Browsing by Author "Zalwango, Sarah"
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Item Acceptability, Usefulness, and Ease of Use of an Enhanced Video Directly Observed Treatment System for Supporting Patients With Tuberculosis in Kampala, Uganda: Explanatory Qualitative Study(JMIR Publications, 2023-11) Sekandi, Juliet Nabbuye; McDonald, Adenike; Nakkonde, Damalie; Zalwango, Sarah; Kasiita, Vicent; Kaggwa, Patrick; Kakaire, Robert; Atuyambe, Lynn; Buregyeya, EstherAbstract BACKGROUNDIn tuberculosis (TB) control, nonadherence to treatment persists as a barrier. The traditional method of ensuring adherence, that is, directly observed therapy, faces significant challenges that hinder its widespread adoption. Digital adherence technologies such as video directly observed therapy (VDOT) are emerging as promising solutions. However, as these novel technologies gain momentum, a critical gap is the lack of comprehensive studies evaluating their efficacy and the unique experiences of patients in Africa.OBJECTIVEThe aim of this study was to assess patients' experiences that affected acceptability, usefulness, and ease of use with an enhanced VDOT system during monitoring of TB treatment.METHODSWe conducted individual open-ended interviews in a cross-sectional exit qualitative study in Kampala, Uganda. Thirty participants aged 18-65 years who had completed the VDOT randomized trial were purposively selected to represent variability in sex, adherence level, and HIV status. We used a hybrid process of deductive and inductive coding to identify content related to the experience of study participation with VDOT. Codes were organized into themes and subthemes, which were used to develop overarching categories guided by constructs adapted from the modified Technology Acceptance Model for Resource-Limited Settings. We explored participants' experiences regarding the ease of use and usefulness of VDOT, thereby identifying the facilitators and barriers to its acceptability. Perceived usefulness refers to the benefits users expect from the technology, while perceived ease of use refers to how easily users navigate its various features. We adapted by shifting from assessing perceived to experienced constructs.RESULTSThe participants' mean age was 35.3 (SD 12) years. Of the 30 participants, 15 (50%) were females, 13 (43%) had low education levels, and 22 (73%) owned cellphones, of which 10 (45%) had smartphones. Nine (28%) were TB/HIV-coinfected, receiving antiretroviral therapy. Emergent subthemes for facilitators of experienced usefulness and ease of VDOT use were SMS text message reminders, technology training support to patients by health care providers, timely patient-provider communication, family social support, and financial incentives. TB/HIV-coinfected patients reported the added benefit of adherence support for their antiretroviral medication. The external barriers to VDOT's usefulness and ease of use were unstable electricity, technological malfunctions in the app, and lack of cellular network coverage in rural areas. Concerns about stigma, disease disclosure, and fear of breach in privacy and confidentiality affected the ease of VDOT use.CONCLUSIONSOverall, participants had positive experiences with the enhanced VDOT. They found the enhanced VDOT system user-friendly, beneficial, and acceptable, particularly due to the supportive features such as SMS text message reminders, incentives, technology training by health care providers, and family support. However, it is crucial to address the barriers related to technological infrastructure as well as the privacy, confidentiality, and stigma concerns related to VDOT. MEDLINE - AcademicItem Assessing a transmission network of Mycobacterium tuberculosis in an African city using single nucleotide polymorphism threshold analysis(MicrobiologyOpen, 2021) Yassine, Edriss; Galiwango, Ronald; Ssengooba, Willy; Ashaba, Fred; Joloba, Moses L.; Zalwango, Sarah; Whalen, Christopher C.; Quinn, FrederickTuberculosis (TB) is the leading cause of death in humans by a single infectious agent worldwide with approximately two billion humans latently infected with the bacterium Mycobacterium tuberculosis. Currently, the accepted method for controlling the disease is Tuberculosis Directly Observed Treatment Shortcourse (TB-DOTS). This program is not preventative and individuals may transmit disease before diagnosis, thus better understanding of disease transmission is essential. Using whole-genome sequencing and single nucleotide polymorphism analysis, we analyzed genomes of 145 M. tuberculosis clinical isolates from active TB cases from the Rubaga Division of Kampala, Uganda. We established that these isolates grouped into M. tuberculosis complex (MTBC) lineages 1, 2, 3, and 4, with the most isolates grouping into lineage 4. Possible transmission pairs containing ≤12 SNPs were identified in lineages 1, 3, and 4 with the prevailing transmission in lineages 3 and 4. Furthermore, investigating DNA codon changes as a result of specific SNPs in prominent virulence genes including plcA and plcB could