Flu: causes, symptoms, effective treatment, and prevention for the 2024-2025 flu season

The flu is one of the most common viral infections that affects millions of people annually, especially during the cold season. Although it may seem like a simple cold, the flu can lead to serious complications, particularly in vulnerable individuals (children, the elderly, those with chronic illnesses).

In this article, you will learn about the causes, symptoms, and treatment of the flu, and how we can prevent illness to successfully get through the flu season.

What is the flu? Viruses that cause infection

The flu is a highly contagious viral infection caused by influenza viruses (types A, B, or C). Of the three, only viruses A and B are capable of causing significant clinical pathology, triggering annual seasonal epidemics, while influenza virus C causes a mild form of the disease (***, 2024).

Causes of the flu. Risk factors

Due to sudden temperature changes and the emergence of influenza viruses during the cold season, the immune system is more vulnerable, which makes the body easier to infect.

How is the flu transmitted? Incubation and contagiousness periods

The influenza virus enters through the nose, mouth, or eyes and can reach the lungs, where it multiplies. It is easily transmitted via aerosols (coughing or sneezing), as well as through direct contact with contaminated surfaces. It has been proven that it can live for 1-2 days on surfaces, 5 minutes on skin, and 15 minutes on paper (Bean, et al., 1982). Children are more predisposed to becoming infected and transmitting this virus further. Statistically, one sick person will infect between 1 and 3 healthy people (***, 2024).

An infected person is contagious 1-2 days before the onset of the first symptoms and 5-7 days after the disease begins. Usually, the risk of infecting others disappears around the seventh day of illness (***, 2024).

People most at risk of infection with influenza viruses

• Children under 2 years of age;
• Adults over 65 years of age;
• Pregnant women;
• People with cardiovascular, respiratory, hematological, hepatic, endocrine, renal, neurological, metabolic, or oncological conditions, or a weakened immune system;
• Those with a body mass index (BMI) of 40 kg/m² or higher;
• Those who are around infected people;
• Those who do not follow the hygiene standards necessary to prevent illness;
• People not immunized with the flu vaccine (***, 2024).

Symptoms of the flu. How to recognize the disease in time?

Flu symptoms appear suddenly and violently, usually 2 days after infection, and can include the following (***, 2024):

• High fever, 39-40°C;
• Chills;
• Headache;
• Myalgia (muscle pain);
• Dysphagia (sore throat);
• Stuffy or runny nose;
• Dry cough that can become productive;
• Severe fatigue;
• Lack of appetite.

In the case of newborns and infants, non-specific symptoms such as vomiting, diarrhea, and abdominal pain may occur, which may indicate a bacterial infection instead (***, 2024).

Symptoms last on average 3-4 days, with the cough potentially persisting for 1-2 weeks.

Signs and symptoms that more easily differentiate the flu from the common cold are as follows (***, 2024):

When should we see a doctor? Signs requiring medical assistance

When symptoms appear, it is recommended to contact your family doctor or pediatrician and follow their recommendations before the actual consultation. Children under 5 years of age, and especially those under 2, as well as patients with chronic diseases, must be seen by a doctor.

In the following cases, emergency medical evaluation is necessary (***, 2024):

• Presence of respiratory distress (difficulty breathing, rapid or wheezing breathing);
• Chest pain or pressure;
• Dizziness;
• Confusion; the patient is not interacting or is not alert;
• Altered general condition;
• Temperature remains high after administering antipyretics or the patient experiences seizures.

For children, we are talking about the same complications, plus the following (***, 2024):

• Cyanosis (bluish tint) of the lips or face;
• Presence of vomiting;
• Refusal of fluids, showing signs of dehydration (dry mucous membranes, absence of tears, sunken eyes, decreased frequency of urination, excessive thirst, fatigue, muscle weakness, headache, dizziness);
• Some symptoms such as fever or cough improve but then return later or worsen.

What tests are necessary to diagnose the flu?

