S Floyd

Summary

Affiliation: London School of Hygiene and Tropical Medicine
Country: UK

Publications

  1. doi request reprint Underestimation of HIV prevalence in surveys when some people already know their status, and ways to reduce the bias
    Sian Floyd
    London School of Hygiene and Tropical Medicine, Keppel Street, WC1E 7HT London, UK
    AIDS 27:233-42. 2013
  2. pmc The effect of antiretroviral therapy provision on all-cause, AIDS and non-AIDS mortality at the population level--a comparative analysis of data from four settings in Southern and East Africa
    Sian Floyd
    London School of Hygiene and Tropical Medicine, London, UK
    Trop Med Int Health 17:e84-93. 2012
  3. pmc Persistence of the immune response induced by BCG vaccination
    Rosemary E Weir
    London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
    BMC Infect Dis 8:9. 2008
  4. pmc Differences between naive and memory T cell phenotype in Malawian and UK adolescents: a role for Cytomegalovirus?
    Anne Ben-Smith
    Department of Infectious and Tropical Diseases, Keppel Street, London WC1E7HT, UK
    BMC Infect Dis 8:139. 2008
  5. ncbi request reprint BCG scars in northern Malawi: sensitivity and repeatability of scar reading, and factors affecting scar size
    S Floyd
    Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, UK
    Int J Tuberc Lung Dis 4:1133-42. 2000
  6. ncbi request reprint The social and economic impact of parental HIV on children in northern Malawi: retrospective population-based cohort study
    S Floyd
    London School of Hygiene and Tropical Medicine, London, UK
    AIDS Care 19:781-90. 2007
  7. doi request reprint The long-term social and economic impact of HIV on the spouses of infected individuals in northern Malawi
    Sian Floyd
    London School of Hygiene and Tropical Medicine, London, UK
    Trop Med Int Health 13:520-31. 2008
  8. ncbi request reprint Kinetics of delayed-type hypersensitivity to tuberculin induced by bacille Calmette-Guérin vaccination in northern Malawi
    Sian Floyd
    Department of Infectious and Tropical Diseases, Infectious Diseases Epidemiology Unit, London School of Hygiene and Tropical Medicine, London, United Kingdom
    J Infect Dis 186:807-14. 2002
  9. pmc Population-level reduction in adult mortality after extension of free anti-retroviral therapy provision into rural areas in northern Malawi
    Sian Floyd
    Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, United Kingdom
    PLoS ONE 5:e13499. 2010
  10. pmc The influence of previous exposure to environmental mycobacteria on the interferon-gamma response to bacille Calmette-Guérin vaccination in southern England and northern Malawi
    R E Weir
    Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
    Clin Exp Immunol 146:390-9. 2006

Collaborators

Detail Information

Publications47

  1. doi request reprint Underestimation of HIV prevalence in surveys when some people already know their status, and ways to reduce the bias
    Sian Floyd
    London School of Hygiene and Tropical Medicine, Keppel Street, WC1E 7HT London, UK
    AIDS 27:233-42. 2013
    ..To quantify refusal bias due to prior HIV testing, and its effect on HIV prevalence estimates, in general-population surveys...
  2. pmc The effect of antiretroviral therapy provision on all-cause, AIDS and non-AIDS mortality at the population level--a comparative analysis of data from four settings in Southern and East Africa
    Sian Floyd
    London School of Hygiene and Tropical Medicine, London, UK
    Trop Med Int Health 17:e84-93. 2012
    ..To provide a broad and up-to-date picture of the effect of antiretroviral therapy (ART) provision on population-level mortality in Southern and East Africa...
  3. pmc Persistence of the immune response induced by BCG vaccination
    Rosemary E Weir
    London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
    BMC Infect Dis 8:9. 2008
    ....
  4. pmc Differences between naive and memory T cell phenotype in Malawian and UK adolescents: a role for Cytomegalovirus?
