The role of environmental factors to transmission of SARS-CoV-2 (COVID-19)
The new outbreak of COVID-19 has recently become a serious threat to the health of people around the world. COVID-19 is caused by the SARS-CoV-2, which is a single-stranded positive-sense RNA virus that causes infection and respiratory failure (Swerdlow and Finelli 2020; Wu et al. 2020) and has led to the thousands of people deaths (Thienemann et al. 2020). Following the WHO announcement, the Global Emergency Commit-tee identified the need for early detection, quarantine, and prompt treatment as a global concern (Sohrabi et al. 2020), because people with the virus do not have clinical symptoms such as fever, cough, etc., in the early stages. For this reason, there is not enough information on how to disinfect and disinfect surfaces and hands, human-to-human transmission through air, food, and water, and the presence of the virus in human wastewater and waste. There are several factors involved in transmitting the virus. These conditions can be included in environment and human behavior (Fig. 1). The distribution of human population, migration, social interactions, climate change (deforestation, habitat invasion), agricultural growth, and direct contact with domestic and wild animals fall into this category (Barratt et al. 2019; Dehghani and Kas-siri 2020). On the other hand, the effect of environmen-tal factors such as ambient temperature, humidity, etc., relating to the COVID-19 pandemic (Fig. 1) has not been sufficiently investigated. How the virus enters the body (eyes, ears, mouth, and nose) is not well known by the elease of aerosols and droplets containing SARS-CoV-2 in human societies. However, previous findings in the epidemic of a virus similar to SARS-CoV-2 can be used in this regard (Sun et al. 2020), because the methods of transmission are not currently known. Therefore CDC recommends standard precautions, contact and air, and eye protection (glasses or face shields) (CDC 2020b, e). It has been reported that even with personal protective equipment (PPE), it is still possible to get infected (Dai 2020) because there is no convincing evidence to sup-port the effect of PPE use in the prevention of infection (Yang 2020). The significant concern about SARS-CoV-2 is its transmission (Dehghani and Kassiri 2020). Accord-ing to the WHO, there is no certainty about the persis-tence of the SARS-CoV-2 on surfaces. However, the virus appears to act like other coronaviruses and can survive on the surface for at least several hours (Parry 2004). For this reason, the following health points in public places, hospitals, and residential houses has a significant role in controlling the transmission of the disease (WHO 2020a). Dealing with COVID-19 and preventing its rapid and dangerous spread is a global challenge. Therefore, the fight against this disease requires global management. However, due to the potential variability of this disease, according to the type of climate and other environmental factors, its prevention and control should be investigated quickly and seriously (Askari et al. 2018). When a new pandemic occurs, a lot of health advice is given. Any-way, it should be noted that these methods may not be the most accurate and correct, but following them can be effective until sufficient knowledge is obtained. Nev-ertheless, a hierarchy to deal with SARS-CoV-2 trans-mission involves three steps: 1) self-care, 2) control of environmental factors, and 3) the use of PPE (Lai et al. 2020). This study aimed to investigate the effect and role of various factors, including environmental factors (cli-mate change, water transfer, air, and food), disinfection of surfaces, and hands in the transmission and prevalence of COVID-19 pandemics
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Water and wastewater and transmission of COVID‑19
Guaranteeing safe water, collecting sewage, and main-taining effective hygiene during infectious diseases, including COVID-19 pandemic, play a key role in sup-porting human health (Eslami et al. 2018; WHO 2020b). The risk of COVID-19 appears to be low through the stool of an infected person. There is evidence that SARS-CoV-2 may lead to intestinal infection and be present in the stool (Bhattacharjee 2020). Studies show that approx-imately 2 to 10 percent of confirmed SARS-CoV-2 cases have been associated with diarrhea (Chen et al. 2020; Huang et al. 2020; Wang et al. 2020a). Two studies have reported the detection of residual SARS-CoV-2 viral RNA in the stool of patients with SARS-CoV-2 (Holshue et al. 2019; Xiao et al. 2020). Yet, only one study has reported the SARS-CoV-2 from a cultured stool sample (WHO 2020b). In the latest study, the report of the pres-ence of the SARS-CoV-2 virus in sewage has been con-firmed. The presence of the virus in the wastewater, even when the prevalence of the virus is low, indicates that the SARS-CoV-2 can survive in the sewage. This find-ing could be a sensitive tool for tracking and monitoring the rate of virus rotation in communities (Lodder and de Roda Husman 2020; Medema et al. 2020). Some studies have reported that coronavirus can remain in water or wastewater sources for days or weeks (Qu et al. 2020). Due to the evidence of the virus surviving in aquatic and sewage environments, its presence in water resources is dependent on essential factors such as temperature, sun-light, and the presence of organic compounds that the virus can adsorb to and protect themself against sunlight. The presence of other antagonistic microorganisms can also affect its survival in water resources. According to the latest WHO report, there is no evidence that human-type coronavirus has been transmitted through contami-nated drinking water (Naddeo and Liu 2020). In general, coated viruses are less environmentally friendly and are more sensitive to oxidants such as chlorine. The SARS-CoV-2 is likely to be significantly inactivated more rapidly than human intestinal viruses without water-borne dis-eases in contact with oxidants (WHO 2020b).
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