characteristics and health risk behaviors.

RESULTS

Of the 7116 study participants, 62.8% were females and 38.2% were males. The mean age of study participants was 35.3 years (SD 12.5). The overall prevalence of hypertension was 15.3% (16.4% for males and 14.4% for females). Twenty two percent of hypertensive participants were previously diagnosed. A logistic regression model revealed that age (AOR: 8.02, 95% CI: 5.63-11.42, p < 0.001), living in semi-urban area (AOR: 1.30, 95% CI: 1.01-1.67, p = 0.040) alcohol consumption (AOR: 1.24, 95% CI: 1.05-1.44, p = 0.009) and, raised BMI (AOR: 3.93, 95% CI: 2.54-6.08, p < 0.001) were significantly associated with hypertension. The risk of having hypertension was 2 times higher among obese respondents (AOR: 3.93, 95% CI: 2.54-6.08, p-value < 0.001) compared to those with normal BMI (AOR: 1.74, 95% CI: 1.30-2.32, p-value < 0.001). Females (AOR: 0.75, 95% CI: 0.63-0.88, p < 0.001) and students (AOR: 0.45, 95% CI: 0.25-0.80, p = 0.007) were less likely to be hypertensive.

CONCLUSION

The findings of this study indicate that the prevalence of hypertension is high in Rwanda, suggesting the need for prevention and control interventions aimed at decreasing the incidence taking into consideration the risk factors documented in this and other similar studies.

Reactogenicity, safety and immunogenicity of a protein-based pneumococcal vaccine in Gambian children aged 2-4 years: A phase II randomized study

Pneumococcal conjugate vaccines (PCVs) have been successful in preventing invasive pneumococcal disease but effectiveness has been challenged by replacement of vaccine serotypes with non-vaccine serotypes. Vaccines targeting common pneumococcal protein(s) found in most/all pneumococci may overcome this limitation. This phase II study assessed safety and immunogenicity of a new protein-based pneumococcal vaccine containing polysaccharide conjugates of 10 pneumococcal serotypes combined with pneumolysin toxoid(dPly) and pneumococcal histidine triad protein D(PhtD) (PHiD-CV/dPly/PhtD-30) in African children. 120 Gambian children (2–4 years, not previously vaccinated against Streptococcus pneumoniae) randomized (1:1) received a single dose of PHiD-CV/dPly/PhtD-30 or PCV13. Adverse events occurring over 4 d post-vaccination were reported, and blood samples obtained pre- and 1-month post-vaccination. Serious adverse events were reported for 6 months post-vaccination. Solicited local and systemic adverse events were reported at similar frequency in each group. One child (PHiD-CV/dPly/PhtD-30 group) reported a grade 3 local reaction to vaccination. Haematological and biochemical parameters seemed similar pre- and 1-month post-vaccination in each group. High pre-vaccination Ply and PhtD antibody concentrations were observed in each group, but only increased in PHiD-CV/dPly/PhtD-30 vaccinees one month post-vaccination. One month post-vaccination, for each vaccine serotype ≥96.2% of PHiD-CV/dPly/PhtD-30 vaccinees had serotype-specific polysaccharide antibody concentrations ≥0.20µg/mL except serotypes 6B (80.8%) and 23F (65.4%), and ≥94.1% had OPA titres of ≥8 except serotypes 1 (51.9%), 5 (38.5%) and 6B (78.0%), within ranges seen in PCV13-vaccinated children. A single dose of PHiD-CV/dPly/PhtD-30 vaccine, administered to Gambian children aged 2–4 y not previously vaccinated with a pneumococcal vaccine, was well-tolerated and immunogenic.

Association of slow recovery of Mycobacterium africanum-infected patients posttreatment with high content of Persister-Like bacilli in pretreatment sputum

OBJECTIVES/BACKGROUND

Mycobacterium africanum that causes 40% of tuberculosis (TB) in West Africa grows more slowly in culture and has similar transmission capacity compared with Mycobacterium tuberculosis, but M. africanum-exposed contacts progress more slowly to active disease. The presence of lipid body (LB) containing M. tuberculosis complex (MTBC) cells in sputum samples has been associated with mycobacterial transcriptomes indicating slow or no growth and persister-like antibiotic tolerance. Slow-growing bacilli have been found to display a persister-like phenotype with the accumulation of LBs and drug tolerance. Our previous study showed that the body mass index and lung damage resolution on chest X-ray were significantly improved slower in M. africanum-infected patients posttreatment than in M. tuberculosis-infected patients; however, the reason for this remains unclear. Therefore, we hypothesized that these differences could be either due to significant differences in drug resistance between the MTBC lineages or a difference in their content of persisters, as indicated by the percentage of LP-positive bacilli in sputum.

METHODS

Sputum isolates collected before treatment from patients with TB were subjected to drug susceptibility testing using the BD BACTEC MGIT 960 SIRE kit. The percentage of acid-fast bacilli (AFB) and LB-positive bacilli in pretreatment sputum was determined by a dual staining procedure using Auramine O and LipidTOX Red neutral lipid stain, respectively, and fluorescence microscopy imaging.

RESULTS

Out of the 77 isolates tested, 9 showed resistance to at least one drug and only 2 showed multidrug (rifampicin and isoniazid) resistance among M. tuberculosis-infected patients. The percentage of AFB-positive smears was similar between the two groups (p=0.821), whereas that of LP-positive bacilli was significantly higher (p=0.0059) in M. africanum-infected patients' sputa (n=24) than in M. tuberculosis-infected patients' sputa (n=36). In addition, the bacillary lengths were significantly higher in M. africanum-infected patients' sputa than in M. tuberculosis-infected patients' sputa (p=0.0007). A high frequency of LP-positive bacilli in pretreatment sputum was associated with a poor body mass index and lung damage on chest X-ray improvement following anti-TB treatment in both the groups (r²=0.022; p=0.017).

CONCLUSION

The slow clinical recovery of M. africanum-infected patients compared with M. tuberculosis-infected patients posttreatment may be at least partially associated with the persistence of drug-tolerant "fat and lazy" bacilli.

