Question

Define emerging infections using SARS-CoV-2 as an example, which causes the disease COVID-19. Provide an explanation of why and how it emerged. Explain why it is now causing a pandemic using terms relevant to the specific immune response.  

Answer 1

Emerging diseases is diseases which are recognized in human host for the first time or has existed previously but is rapidly spreading .It may exhibit successive stages .

SARS CoV-2 is an example of such emerging diseases.
Most of Emerging infectious diseases are zoonotic orgin (emerged from animal) and crossed the species barrier to infect human ,they are unpredictable this scenario is increasing for past 20years and could increase in near future. Efficient transmission between humans can develop into public and global concern( epidemics /pandemics). Corona virus emerged from zoonotic orgin which spread into humans and from person to person transmission in closed space ,within hospitals, finally it became international crisis by travel across different regions.

COVID 19 discoverd during late November of 2019 as a study on mysterious pneumonia outbreak in Wuhan city of China has raised to public concern. It is believed to be transmitted from wet market(livestock market) in Wuhan city . Animal to human spread is considered as first later human to human transmission via infected droplets The current outbreak of corona virus is increasing day by day as a concern to public health emergency internationally. It is due to increased transmission capacity. Before the virus being discovered travel across the world by people made this epidemic into a pandemic. And this virus posses great risk is that it can be transmitted by asymptomatic individual who is carrier , this may have caused increased number if infected people

Based on immune response:

As soon as intubation period over, virus cause non severe symptoms that elicit protective immune responses, at this stage elimination of virus success rate is based on general health and HLA halotype of individual, and those who cannot enters to severe stage which cause damaging inflammatory response in lungs. In some people after discharge from hospital return positive and relapsing condition ,this indicates virus is eliminating immune response and this also cause difficulty in development of vaccine . In context with all these ,Improper travel restriction, use of PPEs and masks , social distancing etc ,made this into a pandemic ,which we are dealing with great precaution now.