Mycobacterium tuberculosis is estimated to infect 80 to 100 million people annually, the majority of whom do not develop clinical tuberculosis (TB) but instead maintain the infection in a latent state. These individuals generally become positive in response to a tuberculin skin test and may develop clinical TB at a later date, particularly if their immune systems are compromised. Latently infected individuals are interesting for two reasons. First, they are an important reservoir of M. tuberculosis, which needs to be considered for TB control. Second, if detected prior to recrudescence of the disease, they represent a human population that is making a protective immune response to M. tuberculosis, which is very important for defining correlates of protective immunity. In this study, we show that while responsiveness to early secretory antigenic target 6 is a good marker for M. tuberculosis infection, a strong response to the 16-kDa Rv2031c antigen (HspX or ␣-crystallin) is largely restricted to latently infected individuals, offering the possibility of differential immunodiagnosis of, or therapeutic vaccination against, TB. Tuberculosis (TB) is easily transmitted by inhalation of infectiousMycobacterium tuberculosis bacilli from the air and is one of the leading causes of death in adults between the ages of 15 and 45 years (43). The global incidence rate of TB is increasing by approximately 0.4% per year (43), driven by factors such as the human immunodeficiency virus (HIV)/ AIDS epidemic, poverty, and increasing population density. Despite the existence of effective treatment regimens, control of TB is complicated by the chronic nature of the disease. Only 5 to 10% of recently exposed individuals develop clinically active TB in the first 2 years after exposure, and this, together with the often transient nature of exposure, makes accurate tracing of recently exposed and potentially infected individuals extremely difficult.A higher percentage of exposed individuals become infected but are able to limit the growth of the mycobacteria and become latently infected. The exact incidence of latent infection remains unclear, but it is estimated that up to 2 billion people globally may harbor latent TB infections (17,22,43). Latency can only be understood as a dynamic process-an active host immune response is essential to keep the disease in the latent stage, as demonstrated by the high rate of TB recrudescence in individuals with HIV infection (8) or the reactivation of the latent infection in individuals given anti-tumor necrosis factor alpha therapy (29). The decline of the immune system due to old age or malnutrition also increases the risk of latent disease becoming clinically significant.Thus, latently infected individuals provide a highly relevant population to study what human protective immune responses against M. tuberculosis look like. However, identifying these people has been problematic in the past. The classical definition of latent infection (conversion to positivity in the purified protein derivative-ba...

The majority of healthy individuals exposed to Mycobacterium tuberculosis will not develop disease and identifying what constitutes “protective immunity” is one of the holy grails of M. tuberculosis immunology. It is known that IFN-γ is essential for protection, but it is also apparent that IFN-γ levels alone do not explain the immunity/susceptibility dichotomy. The controversy regarding correlates of immunity persists because identifying infected but healthy individuals (those who are immune) has been problematic. We have therefore used recognition of the M. tuberculosis virulence factor early secretory antigenic target 6 to identify healthy, but infected individuals from tuberculosis (TB)-endemic and nonendemic regions (Ethiopia and Denmark) and have compared signals for cytokines expressed directly ex vivo with the pattern found in TB patients. We find that TB patients are characterized by decreased levels of Th1 cytokines and increased levels of IL-10 compared with the healthy infected and noninfected community controls. Interestingly, the healthy infected subjects exhibited a selective increase of message for the IL-4 antagonist, IL-4δ2, compared with both TB patients or noninfected individuals. These data suggest that long-term control of M. tuberculosis infection is associated not just with elevated Th1 responses but also with inhibition of the Th2 response.

