You get influenza or the flu disease when the flu virus attacks and infects your body. That is what causes this viral illness. It spreads very easily and rapidly and has caused epidemics and pandemics.
The viruses are airborne throughout the year and you can get flu all the year round. However, the flu season, which is during cold dry winters makes it more conducive for the flu virus to spread. I have explained below the reason, why its season occurs during the fall.
Next question that automatically arises is:
How do you get the flu? Cause
The flu virus is always present in the air, more so during its season. You inhale it and lodge it into your respiratory system.
It is your immune system that keeps the virus in check and does not allow it to rise above the clinical level and give you the symptoms.
However, when the immunity of the person is low and the virulence of the virus is high (as during the flu season), the virus runs amok and multiplies in your body to rise above the subclinical level.
It is the virus, which causes the flu symptoms like fever, running nose, body aches, cold, and cough.
How soon can you get the flu after being exposed?
After you have been exposed to the flu virus, you can fall sick. The symptoms appear within one to four days. Usually, on an average, it is two days. This is called the incubation period.
The symptoms come on suddenly. You could be fine one moment and within an hour or so, you could be down and miserable with the symptoms.
That is why some people tend to call this illness, “the overnight sickness”.
How long after you get the flu are you contagious?
The flu virus can live even outside the body and this property enables the spread of the virus very easily. An infected person throws out the thousands of viruses into the air through coughing and sneezing.
The adult person can be a source of infection for a pretty long time. He can be contagious one day before the symptoms appear and about three to seven days after that. At times, people who do not show any symptoms can also spread the virus.
Kids, however, can be more contagious than adults and for a much longer time. They can be a source of infection even before the symptoms develop and for as long as two weeks after the infection had set in.
Similarly, people with a weakened immune system, such as the elderly, and those with chronic or severe illnesses are contagious for a longer period – up to 10 days.
The most infective days are the second and the third days after the infection has set in.
Another fact about the spread of the virus is that the amount of virus shed is in direct proportion to the severity of the fever – meaning higher the fever, the more amount of virus is shed in the droplets.
It is, therefore, advised that you keep a safe distance from an infected person. Take particular care to protect your children in this fashion.
Even inhaling one droplet is enough to give you influenza. Whether you catch the infection or not depends on how strong your immunity is and the virulence of the flu virus.
How do you know you are contagious?
If the flu virus is detected in your nasal and oral secretions through testing, it means you are capable of spreading the disease.
How does the flu virus spread?
You can catch the flu virus from someone else in the following three ways:
- From the air you breathe
- By direct contact with an infected person
- Through surfaces such as utensils or linen, which have been contaminated with the virus by the infected person.
1. Cause of flu by spread of its virus through air
Crowded places like classrooms, dormitories, offices and hospitals are very easy targets for the spread of flu because of the ability of the virus to spread through air,
Usually, the virus travels in the air through tiny microscopic droplets, which are emitted when the infected person sneezes or coughs. A single sneeze or a cough can release around 40,000 infected droplets.
These droplets stay in the air and land on the mouth or into the nose of another person who is close by. Or, another person can inhale them and lodge them in the respiratory system. This is one way the flu virus can spread through the air and can infect a person up to 6 feet away.
2. Spread of Flu by Direct Contact – person to person
Direct body contact with the infected person facilitates the transmission of the virus. Gestures such as shaking of the hands, which carry the mucoid secretions containing the virus or kissing make you a potential candidate for hosting this virus.
You may then touch your hands to your mouth or the nose or the eyes, which transmits the virus into your body.
3. Spread of flu through contact with infected surfaces
The infected person contaminates his hands with the flu virus either through his saliva or mucus from his nose and his hands subsequently contaminate his linen or the utensils. The microscopic droplets released into the air by sneezing or coughing also contaminate the surfaces of these objects .
The common objects such as banknotes, door knobs, telephones, household utensils, computer keyboards, light switches, etc. can infect you with the virus when you touch them and then rub your hands to your mouth, nose or eyes.
4. Spread of flu viruses from animals to people
Animals, too, have not been spared by this virus. The influenza A viruses are found to infect ducks, chickens, pigs, whales, horses and seals.
According to the Center for Disease Control and Prevention (CDC), it is unusual for animals to infect humans with the flu virus.
However, reports of certain avian influenza A viruses and swine flu A viruses have caused sporadic human infections and outbreaks.
Avian influenza A and swine flu A viruses can spread from animals to humans in the following two ways:
- Directly from birds or by inhaling from the air contaminated with the avian influenza A virus.
- Through an intermediate host, such as a pig. People who live in close proximity with infected pigs, such as in pig barns, fall prey to this type transmission. Infected pigs cough or sneeze and droplets with the virus in them can spread through the air to humans.
How long does the flu virus last on various objects differs?
According to nhs.uk, how long the flu virus lasts outside the body varies.
- On hard surfaces such as plastic or metal, the virus can live for one to two days.
- On paper tissues for 15 minutes
- On skin for about five minutes
- However, if the virus is present with mucus, it can last for much longer periods. For example, the virus can stay alive for about 17 days on a bank note if it is present in the mucoid medium.
When is the flu season and why?
However, if the humidity in the air is high, as, during the rainy season, the infective droplets containing the flu viruses become heavy due to the water in the atmosphere and fall to the ground.
The ultraviolet rays from the sun also do not allow the virus to survive. You, therefore, do not see much of this sickness during summer.
Cold, dark and dry winters, therefore, favor its spread while the hot and humid weather do not.
In the United States, the flu season typically runs from November through March, although you can catch the infection in October or as late as May.
Tropical climates with high humidity and warm weather usually see less of flu epidemics.