Current Perspectives on Anti-Infective Agents

K. Tamreihao, Saikat Mukherjee, Debananda S. Ningthoujam, K. Tamreihao, Saikat Mukherjee, Debananda S. Ningthoujam

• Publisher: Bentham Science Publishers
• Year: 2019
• Print ISBN: 9789811432729
• eBook ISBN: 9789811432736
• Topic: Medicine
• Subtopic: Medical Microbiology & Parasitology

The volume is a comprehensive documentation on major infectious diseases from tropical countries which pose a serious threat to global healthcare programs. These include diseases such as tuberculosis, AIDS, leishmaniasis (kala-azar), elephantiasis, malaria, leprosy, various fungal disorders and emergent viral diseases. Due to the widespread use of antibiotics, there is an emergence of drug resistant pathogens in many regions. Hence, there is a need to search for novel, cost-effective bioactive compounds that demonstrate high efficacy and low toxicity in human cells from unexplored ecosystems to combat emerging drug resistant pathogens. Chapters of this volume focus on the pathogenesis and etiology of each of the mentioned diseases, updated WHO reports wherever applicable, conventional drugs and their pharmacokinetics as well as new approaches to develop anti-infective agents. The authors also present a detailed report on 'superbugs' (multi-drug resistant pathogens) and new measures being taken up to eradicate them. Information about new antimicrobials (bioactive peptides and silk protein sericin) and the approaches taken by scientists and healthcare professionals for successful targeting of these molecules for human medicine. This volume is essential for general readers, healthcare professionals, researchers and academicians actively involved in research on infectious diseases and anti-infective therapeutic drugs.

Emerging Viral Diseases and Potential Therapeutic Agents for Their Control

Sumita Banerjee^*

Department of Oral Pathology & Microbiology, Regional Institute of Medical Sciences, Dental College, Imphal, Manipur, 795004, India

Abstract

The emerging infectious human viral diseases have been the prime concern for public health since the last decade. Various new viruses or virulent strains of old viruses have emerged during this period. Appropriate knowledge of the viral pathogenesis is required to understand their emergence and possible therapies. Various factors have contributed to the emergence of viruses and new human diseases. Some of these human diseases are zoonosis. Zoonosis can be defined as human diseases caused by animal pathogens and that are transmitted to humans. The WHO has been continuously updating the prioritizing list for various infectious, and emerging viruses. In this chapter, we discussed some important emergent viral pathogens such as Ebola virus, Crimean-Congo Haemorrhagic Fever virus, and Marburg virus, Hanta, Hendra, and SARS. Detailed understandings of the emergence, the modes of transmission and pathogenesis, and possible treatment plans are necessary to check the invasion and outbreak caused by these viruses.

Keywords: Emerging viral diseases, Crimean-Congo Haemorrhagic Fever virus, Ebola, Hanta, Hendra, SARS.

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^* Corresponding author Sumita Banerjee: Department of Oral Pathology & Microbiology, Regional Institute of Medical Sciences, Dental College, Imphal, Manipur, 795004, India; Tel: [phone];
E-mail: [email protected]

INTRODUCTION

Infectious diseases cause societal and economic problems causing nearly one in five human deaths worldwide. An emerging infectious pathogen is an infectious agent which has emerged in a population and its geographical ranges gets ex-panding rapidly, an old phenomena documented by Roman and Persian phi-losophers. They wrote about the devastating disease plague in the time of ancient Greece [1, 2]. There is historical evidence of the deadliest Pandemic Emerging infectious diseases (EIDs) such as 14^th century Black Death (75 to 200 million deaths by the pneumonic plague); Spanish influenza pandemic in 1918-1919 (50 to 100 million deaths) [3]. HIV, the most potent killer of infectious origin had a

peak incidence in 1997, along with 3·3 million new infections.

After the development of antiretroviral drugs, the incidence number had declined in 2005, however, total number of HIV/AIDS infected people has reached 38·8 million in 2015 [4].

The first declared pandemic of the 21st century, in 2009, a swine-origin H1N1 influenza got spread rapidly to 213 countries [5]. In 2014, the WHO announced the Ebola outbreak in West Africa a “public health emergency of international concern” [6, 7]. Appearance of 335 infectious diseases in human population from 1940 to 2004 had been reported by Jones and co-workers of which nearly two-thirds originated in wildlife [8]. New patterns of deadly disease outbreaks caused by novel animal viruses are reported such as Nipah prevalence in Malaysia, hantavirus (United States), Hendra virus (Australia), SARS also known as severe acute respiratory syndrome virus and MERS also known as Middle East respiratory syndrome coronavirus. According to Jones and co-workers, EID origins are multifactorial and can be directly correlated ecological, environmental and socio-economic factors that can lead to identification of emerging disease ‘hotspots’ [9].

