Increase in SARS-CoV-2 infected biomedical waste among low middle-income countries: environmental sustainability and impact with health implications

Introduction

The current pandemic of a novel infectious disease caused by severe acute respiratory syndrome corona virus-2 (SARS-CoV-2), officially named coronavirus disease-19 (COVID-19) by the World Health Organization (WHO) [1], has become a global burden and caused major setbacks worldwide [2]. This disease originated in Wuhan, China, in 2019 and has spread to over 213 countries worldwide as of 28 May 2020. Several factors, including age, sex, and underlying health abnormalities, predispose to this disease and promote exponential spread and mortality, making COVID-19 a public health emergency of global concern [3, 4]. While many cases of this disease resolve spontaneously, some patients develop mild symptoms like sore throat, dry cough, fever, dizziness, and septic shock requiring intensive care. Other patients with comorbidity progress to severe illness, including multiple organ failure, severe pneumonia, acute respiratory distress syndrome (ARDS), dyspnea, and death [5, 6]. Among the recommendations made by the WHO toward reducing the spread of this disease include early detection, isolation, immediate treatment, and effective strategies to identify contacts. Thus, reducing the health burden of the virus on the economy and promoting unified response worldwide [7].

Though the causative virus is not air-borne and most contagious in symptomatic people, the easiest mode of transmission of the disease is not clear in its entirety [8]. However, studies have shown that this disease spreads in different ways, including direct contact with infected persons, close contact with the respiratory droplets produced by an infected individual during coughing, sneezing, or talking, and through aerosols, especially during medical procedures like intubation. There is also an increased risk of transmission when a person touches the eyes, nose, or mouth after touching a contaminated surface, i.e., fomite transmission [9, 10]. Accumulating evidence shows that direct interhuman transmission majorly occurs during the asymptomatic incubation period, usually 2–14 days [11, 12].

Preventive measures to curtail the spread of coronavirus

Sequel to the continued increase in the incidence of COVID-19 infections, the high transmission efficiency of the SARS-CoV-2, and unavailability of vaccine, adequate preventive measures are urgently needed to curtail the global spread of this virus as well as damage associated with COVID-19 [13, 14]. In line with this objective, various health organizations around the world have recommended several measures to prevent the further spread of the disease. These recommendations include but not limited to: restrictions to highly contagious areas and maintaining social distancing to reduce contact with disease patients; practice good respiratory hygiene involving covering of mouth and nose with bent elbow or tissue when coughing or sneezing as well as prompt disposal of the used tissue; regular and thorough cleaning of hands with an alcohol-based hand rub or soap and water to kill the virus; early medical attention to sick persons and strict adherence to the information given by health authorities [15, 16]. Also, the use of medical mask or face covering when physical distancing is not possible. This measure protects people around even if asymptomatic [17].

Furthermore, additional measures must be implemented by the healthcare provider caring for COVID-19 patients. The most important measure by this personnel is the use of personal protective equipment (PPE), including selecting the appropriate PPE with adequate training on wearing, removal and disposal after use. The use of PPEs has been a vital means of preventing the spread of SARS-CoV-2 [18].

PPE

PPE is a protective gadget including clothing, helmet, gloves, gown, goggles, face shields/masks, and other apparatus designed to protect the wearer from injury or spread of infection [19]. Healthcare providers commonly use this equipment, majorly in hospitals and laboratories, to form a protective barrier preventing the transmission of contaminants in body fluids and respiratory gases. The choice of appropriate PPE is determined by the type of hazards, e.g., biohazards, air-borne infections, or chemicals the healthcare provider is exposed to. It is worthy to note that PPE does not eliminate the infection source but protects the wearer. Hence, there may be a transmission of infection if not properly used. Also, PPEs can create additional stress and slight discomfort on the wearer, thereby discouraging the wearer and placing them at risk of infection. In light of these, appropriate training on the proper use of PPE by healthcare providers will enhance the effectiveness of this equipment in the prevention of disease [20]. Also, implementations of various guidelines underlining proper use of PPEs with other control measures such as good respiratory hygiene and thorough hand-washing could effectively reduce human-to-human transmission of SARS-CoV-2 infection [21]. For effective use of PPE, the following basic principles must be carefully observed;

1. Always clean the hands thoroughly before using the equipment.

2. Remove or replace damaged PPE promptly once noticed that it is not in its optimal working condition.

3. Quickly remove PPE as soon as possible after completing the task and avoid transferring contaminants to other people around.

