ABSTRACT
Background: After the 2009 influenza pandemic the H1N1pdm09 strain circulate seasonally. In 2015, Puerto Montt Hospital in Chile faced a simultaneous outbreak of both seasonal H3N2 and H1N1pdm09 influenza A (IA). Aim: To evaluate the clinical differences between the two viral strains and recent changes in the behavior of H1N1pdm09 IA. Material and Methods: We set up a retrospective study including every adult hospitalized in Puerto Montt Hospital in 2015 due to IA, confirmed by reverse transcription polymerase chain reaction. We compared epidemiological data, clinical presentation, complications, and the outcome of patients with H1N1pdm09 versus those with seasonal influenza. In parallel, we compared 62 cases of thatH1N1 IA from 2015 with 100 cases who were hospitalized and analyzed in 2009. Results: Between July and October 2015, 119 adults with confirmed IA were hospitalized. From 2009 to 2015, the mean age of patients with IAH1N1pdm09 increased from 40.4 ± 17 to 58.8 ± 16 years (p < 0.01). Pneumonia as the cause of hospitalization decreased from 75 to 58% of patients, (p = 0.04). Likewise, the presence of comorbidities increased from 53 to 74%, (p < 0.01). Compared with seasonal H3N2, patients with IAH1N1pdm09 IA were more likely to require intensive care (p < 0.01) and mechanical ventilation (p < 0.01) and developed septic shock (p = 0.03). Their mortality was non-significantly higher (13 and 5% respectively). Conclusions: The clinical presentation of H1N1pdm09 IA has varied over time and now affects an older population, with a greater number of comorbidities. It also appears to be adopting the clinical behavior of a classic seasonal influenza virus.
Subject(s)
Humans , Male , Female , Adult , Middle Aged , Aged , Aged, 80 and over , Influenza, Human/epidemiology , Influenza, Human/virology , Influenza A Virus, H1N1 Subtype/pathogenicity , Pneumonia, Viral/virology , Seasons , Time Factors , Comorbidity , Chile/epidemiology , Disease Outbreaks , Retrospective Studies , Age Factors , Reverse Transcriptase Polymerase Chain Reaction , Influenza, Human/complications , Influenza A Virus, H1N1 Subtype/isolation & purification , Influenza A Virus, H3N2 Subtype/isolation & purification , Influenza A Virus, H3N2 Subtype/pathogenicity , Pandemics , Hospitalization/statistics & numerical dataABSTRACT
Background: Respiratory viral infections (RVi) can be associated with a wide range of clinical manifestations. Aim: To investigate the frequency and clinical manifestations of RVi among adult patients during winter hospitalizations. Patients and Methods: All patients admitted to the hospital with flu like disease and those with fever or exacerbation of any underlying disease during hospitalization without an evident cause, were prospectively enrolled. A direct immunofluorescence (DIF) of nasopharyngeal aspirate for influenza A (IA) and B, parainfluenza 1, 2 and 3, adenovirus, respiratory syncytial virus (RSV) and metapneumovirus, was performed. Epidemiological and clinical data were recorded. Results: Between May and September 2012, 975 adults were admitted to the Internal Medicine Unit of Puerto Montt Hospital and in 128 (13%) patients, DIF was carried out. DIF was positive in 44 patients (34%) aged 65 ± 20 years, 68.2% females, corresponding to 4.5% of total hospitalizations. Eighty six percent of the latter had at least one co-morbidity, mainly asthma and chronic respiratory diseases in 34.1%, diabetes in 29.5%, cardiac problems in 25% and congestive heart failure in 20.5%. The most common RVi were RSV (n = 21, 48%) and IA (n = 17, 39%). Six patients had a nosocomial RVi. Patients infected with IA had a significantly higher frequency of fever and bronchial hyper reactivity than those infected with RSV. RVi were associated with exacerbation of underlying disease in 62% of cases and pneumonia in 27%. Two patients had a viral pericarditis. Conclusions: RVi are an important cause of adult morbidity and their detection should be routine in adult patients hospitalized during winter.