Israel Medical Association Journal

Background: In March 2009 the pandemic influenza A (H1N1) strain was identified. The disease initially appeared to be accompanied by complications and high mortality rates. It became an endemic virus during the influenza season in our region, along with the classical seasonal H3N2.

Objectives: To identify the burden of pandemic influenza, its effect in pediatric patients, and complicated hospitalizations, compared to seasonal influenza years after the pandemic.

Methods: A retrospective observational study was conducted at a tertiary hospital. Data were collected from the medical records of all children who were hospitalized from April 2009 to 2011 with laboratory-confirmed influenza.

Results: Of 191 patients with influenza, 100 had the 2009 pandemic influenza, 62 had seasonal influenza, and 29 had H1N1 in 2010–2011. Patients with the 2009 H1N1 were characterized by older age, more co-morbidity conditions and more symptoms including fever, cough and rhinitis on admission. No significant differences in outcomes between the groups were recorded. Of patients hospitalized with pandemic influenza in 2009, 28% had complicated hospitalizations, compared with 17.7% of patients hospitalized with seasonal influenza in 2010–11. Children with pandemic influenza received more oseltamivir (Tamiflu®) (94% vs. 19.4%, P < 0.001) and more antibiotics than the other groups.

Conclusions: The type of influenza had no effect on outcome. There were no significant differences between groups in the percentages of in-hospital mortality, admission to intensive care units, prolonged hospitalization (> 9 days), or the development of complications during hospitalization.

 

Background: During an influenza pandemic, clinicians need easily available clinical and laboratory criteria to distinguish influenza from similar respiratory illnesses. We compared A/H1N1/2009-polymerase chain reaction (PCR)-positive and matched PCR-negative hospitalized patients with suspected H1N1 influenza to identify factors that could assist physicians at patient admission.

Objectives: To identify factors significantly associated with A/H1N1/2009 infection.

Methods: A group of 145 patients with PCR-confirmed A/H1N1 2009 influenza admitted between 27 May 2009 and 3 December 2009 was matched with 145 PCR-negative patients by age, epidemiological week and pregnancy status. Epidemiological and clinical parameters and radiological findings on initial chest X-ray were compared between the two groups.

Results: Asthma (PCR+ 26%, PCR- 12%, P = 0.006) and military service (PCR+ 13%, PCR- 4%, P = 0.15) were associated with PCR-positive status in non-pregnant patients. At presentation, fever, cough, myalgia and fulfilling the pandemic influenza case definition were significantly more frequent in non-pregnant PCR+ patients (62/90/43/59% in PCR+ versus 38/69/30/35% in PCR-). In pregnant patients, fever and fulfilling the case definition were significantly associated with PCR-positive status. Mean leukocyte and absolute lymphocyte counts were significantly lower in both pregnant and non-pregnant PCR-positive patients. Significantly more PCR-negative non-pregnant patients (43% vs. 22% PCR+, P = 0.004) had abnormal chest X-ray (CXR) findings on presentation. In PCR-positive patients, patchy consolidation and interstitial infiltrates were the most common abnormalities.

Conclusions: Under the conditions generated by the A/H1N1/2009 pandemic, radiological findings did not distinguish reliably between influenza and other febrile respiratory illnesses. Asthma, military service, the pandemic case definition (particularly fever, cough and myalgia) and lymphopenia were associated with confirmed H1N1 infection.
 

Background: An outbreak of respiratory illness caused by a novel swine-origin influenza virus (influenza A/H1N1 2009) that began in Mexico was declared a global pandemic by the World Health Organization in June 2009. The pandemic affected many countries, including Israel.

Objectives: To compare the course of chest radiographic and computed tomography findings in patients who survived and those who died following admission to the intensive care unit (ICU) or intubation due to severe laboratory-confirmed swine-origin influenza A/H1N1 2009.

Methods: We retrospectively reviewed the patient records (267 radiographs, 8 CTs) of 22 patients (10 males, 12 females) aged 3.5–66 years (median 34) with confirmed influenza A/H1N1 2009, admitted to the ICU and/or intubated in five major Israeli medical centers during the period July–November 2009. We recorded demographic, clinical, and imaging findings –including pattern of opacification, extent, laterality, distribution, zone of findings, and presence/absence of nodular opacities– at initial radiography and during the course of disease, and compared the findings of survivors and non-survivors. Statistical significance was calculated using the Wilcoxon (continuous variables) and Fisher's exact tests (categorical variables).

Results: The most common findings on the initial chest radiography were airspace opacities, which were multifocal in 17patients (77%) and bilateral in 16 (73%), in the lower or lower and middle lung zones in 19 patients (86%). Large airspace nodules with indistinct margins were seen in 8 patients (36%). Twelve patients survived, 10 died. Patients who died had multiple background illnesses and were significantly older than survivors (P = 0.006). Radiologic findings for the two groups were not significantly different.

Conclusion: Airspace opacities, often with nodular appearance, were the most common findings among patients with severeinfluenza A/H1N1 2009. The course of radiologic findings was similar in patients with severe influenza A/H1N1 2009 whosurvived and those who died.

Background: A pandemic (H1N1) influenza A virus was identified in 2009.

Objectives: To investigate predictors for pandemic (H1N1) 2009 virus infection among hospitalized patients with a flu-like illness and to identify parameters suggesting a severe clinical course.

Methods: We analyzed a cohort of all patients hospitalized during a 2 month period with a flu-like syndrome who were tested for pandemic (H1N1) 2009 infection. Demographic, clinical and laboratory, along with outcome parameters, were recorded and compared between pandemic (H1N1) 2009 virus-positive and negative hospitalized patients.

Results: Of the 179 examined hospitalized patients suspected of having pandemic (H1N1) 2009 infection 65 (36%) were found positive. These patients tended to be younger and had significantly fewer comorbidities. In addition, they had a significantly higher frequency of fever (94%), cough (86%) and myalgia (29%). Furthermore, age < 65 years and cough were independent predictors for pandemic (H1N1) 2009 virus positivity in a multivariate regression analysis. Notably, 14 of the 65 positive patients (21.5%) had acute respiratory insufficiency requiring treatment in the intensive care unit. These patients were neither older nor previously sicker than patients with non-severe disease, but were distinguished by augmented inflammatory markers, significant lymphopenia associated with disease severity, and overall mortality of 21.4%.

Conclusions: Pandemic (H1N1) 2009 virus-positive hospitalized patients tend to be younger and have fewer comorbidities as compared to compatible negative patients. A significant number of relatively young and previously healthy positive patients might develop severe disease associated with a robust inflammatory reaction and significant lymphopenia.