The doctor will take a medical history, asking about symptoms and disease history, and then physically examine the patient. Usually, the flu is easily differentiated from other viral infections through specific symptoms.

However, some paraclinical (laboratory) tests can also be performed, such as qualitative screening (necessary to detect the presence of Influenza A and B viruses – by collecting nasal secretions or nasopharyngeal aspirate), which is recommended to be done within 4 days of the onset of symptoms, as well as complete blood count, ESR, fibrinogen, and C-reactive protein. To exclude a diagnosis of pneumonia, a chest X-ray may be necessary (***, 2022).

Complications of the flu. Risks and dangerous disease progressions

If not treated in time, the flu can evolve unfavorably, leading to (***, 2016):

• Pneumonia (acute inflammation of the lungs caused by infection);

• Acute laryngitis (sudden inflammation of the larynx);
• Acute laryngotracheobronchitis/tracheitis/croup (inflammation of the tracheal mucosa) – frequently encountered in children under 6 years of age;
• Acute bronchiolitis (lung infection that causes inflammation of the bronchioles) – frequently encountered in infants and children;
• Exacerbation of bronchial asthma (chronic inflammation of the airways);
• Otitis media (infection of the middle ear that causes inflammation and fluid buildup);
• Sinusitis (inflammation of the nasal sinuses);
• Myocarditis (inflammation of the heart muscle);
• Encephalitis (inflammation of the brain);
• Myositis (inflammation of skeletal muscle tissue), rhabdomyolysis (breakdown of muscle tissue);
• Dehydration.

Treatment of the flu. Medicines and natural remedies

Do not administer medications without first consulting a doctor. Monitor your health status and contact your doctor if symptoms worsen or if complications occur.

As it is a viral infection, antibiotics are contraindicated. They may be necessary only in the event of a secondary bacterial infection diagnosed by a doctor.

The following are recommended (***, 2024), (Iftikhar, 2024):

• Home isolation with bed rest;
• Hydration (water, fresh juices, soups; you can consume teas made with star anise, cloves, turmeric, green or black tea, if there are no contraindications);
• Consumption of foods rich in Vitamin C (citrus fruits, strawberries, blueberries, raspberries, pineapple, kiwi, mango, cabbage, tomatoes, green peppers, broccoli, white and sweet potatoes, etc.) and zinc (lamb, beef, pork, poultry, fish and other seafood, milk and dairy products, eggs, pumpkin seeds, cabbage, peas, beets, etc.);
• Inhalations with steam or essential oils to decongest the nose and soothe the cough;
• Nasal clearance using saline solution, seawater, drops, or nasal decongestant sprays; additionally, in the case of children, it may be necessary to aspirate nasal secretions using a bulb syringe or a nasal aspirator;
• Relieving pain and lowering temperature using analgesics/antipyretics/anti-inflammatories (paracetamol and/or ibuprofen; aspirin is contraindicated in children under 16 due to the risk of Reye's syndrome, a rare and severe condition that mainly affects the brain and liver);
• Administration of orodispersible tablets to hydrate the throat, cough suppressants;
• Treat vomiting and diarrhea according to the doctor's instructions;
• Antivirals (oseltamivir-based) will be administered only at the doctor's indication, by prescription, after evaluating the patient (these are much more effective if administered within the first 48 hours of symptom onset);
• Use a humidifier to increase humidity in rooms where the air is dry.

How to prevent infection? Tips and protective measures

Vaccination is the primary means of preventing the flu and its complications. Since viruses that cause seasonal flu mutate from one season to the next, annual vaccination is necessary. The peak of the flu season is usually between December and February, but cases are present both before and after, and can even be reported in April. Given that immunity is acquired in 2-3 weeks, it is advisable to get vaccinated as early as possible (late September – early October). In exceptional cases, it can also be done in the spring (***, 2024).