indicate potentially important modifications in protein function. Incorporating this analysis with corresponding epidemiological data may provide a blueprint for the integration of public health interventions to decrease TB transmission in a region.Item Association between tuberculosis in men and social network structure in Kampala, Uganda(BMC infectious diseases, 2021) Miller, Paige B.; Zalwango, Sarah; Galiwango, Ronald; Kakaire, Robert; Sekandi, Juliet; Steinbaum, Lauren; Drake, John M.; Whalen, Christopher C.; Kiwanuka, NoahGlobally, tuberculosis disease (TB) is more common among males than females. Recent research proposes that differences in social mixing by sex could alter infection patterns in TB. We examine evidence for two mechanisms by which social-mixing could increase men’s contact rates with TB cases. First, men could be positioned in social networks such that they contact more people or social groups. Second, preferential mixing by sex could prime men to have more exposure to TB cases. Methods: We compared the networks of male and female TB cases and healthy matched controls living in Kampala, Uganda. Specifically, we estimated their positions in social networks (network distance to TB cases, degree, betweenness, and closeness) and assortativity patterns (mixing with adult men, women, and children inside and outside the household). Results: The observed network consisted of 11,840 individuals. There were few differences in estimates of node position by sex. We found distinct mixing patterns by sex and TB disease status including that TB cases have proportionally more adult male contacts and fewer contacts with children. Conclusions: This analysis used a network approach to study how social mixing patterns are associated with TB disease. Understanding these mechanisms may have implications for designing targeted intervention strategies in high-burden populations.Item Body composition among HIV-Seropositive and HIV-Seronegative adult patients with Pulmonary Tuberculosis in Uganda(Elsevier Inc, 2009) Mupere, Ezekiel; Zalwango, Sarah; Chiunda, Allan; Okwera, Alphonse; Mugerwa, Roy; Whalen, ChristopherBody wasting is a prominent and cardinal feature of tuberculosis (TB) (1, 2) and is a marker of disease severity and outcome. In sub-Saharan Africa, a large proportion of patients with TB also have coinfection with human immunodeficiency virus (HIV) (3). Coinfection may worsen the wasting seen in either TB or HIV infection alone (4, 5). Wasting in TB is associated with reduced caloric intake due to anorexia or loss of appetite and increase in consumption of calories due to altered metabolism induced by inflammation and immune response (6–8). Several studies (9–15) in sub-Saharan Africa have shown the impact of dual infection with HIV and TB on nutritionalItem Burden of tuberculosis in Kampala, Uganda(World Health Organization, 2003) Guwatudde, David; Zalwango, Sarah; Kamya, Moses; Debanne, Sara; Mireya, Diaz; Okwera, Alphonse; Mugerwa, Roy; King, Charles; Christopher, WhalenOver the past two decades, the number of tuberculosis cases has risen worldwide, especially in the developing countries of southeast Asia and sub-Saharan Africa, where co-infection with human immunodeficiency virus (HIV) and tuberculosis is common (1, 2). Case notification data often are used to assess the burden of tuberculosis. The wide belief, however, is that a substantial number of cases of tuberculosis are not detected by the health care systems in most of these countries (3, 4), and surveys of the prevalence of tuberculosis in some of these countries support this belief (5, 6). Furthermore, the poor peri-urban areas of developing countries, where living conditions are unsatisfactory with overcrowding, poor hygiene and inadequate sanitation, are usually most affected by tuberculosis (7, 8). Such living conditions, coupled with high prevalence of HIV infection and lack of access to health care and/or poor health-seeking behavior (8, 9), may lead to a vicious circle of transmission of diseases, including tuberculosis. National average notification data often do not reveal the overwhelming burden of tuberculosis in these settings.Item Caregiver socioemotional health as a determinant of child well-being in school-aged and adolescent Ugandan children with and without perinatal HIV exposure(John Wiley & Sons Ltd, 2019) Webster, Kyle; Bruyn, Miko; Zalwango, Sarah; Sikorskii, Alla; Barkin, Jennifer; Familiar-Lopez, Itziar; Musoke, Philippa; Giordani, Bruno; Boivin, Michael; Ezeamama, Amara E.Caregiver socio-emotional attributes are major determinants of child well-being. This investigation in vulnerable school-aged Ugandan children estimates relationships between children’s well-being and their caregiver’s anxiety, depression and social support. methods Perinatally HIV-infected, HIV-exposed uninfected and HIV-unexposed Ugandan children and their caregivers were enrolled. Perinatal HIV status was determined by 18 months of age using DNA-polymerase chain-reaction test; status was confirmed via HIV rapid diagnostic test when children were 6–18 