    Anne Ben-Smith
    Department of Infectious and Tropical Diseases, Keppel Street, London WC1E7HT, UK
    BMC Infect Dis 8:139. 2008
    ....
  5. ncbi request reprint BCG scars in northern Malawi: sensitivity and repeatability of scar reading, and factors affecting scar size
    S Floyd
    Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, UK
    Int J Tuberc Lung Dis 4:1133-42. 2000
    ..Karonga district, northern Malawi...
  6. ncbi request reprint The social and economic impact of parental HIV on children in northern Malawi: retrospective population-based cohort study
    S Floyd
    London School of Hygiene and Tropical Medicine, London, UK
    AIDS Care 19:781-90. 2007
    ....
  7. doi request reprint The long-term social and economic impact of HIV on the spouses of infected individuals in northern Malawi
    Sian Floyd
    London School of Hygiene and Tropical Medicine, London, UK
    Trop Med Int Health 13:520-31. 2008
    ..To assess the social and economic impact of HIV-related illness and death on the spouses of HIV-infected individuals...
  8. ncbi request reprint Kinetics of delayed-type hypersensitivity to tuberculin induced by bacille Calmette-Guérin vaccination in northern Malawi
    Sian Floyd
    Department of Infectious and Tropical Diseases, Infectious Diseases Epidemiology Unit, London School of Hygiene and Tropical Medicine, London, United Kingdom
    J Infect Dis 186:807-14. 2002
    ..The inability of some persons to mount a persistent DTH response probably reflects genetic background and/or environmental exposure history...
  9. pmc Population-level reduction in adult mortality after extension of free anti-retroviral therapy provision into rural areas in northern Malawi
    Sian Floyd
    Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, United Kingdom
    PLoS ONE 5:e13499. 2010
    ..It is important to see if the impact changes with time since the start of treatment scale-up, and as treatment moves to smaller clinics...
  10. pmc The influence of previous exposure to environmental mycobacteria on the interferon-gamma response to bacille Calmette-Guérin vaccination in southern England and northern Malawi
    R E Weir
    Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
    Clin Exp Immunol 146:390-9. 2006
    ..These observations should assist the development and interpretation of human clinical trials of new vaccines against M. tuberculosis in areas of both low and high exposure to environmental mycobacteria...
  11. pmc Declining child mortality in northern Malawi despite high rates of infection with HIV
    A Jahn
    Infectious Disease Epidemiology Unit, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, England
    Bull World Health Organ 88:746-53. 2010
    ..To determine whether routine surveys, such as the Demographic and Health Surveys (DHS), have underestimated child mortality in Malawi...
  12. ncbi request reprint A comparison of dual skin test with mycobacterial antigens and tuberculin skin test alone in estimating prevalence of Mycobacterium tuberculosis infection from population surveys
    A L Bierrenbach
    Department of Infectious and Tropical Disease, London School of Hygiene and Tropical Medicine, London, UK
    Int J Tuberc Lung Dis 7:312-9. 2003
    ..City of Manaus, Amazonas, Brazil...
  13. ncbi request reprint Immunogenicity of Danish-SSI 1331 BCG vaccine in the UK: comparison with Glaxo-Evans 1077 BCG vaccine
    Patricia Gorak-Stolinska
    London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, and Redbridge Primary Care Trust, Goodmayes Hospital, Essex, UK
    Vaccine 24:5726-33. 2006
    ..There was no evidence of a difference in immunogenicity (IFN-gamma and DTH conversion rates) but evidence of lower reactogenicity (scar size) with Danish-SSI 1331 compared to Glaxo-Evans 1077 vaccines...
  14. ncbi request reprint Time delays between patient and laboratory selectively affect accuracy of helminth diagnosis
    R J Dacombe
    London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK
    Trans R Soc Trop Med Hyg 101:140-5. 2007
    ..This is particularly critical when samples are not preserved, even over short periods of time, and even with formalin preservation...
