Marianne A. B. van der Sande

Nontuberculous Mycobacteria, Zambia

One-sentence summary for table of contents: These organisms play an underestimated role in tuberculosis-like diseases in this country.

Mature CD8(+) T lymphocyte response to viral infection during fetal life.

Immunization of newborns against viral infections may be hampered by ineffective CD8(+) T cell responses. To characterize the function of CD8(+) T lymphocytes in early life, we studied newborns with congenital human cytomegalovirus (HCMV) infection. We demonstrate that HCMV infection in utero leads to the expansion and the differentiation of mature HCMV-specific CD8(+) T cells, which have similar characteristics to those detected in adults. High frequencies of HCMV-specific CD8(+) T cells were detected by ex vivo tetramer staining as early as after 28 weeks of gestation. During the acute phase of infection, these cells had an early differentiation phenotype (CD28(-)CD27(+)CD45RO(+), perforin(low)), and they acquired a late differentiation phenotype (CD28(-)CD27(-)CD45RA(+), perforin(high)) during the course of the infection. The differentiated cells showed potent perforin-dependent cytolytic activity and produced antiviral cytokines. The finding of a mature and functional CD8(+) T cell response to HCMV suggests that the machinery required to prime such responses is in place during fetal life and could be used to immunize newborns against viral pathogens.

Body Mass Index at Time of Hiv Diagnosis: A Strong and Independent Predictor of Survival

BackgroundIdentification of basic prognostic indicators of HIV infection is essential before widespread antiretroviral therapy can be implemented in low-technology settings. This study assessed how well body mass index (BMI:kg/m2) predicts survival. MethodsBMI within 3 months of HIV diagnosis was obtained from 1657 patients aged ≥15 years, recruited in a seroprevalent clinical cohort in The Gambia since 1992 and followed up at least once. Baseline CD4+ counts and clinical assessment at time of diagnosis were done. ResultsThe mortality hazard ratio (HR) of those with a baseline BMI <18 compared with those with a baseline BMI ≥18 was 3.4 (95% CI, 3.0–3.9). The median survival time of those presenting with a BMI <16 was 0.8 years, in contrast to a median survival of 8.9 years for those with a baseline BMI ≥22. Baseline BMI <18 remained a highly significant independent predictor of mortality after adjustment for age, sex, co-trimoxazole prophylaxis, tuberculosis, reported wasting at diagnosis, and baseline CD4+ cell count (adjusted HR = 2.5, 95% CI 2.0–3.0). Sensitivity and specificity of baseline BMI <18 was comparable to that of a CD4+ count <200 in predicting mortality within 6 months of diagnosis. DiscussionBMI at diagnosis is a strong, independent predictor of survival in HIV-infected patients in West Africa. In the absence of sophisticated clinical and laboratory support, BMI may also prove a useful guide for deciding when to initiate antiretroviral therapy.

Family history: an opportunity for early interventions and improved control of hypertension, obesity and diabetes

