Influenza virus infection is associated with increased risk of death amongst patients hospitalized with confirmed pulmonary tuberculosis in South Africa, 2010-2011.

Sibongile Walaza,Michelle Groome,Cheryl Cohen,Kathleen Kahn,Halima Dawood,Claire Von Mollendorf,Nicole Wolter,Marthi Pretorius,Adam L Cohen,Stefano Tempia,Marietjie Venter,Jocelyn Moyes,Shabir A Madhi,Ebrahim Variava

doi:10.1186/s12879-015-0746-x

Abstract

BackgroundData on the association between influenza and tuberculosis are limited. We describe the characteristics of patients with laboratory-confirmed tuberculosis, laboratory-confirmed influenza and tuberculosis-influenza co-infection.MethodsPatients hospitalized with severe respiratory illness (acute and chronic) were enrolled prospectively in four provinces in South Africa. Naso/oropharyngeal specimens were tested for influenza virus by real time reverse transcriptase polymerase chain reaction. Tuberculosis testing was conducted as part of clinical management.ResultsFrom June 2010 through December 2011, 8032 patients were enrolled and influenza testing was conducted on 7863 (98%). Influenza virus was detected in 765 (10%) patients. Among 2959 patients with tuberculosis and influenza results, 2227 (75%) were negative for both pathogens, 423 (14%) were positive for tuberculosis alone, 275 (9%) were positive for influenza alone and 34 (1%) had influenza and tuberculosis co-infection. On multivariable analysis amongst individuals with symptoms for ≥7 days, tuberculosis influenza co-infection was associated with increased risk of death, (adjusted relative risk ratio (aRRR) (6.1, 95% confidence interval (CI) 1.6-23.4), as compared to tuberculosis only infection. This association was not observed in individuals with symptoms for <7 days (aRRR.0.8, 95% CI 0.1-7.0).ConclusionTuberculosis and influenza co-infection compared to tuberculosis single infection was associated with increased risk of death in individuals with symptoms ≥7 days. The potential public health impact of influenza vaccination among persons with laboratory-confirmed tuberculosis should be explored.

Highlights

Data on the association between influenza and tuberculosis are limited
We describe the epidemiological and clinical characteristics of patients admitted with laboratory-confirmed tuberculosis, influenza and tuberculosis-influenza co-infection among patients hospitalized with severe respiratory illness (SRI) in South Africa, a country with a high prevalence of human immunodeficiency virus (HIV)
Factors associated with tuberculosis testing on admission Among patients with available influenza results, on multivariable analysis factors associated with tuberculosis testing were age ≥5 years, with the highest proportion tested (56%, 1378/2473) in the 25–44 age group (adjusted odds ratio 3.5, 95% CI 3.0-4.2) as compared to age 7 days, requiring oxygen therapy and antibiotic or tuberculosis treatment started during current admission (Table 1)

Summary

Introduction

We describe the characteristics of patients with laboratory-confirmed tuberculosis, laboratory-confirmed influenza and tuberculosis-influenza co-infection. Despite the availability of efficacious treatment, tuberculosis remains the second most common cause of infectious disease–related deaths worldwide, after human immunodeficiency virus (HIV) and acquired immune deficiency syndrome (AIDS) [1]. 8.8 million incident cases of tuberculosis globally [2]. In South Africa, there were an estimated 390,000 incident cases of tuberculosis in 2011 and 65% were co-infected with HIV [1]. Despite the availability of effective vaccines, influenza virus infection causes substantial annual morbidity and mortality worldwide and in South Africa [4,5,6]. It is estimated that influenza epidemics result in three to five million cases of severe illness, and about

Methods

Results

Discussion

Conclusion