INFLUENZA
BS143-4-AP: Essay 2
Professor: Dr. Benjamin Skinner
By: Ajmal Shekeb Noormal
, Influenza, commonly known as the flu, is a highly contagious respiratory disease caused by
influenza viruses that circulate globally and affects the nose, throat, and lungs. It can cause
mild to severe illness and in extreme cases, it can be fatal (CDC, 2022). Influenza has been
around for thousands of years, and the reason for its persistence is that it is continually
evolving. The flu has claimed the lives of millions of people. For instance, in 1918, a flu
pandemic that infected a third of the world's population resulted in 50 million deaths in just
two years. (WHO, 2023).
The pathophysiology, replication cycle, and natural history of influenza viruses—the root of
both seasonal influenza and pandemics—are succinctly summarised in this infographic
(Hutchinson, 2019).
Figure 1, (Hutchinson, 2019)
Influenza viruses are single-stranded RNA, pleomorphic, enclosed viruses that belong to the
Orthomyxovirus group. Based on distinct ribonucleoprotein antigens, they are divided into
three major serotypes, A, B, and C. Influenza A viruses naturally infect a wide range of species,
including mammals and birds, and tend to go through considerable antigenic changes. They
typically produce more severe illness and more widespread epidemics than the other forms
of influenza. The influenza B virus is more antigenically stable, only known to naturally infect
humans, and tends to cause more isolated outbreaks. Influenza C viruses, which affect both
people and pigs, seem to be comparatively insignificant disease-causing agents (see Table 1)
(Ryan and Ray, 2004).
1
BS143-4-AP: Essay 2
Professor: Dr. Benjamin Skinner
By: Ajmal Shekeb Noormal
, Influenza, commonly known as the flu, is a highly contagious respiratory disease caused by
influenza viruses that circulate globally and affects the nose, throat, and lungs. It can cause
mild to severe illness and in extreme cases, it can be fatal (CDC, 2022). Influenza has been
around for thousands of years, and the reason for its persistence is that it is continually
evolving. The flu has claimed the lives of millions of people. For instance, in 1918, a flu
pandemic that infected a third of the world's population resulted in 50 million deaths in just
two years. (WHO, 2023).
The pathophysiology, replication cycle, and natural history of influenza viruses—the root of
both seasonal influenza and pandemics—are succinctly summarised in this infographic
(Hutchinson, 2019).
Figure 1, (Hutchinson, 2019)
Influenza viruses are single-stranded RNA, pleomorphic, enclosed viruses that belong to the
Orthomyxovirus group. Based on distinct ribonucleoprotein antigens, they are divided into
three major serotypes, A, B, and C. Influenza A viruses naturally infect a wide range of species,
including mammals and birds, and tend to go through considerable antigenic changes. They
typically produce more severe illness and more widespread epidemics than the other forms
of influenza. The influenza B virus is more antigenically stable, only known to naturally infect
humans, and tends to cause more isolated outbreaks. Influenza C viruses, which affect both
people and pigs, seem to be comparatively insignificant disease-causing agents (see Table 1)
(Ryan and Ray, 2004).
1
