SWINE FLU (Syllabus: GS Paper 3 – Sci and Tech)

Context: Recently, the UK reported the first human case of a new strain of swine flu, prompting health authorities to investigate and determine the origin of the virus.

Swine Flu

• About: It is a highly contagious respiratory disease in pigs caused by one of several swine influenza A viruses.
• Also Known as: H1N1 influenza
• Causes: Influenza viruses such as H1N1 infect the cells that line your nose, throat and lungs.
• Symptoms: Fever, Cough, Sore throat, Body aches, Headache, Chills and fatigue, Diarrhea and vomiting (possible).
• In children: signs of severe disease include apnea, tachypnea, dyspnea, cyanosis, dehydration, altered mental status, and extreme irritability.
• In 2009, the H1N1 variant became widespread in humans for the first time.
• The World Health Organization (WHO) declared the H1N1 flu to be a pandemic in 2009.

Influenza: It is an acute viral infection of the respiratory tract which is considered to be one of the life-threatening infectious diseases. Human influenza viruses are single-stranded RNA viruses.

• Types: There are 4 types of seasonal influenza viruses, types A, B, C and D. Influenza A and B viruses circulate and cause seasonal epidemics of disease.

oInfluenza A viruses: They are further classified into subtypes according to the combinations of the hemagglutinin (HA) and the neuraminidase (NA), the proteins on the surface of the virus.  Ex: A(H1N1) and A(H3N2) influenza viruses.  Only influenza type A viruses are known to have caused pandemics.

oInfluenza B viruses: They are not classified into subtypes, but can be broken down into lineages. Currently circulating influenza type B viruses belong to either B/Yamagata or B/Victoria lineage.

oInfluenza C virus: It is detected less frequently and usually causes mild infections, thus does not present public health importance.

oInfluenza D viruses: They primarily affect cattle and are not known to infect or cause illness in people.