  15. pmc Interferon-gamma and skin test responses of schoolchildren in southeast England to purified protein derivatives from Mycobacterium tuberculosis and other species of mycobacteria
    R E Weir
    Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
    Clin Exp Immunol 134:285-94. 2003
    ..marinum (45-60% responders). Heaf test and IFN-gamma responses were associated (P<0.001) for M. tuberculosis, MAIS and M. marinum. These findings have implications for appropriate implementation of vaccination against tuberculosis...
  16. ncbi request reprint Patterns of helminth infection and relationship to BCG vaccination in Karonga District, northern Malawi
    A E Randall
    Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK
    Trans R Soc Trop Med Hyg 96:29-33. 2002
    ....
  17. pmc Tuberculosis transmission attributable to close contacts and HIV status, Malawi
    Amelia C Crampin
    London School of Hygiene and Tropical Medicine, Keppel Street, London, United Kingdom
    Emerg Infect Dis 12:729-35. 2006
    ..We estimate that 9%-13% of TB cases were attributable to recent transmission from identifiable close contacts and that nearly half of the TB cases arising from recent infection had acquired the infection from HIV-positive patients...
  18. pmc Trends in marriage and time spent single in sub-Saharan Africa: a comparative analysis of six population-based cohort studies and nine Demographic and Health Surveys
    M Marston
    Centre for Population Studies, London School of Hygiene and Tropical Medicine, London, UK
    Sex Transm Infect 85:i64-71. 2009
    ..To describe trends in age at first sex (AFS), age at first marriage (AFM) and time spent single between events and to compare age-specific trends in marital status in six cohort studies...
  19. pmc Assessment and evaluation of contact as a risk factor for tuberculosis in rural Africa
    A C Crampin
    Karonga Prevention Study, Chilumba, Malawi
    Int J Tuberc Lung Dis 12:612-8. 2008
    ..A rural district in Malawi...
  20. doi request reprint Ascertainment of childhood vaccination histories in northern Malawi
    A Jahn
    Karonga Prevention Study, Chilumba, Malawi
    Trop Med Int Health 13:129-38. 2008
    ..To assess factors related to recorded vaccine uptake, which may confound the evaluation of vaccine impact...
  21. pmc Recurrent TB: relapse or reinfection? The effect of HIV in a general population cohort in Malawi
    Amelia C Crampin
    Karonga Prevention Study, Chilumba, Malawi
    AIDS 24:417-26. 2010
    ..To estimate rates of recurrent tuberculosis due to reinfection and relapse, by HIV status, in a general population...
  22. pmc Complex cytokine profiles induced by BCG vaccination in UK infants
    Maeve K Lalor
    Immunology Unit, Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK
    Vaccine 28:1635-41. 2010
    ..The pattern of cytokine induction following BCG vaccination is complex and measurement of one of two cytokines does not reveal the whole picture of vaccine-induced protection...
  23. pmc Population differences in immune responses to Bacille Calmette-Guérin vaccination in infancy
    Maeve K Lalor
    Immunology Unit, Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
    J Infect Dis 199:795-800. 2009
    ..We conclude that population differences in immune responses after BCG vaccination are observed among infants, as well as among young adults...
  24. pmc Population-level effect of HIV on adult mortality and early evidence of reversal after introduction of antiretroviral therapy in Malawi
    Andreas Jahn
    London School of Hygiene and Tropical Medicine, London, UK
    Lancet 371:1603-11. 2008
    ..We aimed to investigate mortality in a population before and after the introduction of free antiretroviral therapy, and therefore to assess the effects of such programmes on survival at the population level...
  25. doi request reprint From affected to infected? Orphanhood and HIV risk among female adolescents in urban Zimbabwe
    Isolde J Birdthistle
    Department of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, UK
    AIDS 22:759-66. 2008
    ..Despite the 15 million children orphaned by AIDS, and fears of sexual vulnerability, little is known about the link between orphanhood and HIV risk...