4. Promptly discard all PPE appropriately and ensure hand hygiene immediately.

Regulation of PPE use

To ensure the safe and effective use of PPE, the Food and Drug Administration (FDA) in the United States have set-up adequate regulations and ensure that all PPE meet applicable voluntary consensus standard for protection [22]. However, the proposed standard and regulations differ with the specific type of PPE. The producer must prove that this equipment fulfills specific criteria and obtain approval declaring that the equipment is ‘substantially equivalent’ (SE) before selling legally. A new device granted SE approval means that it is safe and effective as the predicate. These criteria include, but are not limited to, performance, labeling, and intended use to demonstrate substantial equivalence. Among the consensus standard used to validate the acceptance of PPE to be used as a medical device is its ability to function as a barrier, resistance to tear, sterility, biocompatibility, resistance to fluid, and flammability. Also, the manufacturers must present test procedures used to validate conformance to standards and provide supporting data for each test [23].

Use of PPEs in COVID-19 prevention

The use of PPE during the present outbreak of SARS-CoV-2 has become an essential discussion by the healthcare providers working toward curtailing the pandemic. The major PPE used to manage the spread of this virus is air-borne equipment such as the closely fitted high-filtration masks and N95 respirator that can prevent respiratory gases that may contain the virus [24, 25]. Masks (surgical/face): This is a loose-fitting, disposable device that provides a physical barrier between the mouth and nose of the wearer and potential contaminants in the immediate environment. These masks are of different thicknesses and strength; if used correctly, they can provide adequate restriction to contaminants from reaching the mouth and nose as well as reducing saliva and respiratory droplets to others [26]. However, the surgical mask does not always provide complete protection from small contaminants transmitted during sneezing and coughing due to the loose fit between the face and the mask. Also, the use of masks should be discontinued after a single-use, damage, or if it makes breathing uneasy. This should be done safely by dropping it in a plastic bag, trashed and discarded appropriately. Afterward, the hands should be washed thoroughly. N95 Respirators: It is a high-performance filtering mask intended for use in the healthcare setting. It closely fits the face to provide an effective barrier and filtration of gaseous contaminants. N95 respirators filter efficiently when adequately used than face masks, blocking more than 95% of tiny particles. However, due to their close-fitting on the face, people with respiratory and cardiac disorders must observe extra precautions when using it [27].

Respiratory gases from an infected patient can be spread while talking, sneezing, or coughing with varying viral load and infective capacity [28]. A large cluster of particles of different sizes is usually expelled during sneezing and coughing; therefore, the degree of spread by the infected person can significantly be reduced by wearing a fluid-resistant surgical face mask [29]. It is important to note that PPE is only a part of the more extensive protective system to manage contamination of healthcare providers to COVID-19 patients as they stand at higher risk. Thus, other strategies to reduce the spread of infection should also be implemented. However, several pieces of literature have questioned the air-borne transmission of coronaviruses. However, various healthcare regulatory bodies (including the WHO, European Centers for Disease Control, Public Health England) comply with most countries’ directives have recommended appropriate precautions against air-borne transmission and contact with infected patients [30]. Thus, there has been an increasing demand for air-borne precaution PPEs to fight against the spread of COVID-19 [29].

Increase in PPE demands across the globe

PPE helps to protect healthcare providers against infectious materials, toxins, and other contaminants frequently produced during healthcare delivery. Currently, there is a significant shortage of PPE due to excessive demand following the outbreak of highly-infectious SARS-CoV-2 that causes COVID-19. This equipment (PPE) is witnessing high demand globally due to its accessibility, affordability, and effectiveness against the transmission of this ravaging disease. Thus, adequate strategies to optimize PPE include identifying alternative measures to prevent the spread of the virus, nonsupply of PPE to public area, using PPE (e.g., mask) for a longer period where possible, and an increase in their production. This will help to reduce shortage and ensure that PPE is available to health care workers when needed.

Disruption in the global supply chain or increase demand of PPE across the globe

The inappropriate use and excess demand for PPE during this pandemic have disrupted the global supply of PPE [31]. While only a few countries like the United Kingdom and China have a substantial stock of PPE, adequate supply to the healthcare provider, and maintenance of the supply chain, several countries have limited stocks, and supply is uncertain. This disruption in the global supply could, if not corrected promptly, cause a significant setback to the fight against SARS-CoV-2 globally. Currently, the global stock of medical masks, respirators, gowns, and goggles is limited due to increased COVID-19 cases globally, misinformation, panic buying, multiple inconsistency, and inappropriate use [32]. Also, the possibility of increasing production to meet the demand for PPE is limited due to national lockdown strategies implemented in several countries with resultant reduction in the workforce even though there has been an increase in substandard production by local manufacturers. Thus, it is vital to ensure that PPEs are used adequately to avoid transmission and waste [33, 34]. Transmission-based precautions such as social distancing, avoiding high-risk areas, and touching the face with dirty hands should be strongly implemented to minimize PPE usage.

