PMC7365854_01
Symptoms according to day of illness and hospitalization among the cases confirmed SARS-CoV-2. Representative cases were combined the timeline of positive throat and anal swabs. Case07-10 were treated in Jinan infectious disease hospital and the remaining cases were reported in other hospitals. The patients are some particular cases of being discharged. After the throat swab turned to negative, the stool samples of patients became positive again appeared 5-7 days after discharged, or even longer.
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F1
We sorted out 10 representative cases and combed the timeline of the positive throat and stool samples (Figure 1).
Different clinical symptoms reflect different transmission pathways of SARS-CoV-2. Patients with different clinical symptoms may be closely related to the route of the virus during transmission. The infection sites of virus causing different clinical symptoms and directly affects the course of disease.
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F2
We speculated several different clinical symptoms may reflect various transmission pathways of SARS-CoV-2 shown in Figure 2.
The routs of SARS-CoV-2 infection and transmission in eyes. Eyes are important portals of entry for virus. After SARS-CoV-2 infected and replicated in eyes, it will be transmitted through two ways: one is outward transmission, eye secretions, or tears with virus contaminate the hands, and then there is a risk of transmission of the virus through hands. Another route is inward transmission. If the virus infected person though eyes, conjunctival secretions, and tears can flow into the mouth through the nasopharyngeal tube then reach the lungs or gastrointestinal tract and more infections occur.
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F3
The SARS-CoV-2 mainly spread from person to another through small respiratory droplets from the nose or mouth when a person confirmed COVID-19 coughs or exhales (Figures 3, 4). We proposed that the SARS-CoV-2 transmitted and infected through eyes including two routes (Figure 3). Therefore, once SARS-CoV-2 infected and replicated in eyes, it will be transmitted through two ways (Figure 3), one is outward transmission, eye secretions, or tears with virus contaminating the hands, and then there is a risk of viral transmission through hands.
The transmission pathways of the SARS-CoV-2 in vitro and in vivo. Although direct droplet transmission is the main route route of transmission, fecal excretion, environmental contamination, and fomites might contribute to viral transmission. The prevention and control principles of infectious diseases should include the control of spatter and droplet transmission, contact transmission, fecal-eye transmission, nasal-eye transmission, oral-eye transmission, and the transmission of ocular secretions and tears.
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F4
The SARS-CoV-2 mainly spread from person to another through small respiratory droplets from the nose or mouth when a person confirmed COVID-19 coughs or exhales (Figures 3, 4). Thus, this route is a two-way transmission route (Figure 4). It may be a medium channel for other routes (Figure 4).
Possible mechanisms of blood transmission after viral infection. After SARS-CoV-2 enters into the lung from mouth and throat and infects cells, the virus replicates in the cell and releases more new viruses. Massive accumulation of SARS-CoV-2 leads to a surge of immune cells and pro-inflammatory cytokines, which resulting in a rapid increase in CK levels in the blood, or releasing more virus particles into the blood circulation. The virus and cytokines positively induce high expression of ACE2 in the intestinal epithelium and other organs, which accelerates overexpression of ACE2 and viral binding, causing the systemic infections with the virus.
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F5
The virus and cytokines positively induce high expression of ACE2 in the intestinal epithelium and other organs which accelerated over-expression of ACE2 and viral binding, causing systemic infections with the virus (Figure 5).