title: Excess Mortality Associated with Influenza among Tuberculosis Deaths in South Africa, 1999-2009.
abstract: BACKGROUND
  Published data on the interaction between influenza and pulmonary tuberculosis (PTB) are limited. We aimed to estimate the influenza-associated mortality among individuals with PTB in South Africa from 1999-2009.
  
  
  METHODS
  We modelled the excess influenza-associated mortality by applying Poisson regression models to monthly PTB and non-tuberculosis respiratory deaths, using laboratory-confirmed influenza as a covariate.
  
  
  RESULTS
  PTB deaths increased each winter, coinciding with influenza virus circulation. Among individuals of any age, mean annual influenza-associated PTB mortality rate was 164/100,000 person-years (n = 439). The rate of non-tuberculosis respiratory deaths was 27/100,000 (n = 1125) for HIV-infected and 5/100,000 (n = 2367) for HIV-uninfected individuals of all ages. Among individuals aged <65 years, influenza-associated PTB mortality risk was elevated compared to influenza-associated non-tuberculosis respiratory deaths in HIV-infected (relative risk (RR): 5.2; 95% CI: 4.6-5.9) and HIV-uninfected individuals (RR: 61.0; CI: 41.4-91.0). Among individuals aged ≥65 years, influenza-associated PTB mortality risk was elevated compared to influenza-associated non-tuberculosis respiratory deaths in HIV-uninfected individuals (RR: 13.0; 95% CI: 12.0-14.0).
  
  
  CONCLUSIONS
  We observed an increased risk of influenza-associated mortality in persons with PTB compared to non-tuberculosis respiratory deaths. If confirmed in other settings, our findings may support recommendations for active inclusion of patients with TB for influenza vaccination and empiric influenza anti-viral treatment of patients with TB during influenza epidemics.
authors.affiliation: National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa; Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
authors.forename: Sibongile
authors.initials: S
authors.lastname: Walaza
authors.affiliation: National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa; Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
authors.forename: Cheryl
authors.initials: C
authors.lastname: Cohen
authors.affiliation: National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa.
authors.forename: Ananta
authors.initials: A
authors.lastname: Nanoo
authors.affiliation: Influenza Division, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America; Influenza Division, Centers for Disease Control and Prevention, Pretoria, South Africa.
authors.forename: Adam L
authors.initials: AL
authors.lastname: Cohen
authors.affiliation: National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa.
authors.forename: Johanna
authors.initials: J
authors.lastname: McAnerney
authors.affiliation: National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa; Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
authors.forename: Claire
authors.initials: C
authors.lastname: von Mollendorf
authors.affiliation: National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa; Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
authors.forename: Jocelyn
authors.initials: J
authors.lastname: Moyes
authors.affiliation: National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa; Influenza Division, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America; Influenza Division, Centers for Disease Control and Prevention, Pretoria, South Africa.
authors.forename: Stefano
authors.initials: S
authors.lastname: Tempia
mesh_terms: D062665:Epidemiological Monitoring; D006801:Humans; D007251:Influenza, Human / Q000150:complications / Q000401:mortality*; D016012:Poisson Distribution; D012044:Regression Analysis; D012307:Risk Factors; D012621:Seasons; D012720:Severity of Illness Index; D013019:South Africa / Q000453:epidemiology; D014376:Tuberculosis / Q000150:complications / Q000401:mortality*