years old. Five indicators of child well-being (distress, hopelessness, positive future orientation, esteem and quality of life (QOL)) and caregivers’ socioemotional status (depressive symptoms, anxiety and social support) were measured using validated, culturally adapted and translated instruments. Categories based on tertiles of each caregiver psychosocial indicator were defined. Linear regression analyses estimated percent differences (b) and corresponding 95% confidence intervals (CI) for child well-being in relation to caregiver’s psychosocial status results As per tertile increment, caregiver anxiety was associated with 2.7% higher distress (95% CI:0.2%, 5.3%) and lower self esteem/QOL (b = 1.3%/ 2.6%; 95%CI: 5.0%,-0.2%) in their children. Child distress/hopelessness increased (b = 3.3%/7.6%; 95%CI:0.4%, 14.7%) and self-esteem/QOL decreased 2.3% (b = 2.3%/ 4.4%; 95%CI: 7.2%, 1.3%) as per tertile increment in caregiver depression. Higher caregiver social support was associated with lower distress and higher positive outlook (b = 3%; 95%CI:1.4%, 4.5%) in their children. HIV-infected/exposed children had most caregiver depression-related QOL deficit (b = 5.2%/ 6.8%; 95%CI: 12.4%, 0.2%) and HIV-unexposed children had most caregiver social support-related enhancements in positive outlook (b=4.5%; 95%CI:1.9%, 7.1%). conclusions Caregiver anxiety, depressive symptoms and low social support were associated with worse well-being in school-aged and adolescent children. Improvement of caregiver mental health and strengthening caregiver social support systems may be a viable strategy for improving well-being of vulnerable children and adolescents in this setting.Item Clinical and epidemiological characteristics of individuals resistant to M. tuberculosis infection in a longitudinal TB household contact study in Kampala, Uganda(BioMed Central, 2014) Ma, Ningning; Zalwango, Sarah; Malone, LaShaunda L; Nsereko, Mary; Wampande, Eddie M; Thiel, Bonnie A; Okware, Brenda; Igo Jr., Robert P; Joloba3, Moses L.; Mupere, Ezekiel; Mayanja-Kizza, Harriet; Boom, Henry; Stein, Catherine MBackground: Despite sustained exposure to a person with pulmonary tuberculosis (TB), some M. tuberculosis (Mtb) exposed individuals maintain a negative tuberculin skin test (TST). Our objective was to characterize these persistently negative TST (PTST-) individuals and compare them to TST converters (TSTC) and individuals who are TST positive at study enrollment. Methods: During a TB household contact study in Kampala, Uganda, PTST-, TSTC, and TST + individuals were identified. PTST- individuals maintained a negative TST over a 2 year observation period despite prolonged exposure to an infectious tuberculosis (TB) case. Epidemiological and clinical characteristics were compared, a risk score developed by another group to capture risk for Mtb infection was computed, and an ordinal regression was performed. Results: When analyzed independently, epidemiological risk factors increased in prevalence from PTST- to TSTC to TST+. An ordinal regression model suggested age (p < 0.01), number of windows (p < 0.01) and people (p = 0.07) in the home, and sleeping in the same room (p < 0.01) were associated with PTST- and TSTC. As these factors do not exist in isolation, we examined a risk score, which reflects an accumulation of risk factors. This compound exposure score did not differ significantly between PTST-, TSTC, and TST+, except for the 5–15 age group (p = 0.009). Conclusions: Though many individual factors differed across all three groups, an exposure risk score reflecting a collection of risk factors did not differ for PTST-, TSTC and TST + young children and adults. This is the first study to rigorously characterize the epidemiologic risk profile of individuals with persistently negative TSTs despite close exposure to a person with TB. Additional studies are needed to characterize possible epidemiologic and host factors associated with this phenotype.Item Comprehensive definition of human immunodominant CD8 antigens in tuberculosis(NPJ vaccines, 2017) Lewinsohn, Deborah A.; Swarbrick, Gwendolyn M.; Park, Byung; Cansler, Meghan E.; Null, Megan D.; Toren, Katelynne G.; Baseke, Joy; Zalwango, Sarah; Mayanja-Kizza, Harriet; Malone, LaShaunda L.; Nyendak, Melissa; Wu, Guanming; Guinn, Kristi; McWeeney, Shannon; Mori, Tomi; Chervenak, Keith A.; Sherman, David R.; Boom, W. Henry; Lewinsohn, David M.Despite widespread use of the Bacillus Calmette-Guerin vaccine, tuberculosis, caused by infection with Mycobacterium tuberculosis, remains a leading cause of morbidity and mortality worldwide. As CD8+ T cells are critical to tuberculosis host defense and a phase 2b vaccine trial of modified vaccinia Ankara expressing Ag85a that failed to demonstrate efficacy, also failed to induce a CD8+ T cell response, an effective tuberculosis vaccine may need to induce CD8+ T cells. However, little is known about CD8, as compared to CD4, antigens in tuberculosis. Herein, we report the results of the first ever HLA allele independent genome-wide CD8 antigen discovery program. Using