Tuberculosis disease and infection among household contacts of bacteriologically confirmed and non-confirmed tuberculosis patients.

OBJECTIVE: To compare the prevalence of tuberculosis infection and disease in household contacts of patients with bacteriologically confirmed tuberculosis disease and contacts of non-bacteriologically confirmed disease in western Kenya. METHODS: We enrolled newly diagnosed index patients and their household contacts from March 2014 to June 2016. All contacts were evaluated with a symptom questionnaire, tuberculin skin test (TST) and HIV test. Clinical evaluation and sputum testing were performed for those with symptoms, positive TST result or HIV infection. RESULTS: We enrolled 1155 contacts of 330 index patients with bacteriologically confirmed tuberculosis and 192 contacts of 55 index patients with non-bacteriologically confirmed tuberculosis. 3.5% of contacts of patients with bacteriologically confirmed tuberculosis were diagnosed with tuberculosis, whereas no contacts of index patients with non-bacteriologically confirmed tuberculosis were. Of those diagnosed with tuberculosis disease, 58.5% reported symptoms, 34.1% reported no symptoms but had positive TST results, and 7.3% had neither symptoms nor positive TST but were HIV-positive. Among 872 contacts with a TST result, 50.9% of contacts of index patients with bacteriologically confirmed tuberculosis and 41.0% of contacts of index patients with non-bacteriologically confirmed tuberculosis had a positive result (prevalence ratio = 1.16, 95% confidence interval 0.92-1.48). CONCLUSION: In a high-burden setting, tuberculosis disease was more prevalent among contacts of patients with bacteriologically confirmed tuberculosis than contacts of patients with non-bacteriologically confirmed disease. TST was feasible to perform and helped to detect cases that would have been missed had only symptomatic contacts been evaluated.

OBJECTIF: Comparer la prévalence de l'infection et de la maladie tuberculeuses chez les contacts familiaux des patients atteints de tuberculose confirmée bactériologiquement et les contacts de maladies non bactériologiquement confirmées dans l'ouest du Kenya. MÉTHODES: Nous avons recruté des patients indice nouvellement diagnostiqués et leurs contacts familiaux de mars 2014 à juin 2016. Tous les contacts ont été évalués à l'aide d'un questionnaire sur les symptômes, le test cutané à la tuberculine (TCT) et le test VIH. Une évaluation clinique et des tests d'expectoration ont été effectués pour les personnes présentant des symptômes, un résultat positif au TCT ou une infection par le VIH. RÉSULTATS: Nous avons recruté 1.155 contacts de 330 patients index avec une tuberculose confirmée bactériologiquement et 192 contacts de 55 patients indice avec une tuberculose non confirmée bactériologiquement. 3,5% des contacts des patients atteints de tuberculose confirmée bactériologiquement ont été diagnostiqués avec la tuberculose, alors qu'aucun contact des patients indice avec une tuberculose non bactériologiquement confirmée ne l'a été. Parmi les personnes diagnostiquées avec une tuberculose, 58,5% ont signalé des symptômes, 34,1% n'ont signalé aucun symptôme mais avaient des résultats positifs au TCT, et 7,3% n'avaient ni symptômes ni TCT positifs mais étaient VIH positifs. Parmi 872 contacts avec un résultat TCT, 50,9% des contacts des patients indice avec une tuberculose confirmée bactériologiquement et 41,0% des contacts des patients indice avec une tuberculose non bactériologiquement confirmée avaient un résultat positif (rapport de prévalence = 1,16, intervalle de confiance à 95%: 0,92-1,48 ). CONCLUSION: Dans un contexte de charge élevée, la maladie tuberculose était plus fréquente chez les contacts des patients atteints de tuberculose confirmée bactériologiquement que chez les contacts des patients atteints de la maladie non bactériologiquement confirmée. Le TCT était réalisable et a aidé à détecter les cas qui auraient été ratés si seuls les contacts symptomatiques avaient été évalués.

The Incidence of Tuberculosis in Infants, Siaya District, Western Kenya.

