**1. Introduction**

Infectious diseases are types of transmissible or communicable diseases mainly caused by pathogenic living microorganisms. The disease not only can transmit from animal to animal but also transfer from animal to human through the parasite, virus, and bacteria [1]. The sudden invasion of infectious disease is a critical objective for the quietly alive of people in the ground [2]. However, it is not always an easy task to identify and anticipate the small pathogenic like small particles that are responsible for sudden chronic situations increasing incidence in geographic range [3]. Therefore, the situation demands to identify the unpredictable appearance of new infectious diseases as soon as possible that can utilize for further development of new therapeutic agents. Before identifying the causal infectious agents, the inevitable, but unpredictable, the appearance of newly emerging and re-emerging infectious diseases should be understood. The term emerging infectious diseases (EID) refers to infections that are newly arrived or evolved in a certain population, whose incidence can rapidly increase worldwide and threaten for future. On the other hand, infectious diseases that were previously appeared in the population and gradually decrease the incident but currently expanding into new geographical, host, or vector immensely that called re-emerging viral disease [4]. The virus disease has been recognized mostly from zoonotic by infecting a human. The primary source of zoonotic virus from farm and wild animal causes disease in human. Approximately 60 to 75% of known human pathogens ascend from animals [5]. Animal reservoirs have been involved in numerous virus families such as Filoviridae, Arenaviridae, Flaviviridae, and Bunyaviridae that were responsible to transmitted virus animals to humans *vice versa*. Most of the viruses abovementioned can be occurred emerging or re-emerging diseases, which do not have any specific therapeutic agents. Therefore, the development of vaccines and antimicrobial drugs candidates is an urgent issue that can control or prevent emerging or re-emerging diseases as soon as possible.

With the advancement of computational biology and immunoinformatics, rapid detection of pathogens and related proteins responsible for the disease has been developed. The technology helps to determine pathogen types within a short time and is utilized for therapeutic development. For example, immunoinformatic approaches can predict epitopes and their target protein is the recent advancement in vaccine design and development process that controlled the uses of antigen variation as well as hitting conserved epitopes [6]. It mainly designs immunogens by the protective responses of the target-specific receptor [7]. In the consequences of DNA virus infection and replication, it first attaches to the outer cell of the host through the protein receptor and replicates DNA by using host cell enzymes [8]. Finally, DNA goes to messenger RNA and translates it into a viral protein. Complete viral particles have converted by the replicate DNA and viral protein when new viruses were released from the host cell [9]. Additionally, RNA viruses are operated precisely as messenger RNA to make viral proteins. This mechanism of viral infections can be predicted through computational tools and immunoinformatics can identify desired epitopes for designing vaccines against the infections. On the other hand, computer-aided drug design (CADD) consists of a computer-assisted *de novo* design that can predict several models based on drug-target interaction network and help to early stage of drug design through molecular docking, similarity search methods, and deep learning-based model. The confirmation of ligand and the target protein can be initially predicted through molecular docking [10]. However, the performance of docking is quietly dependent on various types of receptors as well as acting best for the hydrophobic vs. hydrophilic pockets, which can also be determined by the CADD approaches.

Furthermore, consistent advancement of medical and pharmaceutical research has been playing an important role in the proper solution of several diseases but remained some problems with viral disease that may suffer or burden to public and *Immunoinformatics and Computer-Aided Drug Design as New Approaches against Emerging… DOI: http://dx.doi.org/10.5772/intechopen.101367*

animal health [11]. Therefore, computational techniques have opened a new avenue for minimizing the problems of drug discovery. The pharmaceutical industry has been starting to take up help from computational methods for drug design and development, drug repurposing, enlightening medicinal efficiency, and clinical trial [12]. The increasing data digitalization in a pharmaceutical company can be solved clinical problems that can also be done through computational methods. They have maintained a large volume of data for solving infectious diseases by their automation. The extremely widespread diseases remain virus diseases that cause infection by a type of microorganisms [13]. The most prominent type of virus diseases is common cold, while another one is an infection of virus that affected the upper respiratory tract such as nose and throat [14]. Furthermore, antibiotics have a magical role in preventing bacterial disease and infections but have no effects on viral disease. The most significant challenge to the researcher is finding out the epidemiology, vaccine design, and eradication in a worthwhile manner [15].

