How Influenza A causes Epidemics and Pandemics - Essay Example

The 1918-1919 influenza pandemic which was the most distressful outbreak of influenza in history and considered as one of the most critical disease pandemics ever experienced came about as a result of H1N1 which is a subtype of influenza A virus (Hays, 2005). During this time the pandemic was known to kill over 25 million people globally (Ricks, 2009; p. 34). This essay will address the antigenic drift and the antigenic shift of the virus and how it has affected people globally. Influenza which is commonly referred to as flu is a contagious disease of mammals and birds which is caused by family orthomyxoviridae and RNA viruses.

In human beings the signs and symptoms of the disease range from sore throat, severe headache, coughing, fever to fatigue and weakness (Shors, 2009). In more severe scenarios the influenza leads to pneumonia which can be deadly especially in infants and the elderly (Stanberry, 2008). Whilst at times it might be taken for common cold. There are different types of viruses making it to for the pandemic to be contained easily. Flu viruses regularly vary via a method known as antigenic drift. This is the unsystematic accretion of mutations in the HA and to the least degree NA genes which are detected by the system of immune.

It is observable in influenza A viruses (Kurstak, 1990). Just like the normal cases of RNA viruses, mutations in the flu viruses take place often due to the replication machinery of the viruses which lacks a proofreading system. Whenever such variations result into mutations in the sites occupied by the antigens of HA or NA that are responsible for the reduction or inhibition of the bond of neutralizing antibodies, the immune system might be avoided by the viruses (Sompayrac, 2002). This procedure gives an explanation of the incident of serial flu epidemics in the course of winter in climatic zones that have temperate conditions and incident of epidemics of varying relentlessness and age groups affect (Betts, Penn