OBJECTIVE To examine whether a family history of high-risk groups for major noncommunicable diseases (NCDs) was a significant risk factor for these conditions among family members in a study population in the Gambia, where strong community and family coherence are important determinants that have to be taken into consideration in promoting lifestyle changes. METHODS We questioned 5389 adults as to any first-degree family history of major noncommunicable diseases (hypertension, obesity, diabetes and stroke), and measured their blood pressure (BP) and body mass index (BMI). Total blood cholesterol, triglyceride, uric acid, and creatinine concentrations were measured in a stratified subsample, as well as blood glucose (2 hours after ingesting 75 g glucose) in persons aged > or = 35 years. FINDINGS A significant number of subjects reported a family history of hypertension (8.0%), obesity (5.4%), diabetes (3.3%) and stroke (1.4%), with 14.6% of participants reporting any of these NCDs. Subjects with a family history of hypertension had a higher diastolic BP and BMI, higher cholesterol and uric acid concentrations, and an increased risk of obesity. Those with a family history of obesity had a higher BMI and were at increased risk of obesity. Individuals with a family history of diabetes had a higher BMI and higher concentrations of glucose, cholesterol, triglycerides and uric acid, and their risk of obesity and diabetes was increased. Subjects with a family history of stroke had a higher BMI, as well as higher cholesterol, triglyceride and uric acid concentrations. CONCLUSIONS A family history of hypertension, obesity, diabetes, or stroke was a significant risk factor for obesity and hyperlipidaemia. With increase of age, more pathological manifestations can develop in this high-risk group. Health professionals should therefore utilize every opportunity to include direct family members in health education.Objetivo Determinar si la existencia de unos antecedentes familiares de alto riesgo de sufrir enfermedades no transmisibles (ENT) constituı́a un factor de riesgo relevante para esas dolencias entre los miembros de la familia en una población de estudio de Gambia, paı́s donde los sólidos lazos comunitarios y la cohesión familiar son determinantes importantes que deben tenerse en cuenta a la hora de promover cambios del estilo de vida. Métodos Pedimos a 5389 adultos que mencionaran cualquier antecedente, entre los familiares de primer grado, de ENT importantes (hipertensión, obesidad, diabetes y accidente cerebrovascular), y medimos su tensión arterial (TA) y su ı́ndice de masa corporal (IMC). Se determinaron las concentraciones de colesterol total, triglicéridos, ácido úrico y creatinina en sangre en una submuestra estratificada, ası́ como la glucosa sanguı́nea (dos horas después de ingerir 75 g de glucosa) en las personas de más de 34 años. Resultados Un número importante de individuos refirieron antecedentes familiares de hipertensión (8,0%), obesidad (5,4%), diabetes (3,3%) y accidente cerebrovascular (1,4%), elevándose al 14,6% los participantes que mencionaron cualquiera de esas ENT. Las personas con antecedentes familiares de hipertensión presentaban una TAdiastólica y un IMC superiores a lamedia, concentracionesmayores de colesterol y de ácido úrico y unmayor riesgo de obesidad. Las personas con historia familiar de obesidad tenı́an un IMC mayor y presentaban un riesgo más elevado de obesidad. Los individuos con antecedentes familiares de diabetes presentaban unmayor IMC, niveles más altos de glucosa, colesterol, triglicéridos y ácido úrico, y unmayor riesgo de obesidad y diabetes. Y los individuos con antecedentes familiares de ictus presentaban un IMC más elevado, ası́ como concentraciones más altas de colesterol, triglicéridos y ácido úrico. Conclusión Unos antecedentes familiares de hipertensión, obesidad, diabetes o accidente cerebrovascular constituyen un factor de riesgo importante de obesidad e hiperlipidemia. Con el aumento de la edad, en este grupo de alto riesgo pueden aparecer más manifestaciones patológicas. Ası́ pues, los profesionales de la salud deben aprovechar cuantas oportunidades tengan de extender a los familiares directos la educación sanitaria.OBJECTIVE: To examine whether a family history of high-risk groups for major noncommunicable diseases (NCDs) was a significant risk factor for these conditions among family members in a study population in the Gambia, where strong community and family coherence are important determinants that have to be taken into consideration in promoting lifestyle changes. METHODS: We questioned 5389 adults as to any first-degree family history of major noncommunicable diseases (hypertension, obesity, diabetes and stroke), and measured their blood pressure (BP) and body mass index (BMI). Total blood cholesterol, triglyceride, uric acid, and creatinine concentrations were measured in a stratified subsample, as well as blood glucose (2 hours after ingesting 75 g glucose) in persons aged 35 years. FINDINGS: A significant number of subjects reported a family history of hypertension (8.0%), obesity (5.4%), diabetes (3.3%) and stroke (1.4%), with 14.6% of participants reporting any of these NCDs. Subjects with a family history of hypertension had a higher diastolic BP and BMI, higher cholesterol and uric acid concentrations, and an increased risk of obesity. Those with a family history of obesity had a higher BMI and were at increased risk of obesity. Individuals with a family history of diabetes had a higher BMI and higher concentrations of glucose, cholesterol, triglycerides and uric acid, and their risk of obesity and diabetes was increased. Subjects with a family history of stroke had a higher BMI, as well as higher cholesterol, triglyceride and uric acid concentrations. CONCLUSION: A family history of hypertension, obesity, diabetes, or stroke was a significant risk factor for obesity and hyperlipidaemia. With increase of age, more pathological manifestations can develop in this high-risk group. Health professionals should therefore utilize every opportunity to include direct family members in health education.