CD8+ T cells derived from humans with latent tuberculosis infection or tuberculosis and an interferon-γ ELISPOT assay, we screened a synthetic peptide library representing 10% of the Mycobacterium tuberculosis proteome, selected to be enriched for Mycobacterium tuberculosis antigens. We defined a set of immunodominant CD8 antigens including part or all of 74 Mycobacterium tuberculosis proteins, only 16 of which are previously known CD8 antigens. Immunogenicity was associated with the degree of expression of mRNA and protein. Immunodominant antigens were enriched in cell wall proteins with preferential recognition of Esx protein family members, and within proteins comprising the Mycobacterium tuberculosis secretome. A validation study of immunodominant antigens demonstrated that these antigens were strongly recognized in Mycobacterium tuberculosisinfected individuals from a tuberculosis endemic region in Africa. The tuberculosis vaccine field will likely benefit from this greatly increased known repertoire of CD8 immunodominant antigens and definition of properties of Mycobacterium tuberculosis proteins important for CD8 antigenicity.Item Contact Investigation for Active Tuberculosis Among Child Contacts in Uganda(Oxford University Press, 2013) Jaganath, Devan; Zalwango, Sarah; Okware, Brenda; Nsereko, Mary; Kisingo, Hussein; Malone, LaShaunda; Lancioni, Christina; Okwera, Alphonse; Joloba, Moses; Mayanja-Kizza, Harriet; Boom, Henry; Stein, Catherine; Mupere, EzekielBackground. Tuberculosis is a large source of morbidity and mortality among children. However, limited studies characterize childhood tuberculosis disease, and contact investigation is rarely implemented in high-burden settings. In one of the largest pediatric tuberculosis contact investigation studies in a resource-limited setting, we assessed the yield of contact tracing on childhood tuberculosis and indicators for disease progression in Uganda. Methods. Child contacts aged <15 years in Kampala, Uganda, were enrolled from July 2002 to June 2009 and evaluated for tuberculosis disease via clinical, radiographic, and laboratory methods for up to 24 months. Results. Seven hundred sixty-one child contacts were included in the analysis. Prevalence of tuberculosis in our child population was 10%, of which 71% were culture-confirmed positive. There were no cases of disseminated tuberculosis, and 483 of 490 children (99%) started on isoniazid preventative therapy did not develop disease. Multivariable testing suggested risk factors including human immunodeficiency virus (HIV) status (odds ratio [OR], 7.90; P < .001), and baseline positive tuberculin skin test (OR, 2.21; P = .03); BCG vaccination was particularly protective, especially among children aged ≤5 years (OR, 0.23; P < .001). Adult index characteristics such as sex, HIV status, and extent or severity of disease were not associated with childhood disease. Conclusions. Contact tracing for children in high-burden settings is able to identify a large percentage of culture-confirmed positive tuberculosis cases before dissemination of disease, while suggesting factors for disease progression to identify who may benefit from targeted screening.Item Defining adequate contact for transmission of Mycobacterium tuberculosis in an African urban environment(BMC public health, 2020) Castellanos, María Eugenia; Zalwango, Sarah; Kakaire, Robert; Ebell, Mark H.; Dobbin, Kevin K.; Sekandi, Juliet; Kiwanuka, Noah; Whalen, Christopher C.The risk of infection from respiratory pathogens increases according to the contact rate between the infectious case and susceptible contact, but the definition of adequate contact for transmission is not standard. In this study we aimed to identify factors that can explain the level of contact between tuberculosis cases and their social networks in an African urban environment. Methods: This was a cross-sectional study conducted in Kampala, Uganda from 2013 to 2017. We carried out an exploratory factor analysis (EFA) in social network data from tuberculosis cases and their contacts. We evaluated the factorability of the data to EFA using the Kaiser-Meyer-Olkin Measure of Sampling Adequacy (KMO). We used principal axis factoring with oblique rotation to extract and rotate the factors, then we calculated factor scores for each using the weighted sum scores method. We assessed construct validity of the factors by associating the factors with other variables related to social mixing. Results: Tuberculosis cases (N = 120) listed their encounters with 1154 members of their social networks. Two factors were identified, the first named “Setting” captured 61% of the variance whereas the second, named ‘Relationship’ captured 21%. Median scores for the setting and relationship factors were 10.2 (IQR 7.0, 13.6) and 7.7 (IQR 6.4, 10.1) respectively. Setting and Relationship scores varied according to the age, gender, and nature of the relationship among tuberculosis cases and their contacts. Family members had a higher median setting score (13.8, IQR 11.6, 15.7) than non-family members (7.2, IQR 6.2, 