BACKGROUND: Infants are a target population for new tuberculosis (TB) vaccines. TB incidence estimates are needed to guide the design of trials. To determine the TB incidence and cohort retention among young children using comprehensive diagnostic methods in a high burden area. METHODS: Infants 0-42 days were enrolled. Through 4 monthly follow-up and unscheduled (sick) visits up to the age of 2 years, infants with presumptive TB based on a history of contact, TB symptoms or pre-determined hospitalization criteria were admitted to a case verification ward. Two induced sputa and gastric aspirates were collected for culture and GeneXpert. Mantoux and HIV tests were done. Clinical management was based on the Keith Edwards score. Cases were classified into microbiologically confirmed or radiologic, diagnosed by blinded expert assessment. Cox regression was used to identify risk factors for incident TB and study retention. RESULTS: Of 2900 infants enrolled, 927 (32%) developed presumptive TB, 737/927 (80%) were investigated. Sixty-nine TB cases were diagnosed (bacteriologic and radiologic). All TB incidence was 2/100 person-years of observation (pyo) (95% CI: 1.65-2.65). Nine were bacteriologic cases, incidence 0.3/100 pyo. The radiologic TB incidence was 1.82/100 pyo. Bacteriologic TB was associated with infant HIV infection, higher Keith Edwards scores. Completeness of 4-month vaccinations and HIV infection were positively associated with retention. CONCLUSIONS: TB incidence was high. An all TB endpoint would require a sample size of a few thousand children, but tens of thousands, when limited to bacteriologic TB.

Decreased HIV-associated mortality rates during scale-up of antiretroviral therapy, 2011-2016.

OBJECTIVE: HIV-associated mortality rates in Africa decreased by 10-20% annually in 2003-2011, after the introduction of antiretroviral therapy (ART). We sought to document HIV-associated mortality rates in the general population in Kenya after 2011 in an era of expanded access to ART. DESIGN: We obtained data on mortality rates and migration from a health and demographic surveillance system (HDSS) in Gem, western Kenya, and data for HDSS residents aged 15-64 years from home-based HIV counseling and testing (HBCT) rounds in 2011, 2012, 2013, and 2016. METHODS: Mortality trends were determined among a closed cohort of residents who participated in at least the 2011 round of HBCT. RESULTS: Of 32 467 eligible HDSS residents, 22 688 (70%) participated in the 2011 round and comprised the study cohort. All-cause mortality rates declined from 10.0 [95% confidence interval (CI) 8.4-11.7] per 1000 in 2011 to 7.4 (95% CI 5·7-9·0) in 2016, whereas the mortality rate was stable among HIV-uninfected residents, at 5.7 per 1000 person-years. Among HIV-infected residents, mortality rates declined from 30.5 per 1000 in 2011 to 15.9 per 1000 in 2016 (average decline 6% per year). The HIV-infected group receiving ART had higher mortality rates than the HIV-uninfected group [adjusted rate ratio (aRR) 2.8, 95% CI 2.2-3.4], as did the HIV-infected group who did not receive ART (aRR 5.3, 95% CI 4.5-6.2). CONCLUSIONS: Mortality rates among HIV-infected individuals declined substantially during ART expansion between 2011 and 2016, though less than during early ART introduction. Mortality trends among HIV-infected populations are critical to understanding epidemic dynamics.

High yield of new HIV diagnoses during active case-finding for tuberculosis.

OBJECTIVE: To evaluate the utility of a broad and nonspecific symptom screen for identifying people with undiagnosed HIV infection. DESIGN: Secondary analysis of operational data collected during implementation of a cluster-randomized trial for tuberculosis case detection. METHODS: As part of the trial, adults reporting cough, fever, night sweats, weight loss, or difficulty breathing for any duration in the past month were identified in health facilities and community-based mobile screening units in western Kenya. Adults reporting any symptom were offered HIV testing. We analysed the HIV testing data from this study, using modified Poisson regression, to identify predictors of new HIV diagnoses among adults with symptoms and initially unknown HIV status. RESULTS: We identified 3818 symptomatic adults, referred 1424 (37%) for testing, of whom 1065 (75%) accepted, and 107 (10%) were newly diagnosed with HIV. The prevalence of new HIV diagnoses was 21% [95% confidence interval (CI) 17-25%] among those tested in health facilities and 5% (95% CI 4-7%) among those tested in mobile units. More men were diagnosed with HIV than women, despite fewer men being screened. People who reported 4-5 symptoms were over twice as likely to be diagnosed with HIV compared to those reporting 1-3 symptoms (adjusted prevalence ratio in health facilities = 2.58, 95% CI 1.65-4.05; adjusted prevalence ratio in mobile units = 2.63, 95% CI 1.37-5.03). CONCLUSION: We observed a high yield of new HIV diagnoses among adults identified by active application of a broad symptom screen. Use of integrated tuberculosis and HIV screening could help close the detection gap for both conditions.