Acceptance of multiple injectable vaccines in a single immunization visit in The Gambia pre and post introduction of inactivated polio vaccine

BACKGROUND

As the World Health Organization (WHO) currently recommends that children be protected against 11 different pathogens, it is becoming increasingly necessary to administer multiple injectable vaccines during a single immunization visit. In this study we assess Gambian healthcare providers' and infant caregivers' attitudes and practices related to the administration of multiple injectable vaccines to a child at a single immunization visit before and after the 2015 introduction of inactivated polio vaccine (IPV). IPV introduction increased the number of injectable vaccines recommended for the 4-month immunization visit from two to three in The Gambia.

METHODS

We conducted a cross-sectional questionnaire-based survey before and after the introduction of IPV at 4months of age in a representative sample of all health facilities providing immunizations in The Gambia. Healthcare providers who administer vaccines at the selected health facilities and caregivers who brought infants for their 4month immunization visit were surveyed.

FINDINGS

Prior to IPV introduction, 9.9% of healthcare providers and 35.7% of infant caregivers expressed concern about a child receiving more than 2 injections in a single visit. Nevertheless, 98.8% and 90.9% of infants received all required vaccinations for the visit before and after IPV introduction, respectively. The only reason why vaccines were not received was vaccine stock-outs. Infant caregivers generally agreed that vaccinators could be trusted to provide accurate information regarding the number of vaccines that a child needed.

CONCLUSION

Healthcare providers and infant caregivers in this resource limited setting accepted an increase in the number of injectable vaccines administered at a single visit even though some expressed concerns about the increase.

Associations between nasopharyngeal carriage of Group B Streptococcus and other respiratory pathogens during early infancy

BACKGROUND

In West Africa, the carriage of Group B Streptococcus (GBS), among infants is poorly characterised. We investigated co-carriage of GBS with other respiratory pathogens in the infants' nasopharynx in The Gambia.

METHODS

We assessed the carriage, serotypes and antibiotic susceptibility of Beta-haemolytic Streptococci (BHS) groups A-G; along with the carriage of Streptococcus pneumoniae; Haemophilus influenzae; Staphylococcus aureus and Moraxella catarrhalis in 1200 two-month old infants.

RESULTS

The BHS prevalence was 20.0 % and GBS dominated (13.8 %), particularly serotypes V and II; serotype V being negatively associated with H. Influenzae carriage (OR 0.41 [95 % CI: 0.18-0.93], p = 0.033). Although co-colonization of GBS and other BHS was not seen, colonization with GBS was positively associated with S. aureus (OR 1.89 [95 % CI: 1.33-2.69], P < 0.001) and negatively associated with S. pneumoniae (OR 0.47 [95 % CI: 0.33-0.67], p < 0.001) and M. catarrhalis (OR 0.61 [95 % CI: 0.40-0.92], p = 0.017). ≥ 89 % of GBS isolates were susceptible to most antibiotics tested, except for tetracycline resistance, which was 89 %.

CONCLUSION

This study provides baseline data on the carriage of GBS in two month old infants from West Africa. The dominant serotypes of GBS in this setting are serotypes V and II. This may be important for future GBS vaccine development for the West African sub-region.

Host Immune Responses Differ between M. africanum- and M. tuberculosis-Infected Patients following Standard Anti-tuberculosis Treatment

Epidemiological differences exist between Mycobacterium africanum (Maf)- and Mycobacterium tuberculosis (Mtb)-infected patients, but to date, contributing host factors have not been characterised. We analysed clinical outcomes, as well as soluble markers and gene expression profiles in unstimulated, and ESAT6/CFP-10-, whole-Maf- and Mtb-stimulated blood samples of 26 Maf- and 49 Mtb-HIV-negative tuberculosis patients before, and after 2 and 6 months of anti-tuberculosis therapy. Before treatment, both groups had similar clinical parameters, but differed in few cytokines concentration and gene expression profiles. Following treatment the body mass index, skinfold thickness and chest X-ray scores showed greater improvement in the Mtb- compared to Maf-infected patients, after adjusting for age, sex and ethnicity (p = 0.02; 0.04 and 0.007, respectively). In addition, in unstimulated blood, IL-12p70, IL12A and TLR9 were significantly higher in Maf-infected patients, while IL-15, IL-8 and MIP-1α were higher in Mtb-infected patients. Overnight stimulation with ESAT-6/CFP-10 induced significantly higher levels of IFN-γ and TNF-α production, as well as gene expression of CCL4, IL1B and TLR4 in Mtb- compared to Maf-infected patients. Our study confirms differences in clinical features and immune genes expression and concentration of proteins associated with inflammatory processes between Mtb- and Maf-infected patients following anti-tuberculosis treatment These findings have public health implications for treatment regimens, and biomarkers for tuberculosis diagnosis and susceptibility.

Use of lateral flow assays to determine IP-10 and CCL4 levels in pleural effusions and whole blood for TB diagnosis

One of the key problems in combating TB is the lack of fast and accurate diagnostic tests that are affordable and easy to use in resource-limited settings. We have used a field-friendly up-converting phosphor (UCP) reporter technology in a lateral flow (LF) based test for the diagnosis of respiratory infections. In this study we analysed samples obtained from patients presenting with symptoms suggestive of TB but prior to confirmation by microbiology in The Gambia. Following clinical and microbiological evaluation they were classified as either having TB or other respiratory disorder (ORD). Analysis of blood was performed for those with pulmonary TB and pleural fluid for those with pleural TB. UCP-LF test for detection and quantitation of IP-10 and CCL4 were used being the two chemokine markers that have been shown to increase in active TB disease. UCP-LF test accurately determined concentrations of both markers as compared to ELISA and multiplex cytokine array. However, only IP-10 could discriminate between TB and ORD, and this was significantly enhanced by analysing the site of infection (pleural fluid), which showed 92% correct classification. Future work will assess the use of multiple markers to increase diagnostic accuracy.