9.4). The median relationship score in family members (9.9, IQR 7.6, 11.5) was also higher than in non-family members (6.9, IQR 5.6, 8.1). For both factors, household contacts had higher scores than extra-household contacts (p < .0001). Contacts of male cases had a lower setting score as opposed to contacts of female cases. In contrast, contacts of male and female cases had similar relationship scores. Conclusions: In this large cross-sectional study from an urban African setting, we identified two factors that can assess adequate contact between tuberculosis cases and their social network members. These findings also confirm the complexity and heterogeneity of social mixing.Item Defining an intermediate category of tuberculin skin test: A mixture model analysis of two high-risk populations from Kampala, Uganda(Creative Commons Attribution License, 2021) Woldu, Henok G.; Zalwango, Sarah; Martinez, Leonardo; Castellanos, Maria Eugenia; Kakaire, Robert; Sekandi, Juliet N.; Kiwanuka, Noah; Whalen, Christopher C.One principle of tuberculosis control is to prevent the development of tuberculosis disease by treating individuals with latent tuberculosis infection. The diagnosis of latent infection using the tuberculin skin test is not straightforward because of concerns about immunologic cross reactivity with the Bacille Calmette-Guerin (BCG) vaccine and environmental mycobacteria. To parse the effects of BCG vaccine and environmental mycobacteria on the tuberculin skin test, we estimated the frequency distribution of skin test results in two divisions of Kampala, Uganda, ten years apart. We then used mixture models to estimate parameters for underlying distributions and defined clinically meaningful criteria for latent infection, including an indeterminate category. Using percentiles of two underlying normal distributions, we defined two skin test readings to demarcate three ranges. Values of 10 mm or greater contained 90% of individuals with latent infection; values less than 7.2 mm contained 80% of individuals without infection. Contacts with values between 7.2 and 10 mm fell into an indeterminate zone where it was not possible to assign infection. We conclude that systematic tuberculin skin test surveys within populations at risk, combined with mixture model analysis, may be a reproducible, evidence-based approach to define meaningful criteria for latent tuberculosis infection.Item Effectiveness of WHO’s pragmatic screening algorithm for child contacts of tuberculosis cases in resource-constrained settings: a prospective cohort study in Uganda(Lancet Respir Med, 2017) Martinez, Leonardo; Shen, Ye; Handel, Andreas; Chakraburty, Srijita; Stein, Catherine M; Malone, LaShaunda L; Boom, Henry; Quinn, Frederick D; Joloba, Moses L; Whalen, Christopher C; Zalwango, SarahBackground Tuberculosis is a leading cause of global childhood mortality; however, interventions to detect undiagnosed tuberculosis in children are underused. Child contact tracing has been widely recommended but poorly implemented in resource-constrained settings. WHO has proposed a pragmatic screening approach for managing child contacts. We assessed the effectiveness of this screening approach and alternative symptom-based algorithms in identifying secondary tuberculosis in a prospectively followed cohort of Ugandan child contacts. Methods We identified index patients aged at least 18 years with microbiologically confirmed pulmonary tuberculosis at Old Mulago Hospital (Kampala, Uganda) between Oct 1, 1995, and Dec 31, 2008. Households of index patients were visited by fieldworkers within 2 weeks of diagnosis. Coprevalent and incident tuberculosis were assessed in household contacts through clinical, radiographical, and microbiological examinations for 2 years. Disease rates were compared among children younger than 16 years with and without symptoms included in the WHO pragmatic guideline (presence of haemoptysis, fever, chronic cough, weight loss, night sweats, and poor appetite). Symptoms could be of any duration, except cough (>21 days) and fever (>14 days). A modified WHO decision-tree designed to detect high-risk asymptomatic child contacts was also assessed, in which all asymptomatic contacts were classified as high risk (children younger than 3 years or immunocompromised [HIV-infected]) or low risk (aged 3 years or older and immunocompetent [HIV-negative]). We also assessed a more restrictive algorithm (ie, assessing only children with presence of chronic cough and one other tuberculosis-related symptom). Findings Of 1718 household child contacts, 126 (7%) had coprevalent tuberculosis and 24 (1%) developed incident tuberculosis, diagnosed over the 2-year study period. Of these 150 cases of tuberculosis, 95 (63%) were microbiologically confirmed with a positive sputum culture. Using the WHO approach, 364 (21%) of 1718 child contacts had at least one tuberculosis-related symptom and 85 (23%) were identified as having coprevalent tuberculosis, 67% of all coprevalent cases detected (diagnostic odds ratio 9·8, 95% CI 6·8–14·5; p<0·0001). 