Diagnostic Imaging of Chest
Influenza A(H1N1) is caused by the conflict of interest between giant organisms and microorganisms. Influenza A and B viruses are single stranded RNA envelope virus composed of 890–2,341 nucleic acids in eight segmented genomes. Presently, only the virus
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Overview
Influenza A (H1N1) is caused by the conflict of interest between giant organisms and microorganisms. Influenza A and B viruses are single stranded RNA envelope virus composed of 890–2,341 nucleic acids in eight segmented genomes. Presently, only the virus subtypes of H1N1 and H3N2 still spread from human to human. The viruses spread and replicate under the following conditions: (1) the viruses enter the human body and duplicate there; (2) the viruses cause diseases; and (3) the viruses can easily spread from person to person. The H1N1 influenza viruses replicate is within only respiratory epithelial cells. The virus entering into the cells causes complex pathological changes of the cells. The columnar epithelial cells stop the selfsynthesis of cellular component proteins. Therefore, the cells die due to their lack of necessary cell component proteins. Influenza A (H1N1) spread from person to person by water duplets (>5 mm) coughed or sneezed out from the nose and throat of infected people. These particles cannot stay in the air, but spread the disease by contacts. The contacts can be direct skin contact or indirect respiratory secretions contact, the latter of which refers to touching his/her own eyes, nose or mouth with his/her own contaminated hands. The patients can spread the virus from 2 days prior to symptoms onset to fifth day after symptoms onset. The infection time of swine-origin influenza A virus (S-OIV) during its incubation period is about 2–7 days. According to data analysis, most patients infected by S-OIV may have their symptoms onset 1 day in advance, or 5–7 days after being infected. The infection period may be prolonged in immunocompromised children or patients with severe psychiatric disorders. It has been unknown whether a infected asymptomatic person is the source of infection, which deserves detailed research. Severe cases and death cases are mostly caused by the occurrence of its complications, including primary viral pneumonia and secondary bacterial pneumonia (especially group A streptococcus, Staphylococcus aureus and Streptococcus
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pneumoniae). Dyspnea, acute respiratory distress syndrome (ARDS) and multiple organs failure are fatal clinical signs of Influenza A (H1N1). The average period from symptoms onset to death is about 9 days. Influenza A (H1N1) virus is particularly prone to virus variation. Based on the studies about the variation of Influenza A (H1N1) virus, it has been believed that the new human pathogenic mutant has completed its genetic fragments combination in the animal body before its direct invasion into human body. The genetic segments studies of influenza virus from the influenza pandemic in the year of 1918 found genes similar to swine and bird flu viruses. Therefore, it is believed that the influenza A pandemic in 1918 was caused by the integration of human influenza virus to a segment of DNA from swine influenza virus to form H1N1 influenza virus that is affinitive to human body. Based on the belief, experts speculate that the gene recombination