Estimating the annual risk of infection with Mycobacterium tuberculosis among adolescents in Western Kenya in preparation for TB vaccine trials.

BACKGROUND: Adolescents are a prime target group for tuberculosis (TB) vaccine trials that include prevention of infection (POI). The BCG vaccine is given at birth and does not prevent TB infection. TB infection, a critical endpoint for POI vaccine trials would need to be documented to estimate sample sizes in target populations. METHODS: Adolescents aged 12-18 years of age were enrolled in an area under continuous demographic surveillance. A tuberculin skin test (TST) survey was conducted as part of a study on TB prevalence and incidence. All adolescents got TSTs at enrolment and returned after 72 h for reading. A TST of ≥10 mm if HIV negative or ≥ 5 mm if HIV positive, was considered positive. RESULTS: Of 4808 adolescents returning for TST readings (96% of those enrolled), mean age was 14.4 (SD 1.9), 4518(94%) were enrolled in school and 21(0.4%) gave a previous history of tuberculosis. Among adolescents with TST reactivity, the mean TST induration was 13.2 mm (SD 5.4). The overall prevalence of latent TB infection was 1544/4808 (32.1, 95% CI 29.2-35.1) with a corresponding annual risk of TB infection (ARTI) of 2.6% (95% CI 2.2-3.1). Risk factors for a positive TST included being male (OR 1.3, 95% CI 1.2,1.5), history of having a household TB contact (OR 1.5, 95% CI 1.2,1.8), having a BCG scar (OR 1.5,95% CI 1.2,1.8), living in a rural area (OR 1.4, 95% CI 1.1,1.9), and being out of school (OR 1.8, 95% CI 1.4,2.3). CONCLUSION: We conclude that the high TB transmission rates we found in this study, suggest that adolescents in this region may be an appropriate target group for TB vaccine trials including TB vaccine trials aiming to prevent infection.

Indirect Effects of 10-Valent Pneumococcal Conjugate Vaccine Against Adult Pneumococcal Pneumonia in Rural Western Kenya.

BACKGROUND: Data on pneumococcal conjugate vaccine (PCV) indirect effects in low-income countries with high human immunodeficiency virus (HIV) burden are limited. We examined adult pneumococcal pneumonia incidence before and after PCV introduction in Kenya in 2011. METHODS: From 1 January 2008 to 31 December 2016, we conducted surveillance for acute respiratory infection (ARI) among ~12 000 adults (≥18 years) in western Kenya, where HIV prevalence is ~17%. ARI cases (cough or difficulty breathing or chest pain, plus temperature ≥38.0°C or oxygen saturation <90%) presenting to a clinic underwent blood culture and pneumococcal urine antigen testing (UAT). We calculated ARI incidence and adjusted for healthcare seeking. The proportion of ARI cases with pneumococcus detected among those with complete testing (blood culture and UAT) was multiplied by adjusted ARI incidence to estimate pneumococcal pneumonia incidence. RESULTS: Pre-PCV (2008-2010) crude and adjusted ARI incidences were 3.14 and 5.30/100 person-years-observation (pyo), respectively. Among ARI cases, 39.0% (340/872) had both blood culture and UAT; 21.2% (72/340) had pneumococcus detected, yielding a baseline pneumococcal pneumonia incidence of 1.12/100 pyo (95% confidence interval [CI]: 1.0-1.3). In each post-PCV year (2012-2016), the incidence was significantly lower than baseline; with incidence rate ratios (IRRs) of 0.53 (95% CI: 0.31-0.61) in 2012 and 0.13 (95% CI: 0.09-0.17) in 2016. Similar declines were observed in HIV-infected (IRR: 0.13; 95% CI: 0.08-0.22) and HIV-uninfected (IRR: 0.10; 95% CI: 0.05-0.20) adults. CONCLUSIONS: Adult pneumococcal pneumonia declined in western Kenya following PCV introduction, likely reflecting vaccine indirect effects. Evidence of herd protection is critical for guiding PCV policy decisions in resource-constrained areas.