## **2. Infectious disease**

Infectious disease is a kind of disorder that is caused by one or more organisms. Many organisms consist of our body where some are normally helpful or infectious with parasites and viruses as well as bacteria and fungi [16]. SARS, recently emerged SARS-CoV-2, tuberculosis (TB), HIV/AIDS, influenza, Chickenpox, the common cold, and Hepatitis A and B are some examples of infectious diseases that can easily transmit from human to human or animal to human under adverse conditions and help to cause diseases. However, the animals or insects are directly or indirectly responsible for transmission to these organisms. Contaminated food items have exposed some infectious to the new environment and move apart from diseases [17]. There are various signs and symptoms of infectious diseases such as fever, fatigue, coughing, muscle aches, and diarrhea, and so on. Infectious diseases can be remedied or controlled by vaccines, but it takes a long time for application. Most infectious diseases controlled by consciousness of diseases such as handwashing can help to protect from many infectious diseases [18].

#### **2.1 Global burden of infectious diseases**

Over the last few centuries, millions of people have lost their lives to infectious diseases throughout the world. The risk of public health has been reduced and controlled through the improvement of the sanitation system, the progress of antibiotics and vaccines, living condition, and food quality, which is linked to the socioeconomic modernization of these societies [16]. Despite the improvement of health care facilities and surveillance systems, there have been some uncertainties that still now lead to an increase the human mortality from infectious diseases. The current threat to global human health is zoonoses [19]. The mutually transmitted 200 diseases occurred between humans and animals. The zoonotic disease has been increasing due to the overpopulation, wars, and food scarcity that are associated with humans who contract face to face [20]. However, the global death increased in 2010 due to infectious disease from HIV/AIDS that constitutes 1.5 million, and hereby malaria raised to 1.17 million [21]. At the same time, about 152,000 people died by the neglected tropical disease, and 1.2 million people died of tuberculosis [22]. Long-term illness, disability, and social stigma are occurring from poverty

and are renamed by infectious diseases of poverty (IDoP). Moreover, coronavirus disease 2019 (COVID-19) has the main worldwide burden in this era expressing itself as a pandemic and killed almost 4,825,433 people from the beginning and has been infecting till now [23]. The global health system has been affected by the pandemic due to the unintentional interruption of service delivery. Until now, a total of 369 infectious diseases have been identified based-on mortality and the estimation of life expectancy according to global burden diseases in 2020. There are several factors responsible for diseases that have compiled during the COVID-19 pandemic by analyzing 286 causes of death, about 369 injuries and infections, and 87 threat issues from the 204 nations [24].

#### **2.2 Emerging and re-emerging infectious disease**

Several infectious pathogens have been halting their activities from the initial discovery and reappearance after a long and short period in several places [25]. Among them are Emerging and Re-Emerging Infectious Diseases (EIDs). They are types of infections that have newly originated or previously existed in a population that is rapidly increasing in incidence or geographic range. The newly emerging and re-emerging viral disease has threatened public and animal health, which is increasing due to human activities [26]. There are many associated factors related to the spread of infectious viral disease from one place to another place such as population migration, urbanization, public gathering, poverty, malnutrition, increased domestic and global connectivity and environmental changes, and so on [4]. The alteration of genetic phenomena has also been responsible for to spread of disease to a greater extent. Most of the infectious diseases have been estimated in zoonotic that constituted 60 to 70% of total diseases [27]. Hence, the animal virus also mutated with a human virus that accelerates infectious viral disease and generates the chronic problem. As a result, thousands of people die without medicine or even without knowing about the threat [28]. Novel pathogens have occurred due to unplanned urbanization of habitat destruction that enhances the contact or susceptibility to infections between human and animal vectors of viral diseases herewith the lack of immunity of these communities [29]. However, many pathogens re-emerging again after many years such as Chikungunya and Zika virus.

#### **2.3 History of emerging and re-emerging virus**

Initially, there was an outbreak of chikungunya between 1963 and 1973 with serious arboviral illness and it re-emerged in 2006, which firstly was observed in the East African strain of chikungunya [30]. Similarly, the Zika virus was initially associated with a serious illness that has conducted by serological studies in 1960 and after a long time, it has identified and reported from Brazil in 2015 [31]. The discovery of novel pathogens in the world has not been clogged and they are associated with economic cost reflect the burden for many developed and underdeveloped countries (**Table 1**). The high cost of medical and intensive care has been banned for all kinds of work from the affected region.