Risk factors for delay in age-appropriate vaccinations among Gambian children

BACKGROUND

Vaccination has been shown to reduce mortality and morbidity due to vaccine-preventable diseases. However, these diseases are still responsible for majority of childhood deaths worldwide especially in the developing countries. This may be due to low vaccine coverage or delay in receipt of age-appropriate vaccines. We studied the timeliness of routine vaccinations among children aged 12-59 months attending infant welfare clinics in semi-urban areas of The Gambia, a country with high vaccine coverage.

METHODS

A cross-sectional survey was conducted in four health centres in the Western Region of the Gambia. Vaccination dates were obtained from health cards and timeliness assessed based on the recommended age ranges for BCG (birth-8 weeks), Diphtheria-Pertussis-Tetanus (6 weeks-4 months; 10 weeks-5 months; 14 weeks-6 months) and measles vaccines (38 weeks-12 months). Risk factors for delay in age-appropriate vaccinations were determined using logistic regression. Analysis was limited to BCG, third dose of Diphtheria-Pertussis -Tetanus (DPT3) and measles vaccines.

RESULTS

Vaccination records of 1154 children were studied. Overall, 63.3% (95 % CI 60.6-66.1%) of the children had a delay in the recommended time to receiving at least one of the studied vaccines. The proportion of children with delayed vaccinations increased from BCG [5.8% (95 % CI 4.5-7.0%)] to DPT3 [60.4% (95 % CI 57.9%-63.0%)] but was comparatively low for the measles vaccine [10.8% (95 % CI 9.1%-12.5%)]. Mothers of affected children gave reasons for the delay, and their profile correlated with type of occupation, place of birth and mode of transportation to the health facilities.

CONCLUSION

Despite high vaccination coverage reported in The Gambia, a significant proportion of the children's vaccines were delayed for reasons related to health services as well as profile of mothers. These findings are likely to obtain in several countries and should be addressed by programme managers in order to improve and optimize the impact of the immunization coverage rates.

Differential transcriptomic and metabolic profiles of M. africanum- and M. tuberculosis-infected patients after, but not before, drug treatment

The epidemiology of Mycobacterium tuberculosis (Mtb) and M. africanum (Maf) suggest differences in their virulence, but the host immune profile to better understand the pathogenesis of tuberculosis (TB) have not been studied. We compared the transcriptomic and metabolic profiles between Mtb and Maf-infected TB cases to identify host biomarkers associated with lineages-specific pathogenesis and response to anti-TB chemotherapy. Venous blood samples from Mtb- and Maf-infected patients obtained before and after anti-TB treatment were analysed for cell composition, gene expression and metabolic profiles. Prior to treatment, similar transcriptomic profiles were seen in Maf- and Mtb-infected patients. In contrast, post-treatment, over 1600 genes related to immune responses and metabolic diseases were differentially expressed between the groups. Notably, the upstream regulator hepatocyte nuclear factor 4-alpha (HNF4α), which regulated 15% of these genes, was markedly enriched. Serum metabolic profiles were similar in both group pre-treatment, but the decline in pro-inflammatory metabolites post-treatment were most pronounced in Mtb-infected patients. Together, the differences in both peripheral blood transcriptomic and serum metabolic profiles between Maf- and Mtb-infected patients observed over the treatment period, might be indicative of intrinsic host factors related to susceptibility to TB and/or differential efficacy of the standard anti-TB treatment on the two lineages.

Increasing the value of health research in the WHO African Region beyond 2015--reflecting on the past, celebrating the present and building the future: a bibliometric analysis

OBJECTIVE

To assess the profile and determinants of health research productivity in Africa since the onset of the new millennium.

DESIGN

Bibliometric analysis.

DATA COLLECTION AND SYNTHESIS

In November 2014, we searched PubMed for articles published between 2000 and 2014 from the WHO African Region, and obtained country-level indicators from World Bank data. We used Poisson regression to examine time trends in research publications and negative binomial regression to explore determinants of research publications.

RESULTS

We identified 107,662 publications, with a median of 727 per country (range 25-31,757). Three countries (South Africa, Nigeria and Kenya) contributed 52% of the publications. The number of publications increased from 3623 in 2000 to 12,709 in 2014 (relative growth 251%). Similarly, the per cent share of worldwide research publications per year increased from 0.7% in 2000 to 1.3% in 2014. The trend analysis was also significant to confirm a continuous increase in health research publications from Africa, with productivity increasing by 10.3% per year (95% CIs +10.1% to +10.5%). The only independent predictor of publication outputs was national gross domestic product. For every one log US$ billion increase in gross domestic product, research publications rose by 105%: incidence rate ratio (IRR=2.05, 95% CI 1.39 to 3.04). The association of private health expenditure with publications was only marginally significant (IRR=1.86, 95% CI 1.00 to 3.47).

CONCLUSIONS

There has been a significant improvement in health research in the WHO African Region since 2000, with some individual countries already having strong research profiles. Countries of the region should implement the WHO Strategy on Research for Health: reinforcing the research culture (organisation); focusing research on key health challenges (priorities); strengthening national health research systems (capacity); encouraging good research practice (standards); and consolidating linkages between health research and action (translation).

Safety and immunogenicity of the M72/AS01 candidate tuberculosis vaccine when given as a booster to BCG in Gambian infants: an open-label randomized controlled trial

We evaluated the candidate tuberculosis vaccine M72/AS01 in Bacille-Calmette-Guérin (BCG)-vaccinated infants after or concomitantly with Expanded-Programme-on-Immunization (EPI) vaccines.

METHODS

In a Phase-II study in The Gambia (NCT01098474), 2 cohorts of 150 BCG-vaccinated infants each were randomized 1:1:1. The 'Outside-EPI' cohort received one or two M72/AS01 doses, or meningitis vaccine, 1-2 months after primary EPI vaccination. The 'Within-EPI' cohort received one or two M72/AS01 doses concomitantly with the third or last two doses of their primary EPI-regimen, respectively, or EPI vaccines alone. Safety, M72-specific humoral (ELISA) and cell-mediated (whole-blood ICS) responses, and humoral responses to EPI vaccines were assessed.