BackgroundThe introduction of Antiretroviral Therapy (ART) has brought a remarkable reduction in HIV-related mortality and morbidity both in adults and children living with HIV/AIDS. Adherence to ART is the key to the successful treatment of patients as well as containment of drug resistance. Studies based on caregivers’ report have shown that adherence to ART among children is generally good. However, subjective methods such as caregivers’ report are known to overestimate the level of adherence. This study determined the rate of adherence and its predictors using unannounced home-based pill count and compared the result with caregivers’ report in a tertiary referral hospital in Ethiopia.MethodsA cross-sectional study was conducted between December 1, 2011 and January 30, 2012. The study participants were 210 children on ART and their caregivers attending pediatric ART clinic of Tikur Anbessa Hospital (TAH), Addis Ababa University. Caregivers were interviewed at the ART clinic using a structured questionnaire. Then, unannounced home-based pill count was done 7 days after the interview.ResultsCaregiver-reported adherence in the past 7 days prior to interview was 93.3%. Estimated adherence using unannounced home-based pill count was found, however, to be 34.8%. On multivariate logistic regression model, children with married [aOR = 7.85 (95% CI: 2.11,29.13)] and widowed/divorced [aOR = 7.14 (95% CI: 2.00,25.46)] caregivers, those who were not aware of their HIV sero-status [aOR = 2.35 (95% CI:1.09, 5.06)], and those with baseline WHO clinical stage III/IV [OR = 3.18 (95% CI: 1.21, 8.40] were more likely to adhere to their ART treatment. On the other hand, children on d4T/3Tc/EFV combination [OR = 0.10 (95% CI: 0.02, 0.53)] were less likely to adhere to their treatment. Caregivers’ forgetfulness and child refusal to take medication were reported as the major reasons for missing doses.ConclusionThe level of adherence based on unannounced home-based pill count was unacceptably low. Interventions are urgently needed to improve adherence to ART among children at TAH. Besides, a longitudinal study measuring adherence combined with clinical parameters (viral load and CD4 count) is needed to identify a simple and reliable measure of adherence in the study area.

Background Tuberculosis, caused by bacteria in the Mycobacterium tuberculosis complex (MTBC), is a major global public health burden. Strain-specific genomic diversity in the known lineages of MTBC is an important factor in pathogenesis that may affect virulence, transmissibility, host response and emergence of drug resistance. Fast and accurate tracking of MTBC strains is therefore crucial for infection control, and our previous work developed a 62-single nucleotide polymorphism (SNP) barcode to inform on the phylogenetic identity of 7 human lineages and 64 sub-lineages. Methods To update this barcode, we analysed whole genome sequencing data from 35,298 MTBC isolates (~ 1 million SNPs) covering 9 main lineages and 3 similar animal-related species (M. tuberculosis var. bovis, M. tuberculosis var. caprae and M. tuberculosis var. orygis). The data was partitioned into training (N = 17,903, 50.7%) and test (N = 17,395, 49.3%) sets and were analysed using an integrated phylogenetic tree and population differentiation (FST) statistical approach. Results By constructing a phylogenetic tree on the training MTBC isolates, we characterised 90 lineages or sub-lineages or species, of which 30 are new, and identified 421 robust barcoding mutations, of which a minimal set of 90 was selected that included 20 markers from the 62-SNP barcode. The barcoding SNPs (90 and 421) discriminated perfectly the 86 MTBC isolate (sub-)lineages in the test set and could accurately reconstruct the clades across the combined 35k samples. Conclusions The validated 90 SNPs can be used for the rapid diagnosis and tracking of MTBC strains to assist public health surveillance and control. To facilitate this, the SNP markers have now been incorporated into the TB-Profiler informatics platform (https://github.com/jodyphelan/TBProfiler).

BackgroundTimely tuberculosis treatment initiation and compliance are the two key factors for a successful tuberculosis control program. However, studies to understand patents’ perspective on tuberculosis treatment initiation and compliance have been limited in Ethiopia. The aim of this study is to attempt to do that in rural Ethiopia.MethodsThis qualitative, phenomenological study conducted 26 in-depth interviews with tuberculosis patients. A thematic content analysis of the interviews was performed using the Open Code software version 3.1.ResultsWe found that lack of geographic access to health facilities, financial burdens, use of traditional healing systems and delay in diagnosis by health care providers were the main reasons for not initiating tuberculosis treatment timely. Lack of geographic access to health facilities, financial burdens, quality of health services provided and social support were also identified as the main reasons for failing to fully comply with tuberculosis treatments.ConclusionsThis study highlighted complexities surrounding tuberculosis control efforts in Dabat District. Challenges of geographic access to health care facilities and financial burdens were factors that most influenced timely tuberculosis treatment initiation and compliance. Decentralization of tuberculosis diagnosis and treatment services to peripheral health facilities, including health posts is of vital importance to make progress toward achieving tuberculosis control targets in Ethiopia.