Assessing the impact of antiretroviral therapy on tuberculosis notification rates among people with HIV: a descriptive analysis of 23 countries in sub-Saharan Africa, 2010-2015.

BACKGROUND: HIV is a major driver of the tuberculosis epidemic in sub-Saharan Africa. The population-level impact of antiretroviral therapy (ART) scale-up on tuberculosis rates in this region has not been well studied. We conducted a descriptive analysis to examine evidence of population-level effect of ART on tuberculosis by comparing trends in estimated tuberculosis notification rates, by HIV status, for countries in sub-Saharan Africa. METHODS: We estimated annual tuberculosis notification rates, stratified by HIV status during 2010-2015 using data from WHO, the Joint United Nations Programme on HIV/AIDS, and the United Nations Population Division. Countries were included in this analysis if they had ≥4 years of HIV prevalence estimates and ≥ 75% of tuberculosis patients with known HIV status. We compared tuberculosis notification rates among people living with HIV (PLHIV) and people without HIV via Wilcoxon rank sum test. RESULTS: Among 23 included countries, the median annual average change in tuberculosis notification rates among PLHIV during 2010-2015 was -5.7% (IQR -6.9 to -1.7%), compared to a median change of -2.3% (IQR -4.2 to -0.1%) among people without HIV (p-value = 0.0099). Among 11 countries with higher ART coverage, the median annual average change in TB notification rates among PLHIV was -6.8% (IQR -7.6 to -5.7%) compared to a median change of -2.1% (IQR -6.0 to 0.7%) for PLHIV in 12 countries with lower ART coverage (p = 0.0106). CONCLUSION: Tuberculosis notification rates declined more among PLHIV than people without HIV, and have declined more in countries with higher ART coverage. These results are consistent with a population-level effect of ART on decreasing TB incidence among PLHIV. To further reduce TB incidence among PLHIV, additional scale-up of ART as well as greater use of isoniazid preventive therapy and active case-finding will be necessary.

What is the true tuberculosis mortality burden? Differences in estimates by the World Health Organization and the Global Burden of Disease study.

Background: The World Health Organization (WHO) and the Global Burden of Disease (GBD) study at the Institute for Health Metrics and Evaluation (IHME) periodically provide global estimates of tuberculosis (TB) mortality. We compared the 2015 WHO and GBD TB mortality estimates and explored which factors might drive the differences. Methods: We extracted the number of estimated TB-attributable deaths, disaggregated by age, HIV status, sex and country from publicly available WHO and GBD datasets for the year 2015. We 'standardized' differences between sources by adjusting each country's difference in absolute number of deaths by the average number of deaths estimated by both sources. Results: For 195 countries with estimates from both institutions, WHO estimated 1 768 482 deaths attributable to TB, whereas GBD estimated 1 322 916 deaths, a difference of 445 566 deaths or 29% of the average of the two estimates. The countries with the largest absolute differences in deaths were Nigeria (216 621), Bangladesh (49 863) and Tanzania (38 272). The standardized difference was not associated with HIV prevalence, prevalence of multidrug resistance or global region, but did show correlation with the case detection rate as estimated by WHO [r = -0.37, 95% confidence interval (CI): -049; -0.24] or, inversely, with case detection rate based on GBD data (r = 0.44, 95% CI: 0.31; 0.54). Countries with a recent national prevalence survey had higher standardized differences (higher estimates by WHO) than those without (P = 0.006). After exclusion of countries with recent prevalence surveys, the overall correlation between both estimates was r = 0.991. Conclusions: A few countries account for the large global discrepancy in TB mortality estimates. The differences are due to the methodological approaches used by WHO and GBD. The use and interpretation of prevalence survey data and case detection rates seem to play a role in the observed differences.

Epidemiology of Pediatric Tuberculosis in Kenya and Risk Factors for Mortality during Treatment: A National Retrospective Cohort Study.