Strategies for optimizing the supply of PPE

To optimize PPE availability globally, drastic measures need to be put in place to limit the disruption in the distribution chain of PPE. Some of these measures are discussed.

BMW

BMW can be solid or liquid substances generated when providing healthcare services to humans or animals or in the course of research relating to production or testing biological samples. These substances contain potentially infectious components and are broadly classified into 10 different categories as follows [42]. Human anatomical wastes (e.g., body parts, tissues, or organs); animal waste (e.g., research animals and waste from veterinary hospitals and animal houses); microbiological and biotechnological waste (e.g., waste from laboratory cultures, live or attenuated vaccines, microbial cultures, and stocks); waste sharps (e.g., needles, syringe. Lancet); discarded medicines and cytotoxic drugs (expired drugs); soiled wastes (e.g., plaster casts, bedding, and other items contaminated with blood and body fluids); solid wastes (e.g., bandages, discarded gloves, catheters); liquid wastes (e.g., discarded blood, saliva, and urine samples as well as waste generated from disinfection and laboratory cleaning); incineration ash (include all wastes obtained during the incineration of BMW) and chemical waste (all chemicals and reagents used in the production of biological and disinfection). BMW generated by various healthcare establishments, research facilities, and laboratories is a potential reservoir of pathogenic microorganisms and requires appropriate, safe, and reliable elimination from society because they can create various health risks [43]. To ensure adequate handling and treatment of these wastes, their physicochemical properties should be evaluated, and management strategies should be implemented accordingly. Amongst the properties to be evaluated are combustibility, total suspended solids, biological oxygen demand (BOD), chemical oxygen demand (COD), heating value, density (physical and chemical properties), pH, aggregate stability, biodegradability, composition (heavy metals, radioactive substances), bioavailability, total hardness, bio-concentration, and moisture content [44] (Figure 1).

Figure 1:

Waste management in developing countries [45].

BMW management practice and challenges among low-middle income countries (LMICs)

Recently, the management of BMW has attracted laudable attention especially given the rapid transmission of coronavirus (SARs-CoV-2) infection present in several countries in the world. This results from the fact that improper management of this waste could enhance the transmission of viruses and other vectors with a significant outbreak of disease. While some developed countries have implemented adequate guidelines to handle effectively and dispose of their BMWs, LMICs have suffered significant setbacks in this regard due to poor infrastructure and inadequate waste management practices [45], [46], [47]. Despite these setbacks, the type and amount of BMW generated in these countries, if not correctly managed, could be a source of future outbreaks and pandemics, ravaging the African continent with several LMICs.

Poor waste management practices in LMICs

The concept and management practice of BMW is receiving significant attention, primarily because of the rapid increase of COVID-19 disease. The impact of BMWs (both solid and liquid waste) on the increasing rate of disease outbreaks in the society is a global health concern as it significantly affects the economic stability of the country and exerts a significant burden on the well-being of the populace. Literature has reported significant health effects concerning individuals residing near waste sites [48]. The primary poor waste management practice in LMICs includes.

1. Disposal of large amounts of these wastes in illegal places [49].

2. Uncontrolled burnt without following appropriate guidelines generate pollutants that contaminate the atmosphere and impose a severe health threat to lives around such premises [50, 51].

3. Improper disposal of these BMWs without treatment into water bodies. This is worrying for both toxicological and esthetical reasons as it tends to damage the quality of the receiving streams and also significantly pathogenic to the marine food chain [52].

Thus, drastic interventions are required to properly manage these BMWs, especially in LMIC with unsustainable management policies to prevent further transmission and outbreak of the disease in these countries [53, 54]. These interventions should be geared towards reducing the generation of BMWs, comprehensive assessment of the environmental impact, and implementation of proper management practices for effective solutions [45] (Figure 2).

Figure 2:

BMW management in developing countries by open dumping [55].

BMW and environmental health

Recently, an increasing trend in BMW production has been observed, resulting from the increased number of health organizations providing healthcare services to the growing human population and the increased usage of medical-related products during disease outbreak [63–65]. Excess BMW generation increases the cost of waste treatment and disposal, rendering the available management practice ineffective [66]. Therefore, waste management agencies advocate for reducing and possibly reusing bio-medical waste [67]. However, COVID-19 infected BMWs should not be recycled due to the viability of the virus and the severity of the accompanying diseases. The improper disposal of BMW can negatively affect water quality because of different contaminants (such as cadmium, lead, aluminum, vanadium, and iron) that may leach out from the waste dumping sites into the groundwater [68]. Studies have shown that incineration of BMW contains a high concentration of toxic chemicals (mercury, dioxin, and lead) that may increase the amounts of contaminants polluting the atmosphere and groundwater. These toxicants increase the risk of several ailments among residents exposed to these contaminants because some may be mutagenic, carcinogenic, or teratogenic [69–72]. Hence, it is crucial to eliminate or reduce the toxicity of such wastes using adequate treatment measures before disposal into landfills or been reused [73]. Groundwater is polluted via the percolation of toxic substances from BMW. Hence, direct disposal of such wastes into landfills without proper treatment should be strongly prohibited by the relevant authorities. Also, heavy metals in landfill leachate from BMW may cause a risk to the environment, especially in unlined landfills where dissipation of leachate into groundwater might occur [68]. Furthermore, unregulated BMW disposal may change soil quality near waste dumping sites because different contaminants may get mixed with the soil, thereby changing the constituents, reducing soil fertility, and affecting the soil ecosystem.

