Preface

Medically important RNA viruses with families include: Togavirus, Bunyavirus, Flavivirus, Filovirus, Arenavirus, Rhabdovirus, Paramyxovirus, Orthomyxovirus, Coronavirus, Retrovirus, Picornavirus, Reovirus, and Calicivirus. Some RNA viruses contain double-stranded RNA (Family Reoviridae) and some viruses have a life cycle that uses reverse transcriptase. Viruses contain ribonucleic acid (RNA) as their genetic material. Particularly, several human diseases are caused by RNA viruses. The main objective of this book on RNA viruses was to understand the RNA virus i.e a seroprevalence study based on molecular epidemiology such as genotyping tools by IgM/IgG, ELISA, PCR, FRNT50 and phylogenetic analysis to further confirm the RNA viruses causing diseases in tropical and subtropical countries. However, pathogenesis mechanisms causing viral diseases among the flaviviruses family have not been clearly understood and also little is known about the host responses to RNA viral infection. This book will surely help with these information gaps and also provide research information to the policymaker or planner for further diagnosis, control and prevention in future outbreaks of RNA virus diseases in tropical and subtropical countries.

> **Yogendra Shah** National Zonosis and Food Hygience Research Center, Nepal

> > **Eltayb Abuelzein** Central Veterinary Research Laboratories, Sudan

**1**

**Chapter 1**

**Abstract**

*Adamu Ishaku Akyala*

indicating it may be more transmissible.

clinical characteristics, viral shedding

**1. Introduction**

**Keywords:** coronavirus disease 2019 (COVID-19), transmission,

In late December, 2019, an epidemic of respiratory disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) began in the city of Wuhan in China which spread to over 30 countries of the world [1]. In the last 25 years, notable highly infectious respiratory viruses with pandemic potentials has emerged and remerged. Notable of which is the influenza virus that issued a

Mode of Transmission and

Emerging New Paradigms

Viral Shedding of SARS-CoV-2:

SAR CoV-2 is an important group of animal and human pathogens that infect respiratory tract, hepatic, gastroenterological, and nervous systems of mouse, bat, bat, humans and other vertebrates. Middle East Respiratory Syndrome (MERS) and severe acute respiratory syndrome (SARS) Outbreaks in 2002–2003 have demonstrated the possibility of human to human transmission, animals to humans transmission of the emerging SARS-CoV-2. The World Health Organization (WHO) On 12 January 2020 renamed novel coronavirus infectious disease (COVID-19) to SARS-CoV-2 In late 2019, the first case of the COVID-19 was reported. A total of 87,137 confirmed cases globally, 79,968 confirmed in China and 7169 outside of China, with 2977 deaths (3.4%) had been reported by WHO in March 1, 2020. Meanwhile, several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly identical genome to bat coronavirus, pointing to bat as the natural host and by proxy has a zoonotic propensity. Angiotensin-converting enzyme 2 (ACE2) is the same receptor been used by the novel coronavirus as that of SARS-CoV and largely spreads through the respiratory tract. Currently, there are few specific antiviral strategies, but several potent candidates of antivirals and repurposed drugs are under urgent investigation. In this review, we summarized the latest research progress on the transmission mode dynamics and viral shedding in provide direction for isolation protocol. R0 estimates for SARS have been reported to range between 2 and 5, which is within the range of the mean R0 for COVID-19 found in this review. Due to similarities of both pathogen and region of exposure, this is expected. On the other hand, despite the heightened public awareness and impressively strong interventional response, the COVID-19 is already more widespread than SARS,
