Influenza A: What is It, Causes, Symptoms, Treatment & Prevention
By Dr. Vishesh Bharucha +2 more
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By Dr. Vishesh Bharucha +2 more
Table of Contents
Each year, influenza affects an estimated one billion people worldwide, with 3 to 5 million cases resulting in severe illness and between 290,000 and 650,000 deaths due to respiratory complications (World Health Organization, 2023)1.
Influenza is primarily classified into four types (A, B, C, and D). Among them, some influenza A viruses are highly contagious and cause acute respiratory illness, spreading rapidly through populations, particularly during seasonal outbreaks2.
Therefore, understanding the scale, transmission dynamics, and subtypes of influenza A is essential, as it is the only type of influenza virus known to cause global pandemics. This article will explore the influenza A symptoms in adults as well as children, setting the stage for further discussion on its diagnosis, treatment, and prevention strategies.
Influenza type A is caused by the influenza A virus, which is a single-stranded RNA virus. It infects the cells lining the respiratory tract and triggers an immune response that leads to the flu2.
Influenza A viruses are classified into subtypes based on the combination of their proteins (hemagglutinin [HA] and neuraminidase [NA]). Currently, the two main influenza A subtypes circulating in humans are A(H1N1) and A(H3N2)1,2.
Influenza A is highly contagious. This virus primarily spreads through respiratory droplets released during coughing, sneezing, or talking, and can also be transmitted by touching surfaces that already have been exposed to the virus. One of the key reasons influenza A is so widespread and potentially severe is its ability to undergo frequent genetic changes3:
Influenza A typically presents with a sudden onset of symptoms, often making individuals feel acutely unwell within a short period. The most common influenza A symptoms in adults and children include4:
In addition to these respiratory symptoms, gastrointestinal symptoms such as nausea, vomiting, and diarrhoea may also occur, especially in children, though they are not always present4.
Note: Although often confused with the common cold, influenza (flu) is generally more severe and comes on more suddenly5. Therefore, accurate diagnosis is important for proper management.
Certain groups of people are more likely to develop serious complications from influenza A. These include:
The initial diagnosis of influenza A usually begins with a clinical evaluation, where doctors assess the patient’s symptoms and medical history7.
To confirm influenza A, the following diagnostic tests may be used:
Note: If you test influenza A positive, it means the virus has been detected in your body, and you may need rest, supportive care, or antiviral medications depending on symptom severity.
Most healthy people with mild flu symptoms recover with rest, fluids, and fever-reducing medicines. However, treatment may be necessary if influenza A symptoms in adults (and children) worsen or do not improve.
Note: They are usually not needed for mild cases in healthy people7. However, patients with mild cases in high-risk group (e.g., elderly, pregnant, chronic illness) may warrant antivirals.
Note: Aspirin should be avoided in children due to the risk of Reye’s syndrome9. It’s ideal to consult a doctor before.
Being influenza A positive indicates an active infection that can be contagious, so isolation and proper hygiene are important to prevent spreading the virus to others. Here are effective ways to protect yourself and others:
While most people recover from influenza type A within a few days to two weeks, it’s important to seek medical care if symptoms worsen or new complications arise. You should see a doctor as soon as possible if you experience10:
Note: If you observe that your symptoms improve for a while but then return with fever and worse cough, it may indicate a secondary bacterial infection. Therefore, it is very important to contact a doctor in such cases.
High-risk individuals should be especially vigilant and contact a doctor early. Complications to watch for in influenza type A include3:
Also Read: What is Influenza (Flu) & Its Types
Understanding and effectively managing influenza A is vital to reducing its impact on individuals and communities. While many cases are mild, the flu can lead to serious complications, especially in high-risk groups. Therefore, timely diagnosis, appropriate treatment, and preventive measures like vaccination, hand hygiene, and staying home when sick can help avoid the spread of the virus significantly.
Additionally, raising awareness about symptoms, risk factors, and when to seek medical help empowers people to take proactive steps, ensures better health outcomes, and avoids severe illness or death from flu-related complications.
Also Read: H1N1 (Swine Flu): Causes, Symptoms, Treatment, and Prevention
Flu symptoms tend to be more sudden and severe than cold symptoms. For example, symptoms such as fever, body aches, and severe fatigue are typically more pronounced in the flu compared to the common cold5.
Yes. There are different subtypes (like H1N1, H3N2), and your immunity to one doesn’t protect you from others if you are infected with one subtype. That’s why yearly vaccination is important2.
Most people are contagious from a day before symptoms appear to about 5 to 7 days after becoming sick2. Children and those with weakened immune systems may be contagious longer.
Only influenza A viruses are known to cause pandemics due to their ability to undergo significant genetic changes and infect multiple species2.
Disclaimer: The information provided here is for educational/awareness purposes only and is not intended to be a substitute for medical treatment by a healthcare professional and should not be relied upon to diagnose or treat any medical condition. The reader should consult a registered medical practitioner to determine the appropriateness of the information and before consuming any medication. PharmEasy does not provide any guarantee or warranty (express or implied) regarding the accuracy, adequacy, completeness, legality, reliability or usefulness of the information; and disclaims any liability arising thereof.
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