1354 (79%) of 1718 child contacts had no symptoms, of whom 41 (3%) had coprevalent tuberculosis. The WHO approach was effective in contacts younger than 5 years: 70 (33%) of 211 symptomatic contacts had coprevalent disease compared with 23 (6%) of 367 asymptomatic contacts (p<0·0001). This approach was also effective in contacts aged 5 years and older: 15 (10%) of 153 symptomatic contacts had coprevalent disease compared with 18 (2%) of 987 asymptomatic contacts (p<0·0001). More coprevalent disease was detected in child contacts recommended for screening when the study population was restricted by HIV-serostatus (11 [48%] of 23 symptomatic HIV-seropositive child contacts vs two [7%] of 31 asymptomatic HIV-seropositive child contacts) or to only cultureconfirmed cases (47 [13%] culture confirmed cases of 364 symptomatic child contacts vs 29 [2%] culture confirmed cases of 1354 asymptomatic child contacts). In the modified algorithm, high-risk asymptomatic child contacts were at increased risk for coprevalent disease versus low-risk asymptomatic contacts (14 [6%] of 224 vs 27 [2%] of 1130; p=0·0021). The presence of tuberculosis infection did not predict incident disease in either symptomatic or asymptomatic child contacts: in symptomatic contacts, eight (5%) of 169 infected contacts and six (5%) of 111 uninfected contacts developed incident tuberculosis (p=0·80).Item Excess Risk of Tuberculosis Infection Among Extra-household Contacts of Tuberculosis Cases in an African City(Clinical Infectious Diseases, 2021) Kakaire, Robert; Kiwanuka, Noah; Zalwango, Sarah; Sekandi, Juliet N.; Quach, Trang Ho Thu; Castellanos, Maria Eugenia; Quinn, Frederick; Whalen, Christopher C.Although households of tuberculosis (TB) cases represent a setting for intense transmission of Mycobacterium tuberculosis, household exposure accounts for <20% of transmission within a community. The aim of this study was to estimate excess risk of M. tuberculosis infection among household and extra-household contacts of index cases. Methods. We performed a cross-sectional study in Kampala, Uganda, to delineate social networks of TB cases and matched controls without TB. We estimated the age-stratified prevalence difference of TB infection between case and control networks, partitioned as household and extra-household contacts. Results. We enrolled 123 index cases, 124 index controls, and 2415 first-degree network contacts. The prevalence of infection was highest among household contacts of cases (61.5%), lowest among household contacts of controls (25.2%), and intermediary among extra-household TB contacts (44.9%) and extra-household control contacts (41.2%). The age-adjusted prevalence difference between extra-household contacts of cases and their controls was 5.4%. The prevalence of infection was similar among the majority of extra-household case contacts and corresponding controls (47%). Conclusions. Most first-degree social network members of TB cases do not have adequate contact with the index case to experience additional risk for infection, but appear instead to acquire infection through unrecognized exposures with infectious cases in the community.Item Four Degrees of Separation: Social Contacts and Health Providers Influence the Steps to Final Diagnosis of Active Tuberculosis Patients in Urban Uganda(BMC infectious diseases, 2015) Sekandi, Juliet N.; Zalwango, Sarah; Martinez, Leonardo; Handel, Andreas; Kakaire, Robert; Nkwata, Allan K.; Ezeamama, Amara E.; Kiwanuka, Noah; Whalen, Christopher C.Delay in tuberculosis (TB) diagnosis adversely affects patients’ outcomes and prolongs transmission in the community. The influence of social contacts on steps taken by active pulmonary TB patients to seek a diagnosis has not been well examined. Methods: A retrospective study design was use to enroll TB patients on treatment for 3 months or less and aged ≥18 years from 3 public clinics in Kampala, Uganda, from March to July 2014. Social network analysis was used to collect information about social contacts and health providers visited by patients to measure the number of steps and time between onset of symptoms and final diagnosis of TB. Results: Of 294 TB patients, 58 % were male and median age was 30 (IQR: 24–38) years. The median number of steps was 4 (IQR: 3, 7) corresponding to 70 (IQR: 28,140) days to diagnosis. New patients had more steps and time to diagnosis compared retreatment patients (5 vs. 3, P < 0.0001; 84 vs. 46 days P < 0.0001). Fifty-eight percent of patients first contacted persons in their social network. The first step to initiate seeking care accounted for 41 % of the patients’ time to diagnosis while visits to non-TB providers and TB providers (without a TB diagnosis) accounted for 34 % and 11 % respectively. New TB patients vs. retreatment (HR: 0.66, 95 % CI; 1.11, 1.99), those who first contacted a non-TB health provider vs. contacting social network (HR: 0.72 95 % CI; 0.55, 0.95) and HIV seronegative vs. seropositive patients (HR: 0.70, 95 % CI; 0.53, 0.92) had a significantly lower likelihood of a timely final diagnosis. Conclusions: There were