Browsing by Author "Zwahlen M"

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    Hepatitis B viral load in dried blood spots: A validation study in Zambia.
    (2015-Nov) Vinikoor MJ; Zürcher S; Musukuma K; Kachuwaire O; Rauch A; Chi BH; Gorgievski M; Zwahlen M; Wandeler G; Department of Infectious Diseases, University Hospital Bern, Switzerland.; Institute of Infectious Diseases, University of Bern, Switzerland.; Institute of Social and Preventive Medicine, University of Bern, Switzerland.; Department of Medicine, University of Alabama at Birmingham, USA; Centre for Infectious Disease Research in Zambia, Lusaka, Zambia; School of Medicine, University of Zambia, Lusaka, Zambia. Electronic address: mjv3@uab.edu.; Department of Infectious Diseases, University Hospital Bern, Switzerland; Institute of Social and Preventive Medicine, University of Bern, Switzerland; Department of Infectious Diseases, University of Dakar, Senegal.; Centre for Infectious Disease Research in Zambia, Lusaka, Zambia; School of Medicine, University of Zambia, Lusaka, Zambia.; Department of Obstetrics and Gynecology, University of North Carolina at Chapel Hill, USA.; Centre for Infectious Disease Research in Zambia, Lusaka, Zambia.; CIDRZ; Centre for Infectious Disease Research in Zambia (CIDRZ)
    BACKGROUND: Access to hepatitis B viral load (VL) testing is poor in sub-Saharan Africa (SSA) due to economic and logistical reasons. OBJECTIVES: To demonstrate the feasibility of testing dried blood spots (DBS) for hepatitis B virus (HBV) VL in a laboratory in Lusaka, Zambia, and to compare HBV VLs between DBS and plasma samples. STUDY DESIGN: Paired plasma and DBS samples from HIV-HBV co-infected Zambian adults were analyzed for HBV VL using the COBAS AmpliPrep/COBAS TaqMan HBV test (Version 2.0) and for HBV genotype by direct sequencing. We used Bland-Altman analysis to compare VLs between sample types and by genotype. Logistic regression analysis was conducted to assess the probability of an undetectable DBS result by plasma VL. RESULTS: Among 68 participants, median age was 34 years, 61.8% were men, and median plasma HBV VL was 3.98logIU/ml (interquartile range, 2.04-5.95). Among sequenced viruses, 28 were genotype A1 and 27 were genotype E. Bland-Altman plots suggested strong agreement between DBS and plasma VLs. DBS VLs were on average 1.59logIU/ml lower than plasma with 95% limits of agreement of -2.40 to -0.83log IU/ml. At a plasma VL ≥2,000IU/ml, the probability of an undetectable DBS result was 1.8% (95% CI: 0.5-6.6). At plasma VL ≥20,000IU/ml this probability reduced to 0.2% (95% CI: 0.03-1.7). CONCLUSIONS: In a Zambian laboratory, we observed strong agreement between DBS and plasma VLs and high sensitivity in DBS at plasma VL ≥2,000IU/ml. As HBV treatment expands, DBS could increase access to HBV VL testing and care in SSA settings.
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    Seasonal variations in tuberculosis diagnosis among HIV-positive individuals in Southern Africa: analysis of cohort studies at antiretroviral treatment programmes.
    (2018-Jan-11) Ballif M; Zürcher K; Reid SE; Boulle A; Fox MP; Prozesky HW; Chimbetete C; Zwahlen M; Egger M; Fenner L; Newlands Clinic, Harare, Zimbabwe.; Department of Internal Medicine, Health Economics and Epidemiology Research Office, School of Clinical Medicine, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.; Division of Infection Diseases, University of Alabama at Birmingham, Birmingham, Alabama, USA.; Centre for Infectious Disease Epidemiology and Research (CIDER), School of Public Health and Family Medicine, University of Cape Town, Cape Town, South Africa.; Division of Infectious Diseases, Department of Medicine, University of Stellenbosch & Tygerberg Academic Hospital, Cape Town, South Africa.; Departments of Epidemiology and Global Health, Boston University, Boston, USA.; Institute of Social and Preventive Medicine, University of Bern, Bern, BE, Switzerland.; Médecins Sans Frontières, Khayelitsha, South Africa.; Tuberculosis Department Unit, Centre for Infectious Disease Research in Zambia (CIDRZ), Lusaka, Zambia.
    OBJECTIVES: Seasonal variations in tuberculosis diagnoses have been attributed to seasonal climatic changes and indoor crowding during colder winter months. We investigated trends in pulmonary tuberculosis (PTB) diagnosis at antiretroviral therapy (ART) programmes in Southern Africa. SETTING: Five ART programmes participating in the International Epidemiology Database to Evaluate AIDS in South Africa, Zambia and Zimbabwe. PARTICIPANTS: We analysed data of 331 634 HIV-positive adults (>15 years), who initiated ART between January 2004 and December 2014. PRIMARY OUTCOME MEASURE: We calculated aggregated averages in monthly counts of PTB diagnoses and ART initiations. To account for time trends, we compared deviations of monthly event counts to yearly averages, and calculated correlation coefficients. We used multivariable regressions to assess associations between deviations of monthly ART initiation and PTB diagnosis counts from yearly averages, adjusted for monthly air temperatures and geographical latitude. As controls, we used Kaposi sarcoma and extrapulmonary tuberculosis (EPTB) diagnoses. RESULTS: All programmes showed monthly variations in PTB diagnoses that paralleled fluctuations in ART initiations, with recurrent patterns across 2004-2014. The strongest drops in PTB diagnoses occurred in December, followed by April-May in Zimbabwe and South Africa. This corresponded to holiday seasons, when clinical activities are reduced. We observed little monthly variation in ART initiations and PTB diagnoses in Zambia. Correlation coefficients supported parallel trends in ART initiations and PTB diagnoses (correlation coefficient: 0.28, 95% CI 0.21 to 0.35, P<0.001). Monthly temperatures and latitude did not substantially change regression coefficients between ART initiations and PTB diagnoses. Trends in Kaposi sarcoma and EPTB diagnoses similarly followed changes in ART initiations throughout the year. CONCLUSIONS: Monthly variations in PTB diagnosis at ART programmes in Southern Africa likely occurred regardless of seasonal variations in temperatures or latitude and reflected fluctuations in clinical activities and changes in health-seeking behaviour throughout the year, rather than climatic factors.