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.

A study to better understand under-utilization of laboratory tests for antenatal care in Senegal.

Objective: To better understand factors contributing to underutilization of laboratory services for health care delivery in sub-Saharan Africa, we conducted a study in Senegalese Antenatal Care clinics (ANC) and laboratories to determine the extent of underutilization, contributing factors, and bottlenecks in the cascade of care from first ANC visit, test uptake, to availability of test results and appropriate clinical management.

Methods: At 16 health facilities, pregnant women attending for their first ANC visit were consecutively recruited and information was prospectively collected on the request, execution, results and clinical management of seven nationally recommended laboratory screening tests for normal pregnancy: hemoglobin concentration (Hb), syphilis serology, HIV serology, determination of proteinuria (PU), determination of blood group and Rhesus factor, Emmel test to detect sickle cell disease, and glycaemia. Health facility staff were interviewed on human resource capacity, management of the ANC and the laboratory, and availability and use of guidelines.

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.

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.

Use of Xpert MTB/RIF in Decentralized Public Health Settings and Its Effect on Pulmonary TB and DR-TB Case Finding in India.

Background: Xpert MTB/RIF, the first automated molecular test for tuberculosis, is transforming the diagnostic landscape in high-burden settings. This study assessed the impact of up-front Xpert MTB/RIF testing on detection of pulmonary tuberculosis (PTB) and rifampicin-resistant PTB (DR-TB) cases in India.

Methods: This demonstration study was implemented in 18 sub-district level TB programme units (TUs) in India in diverse geographic and demographic settings covering a population of 8.

Prevalence of tuberculosis in adolescents, western Kenya: implications for control programs.

Objective: The aim of this study was to determine the prevalence of tuberculosis (TB) in adolescents in western Kenya.

Methods: A cohort study of 5004 adolescents aged 12-18 years was conducted. Adolescents were screened for prevalent TB using clinical criteria, history of TB contact, and a Mantoux test.

Choosing algorithms for TB screening: a modelling study to compare yield, predictive value and diagnostic burden.

Background: To inform the choice of an appropriate screening and diagnostic algorithm for tuberculosis (TB) screening initiatives in different epidemiological settings, we compare algorithms composed of currently available methods.

Methods: Of twelve algorithms composed of screening for symptoms (prolonged cough or any TB symptom) and/or chest radiography abnormalities, and either sputum-smear microscopy (SSM) or Xpert MTB/RIF (XP) as confirmatory test we model algorithm outcomes and summarize the yield, number needed to screen (NNS) and positive predictive value (PPV) for different levels of TB prevalence.

Results: Screening for prolonged cough has low yield, 22% if confirmatory testing is by SSM and 32% if XP, and a high NNS, exceeding 1000 if TB prevalence is ≤0.

Optimal triage test characteristics to improve the cost-effectiveness of the Xpert MTB/RIF assay for TB diagnosis: a decision analysis.

Background: High costs are a limitation to scaling up the Xpert MTB/RIF assay (Xpert) for the diagnosis of tuberculosis in resource-constrained settings. A triaging strategy in which a sensitive but not necessarily highly specific rapid test is used to select patients for Xpert may result in a more affordable diagnostic algorithm. To inform the selection and development of particular diagnostics as a triage test we explored combinations of sensitivity, specificity and cost at which a hypothetical triage test will improve affordability of the Xpert assay.

Risk factors for inadequate TB case finding in Rural Western Kenya: a comparison of actively and passively identified TB patients.

Background: The findings of a prevalence survey conducted in western Kenya, in a population with 14.9% HIV prevalence suggested inadequate case finding. We found a high burden of infectious and largely undiagnosed pulmonary tuberculosis (PTB), that a quarter of the prevalent cases had not yet sought care, and a low case detection rate.

Screening strategies for tuberculosis prevalence surveys: the value of chest radiography and symptoms.

Background: We conducted a tuberculosis (TB) prevalence survey and evaluated the screening methods used in our survey, to assess if screening in TB prevalence surveys could be simplified, and to assess the accuracy of screening algorithms that may be applicable for active case finding.

Methods: All participants with a positive screen on either a symptom questionnaire, chest radiography (CXR) and/or sputum smear microscopy submitted sputum for culture. HIV status was obtained from prevalent cases.

Care seeking and attitudes towards treatment compliance by newly enrolled tuberculosis patients in the district treatment programme in rural western Kenya: a qualitative study.

Background: The two issues mostly affecting the success of tuberculosis (TB) control programmes are delay in presentation and non-adherence to treatment. It is important to understand the factors that contribute to these issues, particularly in resource limited settings, where rates of tuberculosis are high. The objective of this study is to assess health-seeking behaviour and health care experiences among persons with pulmonary tuberculosis, and identify the reasons patients might not complete their treatment.

High prevalence of pulmonary tuberculosis and inadequate case finding in rural western Kenya.

Rationale: Limited information exists on the prevalence of tuberculosis and adequacy of case finding in African populations with high rates of HIV.

Objectives: To estimate the prevalence of bacteriologically confirmed pulmonary tuberculosis (PTB) and the fraction attributable to HIV, and to evaluate case detection.

Methods: Residents aged 15 years and older, from 40 randomly sampled clusters, provided two sputum samples for microscopy; those with chest radiograph abnormalities or symptoms suggestive of PTB provided one additional sputum sample for culture.

Preventing mother-to-child transmission of HIV in Western Kenya: operational issues.

Objectives: To improve uptake in a program to prevent mother-to-child HIV transmission and describe lessons relevant for prevention of mother-to-child transmission programs in resource-poor settings.

Methods: Implementation of a pilot project that evaluates approaches to increase program uptake at health facility level at New Nyanza Provincial General Hospital, a public hospital in western Kenya, an area with high HIV prevalence. Client flow was revised to integrate counseling, HIV testing, and dispensing of single-dose nevirapine into routine antenatal services.