RESULTS

M72/AS01 was acceptably tolerated with no vaccine-related serious adverse events reported. Seropositivity/seroprotection rates against EPI antigens in the Within-EPI cohort were comparable between groups, irrespective of M72/AS01 co-administration. Up to one year post M72/AS01 vaccination, M72-specific humoral and CD4(+) T-cell responses were higher after 2 doses versus 1 dose in both cohorts (p < 0.0001), and comparable between cohorts after either 1 or 2 doses (p > 0.05).

CONCLUSION

M72/AS01 given to infants after or concomitantly with EPI vaccines had an acceptable safety profile. Our results suggest no interference of immunogenicity profiles occurred following co-administration of M72/AS01 and EPI vaccines. Two M72/AS01 doses elicited higher immune responses than one dose.

Antibodies against Haemophilus influenzae type b in The Gambia: investigating the extent of protection across age groups

Following a landmark clinical trial, the vaccine against Haemophilus influenzae type b (Hib) was introduced in The Gambia in 1997. Whilst the immunogenicity of this vaccine is well established subsequent to the doses administered under the EPI schedule, little data exists assessing longevity of protection, using serology. Such data are needed however to predict the susceptibility to Hib at the population level. To determine antibody persistence in 5-6 year old fully vaccinated Gambian children compared with older children, adolescents and young adults, 427 serum samples from healthy 5-37 year old participants were tested for Hib antibodies using VaccZyme Human Anti-Hib ELISA kits. 86% of the children who had received 3 doses of Hib vaccine in infancy had Hib antibody concentrations ≥0.15 mg/l at the age of 5-6 years. This proportion was 76% for adolescents who had also largely been vaccinated and 90% for adults who had never received Hib vaccine. Although most participants had anti-Hib antibody above concentrations putatively defined as protective, significantly fewer had concentrations thought to confer long-term protection. This suggests a population with insufficient or waning antibody that may be susceptible to breakthrough disease and transmission.

Immunogenic Mycobacterium africanum strains associated with ongoing transmission in The Gambia

In West Africa, Mycobacterium tuberculosis strains co-circulate with M. africanum, and both pathogens cause pulmonary tuberculosis in humans. Given recent findings that M. tuberculosis T-cell epitopes are hyperconserved, we hypothesized that more immunogenic strains have increased capacity to spread within the human host population. We investigated the relationship between the composition of the mycobacterial population in The Gambia, as measured by spoligotype analysis, and the immunogenicity of these strains as measured by purified protein derivative–induced interferon-γ release in ELISPOT assays of peripheral blood mononuclear cells. We found a positive correlation between strains with superior spreading capacity and their relative immunogenicity. Although our observation is true for M. tuberculosis and M. africanum strains, the association was especially pronounced in 1 M. africanum sublineage, characterized by spoligotype shared international type 181, which is responsible for 20% of all tuberculosis cases in the region and therefore poses a major public health threat in The Gambia.

Factors affecting immunogenicity of BCG in infants, a study in Malawi, The Gambia and the UK

Background

BCG immunogenicity in infants differs between populations and these differences have been attributed to various factors. In this study, the influence of geographical location, season of birth, timing of vaccination, micronutrient status (zinc) and inflammatory status (C-reactive protein, CRP) were assessed.

Methods

Immunogenicity was assessed by cytokine signature in culture supernatants from diluted whole blood samples stimulated with M. tuberculosis PPD, using a multiplex bead assay. Results were correlated with the plasma zinc and CRP concentrations at the time of sampling, and with interview and household data. BCG vaccinated infants were recruited in Malawi, The Gambia and the UK.

Results

In Malawi, infants vaccinated within the first week after birth showed lower production of most cytokines measured than those vaccinated later. The number of cytokines showing significant differences between Malawian and Gambian infants decreased after adjusting for season of birth. In Malawi, a proportion of infants had zinc deficiency and elevated plasma CRP (>10 mg/L), but neither zinc deficiency nor high CRP was associated with production of any of the cytokines measured.

Conclusions

The cytokine/chemokine signatures observed in response to M. tuberculosis PPD in infants at 3 months post BCG vaccination were affected by geographical location, season of birth, and timing of vaccination but not associated with the concentration of plasma zinc or inflammatory status. These factors should be considered in future trials of new TB vaccines.

Interferon-gamma treatment kinetics among patients with active pulmonary tuberculosis

Introduction:

Interferon-γ (IFN-γ) is essential for defence against Mycobacterium tuberculosis; however, levels in patients with active tuberculosis (TB) and changes during treatment have not been documented in our tuberculosis patients in Nigeria, hence this study has been carried out.

Objective:

To determine variations, treatment kinetics, and predictive value of IFN-γ levels during treatment of active tuberculosis.

Design:

Patients with pulmonary tuberculosis were recruited and subsequently followed up for 3 months during treatment with anti-TB. Peripheral blood was collected for IFN-γ assays, C-reactive protein and others followed by a Mantoux test. IFN-γ levels produced by stimulation with TB antigens were determined by ELISA and repeated measurement of IFN-γ were done at 1 and 3 months of anti-TB therapy. Chi Associations and correlations between IFN-γ were determined. Regression analysis was done to determine association between serial IFN-γ and treatment outcome.

Results:

We recruited 47 patients with active tuberculosis with a mean age of 34.8 ± 3.6 years and M:F ratio of 1.12:1. Six (11%) were HIV positive. The mean level of IFN-γ induced by TB antigens was 629 ± 114.1 pg/ml, higher for HIV-negative PTB patients compared with HIV-positive PTB patients, 609.78 ± 723.9 pg/ml and 87.88 ± 130.0 pg/ml, respectively, P-value = 0.000. The mean level of IFN-γ induced by TB antigen increased significantly from 629 ± 114.1 pg/ml to 1023.46 + 222.8 pg/ml, P-value = 0.03 and reduced to 272.3 ± 87.7 pg/ml by the third month on anti-TB drugs, P-value = 0.001. Negative correlation was observed between the mean of baseline and chest X-ray involvement, P = 0.03. There was no significant correlation between sputum smear grade with baseline and follow-up IFN-γ levels. Three-month IFN-γ level among cured patients were higher than those with treatment failure, regression analysis showed that it does not predict outcome.

