Influenza is considered one of the most contagious diseases and can lead to outbreaks. According to WHO statistics, about 5-10% of adults and 20-30% of children worldwide are infected with influenza each year.
Among these, approximately half a million deaths occur due to health issues related to influenza. In Vietnam, about 1 to 1.8 million cases of seasonal influenza are reported annually.
Influenza can resolve on its own, but it can also cause severe complications in individuals with chronic health conditions such as heart and lung diseases, kidney issues, anemia, metabolic disorders, or those with weakened immune systems, individuals over 65 years old, children under 5, and pregnant women. Complications can include ear infections, bronchitis, pneumonia, encephalitis, and even death.
Current Influenza Virus Strains
There are four strains of the influenza virus designated as A, B, C, and D. Among these, A and B strains are commonly found in humans, C causes mild illness and usually shows no symptoms, while D affects livestock and does not cause illness in humans.
Influenza A
Influenza A is the most common seasonal flu type, accounting for about 75% of influenza infections in humans. The Influenza A virus is classified into various subtypes based on the combination of Hemagglutinin (H) and Neuraminidase (N), which are the main proteins on the virus surface. Under favorable conditions, Influenza A can lead to varying scales of outbreaks. Historical global pandemics have also been caused by subtypes of Influenza A virus, such as the H5N1, H3N2, and H1N1 outbreaks.
Influenza A (H1N1): Infected individuals typically exhibit symptoms such as fever, sore throat, sneezing, runny nose, and muscle aches. Nearly 50% of patients may also experience abdominal pain, nausea, or diarrhea. Like seasonal influenza, the new H1N1 strain can present more severe symptoms, such as pneumonia, which leads to increased coughing, rapid breathing, and difficulty breathing, with X-rays showing lung damage. Some patients may develop acute respiratory distress syndrome (ARDS), pulmonary edema, and even death.
When infected with Influenza A (H5N1), patients often feel headaches and body aches…
Influenza A (H5N1): Infected individuals experience fever, which may be intermittent or continuous throughout the day. Temperatures can rise to 40-41 degrees Celsius; in some cases, mild fevers of 38-38.5 degrees Celsius are seen, particularly in patients with significantly reduced immunity such as the elderly, young children, or those with chronic illnesses.
Skin redness and warmth may appear in patients with high fevers, and those with respiratory distress might show bluish discoloration of the lips and extremities. Patients often report headaches, body aches, and may experience pain around the eyes. In severe cases, patients can have altered consciousness. The disease progresses rapidly with a high mortality rate. Early detection and timely treatment can save lives, so special attention is needed in areas with high poultry mortality (chickens, ducks, geese) and where individuals exhibit symptoms like cough, high fever, headaches, and body aches.
Influenza A (H7N9): So far, most patients infected with H7N9 have developed severe pneumonia. Symptoms include fever, cough, and difficulty breathing. However, information about the diseases that the H7N9 virus can cause remains limited.
Influenza B
Influenza B is also a strain that commonly affects humans, accounting for 25% of seasonal influenza cases each year. Influenza B is transmitted exclusively from person to person, has a strong potential for spreading, and can lead to outbreaks but is less likely to cause pandemics. Nevertheless, it can still have dangerous health impacts in severe cases.
Like Influenza A, common symptoms in children with Influenza B include fever, sore throat, dry cough, headaches, body aches, joint pain, and a feeling of exhaustion. Children with influenza may also experience gastrointestinal symptoms (nausea, vomiting, and diarrhea).
Seasonal influenza is very difficult to distinguish from other respiratory diseases, and diagnosis and treatment must follow health agency guidelines.
Influenza C
Compared to strains A and B, Influenza C is less common, less dangerous, and does not have typical clinical symptoms. The Influenza C virus tends to cause respiratory infections, with symptoms generally mild and not leading to significant health issues. Influenza C symptoms resemble those of the common cold, including: sore throat, sneezing, fever, dry cough, runny nose, headaches, muscle aches, and fatigue.
Influenza D
The Influenza D strain primarily affects livestock and has not been identified as causing illness in humans. The structure and cellular characteristics of the Influenza D virus are similar to those of the Influenza C virus.
Doctor’s Recommendations
According to the Ministry of Health, we are currently in a transitional season, which is favorable for the development of respiratory pathogens, leading to many cases of respiratory infections, particularly seasonal influenza (including both A and B strains).
Symptoms of seasonal influenza are very difficult to distinguish from other respiratory diseases, and diagnosis and treatment must adhere to health agency guidelines.
To proactively prevent seasonal influenza and protect the health of yourself, your family, and the community, the Ministry of Health recommends:
- 1. Individuals showing symptoms of cough, fever, runny nose, headache, or fatigue should not self-test or purchase medications at home but should contact healthcare facilities for timely consultation, examination, and treatment.
- 2. Cover your mouth and nose when coughing or sneezing, preferably with a cloth, handkerchief, disposable tissue, or the inside of your elbow to reduce the spread of respiratory secretions.
- 3. Wear masks, wash hands with soap and clean water or hand sanitizer (especially after coughing or sneezing). Do not spit indiscriminately in public places.
- 4. Limit contact with individuals infected with influenza or suspected cases unless necessary.
- 5. Maintain a healthy lifestyle, increase physical activity, and enhance overall health.
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