#### **2.4 Factor influences emerging and re-emerging viral bond diseases**

Viral diseases have chorionic effects on public health worldwide. The annual death has been attributed to about 20 million by infectious diseases [34]. Most of the death


*Immunoinformatics and Computer-Aided Drug Design as New Approaches against Emerging… DOI: http://dx.doi.org/10.5772/intechopen.101367*


#### **Table 1.**

*Emerging and re-emerging virus figure out with the inauguration periods [32, 33].*

not only occurred by acute respiratory tract infection and gastrointestinal infections but also come out through tuberculosis and malaria that remained unchanged till now [35]. Many factors have been leading to emerging and re-emerging infectious diseases such as demographic factors, population distribution, sexual behavior, childcare, food-borne and water-borne diseases, ecological alteration and land use, chronic manifestations, enhanced pathogen detection, microbial evolution, and failure of community health scheme and bioterrorism shown in **Figure 1** [36]. The variations of the global population have been contributing to the growth and density in per capita, resettlement to the city area, international tourism, migration, and retaining density that directly or indirectly leads to the infectious virus disease [37]. However, there are some intentional reasons too responsible for the emerging and re-emerging virus such as the deliverance of sexual practice, enhanced childcare beyond the family, alcohol and drug abuse, food supply, transportation, and immunization practices [32]. Moreover, the environmental and land use causes of global warming, deforestation, and natural disasters such as floods, drought, and *El Nino* effect will be the lead to current and future infectious diseases [38]. The invention of modern technology can manifest the infectious diseases that are prolonging the life of people in the world. The use of new molecular techniques has enhanced to detection of fastidious and uncultivatable organisms [39]. As a result, a variety of pathogens were discovered in a short time. Nowadays, microbiomes naturally adapt to their environment for survival causing a wide range of microorganisms that

*Immunoinformatics and Computer-Aided Drug Design as New Approaches against Emerging… DOI: http://dx.doi.org/10.5772/intechopen.101367*

#### **Figure 1.**

*Representing different factors that influence the activities of emerging and re-emerging viral bond diseases.*

have become resistant to diseases [40]. Consequently, it can alter the present situation and convey the hazardous situation for human life.

#### **2.5 Preventive measures of emerging and re-emerging disease**

Due to the degradation of the environment, many contagious infections spread out the world for a long time. However, some diseases have been treated through the antibiotic and controlled with the vaccine but most of the disease's remedies remained unchanged still now [41]. Scientists and researchers have been searching for a new link in an infectious chain through their internal activities. The consumption of raw food is one of the triggers of infectious diseases. Raw food usually has lots of harmful microorganisms that can hamper your normal life within a short time [41]. Several factors have been contributing to the vast range of emerging and non-emerging diseases such as changes in human behaviors, enhancement of technology, change in the land pattern and economic progress, tourism, microbial change, and collapse of public health measures [41]. However, the prevention and control have been taken by the Pan American Health Organization (PAHO) that regulates some measures of emerging and re-emerging diseases [42]. First, there is need to increase and strengthen regional surveillance networks that control infectious diseases from one place to another place. Later, the rapid responses of infectious diseases thereby enhance the laboratory equipment and training. Moreover, the development of applied research fields can prevent the disease through the rapid diagnosis of epidemiology as well as prevention [43]. Finally, the enhancement of regional capacity and strength can control and prevent emerging and re-emerging diseases through effective implementation [44].

#### **2.6 Traditional methods of preventing emerging and re-emerging disease**

Emerging viral diseases have occurred previously and resultant pandemics where plant derived was the first choice for treatment. Around 1500 BC, Egyptians were started herbal drug preparation by the medicinal plant where later Greek and Roman have improved it [45]. Emerging infectious diseases have been treated traditionally by the medicinal plant before inventing a drug or vaccine [46, 47]. In China, it was widely used to deal with infectious diseases. They believe that it boosts the immune system and protects the virus to enter the respiratory tract [48]. Many medicinal herbs have a unique antiviral effect and are used as a substitute for an antimicrobial drug against infectious diseases. They have used the whole body of herb or part of the plant such as leaves, roots, bark, fruit, seeds, flowers, and so on, for preventing and healing respiratory tract infections [49]. In the modern time, it has been perceived that the traditional drug safer and healthier than synthetic drug those comes from plant-based traditional medicine. Plantderived drug discovery has been renowned for the last decade [50]. It is considered that plant products will be an indispensable source of a new drug in the future.