People who should be prioritized for vaccination, according to the World Health Organization (***, 2023):

• Children older than 6 months (if they are under 9 years old and have not been previously vaccinated, 2 doses of the vaccine must be given, one month apart);
• Pregnant women (in this way, after birth, babies up to 6 months will generally be protected);
• The elderly over 60 years of age;
• Those with chronic diseases.

Who should not be vaccinated or must ask for a doctor's advice beforehand (***, 2023):

• Children younger than 6 months;
• People with severe allergies to the vaccine or vaccine components;
• Those who have a moderate to severe illness, with or without fever (should wait until they recover to get vaccinated);
• People with a history of Guillain-Barré syndrome (a severe paralytic illness).

Children aged ≥ 6 months and < 19 years, pregnant women, people aged ≥ 19 years and < 65 years who are in one of the situations (chronic cardiovascular diseases, chronic respiratory diseases, chronic kidney diseases, chronic liver diseases, chronic neurological diseases, metabolic diseases, oncological diseases, autoimmune diseases, congenital malformations, obesity, asplenia, people with HIV/AIDS infection, immunosuppressive therapy, transplant, congenital immunosuppression), people over 65 years of age, and medical and auxiliary staff must contact prescribing physicians to issue a 100% compensated prescription (Bihor, 2024).

People aged ≥ 45 years and < 65 years, without chronic diseases, will contact prescribing physicians to issue a 50% compensated prescription (Bihor, 2024).

The rest of the population who do not fall into any of the above situations will be able to purchase the vaccine at the full price (Bihor, 2024).

The highest vulnerability is in children under 6 months who cannot be vaccinated. They can be protected by vaccinating all people who come into contact with them and by following hygiene rules.

Since community settings are where most infections occur, certain personal hygiene measures and measures for the spaces where activities take place must be taken (***, 2024):

• Hand hygiene: hands should be washed frequently (minimum 20 seconds) and/or disinfected (before meals, after using the toilet, after coughing/sneezing, and whenever necessary);
• Respiratory hygiene: cough/sneeze into a single-use tissue or into the elbow, then immediately throw the tissue in the trash and wash/disinfect hands;
• Space hygiene: frequented places should be aired often (at least 10 minutes), and surfaces should be cleaned and disinfected before use;
• Avoid sharing personal items and touching eyes, nose, and mouth with dirty hands;
• Wearing a mask in closed and crowded spaces is also recommended;
• In case of illness, avoid re-entering community settings.

Regarding the choice of disinfectant products for preventing influenza virus infections, in the Klintensiv portfolio you will find a multitude of effective products.

Influenza is one of the most common respiratory infections, which, in the context of an incompletely developed immune system like that of children, or in the presence of chronic diseases, can lead to complications requiring hospitalization. Annual vaccination and adherence to hygiene rules can significantly reduce the risk of illness. Correct identification of symptoms and prompt action can prevent serious complications. Stay informed, protect yourselves, and consult your doctor at the first signs of illness to safeguard your health and avoid further transmission during flu season.

Note: The information in this article is for informational purposes. If you experience symptoms specific to the disease, contact your family doctor to receive the necessary recommendations.

Photo source: Shutterstock

Bibliography

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***. (2024). Retrieved from https://www.mayoclinic.org/diseases-conditions/flu/symptoms-causes/syc-20351719

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***. (2024). Retrieved from https://www.yalemedicine.org/conditions/flu

Bean, B., Moore, B. M., Sterner, B., Peterson, L. R., Gerding, D. N., & H. H. Balfour, J. (1982). Survival of Influenza Viruses on Environmental Surfaces. The Journal of Infectious Diseases, 146(1), 47-51.

Bihor, D. (2024). Retrieved from https://www.dspbihor.gov.ro/2024/09/Comunicate%20de%20presa/Comunicat_presa_25092024.pdf

Iftikhar, N. (2024). Retrieved from https://www.healthline.com/health/natural-flu-remedies#zinc