A study conducted in Ibadan city, Southwest Nigeria, by [74] shows that the soil samples and bottom ash of a hospital incinerator contain a higher concentration of heavy metals (such as zinc, lead, chromium, and cadmium) compared to municipal dumpsites suggesting significant soil pollution resulting from BMW generated from the hospital. This could cause a drastic deteriorating of soil quality and decrease vegetation abundance due to the dumping of BMW [75]. All the metals investigated were above the Dutch and Danish limit values for maximum permissible levels of heavy metals in good soil quality, and therefore, classified as harmful and toxic for human health. Consequently, it should be recommended that lands with an excess concentration of heavy chemicals should be closed from further use, and immediate remedial action should be implemented to minimize future pollution and potential impacts on the environment and local society [76].

It has been reported that the majority of the BMW generated are managed by burning in incinerators [77]. However, uncontrolled and improper burning of BMW may cause air pollution in the atmosphere by producing toxins and mixing different air pollutants to a level that imposes danger to human health. The primary source of these toxins is polyvinyl chloride material in the waste [78]. Arguably, greenhouse gas and particulate emissions are considered a challenging issue from municipal solid waste dumping sites [79]. The burning of BMW at these sites is a severe threat to the environment and human health because it releases harmful chemicals (hydrochloric acid, carbon monoxide, ethane, ethylene, propane, and propylene) that cause various types of respiratory disease among the residents and workers [80]. To this end, some waste management control authorities have restricted the disposing of hazardous infectious waste in landfills without following the appropriate guidelines.

BMW and human health

Generally, the specific characteristics of BMWs implicate them as one of the most dangerous types of waste, and improper management of this waste can negatively affect health with a significant outbreak of infection and poisoning [81]. The huge health risks to humans and the environment posed by BMWs range from direct injury due to exposure and indirect injuries resulting from land, water, and air polluted with toxic chemicals from the medical waste [82] that forms significant components of these wastes [83]. Literature has shown an increasing number of epidemics and waste-related diseases resulting from inadequate waste management practices. Besides, significant health abnormalities that occurred over the years can be linked with improper handling of BMW [84–87]. Also, waste-related diseases accounted for approximately 5.2 million mortality annually, and this has been proposed to increase if adequate measures are not implemented to stop other disasters [88]. Most of the health problems linked with BMW disposal are due to the rapid and uncontrolled growth of medical care facilities and excessive use of biomedical facilities resulting in increased waste generation, improper disposal, and illegal recycling practices [89]. The potential health hazards may affect the public, especially healthcare workers, municipal employees, and rag pickers involved the recycling waste. Waste handlers and other individuals in direct contact with processing and handling of waste have a higher risk of contracting communicable diseases, majorly due to improper handling [90] and exposure via skin contact, open wound, and inhalation.

Although infectious wastes are traditionally treated by incineration, this method has been widely criticized due to the wide variety of pollutants released from the incinerator based on the component of the waste. Heavy metals, acidic and poisonous gases are significant pollutants emitted when burning BMW and may be toxic to human health. Among the possible health abnormalities associated with the burning of BMWs are increasing cancer and respiratory symptoms, eye irritation, congenital abnormalities, gastro-intestinal abnormalities, infertility, organ failure, musculoskeletal problems, and hormonal defects. At the same time, other related issues include global warming, acidification, and ozone destruction [91–93]. Therefore, newer technologies like bio-surfactants for bioremediation from beneficial microbes, hydroclaves and plasma pyrolysis, steam sterilization, microwave treatment, advanced steam sterilization, dry heat sterilization, biological treatment, plasma gasification, and alkaline hydrolysis are now proposed for the incineration of BMWs. This equipment causes reduced environmental degradation, non-significant health impacts, safe handling of treated wastes, ecofriendly, decreased running and maintenance costs, more effective reduction of microorganisms, and safer disposal [43]. Beyond a doubt, medical care is critical to life and the maintenance of health. However, the waste generated from medical activities causes additional problems for humans and the environment [94], especially during pandemics like SARS-CoV-2 (Figure 3).