Conclusion:

IFN-γ may be useful in early detection and monitoring response; however, large scale studies are needed.

Differences in T-cell responses between Mycobacterium tuberculosis and Mycobacterium africanum-infected patients

In The Gambia, Mycobacterium tuberculosis (Mtb) and Mycobacterium africanum (Maf) are major causes of tuberculosis (TB). Maf is more likely to cause TB in immune suppressed individuals, implying differences in virulence. Despite this, few studies have assessed the underlying immunity to the two pathogens in human. In this study, we analyzed T-cell responses from 19 Maf- and 29 Mtb-infected HIV-negative patients before and after TB chemotherapy following overnight stimulation of whole blood with TB-specific antigens. Before treatment, percentages of early secreted antigenic target-6(ESAT-6)/culture filtrate protein-10(CFP-10) and purified protein derivative-specific single-TNF-α-producing CD4(+) and CD8(+) T cells were significantly higher while single-IL-2-producing T cells were significantly lower in Maf- compared with Mtb-infected patients. Purified protein derivative-specific polyfunctional CD4(+) T cells frequencies were significantly higher before than after treatment, but there was no difference between the groups at both time points. Furthermore, the proportion of CD3(+) CD11b(+) T cells was similar in both groups pretreatment, but was significantly lower with higher TNF-α, IL-2, and IFN-γ production in Mtb- compared with that of Maf-infected patients posttreatment. Our data provide evidence of differences in T-cell responses to two mycobacterial strains with differing virulence, providing some insight into TB pathogenesis with different Mtb strains that could be prospectively explored as biomarkers for TB protection or susceptibility.

The immunogenicity and impact on nasopharyngeal carriage of fewer doses of conjugate pneumococcal vaccine immunization schedule

The immunogenicity and impact on carriage of fewer doses of pneumococcal conjugate vaccine (PCV7) followed by booster with pneumococcal polysaccharide vaccine (PPV) were investigated. 684 infants were assigned randomly to one of the three groups that received one (A), two (B) or three (C) doses of PCV7 between 2 and 4 months of age, plus PPV at 10 months. Following primary vaccination protective antibody titers of >0.35 μg/ml against the PCV7 serotypes combined increased significantly with the number of PCV7 doses, 44% vs. 77% vs. 94% (p<0.001), and correlated positively with the opsonophagocytic indices, but negatively with nasopharyngeal carriage of pneumococcus. The differences in antibody responses and pneumococcal carriage between the groups diminished following booster with PPV, implying that administration of one or two doses of PCV7, with a booster dose of PPV might lower the cost of protection against IPD in young children in resource poor countries.

Immunogenicity of antigens from the TbD1 region present in M. africanum and missing from "modern" M. tuberculosis: a cross- sectional study

Background

Currently available tools cannot be used to distinguish between sub-species of the M. tuberculosis complex causing latent tuberculosis (TB) infection. M. africanum causes up to half of TB in West- Africa and its relatively lower progression to disease suggests the presence of a large reservoir of latent infection relative to M. tuberculosis.

Methods

We assessed the immunogenicity of the TbD1 region, present in M. africanum and absent from "modern" M. tuberculosis, in an ELISPOT assay using cells from confirmed M. africanum or M. tuberculosis infected TB patients without HIV infection in the Gambia.

Results

Antigens from the TbD1 region induced IFNγ responses in only 35% patients and did not discriminate between patients infected with M. africanum vs. M. tuberculosis, while PPD induced universally high responses.

Conclusions

Further studies will need to assess other antigens unique to M. africanum that may induce discriminatory immune responses.

T cell memory response to pneumococcal protein antigens in an area of high pneumococcal carriage and disease

BACKGROUND

Streptococcus pneumoniae is a leading cause of vaccine-preventable disease worldwide. Pneumococcal protein antigens are currently under study as components of potential vaccines that offer protection against multiple serotypes. We have therefore characterized T cell pneumococcal immunity acquired through asymptomatic carriage.

METHODS

Peripheral blood mononuclear cells from 40 healthy Gambian adults were stimulated with supernatants derived from S. pneumoniae strain (D39), 2 isogenic mutant strains lacking either pneumolysin or choline binding protein A, and recombinant pneumolysin. Immune responses were measured by cellular proliferation and by interleukin-10 (IL-10) and interferon-gamma (IFN-gamma) enzyme-linked immunosorbent spot and bioplex cytokine assays. Nasopharyngeal swabs were cultured to determine carriage rates.

RESULTS

S. pneumoniae nasopharyngeal carriage was detected in 60% of individuals. Both effector and resting (or central) CD4(+) T cell memory were frequently present to a range of pneumococcal antigens. However, the level of the effector memory response did not relate to current nasopharyngeal carriage. Pneumolysin was not immunodominant in these T cell responses but induced a distinct proinflammatory profile (high IFN-gamma, IL-12[p40], and L-17 levels and low IL-10 and IL-13 levels).

CONCLUSIONS

In this population, T cell-mediated immunological memory potentially capable of pathogen clearance and immune surveillance is common but is not associated with the absolute interruption of pneumococcal carriage. How this naturally acquired immune memory influences pneumococcal vaccine efficacy remains to be determined.

Hemagglutinin Protein Is a Primary Target of the Measles Virus–Specific HLA‐A2–Restricted CD8+T Cell Response during Measles and after Vaccination

To characterize the measles virus (MV)-specific T cell responses important for evaluation of measles vaccines, human leukocyte antigen (HLA)-A2-positive and -negative adults immunized with measles-mumps-rubella vaccine were studied. Both groups developed increases in antibody and in interferon (IFN)- gamma -producing cells in response to pooled hemagglutinin (H) and fusion peptides. HLA-A2-binding peptides were predicted for all MV-encoded proteins and confirmed by T2 cell stabilization. Twenty-nine peptides were tested, and 19 (6 from H) stimulated increased IFN- gamma secretion in a majority of vaccinees. Peptide-loaded HLA-A2 tetramers or immunoglobulin dimers documented MV-specific CD8+ T cell responses after vaccination and during measles and confirmed new A2 epitopes in H (250-259 and 516-525 aa) and matrix (M; 50-58 aa) protein and previously described epitopes in H (30-38 aa), M (211-219 aa), and nonstructural protein C (84-92 aa). No single peptide dominated the response. We conclude that H is an important stimulus for CD8+ T cell as well as for antibody responses in HLA-A2-positive individuals.

