Impact of influenza season and environmental factors on the clinical presentation and outcome of invasive pneumococcal disease

Abstract

Influenza and meteorological factors have been associated with increases in the incidence of invasive pneumococcal disease (IPD). However, scant data regarding the impact of influenza and the environment on the clinical presentation of IPD are available. An observational study of all adults hospitalized with IPD was performed between 1996 and 2012 in our hospital. The incidence of IPD correlated with the incidence rates of influenza and with environmental data. A negative binominal regression was used to assess the relationship between these factors. Clinical presentation of IPD during the influenza and non-influenza periods was compared. During the study, 1,150 episodes of IPD were diagnosed. After adjusting for confounding variables, factors correlating with the rates of IPD were the incidence of influenza infection (IRR 1.229, 95% CI 1.025-1.472) and the average ambient temperature (IRR 0.921, 95% CI 0.88-0.964). Patients with IPD during the influenza period had a worse respiratory status. A greater proportion of patients had respiratory failure (45.6% vs 52%, p = 0.032) and higher requirements for ICU admission (19.3% vs 24.7%, p = 0.018) and mechanical ventilation (11% vs 15.1%, p = 0.038). When we stratified by invasiveness of pneumococcal serotypes and the presence of comorbid conditions, the increase in the severity of clinical presentation was focused on healthy adults with IPD caused by nonhighly invasive serotypes. Beyond the increase in the burden of IPD associated with influenza, a more severe clinical pattern of pneumococcal disease was observed in the influenza period. This effect varied according to pneumococcal serotype, host comorbidities, and age.

HIV Infection and the Epidemiology of Invasive Pneumococcal Disease (IPD) in South African Adults and Older Children Prior to the Introduction of a Pneumococcal Conjugate Vaccine (PCV)

“…However, in HIV-infected populations additional preventative interventions could be considered such as direct vaccination of selected groups with pneumococcal vaccine, increased uptake of the seasonal influenza vaccine and increased use of ART. [ 46 – 49 ]…”

Postviral Complications

“…The incidence of bacterial pneumonia mirrors the seasonal nature of viral infections, with increases during peak viral seasons. 19 , 28 , 29 , 30 , 31 Data from the 2009 H1N1 epidemic show that coinfection usually occurs within the first 6 days of influenza infection, 32 , 33 although it can develop up to 14 days after other viral infections. This delay likely represents the time needed for viral replication and the immunomodulatory effects of infection to occur.…”

The problem of early mortality in pneumococcal pneumonia: a study of risk factors

“…First, the study included only patients with IPP, and therefore it is difficult to generalise the findings to all cases of pneumococcal pneumonia. Secondly, other factors that might modulate the clinical presentation of pneumococcal pneumonia, such as the genetic properties of S. pneumoniae or the host, or the effect of viral co-infections, have not been evaluated [5]. Finally, we have not evaluated the inflammatory response of the host or anti-inflammatory therapy, so we cannot fully support our hypothesis concerning the effect of encapsulated serotypes or immunosuppressive conditions on mortality.…”

“…Different factors related to the mortality of pneumococcal disease have been described, including host factors such as age, comorbidities or immunosuppressive conditions [4], and organism-related factors such as serotype, bacterial load or viral co-infection [3,[5][6][7]. These factors have all been primarily identified to predict overall mortality, but information regarding the determinants of early mortality is scarce.…”