OBJECTIVES: To describe the epidemiology of childhood tuberculosis (TB) in Kenya, assess the magnitude of TB/human immunodeficiency virus (HIV) co-infection and identify risk factors for mortality during TB treatment. STUDY DESIGN: We conducted a retrospective analysis of the Kenyan national TB program data for patients enrolled from 2013 through 2015. A total of 23 753 children aged less than 15 years were included in the analysis. Survival analysis was performed with censorship at 9 months and mortality was the main outcome. We used Cox proportional hazards regression for assessing risk factors for mortality. RESULTS: Childhood TB accounted for 9% (n = 24 216) of all patients with TB; 98% of the notified children (n = 23 753) were included in the analysis. TB/HIV co-infection was 28% (n = 6112). Most TB cases (71%; n = 16 969) were detected through self-referral. Treatment was successful in 90% (n = 19 088) and 4% (n = 1058) died. Independent risk factors for mortality included being HIV infected but not on antiretroviral therapy (adjusted hazard ratio [aHR], 4.84; 95% CI, 3.59-6.51), being HIV infected and on antiretroviral therapy (aHR, 3.69; 95% CI, 3.14-4.35), children aged less than 5 years (aHR, 1.25; 95% CI, 1.08-1.44), and being diagnosed with smear negative pulmonary disease (aHR, 1.68; 95% CI, 1.27-2.24). CONCLUSIONS: Most childhood TB cases in Kenya were detected through passive case finding. TB/HIV co-infection is high among children on treatment for TB, and HIV is associated with an increased risk of death. There is a need to intensify active case finding among children. TB prevention interventions among HIV-infected children, early diagnosis of HIV, and early antiretroviral therapy initiation among children on TB treatment should be strengthened.

Tuberculosis case finding using population-based disease surveillance platforms in urban and rural Kenya.

BACKGROUND: Tuberculosis (TB) case finding is an important component of TB control because it can reduce transmission of Mycobacterium tuberculosis (MTB) through prompt detection and treatment of infectious patients. METHODS: Using population-based infectious disease surveillance (PBIDS) platforms with links to health facilities in Kenya we implemented intensified TB case finding in the community and at the health facilities, as an adjunct to routine passive case finding conducted by the national TB program. From 2011 to 2014, PBIDS participants ≥15 years were screened either at home or health facilities for possible TB symptoms which included cough, fever, night sweats or weight loss in the preceding 2 weeks. At home, participants with possible TB symptoms had expectorated sputum collected. At the clinic, HIV-infected participants with possible TB symptoms were invited to produce sputum. Those without HIV but with symptoms lasting 7 days including the visit day had chest radiographs performed, and had sputum collected if the radiographs were abnormal. Sputum samples were tested for the presence of MTB using the Xpert MTB/RIF assay. TB detection rates were calculated per 100,000 persons screened. RESULTS: Of 11,191 participants aged ≥15 years screened at home at both sites, 2695 (23.9%) reported possible TB symptoms, of whom 2258 (83.8%) produced sputum specimens. MTB was detected in 32 (1.4%) of the specimens resulting in a detection rate of 286/100,000 persons screened. At the health facilities, a total of 11,762 person were screened, 7500 (63.8%) had possible TB symptoms of whom 1282 (17.1%) produced sputum samples. MTB was detected in 69 (5.4%) of the samples, resulting in an overall detection rate of 587/100,000 persons screened. The TB detection rate was higher in persons with HIV compared to those without at both home (HIV-infected - 769/100,000, HIV-uninfected 141/100,000, rate ratio (RR) - 5.45, 95% CI 3.25-22.37), and health facilities (HIV-infected 3399/100,000, HIV-uninfected 294/100,000, RR 11.56, 95% CI 6.18-18.44). CONCLUSION: Facility-based intensified TB case finding detected more TB cases per the number of specimens tested and the number of persons screened, including those with HIV, than home-based TB screening and should be further evaluated to determine its potential programmatic impact.

HIV incidence in western Kenya during scale-up of antiretroviral therapy and voluntary medical male circumcision: a population-based cohort analysis.