Sense and the science of childhood immunization: Can we achieve more with less?

The threat of biological terrorism with small pox virus and a global influenza pandemic in the face of limited vaccine supply recently stimulated research into the evaluation of fractional dose vaccine regimens, with promising immunogenicity results. While this approach is not new, it has been less applied to vaccines for less sensational but nevertheless, significant killer diseases. This manuscript provides an overview of the basics of immunization as it applies to the current practice of immunization in children, comments on the untapped avenues for cost reduction of vaccine delivery, and the potential for saving more lives with currently available resources.

Protective immunity provided by HLA-A2 epitopes for fusion and hemagglutinin proteins of measles virus

Natural infection and vaccination with a live-attenuated measles virus (MV) induce CD8(+) T-cell-mediated immune responses that may play a central role in controlling MV infection. In this study, we show that newly identified human HLA-A2 epitopes from MV hemagglutinin (H) and fusion (F) proteins induced protective immunity in HLA-A2 transgenic mice challenged with recombinant vaccinia viruses expressing F or H protein. HLA-A2 epitopes were predicted and synthesized. Five and four peptides from H and F, respectively, bound to HLA-A2 molecules in a T2-binding assay, and four from H and two from F could induce peptide-specific CD8+ T cell responses in HLA-A2 transgenic mice. Further experiments proved that three peptides from H (H9-567, H10-250, and H10-516) and one from F protein (F9-57) were endogenously processed and presented on HLA-A2 molecules. All peptides tested in this study are common to 5 different strains of MV including Edmonston. In both A2K(b) and HHD-2 mice, the identified peptide epitopes induced protective immunity against recombinant vaccinia viruses expressing H or F. Because F and H proteins induce neutralizing antibodies, they are major components of new vaccine strategies, and therefore data from this study will contribute to the development of new vaccines against MV infection.

Emerging diseases: Measles

High vaccination coverage rates and the administration of a second dose of measles vaccine have resulted in a significant decline in the incidence of measles and neurologic diseases due to measles in many countries. However, intermittent outbreaks of measles still occur even in countries with excellent vaccination coverage, suggesting the existence of high rates of measles virus introduction from endemic regions and/or waning of vaccine-induced immunity. Strategies to sustain high levels of global immunity to measles virus by increasing vaccine coverage with routine and supplementary vaccination campaigns must be supported.

Measles: immune suppression and immune responses

Measles is a highly contagious viral disease that remains the leading vaccine-preventable cause of child mortality worldwide. Deaths from measles are due largely to an increased susceptibility to secondary bacterial and viral infections, attributed to a prolonged state of immune suppression. Several abnormalities of the immune system have been described, including changes in lymphocyte number and function, shifts in cytokine responses, immunomodulatory effects of interleukin-10, down regulation of interleukin-12, impaired antigen presentation, and altered interferon alpha/beta signaling pathways. Although the current vaccine is very effective, knowledge of the molecular basis of the immune responses to measles virus could contribute to the development of a safer, more immunogenic measles vaccine. However, the safety of new measles vaccines must be carefully investigated, as two measles vaccines have resulted in unintended immunologic consequences: atypical measles following administration of the formalin-inactivated measles vaccine and increased mortality in girls following administration of high-titer measles vaccines.

Survival of HIV-1 and HIV-2 perinatally infected children in The Gambia

BACKGROUND

The risk of mother-to-child transmission (MTCT) of HIV-2 is much lower than that of HIV-1, but the long-term prognosis of perinatally infected HIV-2 children is unknown. We re-visited children who were part of a large MTCT study in The Gambia (conducted during 1993-1997), in order to compare the long-term survival of children perinatally infected with HIV-2 with that of seronegative and of HIV-1 infected children.

METHODS

Five to eight years' follow-up of a cohort of children born to HIV-negative, HIV-1 positive, and HIV-2 positive mothers.

RESULTS

Seven hundred and seventy-four children were followed up for a median of 6.6 years. Of 17 perinatally HIV-1 infected children, three were still alive on 1 July 2001, two had been lost to follow-up, and 12 had died. The median survival was 2.5 years. Of eight HIV-2 infected children five were still alive, none were lost to follow-up and three had died. The mortality hazards ratio of both HIV-1 [9.9; 95% confidence interval (CI), 5.2-19], and of HIV-2 infected children (3.9; CI, 1.2-12) was significantly increased compared with children of seronegative mothers. The mortality hazards ratio of HIV uninfected children of HIV-1 or HIV-2 infected mothers was not significantly increased compared to that of children of seronegative mothers (P = 0.17 and P = 0.5 respectively).

CONCLUSIONS

Children with perinatally acquired HIV-2 infection have a higher mortality than children of seronegative mothers. Guidelines for treatment of HIV-1 infected children should be used for treatment of HIV-2 infected children.

Plasmodium falciparum infection of the placenta affects newborn immune responses

The effects of exposure to placental malaria infection on newborn immunological responses, in particular Th1/Th2 cytokines and antigen-presenting cell (APC) function, were compared between cord blood mononuclear cells (CBMC) from parasitized and non-parasitized placentas of Gambian women. Cells were analysed in vitro for their ability to respond to mitogens [phorbol myristate acetate (PMA)/ionomycin, phytohaemagglutinin (PHA)], a malaria-unrelated test antigen [purified protein derivative of Mycobacterium tuberculin[purified protein derivative (PPD)] and Plasmodium falciparum schizont extracts. Mitogens induced strong proliferation and secretion of high concentrations of both IL-13 and sCD30 in CBMC from both groups. Conversely, significantly lower amounts of IFN-gamma were induced in the parasitized group in response to low doses of PHA. Protein antigens induced very low amounts of all tested cytokines, in particular IFN-gamma. However, a significantly higher release of sCD30 was observed in response to schizont extracts in the parasitized group. Addition of LPS to activate APC to low doses of PHA or schizont extracts increased the IFN-gamma production in both groups but levels remained lower in CBMC from the parasitized group. This result correlates with the lower production of IL-12 found following lipopolysaccharide (LPS) stimulation in this group. Taken together, these data show that placental infection with P. falciparum affects Th1 differentiation and sCD30 priming of neonatal lymphocytes and that the probable mode of action is via APC.