Effectiveness of yearly, register based screening for chlamydia in the Netherlands: controlled trial with randomised stepped wedge implementation

Objective To evaluate the effectiveness of register based, yearly chlamydia screening. Design Controlled trial with randomised stepped wedge implementation in three blocks. Setting Three regions of the Netherlands: Amsterdam, Rotterdam, and South Limburg. Participants 317 304 women and men aged 16-29 years listed on municipal registers at start of trial. Intervention From March 2008 to February 2011, the Chlamydia Screening Implementation programme offered yearly chlamydia screening tests. Postal invitations asked people to use an internet site to request a kit for self collection of samples, which would then be sent to regional laboratories for testing. Treatment and partner notification were done by the general practitioner or at a sexually transmitted infection clinic. Main outcome measures Primary outcomes were the percentage of chlamydia tests positive (positivity), percentage of invitees returning a specimen (uptake), and estimated chlamydia prevalence. Secondary outcomes were positivity according to sex, age, region, and sociodemographic factors; adherence to screening invitations; and incidence of self reported pelvic inflammatory disease. Results The participation rate was 16.1% (43 358/269 273) after the first invitation, 10.8% after the second, and 9.5% after the third, compared with 13.0% (6223/48 031) in the control block invited at the end of round two of the intervention. Chlamydia positivity in the intervention blocks at the first invitation was the same as in the control block (4.3%) and 0.2% lower at the third invitation (odds ratio 0.96 (95% confidence interval 0.83 to 1.10)). No substantial decreases in positivity were seen after three screening rounds in any region or sociodemographic group. Among the people who participated three times (2.8% of all invitees), positivity fell from 5.9% to 2.9% (odds ratio 0.49 (0.47 to 0.50)). Conclusions There was no statistical evidence of an impact on chlamydia positivity rates or estimated population prevalence from the Chlamydia Screening Implementation programme after three years at the participation levels obtained. The current evidence does not support a national roll out of this register based chlamydia screening programme. Trial registration NTR 3071 (Netherlands Trial Register, www.trialregister.nl).

Stroke Presentation and Outcome in Developing Countries A Prospective Study in The Gambia

Background and Purpose— Despite increasing burden of stroke in Africa, prospective descriptive data are rare. Our objective was to describe, in The Gambia, the clinical outcome of stroke patients admitted to the Royal Victoria Teaching Hospital in the capital Banjul, to assess mortality and morbidity, and propose preventive and therapeutic measures. Methods— Prospective data were collected on consecutive patients older than 15 years old admitted between February 2000 and February 2001 with the diagnosis of nonsubarachnoid stroke. Risk factors, clinical characteristics, and social consequences were assessed using a modified National Institutes of Health Stroke Scale (mNIHSS), the Barthel Activity in Daily Living scale, the Siriraj score for subtypes, and the Bamford criteria for location/extension. Patients were followed-up at home up to 1 year after discharge. Results— Ninety-one percent (148/162) of eligible patients were enrolled and followed-up. Hypertension and smoking were the most prevalent risk factors. Severity was high at admission, especially in women, and was strongly correlated to the outcome. mNIHSS and consciousness level on admission were strong predictors of the mortality risk. Swallowing difficulties at admission, fever, lung infection, and no aspirin treatment were, independently, risk factors for a lethal outcome susceptible to being addressed by treatment. Mortality was 41% in-hospital and 62% after 1 year. In survivors, autonomy levels improved over time. Drug compliance was poor. At home, family members provided care. Long-term socioeconomic and cultural activities were affected in most patients. Conclusions— Case-fatality was high compared with Western cohorts. Preventive measures can be developed. Rational treatment, in the absence of head imaging for initial assessment, requires adapted protocols. Providers should be trained, both at hospital and community levels.

Cytomegalovirus Infection in Gambian Infants Leads to Profound CD8 T-Cell Differentiation

ABSTRACT Cytomegalovirus (CMV) infection is endemic in Gambian infants, with 62% infected by 3 months and 85% by 12 months of age. We studied the CD8 T-cell responses of infants to CMV following primary infection. CMV-specific CD8 T cells, identified with tetramers, showed a fully differentiated phenotype (CD28− CD62L− CD95+ perforin+ granzyme A+ Bcl-2low). Strikingly, the overall CD8 T-cell population developed a similar phenotype following CMV infection, which persisted for at least 12 months. In contrast, primary infection was accompanied by up-regulation of markers of activation (CD45R0 and HLA-D) on both CMV-specific cells and the overall CD8 T-cell population and division (Ki-67) of specific cells, but neither pattern persisted. At 12 months of age, the CD8 T-cell population of CMV-infected infants was more differentiated than that of uninfected infants. Although the subpopulation of CMV-specific cells remained constant, the CMV peptide-specific gamma interferon response was lower in younger infants and increased with age. As the CD8 T-cell phenotype induced by CMV is indicative of immune dysfunction in the elderly, the existence of a similar phenotype in large numbers of Gambian infants raises the question of whether CMV induces a similarly deleterious effect.