four degrees of separation between the onset of symptoms in a TB patient and a final diagnosis. Both social and provider networks of patients influenced the diagnostic pathways. Most delays occurred in the first step which represents decisions to seek help, and through interactions with non-TB health providers. TB control programs should strengthen education and active screening in the community and in health care settings to ensure timely diagnosis of TB.Item Genetic and Shared Environmental Influences on Interferon-g Production in Response to Mycobacterium tuberculosis Antigens in a Ugandan Population(The American Society of Tropical Medicine and Hygiene, 2010) Tao, Li; Zalwango, Sarah; Chervenak, Keith; Thiel, Bonnie; Malone, LaShaunda L.; Feiyou, Qiu; Mayanja-Kizza, Harriet; Boom, Henry; Stein, Catherine M.Interferon-g (IFN-g) is a key cytokine in the immune response to Mycobacterium tuberculosis (Mtb). Many studies established IFN-g responses are influenced by host genetics, however differed widely by the study design and heritability estimation method. We estimated heritability of IFN-g responses to Mtb culture filtrate (CF), ESAT-6, and Antigen 85B (Ag85B) in 1,104 Ugandans from a household contact study. Our method separately evaluates shared environmental and genetic variance, therefore heritability estimates were not upwardly biased, ranging from 11.6% for Ag85B to 22.9% for CF. Subset analyses of individuals with latent Mtb infection or without human immunodeficiency virus infection yielded higher heritability estimates, suggesting 10–30% of variation in IFN-g is caused by a shared environment. Immunosuppression does not negate the role of genetics on IFN-g response. These estimates are remarkably close to those reported for components of the innate immune response. These findings have implications for the interpretation of IFN-g response assays and vaccine studies.Item Genetic susceptibility to tuberculosis associated with cathepsin Z haplotype in a Ugandan household contact study(Elsevier Inc., 2011) Baker, Allison R.; Zalwango, Sarah; Malone, LaShaunda L.; Igo Jr, Robert P.; Qiu, Feiyou; Nsereko, Mary; Adams, Mark D.; Supelak, PamelaTuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), causes 9 million new cases worldwide and 2 million deaths annually. Genetic linkage and association analyses have suggested several chromosomal regions and candidate genes involved in TB susceptibility. This study examines the association of TB disease susceptibility with a selection of biologically relevant genes on regions on chromosomes 7 (IL6 and CARD11) and 20 (CTSZ and MC3R) and fine mapping of the chromosome 7p22–p21 region identified through our genome scan. We analyzed 565 individuals from Kampala, Uganda, who were previously included in our genome-wide linkage scan. Association analyses were conducted for 1,417 single-nucleotide polymorphisms (SNP) that passed quality control. None of the candidate gene or fine mapping SNPs was significantly associated with TB susceptibility (p 0.10). When we restricted the analysis to HIV-negative individuals, 2 SNPs on chromosome 7 were significantly associated with TB susceptibility (p 0.05). Haplotype analyses identified a significant risk haplotype in cathepsin X (CTSZ; p 0.0281, odds ratio 1.5493, 95% confidence interval [1.039, 2.320]).Item Genome Scan of M. tuberculosis Infection and Disease in Ugandans(PLoS ONE, 2018) Stein, Catherine M.; Zalwango, Sarah; Malone, LaShaunda L.; Won1, Sungho; Mayanja- Kizza, Harriet; Mugerwa, Roy D.; Leontiev, Dmitry V.; Thompson, Cheryl L.; Cartier, Kevin C.; Elston, Robert C.; Iyengar, Sudha K.; Boom, Henry; Whalen, Christopher C.Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), is an enduring public health problem globally, particularly in sub-Saharan Africa. Several studies have suggested a role for host genetic susceptibility in increased risk for TB but results across studies have been equivocal. As part of a household contact study of Mtb infection and disease in Kampala, Uganda, we have taken a unique approach to the study of genetic susceptibility to TB, by studying three phenotypes. First, we analyzed culture confirmed TB disease compared to latent Mtb infection (LTBI) or lack of Mtb infection. Second, we analyzed resistance to Mtb infection in the face of continuous exposure, defined by a persistently negative tuberculin skin test (PTST-); this outcome was contrasted to LTBI. Third, we analyzed an intermediate phenotype, tumor necrosis factor-alpha (TNFa) expression in response to soluble Mtb ligands enriched with molecules secreted from Mtb (culture filtrate). We conducted a full microsatellite genome scan, using genotypes generated by the Center for Medical Genetics at Marshfield. Multipoint model-free linkage analysis was conducted using an extension of the Haseman-Elston regression model that includes half sibling pairs, and HIV status was included as a covariate in the model. The analysis included 803 individuals from 193 pedigrees, comprising 258 full sibling pairs and 175 half sibling pairs. Suggestive linkage (p,1023) was observed on chromosomes 2q21-2q24 and 5p13-5q22 for PTST-, and on chromosome 7p22-7p21 for TB; these findings for PTST- are novel and the chromosome 7 region contains the IL6 gene. In addition, we replicated recent linkage findings on chromosome 20q13 for TB (p = 0.002). We also observed linkage at the nominal a = 0.05 threshold to a number of promising candidate genes, SLC11A1 (PTST- p = 0.02), IL-1 complex (TB p = 0.01), IL12BR2 (TNFa p = 0.006), IL12A (TB p = 0.02) and IFNGR2 (TNFa p = 0.002). These results confirm not only that genetic factors influence the interaction between humans and Mtb but more importantly that they differ according to the outcome of that interaction: exposure but no infection, infection without progression to disease, or progression of infection to disease. Many of the genetic factors for each of these stages are part of the innate immune system.Item Infectiousness of HIV-Seropositive Patients with Tuberculosis in a High-Burden African Setting(PloS one, 2016) Martinez, Leonardo; Sekandi, Juliet N.; Castellanos, Maria E.; Zalwango, Sarah; Whalen, Christopher C.Policy recommendations on contact investigation of HIV-seropositive patients with tuberculosis have changed several times. Current epidemiologic evidence informing these recommendations is considered low quality, and few large studies investigating the infectiousness of HIV-seropositive and -seronegative index cases have been performed in sub-Saharan Africa. Objectives: We assessed the infectiousness of HIV-seropositive and -seronegative patients with tuberculosis to their household contacts and examined potential modifiers of this relationship. Methods: Adults suffering from their first episode of pulmonary tuberculosis were identified in Kampala, Uganda. Field workers visited index households and enrolled consenting household contacts. Latent tuberculosis infection was measured through tuberculin skin testing, and relative risks were calculated using modified Poisson regression models. Standard assessments of interaction between latent tuberculosis infection, the HIV serostatus of index cases, and other variables were performed.Item Innate and Adaptive Immune Responses during Acute M. tuberculosis Infection in Adult Household Contacts in Kampala, Uganda(The American journal of tropical medicine and hygiene, 2011) Mahan, C. Scott; Zalwango, Sarah; Thiel, Bonnie A.; Malone, LaShaunda L.; Chervenak, Keith A.; Baseke, Joy; Dobbs, Dennis; Stein, Catherine M.; Mayanja, Harriet; Joloba, Moses; Whalen, Christopher C.; Boom, W. HenryContacts of active pulmonary tuberculosis (TB) patients are at risk for Mycobacterium tuberculosis (MTB) infection. Because most infections are controlled, studies during MTB infection provide insight into protective immunity. We compared immune responses of adult household contacts that did and did not convert the tuberculin skin test (TST). Innate and adaptive immune responses were measured by whole blood assay. Responses of TST converters (TSTC) were compared with persistently TST negative contacts (PTST–) and contacts who were TST+ at baseline (TST+). TLR-2, TLR-4, and IFN-gR responses to IFN-g did not differ between the groups, nor did gd T cell responses. T cell responses to MTB antigens differed markedly among TSTC, PTST–, and TST+ contacts. Thus, no differences in innate responses were found among the three household contact groups. However, adaptive T cell responses to MTB antigens did differ before and during MTB infection among PTST–, TSTC, and TST+ contacts.Item Lean Tissue Mass Wasting is Associated With Increased Risk of Mortality Among Women With Pulmonary Tuberculosis in Urban Uganda(Elsevier Inc., 2012) Mupere, Ezekiel; Malone, Lashaunda; Zalwango, Sarah; Chiunda, Allan; Okwera, Alphonse; Parraga, Isabel; Stein, Catherine M.; Tisch, Daniel J.; Mugerwa, Roy; Boom, W. Henry; Mayanja, Harriet; Whalen, Christopher C.OBJECTIVES: We assessed the impact of wasting on survival in patients with tuberculosis by using a precise height-normalized lean tissue mass index (LMI) estimated by bioelectrical impedance analysis and body mass index (BMI). METHODS: In a retrospective cohort study, 747 adult pulmonary patients with tuberculosis who were screened for HIV and nutritional status were followed for survival. RESULTS: Of 747 patients, 310 had baseline wasting by BMI (kg/m2) and 103 by LMI (kg/m2). Total deaths were 105. Among men with reduced BMI, risk of death was 70% greater (hazard ratio [HR] 1.7, 95% confidence interval [95% CI] 1.03–2.81) than in men with normal BMI. Survival did not differ by LMI among men (HR 1.1; 95% CI 0.5–2.9). In women, both the BMI and LMI were associated with survival. Among women with reduced BMI, risk of death was 80% greater (HR 1.8; 95% CI 0.9–3.5) than in women with normal BMI; risk of death was 5-fold greater (HR 5.0; 95% CI 1.6–15.9) for women with low LMI compared with women with normal LMI. CONCLUSIONS: Wasting assessed by reduced BMI is associated with an increased risk for death among both men and women whereas reduced LMI is among women with tuberculosis.