Dr. Muhammad Torequl Islam :
The outbreak of novel coronavirus 2019 (nCoV-19) has been evident to spread almost all the regions and countries in the world. It becomes pandemic and causes death of thousands of people around the world. However, the survival of human coronaviruses (hCoVs) outside the host depends on some factors, such as temperature and humidity, pH, sunlight, air, water and earth quality, and surface state (e.g., solid or liquid). Higher temperature and humidity, high or low pH, oxidants present in air or water, earth minerals and sunlight all facilitate virus reduction. This letter depicts a current scenario on the environmental components that affects the spreadability of hCoVs, especially the nCoV-19.
The nCoV-19 is evident to spread in tiny droplets released from the nose and mouth of an infected person during sneezing and coughing. A single cough can produce up to 3,000 droplets. These particles can remain in the air, land on other people, clothing and surfaces around them. The nCoV-19 can survive and remain infectious for up to 3 days on hard surfaces like plastic and stainless steel at temperatures of between 21 to 25 ?C at 40-50% relative humidity. The severe acute respiratory syndrome (SARS) coronavirus that outbreak in 2003 has also been found to survive best in cooler, drier conditions. However, virus viability loses rapidly at higher temperatures (e.g., 38 °C) and higher relative humidity (e.g., >95%). This virus dies after heating at 56 °C for 15 minutes, however, it may stable for at least 2 days following drying on plastic. This temperature condition (56 °C) is evident to kill about 10,000 viral particles within 15 minutes. It can be inactivated completely by using common fixatives used in laboratory, ultraviolet light, alkaline (pH >12 ) or acidic (pH <3) conditions. The virus is stable for 3 weeks at room temperature (20 to 25 °C or 68 to 77 °F ) in a liquid environment. It spreads rapidly in cities and regions of the world where average temperatures have been around 5-11 °C (41-52 °F) and relative humidity has been low. It can can also survive on metal, glass and plastic for as long as 9 days, unless properly disinfected. This virus can survive for more than 28 days at 4 ?C. 100 °C with CO2 can kill the virus rapidly.
Air pollution causes weakening our immune system, reduces the ability to fight against infectious agents. Suspended particles may carry the virus particles that remain in the air. A correlation between the novel coronavirus disease 2019 (COVID-19) mortality rates and high levels of air pollution has been seen in Italy and USA. A study conducted in 2003 suggests that patients with SARS were 84% more likely to die if they lived in areas with high levels of air pollution. A small increases in fine particulate matter (e.g., PM2.5) have been found to increase the nCoV-19 transmission. For example, an increase of just 1 microgram per cubic metre corresponded to a 15% increase in COVID-19 deaths.
Water either transmits the CoVs in human still remains controversial. According to Casanova et al. CoVs can remain infectious for long periods (days to weeks) in water and pasteurized settled sewage, therefore, these may affect people and other animals if aerosols are generated. On the other hand, Rosa et al. demonstrated that CoVs have low stability in the environment and is very sensitive to oxidants (e.g., chlorine). These are inactivated significantly faster in water. One study reports that SARS CoV can survive in wastewater, tap water and water at 4 °C by 2-4, 10 and >100 days, respectively. Recently, nCoV-19 along with other CoVs has been found in the fecal samples and anal swabs of some patients, therefore, there is a possibility of fecal-oral (including waterborne) transmission of this class of virus. Moreover, nCoV-19 is evident to infect human small intestinal enterocytes and has been demonstrated to be found on the human ocular surface One study found that other human CoVs survived only 2 days in dechlorinated tap water and in hospital wastewater at 20 °C. Significant (99.9% removal) of CoVs was observed at 2 weeks in pasteurized settled sewage at 25 °C and 4 weeks in reagent grade water at 25 °C.
Some other environmental substance such as codium chloride (NaCl), natural adsorbents (e.g., clay, charcoal, and clay minerals), minerals (e.g., selenium, copper, iron, chromium, potassium, zinc, etc.), medicinal plants (e.g., Garlic, zinger, black seeds, etc.) or their derivatives are also evident to act against hCoVs. Many of these substances have been also found to act against nCoV-19.
It is clear that, to date, we do not have even a single remedy for COVID-19. However, along with the other preventive measures if we can manage the above-mentioned environmental constraints properly, it should be possible to fight against the pandemic COVID-19. Additionally, it is also necessary to study all the environmental components that affect hCoVs survival, replication, spreadability or transmission and pathogenicity in human and other animals (e.g., wild and pet).