BACKGROUND: In Kenya, coverage of antiretroviral therapy (ART) among people with HIV infection has increased from 7% in 2006, to 57% in 2016; and, in western Kenya, coverage of voluntary medical male circumcision (VMMC) increased from 45% in 2008, to 72% in 2014. We investigated trends in HIV prevalence and incidence in a high burden area in western Kenya in 2011-16. METHODS: In 2011, 2012, and 2016, population-based surveys were done via a health and demographic surveillance system and home-based counselling and testing in Gem, Siaya County, Kenya, including 28 688, 17 021, and 16 772 individuals aged 15-64 years. Data on demographic variables, self-reported HIV status, and risk factors were collected. Rapid HIV testing was offered to survey participants. Participants were tracked between surveys by use of health and demographic surveillance system identification numbers. HIV prevalence was calculated as a proportion, and HIV incidence was expressed as number of new infections per 1000 person-years of follow-up. FINDINGS: HIV prevalence was stable in participants aged 15-64 years: 15% (4300/28 532) in 2011, 12% (2051/16 875) in 2012, and 15% (2312/15 626) in 2016. Crude prevalences in participants aged 15-34 years were 11% (1893/17 197) in 2011, 10% (1015/10 118) in 2012, and 9% (848/9125) in 2016; adjusted for age and sex these prevalences were 11%, 9%, and 8%. 12 606 (41%) of the 30 520 non-HIV-infected individuals enrolled were seen again in at least one more survey round, and were included in the analysis of HIV incidence. HIV incidence was 11·1 (95% CI 9·1-13·1) per 1000 person-years from 2011 to 2012, and 5·7 (4·6-6·9) per 1000 person-years from 2012 to 2016. INTERPRETATION: With increasing coverage of ART and VMMC, HIV incidence declined substantially in Siaya County between 2011 and 2016. VMMC, but not ART, was suggested to have a direct protective effect, presumably because ART tended to be given to individuals with advanced HIV infection. HIV incidence is still high and not close to the elimination target of one per 1000 person-years. The effect of further scale-up of ART and VMMC needs to be monitored. FUNDING: Data were collected under Cooperative Agreements with the US Centers for Disease Control and Prevention, with funding from the President's Emergency Fund for AIDS Relief.

Incidence of Active Tuberculosis and Cohort Retention Among Adolescents in Western Kenya.

SETTING: Siaya County, with the highest tuberculosis notification rates in Kenya. OBJECTIVES: To determine the incidence of active tuberculosis and 1-year cohort retention in 12-18-year-old adolescents, in preparation for phase III tuberculosis vaccine trials. METHODS: Adolescents were enrolled and followed up for 1-2 years to determine tuberculosis incidence. Adolescents with a positive tuberculin skin test, history of cohabitation with a tuberculosis case or at least 1 tuberculosis symptom received clinical and sputum examination and a chest radiograph. Definite tuberculosis cases were bacteriologically confirmed and clinical cases diagnosed by a clinician based on a suggestive chest radiograph and having clinical symptoms. Risk factors were explored using Poisson regression. RESULTS: Among 4934 adolescents without tuberculosis at baseline, 26 tuberculosis cases were identified during follow-up with a corresponding incidence density of 4.4 [95% confidence interval (CI): 3.0-6.4] events per 1000 person-years of observation, 12 definite tuberculosis cases; incidence density of 2.0 (95% CI: 0.9-3.1). Having previous tuberculosis (rate ratio: 12.5; CI: 1.8-100) and presence of tuberculin skin test conversion (rate ratio: 3.4; CI: 1.5-7.7) were significantly associated with higher risk of tuberculosis. Overall (4086/4925), 83.0% of adolescents were retained in the study after 1 year of follow-up. Being female, older, out of school and being orphaned were significant risk factors for loss to follow-up. CONCLUSION: The tuberculosis incidence in adolescents will help inform future tuberculosis vaccine trial sample size calculations for this setting. The predictive factors for tuberculosis and retention can be further explored in future trials.

Predictors of post neonatal mortality in Western Kenya: a cohort study.