Influence of placental malaria infection on foetal outcome in the Gambia: twenty years after Ian Mcgregor

Malaria infection in pregnancy has serious health consequences among mothers and offspring. The influence of placental malaria infection on foetal outcome was studied in a Gambian rural setting where few pregnant women take antimalarial chemoprophylaxis. During July-December 1997, three hundred thirteen mother-newborn pairs (singletons only) were consecutively recruited into a study of the effects of placental malaria infection on the outcome of pregnancy. Placental blood and tissue were collected at delivery. Babies were clinically assessed until discharge. The overall prevalence of placental malaria infection was 51.1% by placental histology and 37.1% by blood smear. The primigravid women were more susceptible to placental malaria than the multigravidae (65.3% vs 44.7%, p=0.01). Placental malaria was significantly associated with pre-term deliveryand intrauterine growth retardation (p<0.01), and there was a four-fold risk of delivering low-birth-weight babies if mothers had parasitized placentae [OR=4.42, 95% confidence interval (CI) 2.10-9.27]. A reduction of mean birth-weight of babies by 320 g was associated with placental malaria infection (p<0.001). Similarly, a two-fold risk of stillbirth delivery (OR=2.22, 95% CI 1.04-4.72) was observed among the infected mothers. The findings showed that there was still an overall poor foetal outcome associated with placental malaria infection. The findings of this study confirm the findings of an earlier study by McGregor in the Gambia that the low birth-weight rate is significantly higher if the placenta is parasitized. In addition, this study observed that the high stillbirth and prematurity rates were associated with placental malaria infection. The findings of the present study suggest undertaking of effective malaria-control strategies during pregnancy, such as use of insecticide-impregnated bednets, intermittent and early treatment for malaria, and antimalarial chemoprophylaxis, in the Gambia.

The influence of placental malaria infection and maternal hypergammaglobulinemia on transplacental transfer of antibodies and IgG subclasses in a rural West African population

Two hundred thirteen mother-baby pairs in The Gambia were studied to determine the influence of placental malaria infection and maternal hypergammaglobulinemia on transplacental antibody transfer. Antibody transfer for herpes simplex virus 1 (HSV-1), respiratory syncytial virus (RSV), and varicella-zoster virus (VZV) was significantly reduced by placental malaria infection by 69%, 58%, and 55%, respectively. Maternal hypergammaglobulinemia was associated with a significant reduction in antibody transfer for HSV-1, RSV, VZV, and pneumococcus by 89%, 90%, 91%, and 88%, respectively. In addition, placental malaria infection was associated with a significant reduction in transfer of IgG1, IgG2, and IgG4 (P<.01, P=.01, and P=.03, respectively) but not of IgG3 (P=.59). Maternal hypergammaglobulinemia significantly impaired the transfer of IgG1 and IgG2 (P=.01) but not of IgG3 or IgG4 (P=.62 and P=.59, respectively). Placental malaria infection and maternal hypergammaglobulinemia were associated with reduction in the transplacental transfer of these specific antibodies, IgG1, and IgG2 in this Gambian population.

Peripheral gangrene complicating Salmonella typhi septicaemia in a Gambian infant

A 1-year-old malnourished boy, who presented with Salmonella typhi septicaemia with a 4-day history of febrile illness, dehydration and severe anaemia, developed bilateral dry gangrene of the hands and feet. Although he improved appreciably, he suffered auto-amputation of the distal phalanges of the left foot after 3 weeks of illness. A high index of suspicion and prompt treatment is highly critical in the treatment of septicaemia in young children.

Influence of placental malaria infection and maternal hypergammaglobulinaemia on materno-foetal transfer of measles and tetanus antibodies in a rural west African population

Placental malaria infection jeopardizes pregnancy outcome, and its influence may also impair the transplacental transfer of some antibodies. Two hundred and thirteen Gambian mother-baby pairs were studied to determine the influence of placental malaria infection and maternal hypergammaglobulinaemia on transplacental transfer of measles and tetanus antibodies in Gambian population. Placental blood and tissue were collected for placental malaria diagnosis. Cord and maternal sera were tested for total IgG concentration by laser nephelometry and for IgG antibody to tetanus toxoid and measles by ELISA. The prevalence of placental malaria infection was 51.1%. Mothers whose placentae were parasitized had a significantly higher mean total serum IgG (22.0 g/L vs 11.3 g/L, p < 0.001) and measles antibody level (4.02 IU/mL vs 1.21 IU/mL, p < 0.01), but not tetanus antibody, than mothers with non-parasitized placentae. Results of multiple regression analysis showed that placental malaria infection and maternal hypergammaglobulinaemia were associated with the reduction of 72% (95% CI 67.84) and 86% (95% CI 76.91) in transplacental transfer of measles antibody respectively but did not influence the transfer of tetanus antibody. It is concluded that the combined influence of placental malaria infection and maternal hypergammaglobulinaemia is significantly associated with the transfer of impaired measles antibody in this population.

Neonatal bacillus Calmette-Guérin vaccination induces adult-like IFN-gamma production by CD4+ T lymphocytes

The immaturity of the neonatal immune system in mice is associated with defective IFN-gamma production and Th2-biased immune responses. In this study, infants vaccinated at birth with BCG produced similar concentrations of IFN-gamma in response to PPD and showed similar frequencies of IFN-gamma-producing lymphocytes as compared to immune adults. Infants and adults produced only low concentrations of IL-4 and IL-5. CD4+ T lymphocytes were the main source of IFN-gamma. Similar proportions of Th1 and Th0 PPD-specific T cell clones were observed in infants and adults. This study demonstrates that the human neonatal immune response to BCG is not biased towards Th2 and is characterized by the predominant production of IFN-gamma by CD4+ T lymphocytes.