  26. pmc Use of antenatal clinic surveillance to assess the effect of sexual behavior on HIV prevalence in young women in Karonga district, Malawi
    Amelia Catharine Crampin
    Department of Epidemiology and Public Health, London School of Hygiene and Tropical Medicine, London, United Kingdom
    J Acquir Immune Defic Syndr 48:196-202. 2008
    ..Sexual behavior monitoring to explain HIV distribution and trends is seldom attempted in ANC surveys. We explore the use of marital history in ANC surveillance as a proxy for sexual behavior...
  27. doi request reprint Is education the link between orphanhood and HIV/HSV-2 risk among female adolescents in urban Zimbabwe?
    Isolde Birdthistle
    London School of Hygiene and Tropical Medicine, London, United Kingdom
    Soc Sci Med 68:1810-8. 2009
    ....
  28. ncbi request reprint DNA fingerprint changes in tuberculosis: reinfection, evolution, or laboratory error?
    Judith R Glynn
    Infectious Disease Epidemiology Unit, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, United Kingdom
    J Infect Dis 190:1158-66. 2004
    ..We explored the importance of these factors...
  29. pmc The effects of high HIV prevalence on orphanhood and living arrangements of children in Malawi, Tanzania, and South Africa
    Victoria Hosegood
    London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK
    Popul Stud (Camb) 61:327-36. 2007
    ..For example, we find no evidence that the prevalence of child-headed households is significant or has increased in the three study areas...
  30. ncbi request reprint Trends in tuberculosis and the influence of HIV infection in northern Malawi, 1988-2001
    Judith R Glynn
    London School of Hygiene and Tropical Medicine, UK
    AIDS 18:1459-63. 2004
    ..To document the changing incidence and patterns of tuberculosis (TB) in rural Africa and the extent to which they are influenced by HIV...
  31. pmc Mycobacterial purified protein derivatives stimulate innate immunity: Malawians show enhanced tumor necrosis factor alpha, interleukin-1beta (IL-1beta), and IL-10 responses compared to those of adolescents in the United Kingdom
    Rosemary E Weir
    Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
    Infect Immun 72:1807-11. 2004
    ..Priming for regulatory IL-10 may contribute to the smaller increase in gamma interferon responses in Malawians compared to United Kingdom subjects following BCG vaccination...
  32. pmc Mycobacterium tuberculosis Beijing genotype, northern Malawi
    Judith R Glynn
    London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, United Kingdom
    Emerg Infect Dis 11:150-3. 2005
    ..All the Beijing genotype strains were fully drug sensitive. Contact histories, TB type, and case-fatality rates were similar for Beijing and non-Beijing genotype TB...
  33. ncbi request reprint HIV and mortality of mothers and children: evidence from cohort studies in Uganda, Tanzania, and Malawi
    Basia Zaba
    Centre for Population Studies, London School of Hygiene and Tropical Medicine, 49 51 Bedford Square, London WC1B 3DP, UK
    Epidemiology 16:275-80. 2005
    ..However, the census and household survey data that generally are used to produce estimates of child mortality do not permit precise measures of the adverse effect of HIV on child mortality...
  34. ncbi request reprint Comparison of IFN-gamma responses to mycobacterial antigens as markers of response to BCG vaccination
    Rosemary E Weir
    Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK
    Tuberculosis (Edinb) 88:31-8. 2008
    ..We therefore conclude that Mtb PPD is the antigen preparation of choice for assessing the immunogenicity of BCG vaccination...
  35. pmc Child mortality in rural Malawi: HIV closes the survival gap between the socio-economic strata
    Andreas Jahn
    Department of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, United Kingdom
    PLoS ONE 5:e11320. 2010
    ..As HIV-related deaths increase in a population the usual association between low socioeconomic status and child mortality may change, particularly as death rates from other causes decline...
  36. pmc Implication of new WHO growth standards on identification of risk factors and estimated prevalence of malnutrition in rural Malawian infants
    Marc André Prost
    Epidemiology and Population Health Department, London School of Hygiene and Tropical Medicine, London, United Kingdom
    PLoS ONE 3:e2684. 2008
    ..We assessed how switching from the NCHS to the newly released WHO Growth Standards affects the estimated prevalence of wasting, underweight and stunting, and the pattern of risk factors identified...