INTRODUCTION: to determine the predictors of mortality in infants in Siaya, western Kenya, ahead of novel tuberculosis (TB) vaccine trials in the same population. METHODS: in a study to determine tuberculosis incidence, 2900 infants aged 0-45 days, weighing ≥ 1700g were enrolled. Four monthly follow up visits were conducted for at least 12 months. HIV testing was done at six weeks of age. Free ancillary care was provided. Deaths were reported by parents, study staff and community workers. Cox proportional Hazard analysis was used to identify risk factors. The period of analysis commenced at six weeks old and was censored at 12 months of age. RESULTS: included in the analysis were 2528 infants with 2020 person years of follow up (pyo). There were 117 deaths (4.6 %). The post-neonatal mortality rate was 58 (95% CI: 48, 69) per 1000 pyo. In multivariate analysis, health facility births were protective against mortality (Hazard Ratio (HR) 0.54; 95% CI: 0.34, 0.84) and infant HIV infection at baseline was associated with increased mortality (HR 10.3; 95% CI: 6.40, 16.7). HIV uninfected infants born to HIV infected mothers had increased hazards of mortality (HR 1.73; 95% CI: 1.03, 2.90). Gender, weight at six weeks, maternal education and occupation were not significant predictors of mortality. CONCLUSION: infant mortality was high and was associated with being born outside a health facility, maternal HIV infection and HIV infection of the infant. Measures to decrease mother to child transmission and other HIV control measures need to be strengthened further to see incremental reductions in infant mortality.

Reduction of HIV-associated excess mortality by antiretroviral treatment among tuberculosis patients in Kenya.

BACKGROUND: Mortality from TB continues to be a global public health challenge. TB ranks alongside Human Immunodeficiency Virus (HIV) as the leading infectious causes of death globally. HIV is a major driver of TB related morbidity and mortality while TB is the leading cause of mortality among people living with HIV/AIDS. We sought to determine excess mortality associated with HIV and the effect of antiretroviral therapy on reducing mortality among tuberculosis patients in Kenya. METHODS: We conducted a retrospective analysis of Kenya national tuberculosis program data of patients enrolled from 2013 through 2014. We used direct standardization to obtain standardized mortality ratios for tuberculosis patients compared with the general population. We calculated the population attributable fraction of tuberculosis deaths due to HIV based on the standardized mortality ratio for deaths among TB patients with HIV compared to TB patients without HIV. We used Cox proportional hazards regression for assessing risk factors for mortality. RESULTS: Of 162,014 patients included in the analysis, 6% died. Mortality was 10.6 (95% CI: 10.4-10.8) times higher among TB patients than the general population; 42% of deaths were attributable to HIV infection. Patients with HIV who were not receiving ART had an over four-fold risk of death compared to patients without HIV (aHR = 4.2, 95% CI 3.9-4.6). In contrast, patients with HIV who were receiving ART had only 2.6 times the risk of death (aHR = 2.6, 95% CI 2.5-2.7). CONCLUSION: HIV was a significant contributor to TB-associated deaths in Kenya. Mortality among HIV-infected individuals was higher among those not on ART than those on ART. Early initiation of ART among HIV infected people (a "test and treat" approach) should further reduce TB-associated deaths.

Drivers of Tuberculosis Transmission.

Measuring tuberculosis transmission is exceedingly difficult, given the remarkable variability in the timing of clinical disease after Mycobacterium tuberculosis infection; incident disease can result from either a recent (ie, weeks to months) or a remote (ie, several years to decades) infection event. Although we cannot identify with certainty the timing and location of tuberculosis transmission for individuals, approaches for estimating the individual probability of recent transmission and for estimating the fraction of tuberculosis cases due to recent transmission in populations have been developed. Data used to estimate the probable burden of recent transmission include tuberculosis case notifications in young children and trends in tuberculin skin test and interferon γ-release assays. More recently, M. tuberculosis whole-genome sequencing has been used to estimate population levels of recent transmission, identify the distribution of specific strains within communities, and decipher chains of transmission among culture-positive tuberculosis cases. The factors that drive the transmission of tuberculosis in communities depend on the burden of prevalent tuberculosis; the ways in which individuals live, work, and interact (eg, congregate settings); and the capacity of healthcare and public health systems to identify and effectively treat individuals with infectious forms of tuberculosis. Here we provide an overview of these factors, describe tools for measurement of ongoing transmission, and highlight knowledge gaps that must be addressed.

The incidence of tuberculosis among hiv-positive individuals with high CD4 counts: implications for policy.