The outbreak of novel coronavirus 2019 (nCoV-19) has been evident to spread almost all the regions and countries in the world. It becomes pandemic and causes death of thousands of people around the world. However, the survival of human coronaviruses (hCoVs) outside the host depends on some factors, such as temperature and humidity, pH, sunlight, air, water and earth quality, and surface state (e.g., solid or liquid). Higher temperature and humidity, high or low pH, oxidants present in air or water, earth minerals and sunlight all facilitate virus reduction. This letter depicts a current scenario on the environmental components that affects the spreadability of hCoVs, especially the nCoV-19.
The nCoV-19 is evident to spread in tiny droplets released from the nose and mouth of an infected person during sneezing and coughing. A single cough can produce up to 3,000 droplets. These particles can remain in the air, land on other people, clothing and surfaces around them. The nCoV-19 can survive and remain infectious for up to 3 days on hard surfaces like plastic and stainless steel at temperatures of between 21 to 25 ?C at 40-50% relative humidity. The severe acute respiratory syndrome (SARS) coronavirus that outbreak in 2003 has also been found to survive best in cooler, drier conditions. However, virus viability loses rapidly at higher temperatures (e.g., 38 °C) and higher relative humidity (e.g., >95%). This virus dies after heating at 56 °C for 15 minutes, however, it may stable for at least 2 days following drying on plastic. This temperature condition (56 °C) is evident to kill about 10,000 viral particles within 15 minutes. It can be inactivated completely by using common fixatives used in laboratory, ultraviolet light, alkaline (pH >12 ) or acidic (pH <3) conditions. The virus is stable for 3 weeks at room temperature (20 to 25 °C or 68 to 77 °F ) in a liquid environment. It spreads rapidly in cities and regions of the world where average temperatures have been around 5-11 °C (41-52 °F) and relative humidity has been low. It can can also survive on metal, glass and plastic for as long as 9 days, unless properly disinfected. This virus can survive for more than 28 days at 4 ?C. 100 °C with CO2 can kill the virus rapidly.
Air pollution causes weakening our immune system, reduces the ability to fight against infectious agents. Suspended particles may carry the virus particles that remain in the air. A correlation between the novel coronavirus disease 2019 (COVID-19) mortality rates and high levels of air pollution has been seen in Italy and USA. A study conducted in 2003 suggests that patients with SARS were 84% more likely to die if they lived in areas with high levels of air pollution. A small increases in fine particulate matter (e.g., PM2.5) have been found to increase the nCoV-19 transmission. For example, an increase of just 1 microgram per cubic metre corresponded to a 15% increase in COVID-19 deaths.
Water either transmits the CoVs in human still remains controversial. According to Casanova et al. CoVs can remain infectious for long periods (days to weeks) in water and pasteurized settled sewage, therefore, these may affect people and other animals if aerosols are generated. On the other hand, Rosa et al. demonstrated that CoVs have low stability in the environment and is very sensitive to oxidants (e.g., chlorine). These are inactivated significantly faster in water. One study reports that SARS CoV can survive in wastewater, tap water and water at 4 °C by 2-4, 10 and >100 days, respectively. Recently, nCoV-19 along with other CoVs has been found in the fecal samples and anal swabs of some patients, therefore, there is a possibility of fecal-oral (including waterborne) transmission of this class of virus. Moreover, nCoV-19 is evident to infect human small intestinal enterocytes and has been demonstrated to be found on the human ocular surface One study found that other human CoVs survived only 2 days in dechlorinated tap water and in hospital wastewater at 20 °C. Significant (99.9% removal) of CoVs was observed at 2 weeks in pasteurized settled sewage at 25 °C and 4 weeks in reagent grade water at 25 °C.
Some other environmental substance such as codium chloride (NaCl), natural adsorbents (e.g., clay, charcoal, and clay minerals), minerals (e.g., selenium, copper, iron, chromium, potassium, zinc, etc.), medicinal plants (e.g., Garlic, zinger, black seeds, etc.) or their derivatives are also evident to act against hCoVs. Many of these substances have been also found to act against nCoV-19.
It is clear that, to date, we do not have even a single remedy for COVID-19. However, along with the other preventive measures if we can manage the above-mentioned environmental constraints properly, it should be possible to fight against the pandemic COVID-19. Additionally, it is also necessary to study all the environmental components that affect hCoVs survival, replication, spreadability or transmission and pathogenicity in human and other animals (e.g., wild and pet).
(Dr. Muhammad Torequl Islam, Department of Pharmacy, Life Science Faculty, Bangabandhu Sheikh Mujibur Rahman Science and Technology University).