Figure 3:

Solid waste management during COVID-19 pandemic [95].

General principles of hygiene and sanitation

This is a vital component of a good BMW policy. This principle involves cleanliness, availability of adequate and safe water, sanitary facilities, and good ventilation to health care facilities, service providers, and other stakeholders. Implementing this principle will reduce the breeding and growth of microbes, thus, enhancing healthy living practices [98].

Waste reduction

This is another means of managing BMW, especially those generated from hospitals and laboratories. This step involves proper identification and quantification of the waste generated, achievable by keeping proper inventories, the record of wastage of consumable items, and any damages. Using this approach, the quantity of waste disposed of can also be reduced by recycling or reusing some ‘wastes’ such as glassware and plastics after thorough cleaning and disinfection [99].

Waste segregation and storage

This can be adjudged the most crucial step in the waste management chain as it determines the eventual amount of waste to be treated and disposed of. At this step, designated storage facilities and a central storage site should be provided within the health facilities where wastes can be temporarily stored before they are transported offsite [100]. The WHO prescribed that medical waste should be sorted and dumped into separate waste containers from the source and afterward stored in a safe place inaccessible to rodents and unauthorized people for a maximum of 48 h before treatment or disposal [101]. If this guideline is strictly followed, the quantity of medical waste eventually passed to treatment/disposal facilities will be small and manageable. However, if the wastes are all mixed, they are all treated as hazardous and become difficult to recycle without pretreatment [99]. Inadequate knowledge of the characteristics of medical waste may be responsible for the poor segregation practice [102].

Waste transportation

Transfer of BMW within the health care facility should be done by designated and adequately trained personnel using appropriate equipment like trolleys and carts, which are not used for any other purpose. Also, suitable vehicles marked with biohazard symbols should be used to transport waste to sites for disposal [101]. The personnel involved in the transportation of medical waste should be trained on the different classifications of the waste and their containers to help them handle the waste and prevent them from mixing different categories of previously segregated waste [100].

Waste treatment and disposal

The methods which have been adopted for BMW treatment and disposal include the traditional open dumping on lands or water bodies, deep burial, burning and the modern incineration, autoclaving, shredding, superheated steam sterilization, microwave disinfection, wet oxidation technology, and electron beam gun technology [103]; though the World Bank permits open burning of toxic waste as a last resort on the condition that the site of burning is in the rural area, far away from busy complexes to limit the number of people being exposed to the adverse effects of the event [104]. Modern methods that are more environmental-friendly were developed to minimize the risks posed to people and the environment by the traditional methods. However, many modern methods are costly and not available in many developing countries [86]. Selecting suitable techniques used for waste treatment and disposal depends on the unique characteristics of the waste as well as proper separation at the point of production. The WHO also recommends that the choice of the mode of treatment and disposal should be guided by cost-effectiveness, easy implementation, and environmental friendliness [105]. However, the final disposal of these wastes is usually in a landfill. The techniques which have been documented for treatment and disposal of BMW include open dumping/burning [106], incineration [105], autoclaving [107], microwave disinfection [108], and landfilling [103]. However, in many developing countries, landfills are operated like open dumping, where all forms of waste are dumped and later burned [105]. Where the landfill is not adequately constructed, erosion may cause the waste to wash into water bodies, thus contaminating the water.

However, an international organization such as Institute for Global Environmental Strategies (IGES) has provided guidelines for adequate segregation, storage, transportation, treatment, and final disposal of BWM generated during the COVID-19 pandemic. Individual countries and authors have also suggested slight modifications to waste management during COVID-19 pandemic. These include chemical disinfection with mechanical crushing, steam disinfection/autoclave, reverse polymerization of solid wastes, while liquid waste can be subjected to chlorination, ultraviolet irradiation, ozonation, and ultrafiltration [109–111].

SARS-CoV-2 infected BMW output during pandemic

The WHO estimated that infectious diseases caused about one-quarter of all deaths worldwide [112], and approximately 50% of these deaths result from airway infections and diarrhea, which are mostly preventable with proper hygiene and adequate immunization. There is continuous emergence of new pathological infectious viral diseases that sometimes reach epidemic or even pandemic status. These ranges from HIV discovered in 1980 to various hepatitis viruses in 1990 also West Nile encephalitis virus. In the last decade, a new strain of the avian influenza virus and the SARS virus was discovered. Acute respiratory infections (ARIs) (which share some similarities with SARS-CoV-2) are the leading cause of morbidity and mortality worldwide, among other infectious diseases following self-inoculation from environmental contaminants [113]. Human activities have the aftermath of waste generation, which may carry consequences if proper handling is not instituted. The evolution of BMW as a separate category of waste dates back to the late 1970s when medical wastes were found on the USA’s beaches on the east coast. This followed the enactment of the US Medical Waste Tracking Act (MWTA) in 1988. The sources of BMW are from treatment, diagnosis, immunization, research, and even to a great extent, human and animal corpses died of contagious infectious ailment [114].