Maintenance of HIV-Specific CD4+ T Cell Help Distinguishes HIV-2 from HIV-1 Infection

Unlike HIV-1-infected people, most HIV-2-infected subjects maintain a healthy CD4+ T cell count and a strong HIV-specific CD4+ T cell response. To define the cellular immunological correlates of good prognosis in HIV-2 infection, we conducted a cross-sectional study of HIV Gag-specific T cell function in HIV-1- and HIV-2-infected Gambians. Using cytokine flow cytometry and lymphoproliferation assays, we show that HIV-specific CD4+ T cells from HIV-2-infected individuals maintained proliferative capacity, were not terminally differentiated (CD57−), and more frequently produced IFN-γ or IL-2 than CD4+ T cells from HIV-1-infected donors. Polyfunctional (IFN-γ+/IL-2+) HIV-specific CD4+ T cells were found exclusively in HIV-2+ donors. The disparity in CD4+ T cell responses between asymptomatic HIV-1- and HIV-2-infected subjects was not associated with differences in the proliferative capacity of HIV-specific CD8+ T cells. This study demonstrates that HIV-2-infected donors have a well-preserved and functionally heterogeneous HIV-specific memory CD4+ T cell response that is associated with delayed disease progression in the majority of infected people.

Nationwide prevalence study of hypertension and related non‐communicable diseases in The Gambia

The prevalence of hypertension, diabetes and obesity in The Gambia was assessed in a 1% population sample of 6048 adults over 15 years of age. 572 (9.5%) subjects were hypertensive according to WHO criteria (a diastolic blood pressure (DBP) of 95 mmHg or above and/or a systolic blood pressure (SBP) of 160 mmHg or above); 325 (5.4%) had a DBP of 95 mmHg or above, and 39 (2.3%) a DBP of 105 mmHg or above; 428 (7.1%) had a SBP of 160 mmHg or above. By less conservative criteria (a DBP of 90 mmHg or above and/or SBP of 140 mmHg or above), 24.2% of subjects were hypertensive. The prevalence of hypertension was similar in the major ethnic groups and in urban and rural communities. Age and obesity were risk factors for hypertension; female sex was an additional risk factor for diastolic hypertension. Several communities had a prevalence of diastolic hypertension double the national rate, and significant community clustering of diastolic hypertension (P < 0.01) was confirmed by Monte Carlo methods. Genetic and/or localized environmental factors (such as diet or Schistosoma haematobium infection), may be involved. 140 (2.3%) subjects were obese. Obesity was associated with female sex, increasing age, urban environment, non‐manual work and diastolic hypertension. Only 14 (0.3%) subjects were found to be diabetic. Hypertension appears to be very prevalent in The Gambia, with a substantial population at risk of developing target organ damage. Further studies to delineate this risk and appropriate interventions to reduce it are needed.

Host Genetic Factors and Vaccine-Induced Immunity to Hepatitis B Virus Infection

Background Vaccination against hepatitis B virus infection (HBV) is safe and effective; however, vaccine-induced antibody level wanes over time. Peak vaccine-induced anti-HBs level is directly related to antibody decay, as well as risk of infection and persistent carriage despite vaccination. We investigated the role of host genetic factors in long-term immunity against HBV infection based on peak anti-HBs level and seroconversion to anti-HBc. Methods We analyzed 715 SNP across 133 candidate genes in 662 infant vaccinees from The Gambia, assessing peak vaccine-induced anti-HBs level and core antibody (anti-HBc) status, whilst adjusting for covariates. A replication study comprised 43 SNPs in a further 393 individuals. Results In our initial screen we found variation in IFNG, MAPK8, and IL10RA to affect peak anti-HBs level (GMTratio of <0.6 or >1.5 and P≤0.001) and lesser associations in other genes. Odds of core-conversion was associated with variation in CD163. A coding change in ITGAL (R719V) with likely functional relevance showed evidence of association with increased peak anti-HBs level in both screens (1st screen: s595_22 GMTratio 1.71, P = 0.013; 2nd screen: s595_22 GMTratio 2.15, P = 0.011). Conclusion This is to our knowledge the largest study to date assessing genetic determinants of HBV vaccine-induced immunity. We report on associations with anti-HBs level, which is directly related to durability of antibody level and predictive of vaccine efficacy long-term. A coding change in ITGAL, which plays a central role in immune cell interaction, was shown to exert beneficial effects on induction of peak antibody level in response to HBV vaccination. Variation in this gene does not appear to have been studied in relation to immune responses to viral or vaccine challenges previously. Our findings suggest that genetic variation in loci other than the HLA region affect immunity induced by HBV vaccination.