Flu caused by H3N2 and H1N1 viruses

What is Flu?

Influenza is commonly known as Flu. The flu viruses are categorized into four types: A, B, C, and D, based on the core proteins. Only types A and B are pathogenic in humans. Influenza A virus is commonly found in birds. Influenza A virus is divided into subtypes based on the presence of two glycoproteins on its surface: HA (haemagglutinin) and NA (neuraminidase). 16 HA and 9NA avian viruses are known to us. Subtypes A(H1N1)pdm09, and A(H3N2) are the cause of current infections.

H1N1

Image of H1N1 virus. Image source: https://www.cdc.gov/h1n1flu/images.htm

H1N1 is a subtype of the influenza A virus and is commonly known as Swine flu because people in contact with the pigs had gotten infected by the virus. The 1918 Spanish flu, the 1977 Russian flu, and the 2009 Swine flu pandemics were caused by the H1N1 virus. The H1N1 virus is also called H1N1v. The 'v' in nomenclature means it is found both in animals and humans.

How it spreads? - It is contagious and spreads through sneezing and coughing of the infected person.

Symptoms- fever, cough, chills, sore throat, body ache, headache, fatigue. It can be troublesome for diabetes and asthma patients.

Diagnosis- Rapid flu test

Treatment- 1 Take bed rest.

2. Stay hydrated

Drugs - Antiviral drugs like oseltamivir (Tamiflu) and Zanamivir. Acetaminophen is given to reduce body aches and fever. Adamantanes, such as amantadine and rimantadine are also effective against H1N1.

Mechanism of action-

1. oseltamivir and Zanamivir - It blocks the viral sialic acid neuraminidase enzyme and prevents the virus release from infected cells.

2. Adamantanes - Blocks M2 protein which helps the virus to gain entry into healthy human cells.

Prevention: 1. Washing hands.

2. Using masks.

3. Isolation of infected patients.

4. Flu vaccines or shots can be taken every year for prevention.

H3N2

H3N2 or “Hong Kong flu” is a type of influenza virus that can cause respiratory illness in humans. The other name is H3N2v.

Symptoms of H3N2 are similar to other types of influenza and include fever, cough, sore throat, runny or stuffy nose, body aches, headache, chills, and fatigue.

Diagnosis - Rapid Influenza diagnostic test (RIDTS).

Treatment - 1 Take bed rest.

2. Stay hydrated.

Drugs - Antiviral drugs like oseltamivir, peramivir, and baloxavir. Adamantanes are not effective against H3N2.

Prevention: same as H1N1

Difference between H1N1 and H3N2 - The key difference between H1N1 and H3N2 is that H1N1 contains main surface proteins known as H1 (hemagglutinin1) and N1 (neuraminidase1), while H3N2 contains main surface proteins known as H3 (hemagglutinin3) and N2 (neuraminidase2). It is more severe in terms of fever, leukopenia, and C-reactive protein.