  37. pmc Gamma interferon responses induced by a panel of recombinant and purified mycobacterial antigens in healthy, non-mycobacterium bovis BCG-vaccinated Malawian young adults
    Gillian F Black
    Karonga Prevention Study, Chilumba, Malawi
    Clin Diagn Lab Immunol 10:602-11. 2003
    ..tuberculosis antigens tested it provided the best indication of exposure to, or infection with, M. tuberculosis...
  38. ncbi request reprint Long-term follow-up of HIV-positive and HIV-negative individuals in rural Malawi
    Amelia C Crampin
    Karonga Prevention Study, PO Box 46, Chilumba, Malawi
    AIDS 16:1545-50. 2002
    ..To measure the effect of HIV on survival in rural Africa...
  39. ncbi request reprint BCG-induced increase in interferon-gamma response to mycobacterial antigens and efficacy of BCG vaccination in Malawi and the UK: two randomised controlled studies
    Gillian F Black
    Karonga Prevention Study, Chilumba, Malawi
    Lancet 359:1393-401. 2002
    ..To investigate the mechanism underlying these differences, randomised controlled studies were set up to measure vaccine-induced immune responsiveness to mycobacterial antigens in both populations...
  40. ncbi request reprint The long-term impact of HIV and orphanhood on the mortality and physical well-being of children in rural Malawi
    Amelia C Crampin
    Karonga Prevention Study, Chilumba, Karonga, Malawi
    AIDS 17:389-97. 2003
    ..To assess the influence of maternal HIV status and orphanhood on child mortality and physical well-being...
  41. pmc Cotrimoxazole prophylaxis reduces mortality in human immunodeficiency virus-positive tuberculosis patients in Karonga District, Malawi
    Frank B D Mwaungulu
    Karonga Prevention Study, Karonga, Malawi
    Bull World Health Organ 82:354-63. 2004
    ..To estimate the impact of cotrimoxazole prophylaxis on the survival of human immunodeficiency virus (HIV)-positive tuberculosis (TB) patients...
  42. ncbi request reprint Large-scale candidate gene study of leprosy susceptibility in the Karonga district of northern Malawi
    Jodene Fitness
    Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
    Am J Trop Med Hyg 71:330-40. 2004
    ..These data provide evidence of inter-population heterogeneity in leprosy susceptibility...
  43. ncbi request reprint Large-scale candidate gene study of tuberculosis susceptibility in the Karonga district of northern Malawi
    Jodene Fitness
    Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
    Am J Trop Med Hyg 71:341-9. 2004
    ..Genetic susceptibility to TB in Africans appears polygenic. The relevant genes and variants may vary significantly between populations, and may be affected by HIV infection status...
  44. ncbi request reprint The PPD-specific T-cell clonal response in UK and Malawian subjects following BCG vaccination: a new repertoire evolves over 12 months
    Andrea R Bennett
    Edward Jenner Institute for Vaccine Research, Compton, Berkshire RG20 7NN, UK
    Vaccine 24:2617-26. 2006
    ..The magnitude of the clonal response did not correlate well with results of the other assays. These data indicate that single assays may not be reliable and that a stable memory T-cell repertoire is slow to develop...
  45. pmc Distribution of environmental mycobacteria in Karonga District, northern Malawi
    Benson Z Chilima
    Plant Pathogen Interactions Division, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, United Kingdom
    Appl Environ Microbiol 72:2343-50. 2006
    ..This study revealed a complex pattern for the environmental mycobacterial flora but identified no clear differences between the northern and southern parts of Karonga District...
  46. pmc CD209 genetic polymorphism and tuberculosis disease
    Fredrik O Vannberg
    Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
    PLoS ONE 3:e1388. 2008
    ..The present study investigates the role of the CD209 -336A/G variant in susceptibility to tuberculosis in a large sample of individuals from sub-Saharan Africa...