Until the outbreak of human immunodeficiency virus and hepatitis B virus, BMWs were carelessly handled and improperly managed; this has woken the healthcare management to time bomb posted by a carefree predisposition to the subject [115]. Although a larger percentage of the BMW has been found not to be infectious worldwide, reevaluation of this report is critical, especially with the recent outbreak of COVID-19 in which an increase of 20% of waste becoming infectious [116]. Prüss-Üstün et al. [117] estimated the percentage of various type of BMW generated; 15% pathological and infectious waste, 80% general healthcare waste, 3% chemical/pharmaceutical waste, 1% sharps waste, less than 1% other waste, like radioactive waste or broken thermometers. It should be noted that these figures may change due to COVID 19 pandemic worldwide.

Farzadika and colleagues reported that several African countries give poor attention to the proper handling of infectious BMW as evidence by improper documentation of the amount generated, the composition, and standardized management approach [118]. Admixture of noninfectious BMW invariably makes the whole waste classified as infectious and harmful, especially in COVID-19. According to WHO, about 8–16 million new cases of hepatitis B virus yearly, 2.3–4.7 million cases of hepatitis C virus, and 80,000 to 160,000 cases of human immune deficiency virus (HIV) are due to unsafe injections and mainly due to indigent waste management systems [119]. Studies have revealed that nosocomial infections (also known as hospital-acquired infections) exert a heavy financial toll on the economy and account for significant mortality and morbidity globally, with 6–19% of patients from LMICs and approximately 8.7% of patients had infections that are secondary to infectious waste [120–123].

In recent times, during the Ebola outbreak in LMICs, the health worker’s primary recommendation to contain the pandemic was proper disinfection and disposal of infectious waste whenever a suspected or confirmed case is being handled [124]. In the face of increased generation of infectious BMW during this pandemic, infection prevention and control (IPC) measure is the key to averting the spread of disease to patients, health workers, and the populace.

According to WHO, proper waste management, provision of potable water, sanitization, and maintenance of an utmost level of hygiene (WASH) in health care facilities, including (public and private places) will go a long way to curb or reduce the menace posed by the COVID-19 outbreak [125]. This means that the amount of infectious waste generated from the COVID-19 outbreak invariable will increase and pose a significant health threat if not adequately managed, especially in the developing world, both in the health facilities and the community at large. There is no confirmed case of faeco–oral transmission of COVID-19, nor it close associate SARS in the past among sewage or waste management workers; despite this, such waste from a confirmed or suspected case of COVID-19 should also be treated as a biohazard and should be carefully handled [126]. In developed countries (such as Germany and Austria), there is an adequate sewerage system; unlike LMIC, the risk of the possibility of this system leak needs to be assessed to mitigate the unintentional spread of COVID-19 and careful disposal of wastes where necessary [127]. It is common knowledge that open defecation is a ban in the developing world which further poses a significant risk to infection control, especially in asymptomatic individuals. Used water for the treatment of COVID-19 should be considered infectious liquid waste, which must be adequately managed, especially in poor resource countries [128].

Survival of SARS-CoV-2 and other microorganisms in the environment

Several micro-organisms, including viruses, exist in almost every natural habitat and can be transmitted from infected hosts to the environment and vice-versa. Therefore, natural evolution and human activities that frequently change the environmental conditions can hamper or influence the survival of these organisms. Thus, the appropriate response of microorganisms to significant changes in their natural environment can enhance their adaptation and promote survival. These responses are mediated by well-adapted regulatory mechanisms that mediate genetic modifications underlying physiological responses to changes in environmental conditions. These regulatory mechanisms involve the activation of several pathways responsible for transcription and translation as well as the stability of mRNA and active proteins that elicit suitable responses observed in the microorganisms. The inhibition of these pathways involved in the survival of microorganisms can prevent the transmission of these organisms and the accompanying infections in humans.

