Types of Influenza Viruses

Influenza viruses have always been a concern to humans due to their harmful effects on health. Let’s look at some common flu viruses and their essential characteristics corresponding to each type.

List common flu viruses.

Influenza virus belongs to the family Orthomyxoviridae, which usually has an irregular spherical shape. The structure consists of a multi-layered envelope covered with two types of polypeptide spikes; the inner layer is a peptide membrane. The coating allows the virus to attach to the surface of the respiratory mucosa (Hemagglutinin). They then secrete the enzyme Noraminidase to release the viruses from the existing cell and infect other healthy cells.

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Influenza viruses are very contagious and are harmful to health

Hemagglutinin and Noraminidaza, abbreviated as H, N, can continuously change when significant enough change. The mutation will cause a new virus to appear, becoming a considerable threat to human health.

Influenza is a disease that is easily transmitted through the air (drops when coughing, sneezing) or after contact with contaminated instruments, from which viruses enter through the respiratory system and cause damage—Mucosa here, leading to a type of symptom that affects your health. Currently, the influenza virus detected includes three strains called A, B, and C. In which:

Influenza A virus

Influenza A virus has up to 18 groups of Hemagglutinin and 11 types of Neuraminidase; 131 varieties have been found in nature. Large epidemics often have the presence of strains such as the H1N1 influenza virus (which broke out in our country in 2009), H2N2, H3N2, H5N1 (avian flu in Vietnam in 2006 – 2007), …

This strain is also capable of causing disease and transmission in both humans and animals. If favorable conditions are met, outbreaks of different large and small attacks can occur.

BIG flu virus

This strain has two main subtypes, Victoria and Yamagata, which are not divided into subgroups. This virus only causes disease in humans and is somewhat milder than type A. Mutations of the influenza B virus usually occur slowly, and the prevalence depends on each place’s environmental characteristics and geographical areas.

Influenza virus C

This strain is rare and also milder than cases caused by viruses of groups A and B. The disease has atypical clinical symptoms and does not cause epidemics.

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Influenza viruses can be transmitted from animals to humans or from person to person through the air.

General manifestations of influenza viruses

The actual situation depends on the type and branch of the acquired virus and the patient’s physical condition. Usually, the body will appear the following symptoms:

  • Incubation period: relatively short, maybe only after a day or a few days
  • Fever: hot fever or chills, body temperature can reach about 39-40 degrees Celsius in this first onset of illness, then last for another 3-5 days.
  • They are accompanying symptoms: fatigue, headache, body aches, weakness, fatigue, red face, hot, dry skin, watery eyes and runny nose, possible nosebleeds, bitter mouth, nausea, apple constipation, or diarrhea. Some patients may have a cough, sputum production, etc.
  • Remission: symptoms will subside after 5-7 days. But for people with weak health (older adults, young children), the recovery can be long and slow.

Common major complications

Patients mainly experience respiratory complications. This is also the most severe complication, including:

Primary pneumonia

Because the virus invades in large numbers and has an exceptional nature, it can cause severe symptoms for patients such as:

  • Continuous fever: the patient has a high fever, lasts about 3 – 5 days without reducing the temperature, is challenging to respond to antipyretic drugs
  • Respiratory: difficulty breathing, rapid, rapid breathing, can cause respiratory failure, circulatory arrest
  • Some accompanying manifestations: sputum, possibly with blood; lips, limbs, or whole-body pale

Secondary pneumonia

This condition occurs when the body is infected with the flu, the immune system is weakened, so it is also invaded by other bacteria, also known as superinfection. Cases at high risk of superinfection such as the elderly, currently suffering from chronic underlying diseases of the lungs, kidneys, heart, liver, etc., with some symptoms as follows:

  • Fever: After the illness subsides for about 2-3 days, the body temperature suddenly rises again.
  • Symptoms of pulmonary congestion: shortness of breath, chest pain, coughing up phlegm or coughing up blood, pale or purple skin, headache, fatigue, weakness, etc.
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Pregnant women need to be very careful with the flu to protect their health and help the baby be born healthy.

Some other complications

After being sick for a long time, the flu virus can cause the body to experience some more serious complications such as:

  • Cardiovascular: myocarditis, pericarditis, circulatory failure
  • Neurological: encephalitis, meningitis, encephalitis, polyneuritis, radiculitis
  • With infants: ear infections, mastoiditis, or even neurotoxicity.
  • With pregnant women: these subjects often experience lung complications and directly affect the fetus. The most serious can cause miscarriage.

The way for flu viruses to enter and cause illness in the body is straightforward. Therefore, to protect health, each individual should update himself with relevant information and knowledge, use measures to prevent virus penetration such as masks, antiseptic solutions, anti-droplet glasses, and regularly check their health (at least every six months).

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