Possible Causes Behind the Emergence of New Viral Diseases

There is a plethora of determinants that can lead to the emergence of infectious diseases (Table 1).

Table 1 Causes for Emergence or Re-emergence of Viral Diseases [1^-9].

Factors Leading to Emergence	Determinants
Economic and social development	Population growth, density, distribution Environmental changes such as deforestation, dam building, global warming Increased global travel Increased international commerce Agribusiness, food processing, distribution Ecological changes and agricultural development
Poverty	Inadequate public health systems Open defecation Lack of safe water Breakdown of public Health measures and deficiencies in Public health infrastructure
Societal breakdown	Civil chaos War Changes in human demographics and behaviour
Human factors	Sexual activity Substance abuse
Biological factors	Natural mutation Antimicrobial resistance Immunosuppression
Climate change	It also plays important role in the emergence of an infectious disease

In some instances, the “emergence” of a viral disease represents the first identification of the cause of a well-recognized disease. Emergence of novel disease reflected a new found ability to identify the etiologic entity [10].

Disease Caused by an Existing Virus: Many times, a virus which is already existing can cause epidemic or endemic because of increased ratio of cases to infections. an already wide spreading virus in a population can emerge as a cause of epidemic or endemic disease, due to an increase in the ratio of cases to infections. This can be caused by enhancement of virus virulence or increased host susceptibility such as Poliomyelitis which caused summer outbreaks of acute infantile paralysis in United States and Sweden in nineteenth century. Through extensive vaccination efforts, eradicating polio is perhaps the largest worldwide public health initiative in history [6]. Unfortunately, poliovirus has begun to re-emerge in once polio-free countries and infections now occurred in susceptible children, resulting in outbreaks of infantile paralysis [11^-13].

Increase in Viral Virulence: An emergence of the dramatic outbreak of viral infections can be attributed to sudden increases in virulence factor. In early 1983, a lethal outbreak of avian influenza was reported in Pennsylvania. Initially, the infections were mild but the 2^nd attack in the same region was severely wide spreading making it pandemic. However, the viral strains from both the isolates had exactly similar genomes. The virulent strain had a point mutation in hemagglutinin enabling hemagglutinin cleavage and made it capable for replication outside respiratory tract, thereby increased virulence [7]. The most challenging viral adaptation mechanism is gene mutation and RNA viruses very commonly acquire this mutation. RNA viruses have a mutation rate of 10^-4 to 10^-6 /bp/generation [14]. Mutations facilitate the viral population to adapt to a new host or changing environment. Reassortment, and recombination are the two other adaptation mechanisms. Reassortment is very common for Influenza virus. When two viral strains of e.g., avian and human influenza viruses) infects the host simultaneously, a new virus progeny with recombined genome could appear and the host further gets susceptible to the new strain of viruses due to the lack of available immunity to the specific strain. ...

Table of contents

• Welcome
• Table of Contents
• Title
• BENTHAM SCIENCE PUBLISHERS LTD.
• PREFACE
• List of Contributors
• Prospects of Actinobacteria from Underexplored Ecosystems as Anti-infective Agents against Mycobacterium tuberculosis
• Protozoan and Helminth Infections: Epidemiology and Anti Infective Therapy
• Therapeutic Drugs Used for Effective Lifelong Control of HIV and AIDS
• Bioactive Peptides and Their Therapeutic Potential as Antimicrobial Drugs
• Drugs for Superbugs: Strategies and Methods to Discover New Antibiotics against Drug Resistant Pathogens
• Antifungal Agents: Therapeutic Approaches and Future Perspectives
• Emerging Viral Diseases and Potential Therapeutic Agents for Their Control
• Leprosy: Clinical / Diagnostic Features and Current Status of Anti-leprosy Drugs
• Silk Protein Sericin: Structure, Secretion, Composition and Antimicrobial Potential
• Understanding the Realm of Antibiotics: Mechanisms of Action and Their Applications as Anti-infective Agents
• The Use of Medicinal Plants in Treatment of Malaria