Electrolyte derangement in cerebral malaria: a case for a more aggressive approach to the management of hyponatraemia

Although hyponatraemia has been consistently shown to occur in a large proportion of children with cerebral malaria, no statistical relationship has been established between the incidence of hyponatraemia and that of malaria-attributable mortality. However, hyponatraemia is not a benign state in other conditions (such as meningitis) or in surgical patients, and is likely to add to malarial deaths. The high mortality rate seen among cases of cerebral malaria, despite all efforts to curb it, therefore calls for a more aggressive approach to the management of hyponatraemia. Current methods for the administration of hypotonic saline and isotonic glucose solutions need review. In addition, children admitted with cerebral malaria should have their electrolyte status monitored to identify new or ongoing hyponatraemia. When hyponatraemia is discovered, it should be quickly and actively corrected.

Maternal HIV-1 and HIV-2 infection and child survival in The Gambia

OBJECTIVE

To compare the survival of children born to HIV-1 or HIV-2 seropositive mothers with that of children born to HIV-seronegative mothers and to evaluate risk factors for mortality.

DESIGN

Physician-blinded prospective study.

METHODS

One hundred and one HIV-1-seropositive, 243 HIV-2-seropositive pregnant women, and 468 HIV-seronegative women (control group) matched by age, parity, and health centre, were followed up in a study of mother-to-child transmission of HIV. Mothers and children were seen at 2 and 6 months of age and subsequently followed at 3-monthly intervals up to 18 months of age. HIV infection in children was diagnosed by polymerase chain reaction at 2, 9 or 18 months and by antibody assays at 18 months.

RESULTS

Fifteen per cent of children born to HIV-1-infected mothers died compared with 7% of children born to HIV-2-infected mothers [hazard ratio, 2.3; 95% confidence interval (CI), 1.1-4.7; P = 0.02], and 6% of HIV-seronegative mothers (hazard ratio, 2.6; 95% CI, 1.4-5.0; P = 0.003). Six of the 17 children known to be HIV-1 infected died compared with none among the eight HIV-2-infected children (P = 0.13). High proviral load in the babies, high antenatal maternal RNA plasma viral load, and maternal death increased child mortality significantly.

CONCLUSIONS

More children born to HIV-1-infected mothers died in comparison with those born to HIV-2-infected mothers or to mothers from the control group. This effect was due to excess death in HIV-1-infected infants which was associated with a high viral load in the affected mother and child.

The host response in malaria and depression of defence against tuberculosis

Malaria causes significant morbidity and mortality world-wide. Both asymptomatic and symptomatic malarial infections cause immune depression, which predisposes the host to infection with other microorganisms. Specific clinical investigations have shown, for example, that those with malaria-attributable anaemia are particularly likely to have Salmonella septicaemia, and that asymptomatic malarial infection causes diminished response to polysaccharide vaccine. The results of clinical studies and experiments with animal models have revealed that malarial parasites can decrease their vertebrate host's effective humoral and cellular immune responses. In this review, the possible ways in which this malaria-induced immune impairment could affect the host's response to Mycobacterium tuberculosis infection are considered. Could malarial infection be one of the reasons for the persistence of tuberculosis in malaria-endemic regions?

Newborns develop a Th1-type immune response to Mycobacterium bovis bacillus Calmette-Guérin vaccination

Data obtained in animals indicate that neonatal immune responses are biased toward Th2. This could reduce the efficacy of vaccines against viral and mycobacterial diseases. The ability of human newborns to develop a Th1 immune response upon immunization has not been studied. Since the vaccine Mycobacterium bovis bacillus Calmette-Guérin (BCG) triggers a Th1-type response in adults, we investigated whether it induces a similar response in newborns and whether age at vaccination influences immunogenicity. We found that BCG vaccination at birth induces a memory Th1-type response of similar magnitude to that when given later in life. This study demonstrates that human newborns can be immunized against pathogens controlled by a Th1 immune response.

Newborns Develop a Th1-Type Immune Response to Mycobacterium bovis Bacillus Calmette-Guérin Vaccination

Data obtained in animals indicate that neonatal immune responses are biased toward Th2. This could reduce the efficacy of vaccines against viral and mycobacterial diseases. The ability of human newborns to develop a Th1 immune response upon immunization has not been studied. Since the vaccine Mycobacterium bovis bacillus Calmette-Guérin (BCG) triggers a Th1-type response in adults, we investigated whether it induces a similar response in newborns and whether age at vaccination influences immunogenicity. We found that BCG vaccination at birth induces a memory Th1-type response of similar magnitude to that when given later in life. This study demonstrates that human newborns can be immunized against pathogens controlled by a Th1 immune response.

Changes in the pattern of infant and childhood mortality in upper river division, The Gambia, from 1989 to 1993

A surveillance system was used to detect births and deaths in children in a large, rural, West African population from 1989 to 1993. Cause of death was investigated using post-mortem questionnaires. Overall infant (age 0-11 months) and child (age 1-4 years) mortality rates of 80.1 and 18.8 per 1000 per year were recorded. These were reasonably consistent over the period of surveillance. The most frequent cause of death in infants was acute respiratory infection (ARI), whereas in children it was malaria: these two conditions accounted for 41% of the deaths in children under 5 years old. Other leading causes of death were acute gastroenteritis, malnutrition, and septicaemia. Deaths attributed to ARI decreased over the 5-year period, but mortality rates from other causes were either unchanged or increased slightly. Mortality from all causes peaked in the rainy season and was slightly higher in villages which were part of a primary health care programme than in those which were not. There were also no differences between male and female mortality rates beyond one year of age. Despite the introduction of a number of health interventions, there has been no major change in the overall pattern of mortality in children in a rural area of The Gambia. Malaria and ARI remain the main causes of death.