The molecular mechanism underlying the survival of microorganism in the environment

One particular feature of microorganisms is their ability to detect changes (such as radiation, decrease nutrient, temperature, pH, and chemicals) in their natural habitat and elicit an appropriate response to such changes for growth and survival. These organisms respond to such changes by activating several transcriptions and translational processes that preserve physiological and metabolic functions under unfavorable environmental conditions [129–131]. Microorganisms utilize different measures to cope with various environmental stressors that threaten their survival. These measures include changes in their membrane morphology, formation of spores and cysts, synthesis of different molecules for relieving stress, and activation of enzymatic processes necessary repair after damage [132]. Persistent exposure to environmental stressors induces genetic modifications underlying the adaptive mechanism of these organisms against successive stresses and coping with the new condition [133]. Some organisms respond to stressors by altering their cell morphology and synthesizing toxicants against the predators to enable their continual existence in their natural environment [134]. While some microbes reduce their energy-driven and nutrient-consuming metabolic activities to survive and protect against unfavorable environmental conditions, nondividing cells secrete resuscitation-promoting factor (Rpf), a protein that promotes resuscitation and growth activity in these organisms [135–137]. Another alternative strategies used for survival by microorganisms, including viruses, is applying adequate chemotactic behavior in which these organisms move away from unfavorable environmental conditions. Also, a programmed cell death mechanism is an indirect means of survival in which some cells in the microbes naturally die under extreme environmental conditions resulting in is less competition in the microbial population. Using this strategy, some microbial populations enhance their survival by utilizing nutrients derived from the dead cells [138, 139].

Micro-organisms have a well-modified regulatory system that identifies significant deviations in environmental conditions. These systems are very similar and well-conserved in all classes of microorganisms but are stimulated differently from an individual organism. Using different experimental approaches, it was reported that gene transcription and induction of several genes in relation to a specific change in the environmental condition provided evidence that an existing regulatory mechanism mediates adaptation to these environmental changes and the ultimate survival of these organisms [140, 141]. To ensure that these organisms survive, these regulatory genes are either upregulated or down-regulated depending on the controlling environmental conditions. This regulation occurs at both transcription and posttranscriptional levels. Regulation at the transcriptional level involves RNA synthesis (with the limiting enzyme-core RNA polymerase) and its control, altering the genetic expression. A microorganism with a well-studied survival mechanism is E. coli, with seven known sigma factors (σ⁷⁰) serving as the master regulator competing for the major component of the transcription mechanism (i.e., core RNA polymerase) [142, 143]. Other factors such as repressor, activator, sigma-binding antisigma factors, and small RNAs regulate the genetic transcription process [144–146].

Additionally, proteolysis and modulation of the transcript stability are also part of the control regulatory machinery involved in microorganism response to environmental stress [147–149]. All these biomolecules modulate genetic expression during environmental stress and create a complex regulatory network that promotes adaptation and survival despite significant deviations in environmental conditions. Thus, the survival of microorganisms in the environment is determined by their appropriate stress-response mechanism modulated by various regulatory patterns highlighted as follows; (A) control at the transcriptional stage by a specific or alternative sigma factor. This is the rate-limiting stage in the survival regulatory pattern implemented by microorganisms. These sigma factors modify the specific genes that mediate response. The action of this sigma factor is directly proportional to the environmental condition that elicits the observed response. (B) Transcriptional control by repressor binding to a DNA control element. (C) Transcriptional control by proteolysis is mediated by several auto-regulatory proteases. This mechanism can also regulate alternative sigma factors and other adaptation processes [150]. (D) Transcriptional control by small RNAs. This helps to mediate suitable responses to oxidative stress and other pathogenic stimuli [151].

Regulation at the posttranscriptional level affects all the modification processes involved in translating the genes to the active proteins. These modifications involve enhancing mRNA stability, initiating and regulating the translation processes, and the stability of the active proteins. Thus, all these control processes of transcription and translation mediate adequate physiological responses to changes in the environmental conditions and ultimate survival of these organisms [129, 130]. In addition to the above regulatory mechanism of survival, the spike protein present on the coronavirus envelope plays a vital role in SARs-CoV-2 survival. The virus uses this protein to attach to its host cell, mediate membrane fusion, and determine the solubility and infectivity of this virus. Also, the spike protein of SARS-CoV-2 has lower free energy than SARS-CoV, thereby making it more stable and able to survive at a higher temperature [152, 153].

