All about the flu: From mild to deadly

Both the flu virus and coronavirus are spread through droplets emitted from an infected person's mouth and nose into the air around them. — Pixabay

There have been a lot of articles lately about two actors who died of the flu or of pneumonia that resulted from the flu. I have caught flu many times, but it was never so bad. Why is this?

There are many types of flu.

Some types cause mild symptoms. Others can make you very sick.

But first, let us discuss what flu is.

Flu is short for influenza.

It’s a respiratory infection caused by a variety of flu viruses, and is extremely infectious.

What are the symptoms of flu? Do the different types have different symptoms?

The symptoms of flu are non-specific to the virus.

It is like most other viral diseases – it may cause headaches, fever, muscle aches and fatigue.

Because it is a respiratory tract illness, it can give you a runny nose too.

But the flu is different from the common cold, because the common cold virus runs a mild course and is very much contained to your upper respiratory tract most of the time.

As a result, in the common cold, you get sneezing, a stuffy nose, a runny nose, a cough and a sore throat.

But you rarely get fever, body aches and muscle aches.

However, with the flu, you get fever, body aches and tiredness that is far more pronounced.

A runny nose and sore throat only happens sometimes.

The common cold viruses are many, including rhinovirus and certain seasonal types of coronaviruses (not the SARS-CoV-2 kind that causes Covid-19).

But the flu is only caused by influenza viruses.

How is the flu different from Covid-19?

Covid-19 spreads faster than the flu and is more contagious for longer periods of time.

The symptoms are very much alike for both diseases.

But Covid-19 causes loss of taste and smell more often than flu.

What are the types of flu?Humans are affected by three types of flu viruses.

> Type A

This is one of the types that causes the annual flu epidemics.

Entire populations can be affected by this viral strain.

For example, it is noted that Japan had a big flu epidemic in December (2024), and that many Malaysians who travelled there also caught the flu.

The type A flu virus constantly changes its morphology or shape, which makes it very successful in infecting people.

Once a person has sneezed in a room, and if they touch things, it is common for the virus to linger on those things and for another person to get infected by touching them.

That is why you should always wash or sanitise your hands.

Type A has several subtypes.

Wild birds are common hosts for this virus type.

> Type B

This type is only found in humans.

It causes less severe symptoms than Type A.

Type B does not cause pandemics and does not have subtypes.

> Type C

This one is even milder than Types A and B.

It certainly does not cause epidemics or pandemics, and people don’t generally get very ill from Type C.

What is H1N1 then? Is it also a flu virus?

H1N1 is swine influenza. It is actually a type of Influenza A virus.

There was a H1N1 pandemic in 2009, when a new type of H1N1 was discovered making its rounds.

It was a new combination of influenza viruses that infected pigs, humans and birds.

That year, the H1N1 virus itself caused more than a quarter of a million deaths worldwide.

Today, it has become one of the Influenza A strains that causes seasonal flu.

Different strains of the flu virus mutate over time and replace the older strains.

Like Covid-19, they are extremely successful as they adapt to us adapting to them.

The idea of success if you are a virus is that you should be able to co-exist with your hosts in the world (which can be people or animals) for as long as you can.

You should not try to wipe your host population out because then you would be wiped out too!

Is bird flu also flu?

Bird flu is caused by the avian influenza virus.

There are three main subtypes: H5, H7 and H9.

The most dangerous are H5 and H7.

The subtypes that can spread to humans are H5N1 and H7N9.

The good thing is that it doesn’t spread from human to human, only bird (and bird fluids/excretions) and other animals to human.

You have to be very careful of birds leaving their poop all over your property.

It is important to know that you can get bird flu not only from birds, but also other animals that have been infected with it, such as cows and farm animals.

Bird flu symptoms are pretty much the same as other flus, but may also include conjunctivitis.

But it is suspected when you have a vocation or hobby that works with birds (all types, including chickens) and dairy cows.

And no, you won’t get it if you eat cooked chicken!

Can I prevent all these types of flu?

If you mean that if there is a vaccine for all of them, then indeed there are vaccines that cover many of them.

That is why the flu shot is a yearly affair, because the manufacturers have to adjust the vaccine to target the most recent incarnation of these viruses, seeing as how they keep mutating and replacing their old versions.

The vaccines take about two weeks to work.

Then you are protected for that year.

And the next year, you need to get another shot.

Dr YLM graduated as a medical doctor, and has been writing for many years on various subjects such as medicine, health, computers and entertainment. For further information, email [e-mail]. The information provided is for educational and communication purposes only, and it should not be construed as personal medical advice. Neither The Star nor the author gives any warranty on accuracy, completeness, functionality, usefulness or other assurances as to such information. The Star and the author disclaim all responsibility for any losses, damage to property or personal injury suffered directly or indirectly from reliance on such information.