Clinical features, treatments and prognosis of the initial cases of pandemic influenza H1N1 2009 virus infection in Shanghai China

Abstract

Background and objective: As of 13 December 2009, more than 208 countries and overseas territories or communities have reported laboratory-confirmed cases of pandemic influenza H1N1 2009, which have resulted in at least 10 582 deaths. As of 7 December 2009, 4328 severe cases were reported in Mainland China, resulting in 326 deaths. This study's objective was to determine the clinical features, treatments and prognosis of the initial cases of Pandemic influenza H1N1 2009 virus infection in Shanghai, China, and how its clinical features related to patient gender.

Methods: A total of 224 confirmed 2009 influenza A/H1N1-infected patients treated and discharged by Shanghai Public Health Clinical center between 24 May and 20 July 2009 were included in the study. Patients' personal information, signs and symptoms, laboratory and imagery data, disease course, hospitalization period and seroconversion duration for viral nucleic acid after antiviral treatment were analyzed.

Results: Among the 224 patients, 118 were male and 106 were female, yielding a sex ratio of 1.1:1. Approximately 52% of the patients came from Australia, and 63.8% were between 18 and 40 years old. Clinical manifestations included fever, cough and congestion of the throat, and lab findings were characterized by elevated C-reaction protein (CRP) and neutrophils. Female patients had significantly lower serum Prealbumin (PA) levels than male patients (P < 0.05). The patients' serum CRF levels significantly decreased after treatment (P < 0.05), while the levels of CD3, CD4 and CD8 significantly increased after treatment (P < 0.01). Approximately 29.9% of the patients had abnormal signs on chest computer tomography scan, and 21.9% had obvious signs indicating pneumonia. However, blood cultures were negative in these patients. The average disease course was 3.9 +/- 1.4 days, the average hospitalization period was 5.0 +/- 1.7 days, and the seroconversion duration for viral nucleic acid after antiviral treatment was 3.8 +/- 1.3 days.

Conclusion: Initial cases of pandemic influenza H1N1 2009 were characterized by fever, cough and throat congestion, with elevated CRP and neutrophils being the most significant lab findings. The pandemic influenza H1N1 2009 strain was able to affect multiple organs, including the hepatic synthesis of PA and immune functioning. The novel 2009 Influenza A/H1N1 virus was mild clinically, with a short disease course and good prognosis.