Clinical diagnosis
Case 190
【Progress】
They were transported to the expert hospital to check whether PCR test was positive or not. Their nasal fluids were used for the examination. They showed viral infection but not COVID-19.
【Discussion】
It is known that there are more than 20 viruses which cause common cold (1, 2). The most common virus is Rhino virus followed by corona virus, respiratory syncytial (RS) virus, parainfluenza virus and adenovirus (3). Corona virus includes 6 species which infect humans. Four of the six cause common cold and other two cause severe pneumonia of middle east respiratory syndrome (MERS) and severe acute respiratory syndrome (SERS) (4). This year, new corona virus emerged in main China, hosted by bat and transmitted to human via pangolin (4).
Following bacterial pneumonia, viral pneumonia is probably second community acquired pneumonia and hospital acquired pneumonia. Viral pneumonia occurs by influenza virus, RS virus, parainfluenza virus, adenovirus, human metapneumovirus, et al. Pandemic influenza occurred two times during the past twenty years; avian influenza in 2003: swine influenza in 2009 (5, 6).This year COVID-19 occurred in main china and prevailed all over the world.
There are two types in virus to invade host cells: envelope type and non-envelope type. Influenza virus and corona virus have an envelope, while adeno virus does not. Adeno virus invade to host cell with lysis of cell membrane, and influenza virus and corona virus invade with spikes of the envelope embedding to cell membrane. Influenza virus owns spikes: hemagglutinin (HA), neuraminidase (NA), ion channel (M2). Antivirus drugs were created to target to these spikes. Namely, Relenza and Tamiflu targeted to NA protein, and Amantadine and Rimantadine did to M2 protein (6, 7). Spikes of corona virus envelope are not clarified and antivirus drugs are future subjects. Latest news showed avigan and remdesivir which are anti-RNA polymerase (6, 7), blocking RNA duplication of RNA virus are beginning to give to patients with COVID-19.
COVID-19 causes pneumonia and its radiological findings on CT were reported from main China last week (4). It said that the highest patterns on chest CT findings are; multiple lesions; gland-glass opacity: lower lobe predilection; subpleural distribution. The clinical symptoms are diverse from common cold to acute respiratory distress syndrome (ARDS).
Chest CT of our cases showed multiple ground glass opacity in Case 1 and ground glass opacity in left lower lobe in Case 2, suspicious of viral pneumonia. They were negative in PCR test, indicative of other viral pneumonia.
【Summary】
Corona virus following Rhino virus is the second most virus causing common cold. Human corona virus has six species; 4, common cold; one SERS; one MERS. This year, COVID 19 occurred in main China, hosted by bat and transmitted to human via pangolin. Viral pneumonia occurs most by influenza virus followed by RS virus, parainfluenza virus, adenovirus , et al. Influenza virus and corona virus own envelope with spikes which invade to host cell membrane. Anti-influenza drugs were created to target the spike proteins. Avigan and remdesivir which are anti-RNA polymerase, blocking RNA duplication of RNA virus are expected to use. The highest patterns of COVID 19 on chest CT findings are; multiple lesions; gland-glass opacity: lower lobe predilection; subpleural distribution. These findings are non-specific for viral pneumonia. In our cases chest CT showed multiple ground glass opacity in Case 1 and ground glass opacity in left lower lobe in Case 2.Their PCR tests were negative, indicative of other viral pneumonia rather than COVID 19.
【References】
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4.Yue Zu ZY et al. Coronavirus Disease 2019 (COVID-19): A Perspective from China. HomeRadiologyRecently Published. Internet online
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6.Alimi Y, et al. Systematic review of respiratory viral pathogens identified in adults with community-acquired pneumonia in Europe. J. Clin. Virol. 2017 Oct;95:26-35.
7.Garten R, et al. Update: Influenza Activity in the United States During the 2017-18 Season and Composition of the 2018-19 Influenza Vaccine. MMWR Morb. Mortal. Wkly. Rep. 2018 Jun 08;67(22):634-642.
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2020.5.20