BACKGROUND: Intensified case finding (ICF) and earlier antiretroviral therapy (ART) initiation are strategies to reduce burden of HIV-associated tuberculosis (TB). We describe incidence of and associated factors for TB among HIV-positive individuals with CD4 counts > 350 cells/µl in South Africa. METHODS: Prospective cohort study of individuals recruited for a TB vaccine trial. Eligible individuals without prevalent TB were followed up at 6 and 12 months after enrolment. Cox proportional hazards regression was used to determine factors associated with risk of incident TB. RESULTS: Six hundred thirty-four individuals were included in the analysis [80.9 % female, 57.9 % on ART, median CD4 count 562 cells/µl (IQR 466-694 cells/µl)]. TB incidence was 2.7 per 100 person-years (pyrs) (95 % CI 1.6-4.4 per 100 pyrs) and did not differ significantly between those on ART and those not on ART [HR 0.65 (95 % CI 0.24-1.81)]. Low body mass index (BMI <18.5 kg/m(2)) was associated with incident TB [HR 3.87 (95 % CI 1.09-13.73)]. Half of the cases occurred in the first 6 months of follow up and may have been prevalent or incubating cases at enrolment. CONCLUSIONS: TB incidence was high and associated with low BMI. Intensified case finding for TB should be strengthened for all HIV positive individuals regardless of their CD4 count or ART status.

A Tuberculin Skin Test Survey and the Annual Risk of Mycobacterium tuberculosis Infection in Gambian School Children.

BACKGROUND: A Tuberculin skin test (TST) survey was conducted to assess the prevalence of latent TB Infection (LTBI) and to estimate the annual risk of M. tuberculosis infection (ARTI) in Gambian school children. The results are expected to contribute to understanding of Tuberculosis epidemiology in The Gambia. METHODS: This was a nationwide, multi-cluster survey in children aged 6-11 years. Districts, 20 of 37, were selected by probability proportional to size and schools by simple random sampling. All TST were performed using the Mantoux method. Height and weight measurements were obtained for all participants. We calculated prevalence of LTBI using cut-off points of 10mm, the mirror and mixture modelling methods. RESULTS: TST readings were completed 13,386 children with median age of 9 years (interquartile range [IQR] 8-10 years). Mixture analysis yielded a cut-off point of 12 mm, and LTBI prevalence of 6.9% [95%CI 6.47-7.37] and the ARTI was 0.75% [95%CI 0.60-0.91]. LTBI was associated gender and urban residence (p <0.01). Nutritional status was not associated with non-reactive TST or sizes of TST indurations. ARTI did not differ significantly by age, gender, BCG vaccination or residence. CONCLUSIONS: This estimates for LTBI prevalence and ARTI were low but this survey provides updated data. Malnutrition did not affect estimates of LTBI and ARTI. Given the low ARTI in this survey and the overlapping distribution of indurations with mixture modelling, further surveys may require complementary tests such as interferon gamma release assays or novel diagnostic tools.

Transmission and Progression to Disease of Mycobacterium tuberculosis Phylogenetic Lineages in The Netherlands.

The aim of this study was to determine if mycobacterial lineages affect infection risk, clustering, and disease progression among Mycobacterium tuberculosis cases in The Netherlands. Multivariate negative binomial regression models adjusted for patient-related factors and stratified by patient ethnicity were used to determine the association between phylogenetic lineages and infectivity (mean number of positive contacts around each patient) and clustering (as defined by number of secondary cases within 2 years after diagnosis of an index case sharing the same fingerprint) indices. An estimate of progression to disease by each risk factor was calculated as a bootstrapped risk ratio of the clustering index by the infectivity index. Compared to the Euro-American reference, Mycobacterium africanum showed significantly lower infectivity and clustering indices in the foreign-born population, while Mycobacterium bovis showed significantly lower infectivity and clustering indices in the native population. Significantly lower infectivity was also observed for the East African Indian lineage in the foreign-born population. Smear positivity was a significant risk factor for increased infectivity and increased clustering. Estimates of progression to disease were significantly associated with age, sputum-smear status, and behavioral risk factors, such as alcohol and intravenous drug abuse, but not with phylogenetic lineages. In conclusion, we found evidence of a bacteriological factor influencing indicators of a strain's transmissibility, namely, a decreased ability to infect and a lower clustering index in ancient phylogenetic lineages compared to their modern counterparts. Confirmation of these findings via follow-up studies using tuberculin skin test conversion data should have important implications on M. tuberculosis control efforts.