Clinical and epidemiological characteristics of the 6 confirmed human cases with novel influenza A (H7N9) virus infection in Zhejiang / 中华流行病学杂志

ABSTRACT

<p><b>OBJECTIVE</b>To explore the clinical spectrum, geographic location of human H7N9 avian influenza as well as the characteristics of population at high risk of infection, in order to develop strategies for the prevention and control of the infection. Clinical and epidemiological characteristics on the 6 confirmed human cases in Zhejiang were also analyzed.</p><p><b>METHODS</b>Real-time fluorescent quantitative PCR was used to test the nucleic acid of human H7N9 avian influenza infection, from pharyngeal swabs of the patients and their close contacts. Face to face interview and descriptive method were used to collect related clinical and epidemiological data. Statistical analysis was performed by SPSS 17.0.</p><p><b>RESULTS</b>Six confirmed cases were distributed in Hangzhou and Huzhou cities. The 6 confirmed human cases, including 5 males and 1 female were all confirmed with novel influenza A (H7N9) virus infection, with an average age as 60.83 years (with median as 64.50 years). Cough was the most common initial symptom to be noticed. The clinical manifestations would include fever, dizziness, pain of muscles, coughing, expectoration and short of breath. All the X-ray chest films showed severe pneumonia, and 5 of them having had other chronic diseases. None of the cases admitted to have had a history of exposure to ill/death avians. However, all of the cases had been frequently exposed to the agricultural-byproduct-trading-markets where the positive rate of novel influenza A (H7N9) virus in environmental specimens was up to 43.21%. 32 of the 375 close contacts (8.53%) to the 6 cases appeared abnormal symptoms, but no positive result related to novel influenza A (H7N9) virus nucleic acid was detected from their throat swabs.</p><p><b>CONCLUSION</b>Acute infection on the respiratory system seemed the main clinical manifestation. Elderly men, especially those with chronic diseases were under high risk of human infection with H7N9 avian influenza. The source of infection might be associated with the exposure to poultry. There was still lack of evidence to confirm the route of person to person transmission on H7N9 avian influenza.</p>