Regulatory T (Treg) cells are known for their role in maintaining self-tolerance and balancing immune reactions in autoimmune diseases and chronic infections. However, regulatory mechanisms can also lead to prolonged survival of pathogens in chronic infections like leprosy and tuberculosis (TB). Despite high humoral responses against Mycobacterium leprae (M. leprae), lepromatous leprosy (LL) patients have the characteristic inability to generate T helper 1 (Th1) responses against the bacterium. In this study, we investigated the unresponsiveness to M. leprae in peripheral blood mononuclear cells (PBMC) of LL patients by analysis of IFN-γ responses to M. leprae before and after depletion of CD25+ cells, by cell subsets analysis of PBMC and by immunohistochemistry of patients' skin lesions. Depletion of CD25+ cells from total PBMC identified two groups of LL patients: 7/18 (38.8%) gained in vitro responsiveness towards M. leprae after depletion of CD25+ cells, which was reversed to M. leprae-specific T-cell unresponsiveness by addition of autologous CD25+ cells. In contrast, 11/18 (61.1%) remained anergic in the absence of CD25+ T-cells. For both groups mitogen-induced IFN-γ was, however, not affected by depletion of CD25+ cells. In M. leprae responding healthy controls, treated lepromatous leprosy (LL) and borderline tuberculoid leprosy (BT) patients, depletion of CD25+ cells only slightly increased the IFN-γ response. Furthermore, cell subset analysis showed significantly higher (p = 0.02) numbers of FoxP3+ CD8+CD25+ T-cells in LL compared to BT patients, whereas confocal microscopy of skin biopsies revealed increased numbers of CD68+CD163+ as well as FoxP3+ cells in lesions of LL compared to tuberculoid and borderline tuberculoid leprosy (TT/BT) lesions. Thus, these data show that CD25+ Treg cells play a role in M. leprae-Th1 unresponsiveness in LL.

BackgroundTuberculosis (TB) case detection rate remains low in Ethiopia. One of the underlying reasons is the emphasis on passive case finding strategy which may seriously underestimate the burden of the disease. Estimating the prevalence of smear-positive pulmonary TB through active case finding at population level can help assessing the degree to which passive case detection is successful.Methods and findingsThis is population based cross-sectional study. The study population was all individuals aged ≥14 years. Interviews using a uniform questionnaire were done initially to identify individuals with chronic cough (≥15 days) and the two sputum (spot and morning) samples were gathered for standard smear microscopy. A total of 23,590 individuals aged ≥14 years were interviewed and 984 had a chronic cough for ≥15 days. Of 831 individuals who provided two sputum samples for acid fast bacilli (AFB), 41 had positive smears. A total of 22 smear-positive TB cases detected through passive case finding were on anti-TB treatment. The prevalence of new smear-positive TB was 174 per 100,000 in persons aged ≥14 years (95% CI: 121–227).The ratio of active to passive case finding was 2∶1. Higher rates of smear-positivity were observed among females [AOR: 3.28, 95% CI (1.54–6.77)], and in the age group ≥45 years [AOR: 2.26, 95% CI (1.12–4.59).ConclusionsThe study revealed that about two-thirds of patients with active TB remain undiagnosed and thus untreated. This may indicate the need for strengthening case detection at the community level. Furthermore, the high burden of TB among females and in the age group ≥45 years warrants appropriate measures to control the disease.

BackgroundBreast cancer is a heterogeneous disease with several morphological and molecular subtypes. Widely accepted molecular classification system uses assessment of estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2) and proliferation marker Ki67. Few studies have been conducted on the incidence and molecular types of breast cancer in Sub-Saharan Africa. Previous studies mainly from Western and Central Africa, showed breast cancer to occur at younger ages and to present with aggressive features, such as high-grade, advanced stage and triple-negative phenotype (negative for ER, PR and HER2). Limited data from East Africa including Ethiopia however shows hormone receptor negative tumors to account for a lower proportion of all breast cancers than has been reported from elsewhere in Africa.MethodsIn this study from Tikur Anbessa Specialized Hospital, 114 breast cancer patients diagnosed between 2012 and 2015 were enrolled. ER, PR, Ki67 and HER2 receptor status were assessed using immunohistochemistry from tissue microarrays. FISH was used for assessment of gene amplification in all equivocal tumor samples and for confirmation in HER2-enriched cases.ResultsThe distribution of molecular subtypes was: Luminal A: 40%; Luminal B: 26%; HER2-enriched: 10%; TNBC: 23%. ER were positive in 65% of all tumors and 43% the cases were positive for PR. There was statistically significant difference in median age at diagnosis between the molecular subtypes (P < 0.05). There was a bimodal distribution of molecular subtypes in different age ranges with Luminal B subtype being more common at younger ages (median = 36) and Luminal A subtype more prevalent at older ages (median = 42). There were no statistically significant differences in tumor grade, histology, and stage between the molecular subtypes of breast cancer.ConclusionThe present study detected Luminal A breast cancer to be the most common subtype and reveals a relatively low rate of hormone receptor negative and TNBC. Our findings and results from other East African studies suggest geographic variability in the distribution of the molecular subtypes of breast cancer in Africa and hence have important clinical and policy implications for breast cancer control and treatment in Ethiopia.