Pathophysiological implications on health

The fight against COVID-19 infections caused by SARS-CoV-2 has been one of the fiercest in history that is different from SARS-CoV and MERS-CoV infections in term of biological property, transmission, and treatment strategy [154, 155]. Coronaviruses are positive-sense single-stranded RNA genomes, enveloped viruses (26–32 kb) [156]. Studies have shown that they possess about four genera of coronavirus (α, β, γ, δ). Human coronavirus is only found in α and β coronavirus genera, for α coronavirus; we have the following viruses HCoV-229E and NL63 and β coronavirus; MERS-CoV, SARS-CoV, HCoV-OC43, and HCoV-HKU1 as classified by The International Virus Classification Commission naming the novel β-CoV “SARS-CoV-2” [157, 158]. The genome of SARS-CoV-2 is closely similar to typical CoVs with more than 10 open reading frames (ORFs). Two large polyproteins are gotten from (ORF1a/b), about two-thirds of viral RNA is for nonstructural proteins [159] while the other ORFs of SARS-CoV-2 about one-third of the genomes are for main structural proteins: envelope (E), spike (S), nucleocapsid (N), and membrane (M) proteins with many accessory proteins with unknown functions [158]. The viral replicate transcriptase complex is formed from 16 nonstructural proteins (nsp1–nsp16), which are in turn processed from polyproteins (pp1a and pp1ab); the non-structural proteins rearrange the membrane produce from the rough endoplasmic reticulum by forming double-membrane vesicles, which are used for viral replication and transcription [159].

SARS-CoV-2 requires the angiotensin-converting enzyme 2 (ACE2) as a receptor to penetrate cells which is a significant step in the pathogenesis of the disease, with the help of coronavirus S protein which helps the virus to enter into the host cell [158, 160]. Cells with ACE2, such as lungs, heart, kidneys, arteries, intestines, brain, testis, and ovary, are highly susceptible to SARS-CoV-2 attack different pathological implications based on the biological functions of the organ [161]. After binding to the receptors, there is a fusion between the virus and plasma membrane in SARS-CoV mediated by SARS-CoV S protein at position (S2’) [162]. The second way it enters the cell is by clathrin-dependent and -independent endocytosis mediated SARS-CoV [163]. After successfully penetrating the cell membrane, the viral RNA genome moved into the cytoplasm, and two polyproteins and structural proteins are translated from the RNA, following which the viral genome begins to replicate [157]. New viruses are formed by combining genomic RNA and nucleocapsid protein forming the nucleocapsid, which is enclosed in envelope glycoproteins inserted into the membranes of Golgi or endoplasmic reticulum membrane and later extruded from the cell by fusing with the plasma membrane [164].

There is a paucity of information in understanding the relative effects of receptor binding and protease action predicting the infective potential of specific zoonotic coronavirus [158]. The frontier of knowledge of the pathogenesis of COVID-19 is still flawed. However, clinically they present with fever, nonproductive cough, difficulty in breathing, myalgia, fatigue, normal or decreased leukocyte counts, and X-ray evidence of pneumonia, but its pathogenesis has been likened to the mechanism of SARS-CoV and MERS-CoV [158, 165]. Antigenic peptides of the virus are presented by major histocompatibility complex (MHC; or human leukocyte antigen [HLA] in humans) by antigen presentation cells (APC), which is recognized by virus-specific cytotoxic T lymphocytes (CTLs). This is important for understanding SARS-CoV-2 pathogenesis, which is lacking [12]. Virus-specific B and T cells mediate the body’s humoral and cellular immunity following stimulation by antigen presentation by producing IgM and IgG [164, 166]. Studies have shown that IgM lasts for about three months, IgG may last longer, while cellular immunity appears to wane, as evidenced by the reduction in the number of CD4+ and CD8+ T cells in the blood. This is similar to what was obtained in patients with SARS-CoV [154]. The memory cells formed in patients with SARS-CoV can last for about four years or more. The primary cause of death in these patients is ARDS, mainly resulting from cytokine storm (an excessive immunological attack on the body). The release of large amounts of proinflammatory cytokines and chemokines causes uncontrolled systemic inflammation, multiple organ failure, and eventually death [165, 167]. There is a lot to learn about the pathogenesis of SARS-CoV-2, but the knowledge about SARS-CoV and MERS-CoV helps understand the dynamic pathophysiology of the novel SARS-CoV-2.

Conclusions

In conclusion, the outbreak of SARS-CoV-2 that causes COVID-19 infections has become a pandemic of global challenge due to its continuous spread across the countries of the world. Studies have reported that this virus is majorly transmitted by direct contact with an infected person. Hence, strategies that create an effective barrier to minimize direct contact have been proposed to reduce the continuous outbreak of this disease. PPE plays a significant role in reducing the transmission of this virus by providing an effective physical barrier against the infected patients, thus helping manage this disease. Hence, appropriate measures must be put in place to accommodate, manage, and treat the increased rate of SARS-CoV-2 infected BMW generation. In most developing countries, BMW disposal directly into water bodies is regarded as a poor method. However, this polluted runoff water has been linked to a significant increase in waterborne disease in LMIC because households and agricultural activities in rural communities are dependent on this water. It has been estimated that 80% of diseases worldwide are waterborne. This calls for the development of a robust, affordable, and sustainable BMW treatment plan. Also, SARS-CoV-2 infected BMWs from health care facilities accommodating COVID-19 infected patients should not be recycled without adequate treatment.