Flu

Introduction

The flu is an acute respiratory infection caused by Influenza viruses, mainly type A and B. It spreads every winter in the form of seasonal epidemics, affecting about 5 to 10% of the adult population and 20 to 30% of children. The flu is distinguished from a simple cold by its sudden onset, its high fever and its marked impact on the general condition. Mild in the majority of cases, it can be severe, even fatal, in the elderly and fragile patients. Annual vaccination remains the best means of prevention.

If you present a severe flu syndrome or if you belong to a high-risk population, contact your primary care physician first. If they are unavailable, Docadom offers an emergency consultation by a home doctor: call 021 845 45 45 or use our app available on the App Store and Google Play.

Who is at risk?

Anyone can catch the flu. Some profiles are particularly exposed to severe forms: people aged 65 and over, pregnant women, infants, patients with chronic diseases (diabetes, asthma, COPD, heart failure, renal failure, cancer, HIV), immunocompromised patients, obese individuals, and nursing home residents. Healthcare professionals, teachers, and people living in communities are also more exposed to contamination.

Symptoms of influenza

Symptoms appear suddenly, 1 to 4 days after contamination, and generally last 5 to 7 days. Fatigue can persist for several weeks.

Main symptoms

• High fever (often > 38.5 °C), sometimes > 39 °C, with chills.

• Intense headaches, pain behind the eyes.

• Aches, diffuse muscle and joint pain.

• Dry cough, sometimes painful.

• Sore throat, runny nose, sneezing.

• Intense fatigue, asthenia, loss of appetite.

• More rarely: digestive system disorders (nausea, vomiting, diarrhea), especially in children.

When to seek urgent medical attention?

An emergency consultation is necessary in the following situations:

• Dyspnea, chest pain, purulent sputum (suspicion of pneumonia).

• Sudden worsening after a few days of improvement.

• Fever persisting more than 5 days or febrile relapse.

• Neurological signs: confusion, drowsiness, convulsions (in children) — call 144.

• Patient belonging to a high-risk population (advanced age, pregnancy, chronic illness, immunosuppression).

• Dehydration, consciousness disorders.

What to do before calling Docadom? Rest, stay hydrated, take paracetamol, and contact your primary care physician first. If they are unreachable or if you need a home doctor outside of opening hours, call Docadom at 021 845 45 45 or make your request directly from our smartphone app (App Store and Google Play). In case of signs of severity (dyspnea, chest pain, confusion), dial 144 immediately.

Causes and transmission

Influenza is caused by Influenza viruses, mainly type A (the most virulent, at the origin of pandemics — H1N1, H3N2) and type B. The viruses mutate every year, which explains the need for annual vaccination and the lack of long-term immunity.

Transmission occurs via respiratory droplets during coughing or sneezing, and through contaminated hands or surfaces. The period of contagiousness begins the day before the first symptoms and lasts about 5 to 7 days.

Diagnosis of influenza

The diagnosis is essentially clinical during an epidemic period. Rapid tests can confirm the diagnosis in case of doubt or for high-risk patients.

Diagnostic methods

• Anamnesis and clinical examination: search for the typical presentation during an epidemic period.

• Nasopharyngeal rapid diagnostic test (RDT).

• Respiratory multiplex PCR to differentiate flu, COVID-19, RSV, and other viruses.

• Biological evaluation (CBC, CRP) in case of signs of severity or co-infection.

• Chest X-ray in case of suspected pneumonia.

Alternative diagnoses

• COVID-19 and other respiratory viral infections (RSV, metapneumovirus, parainfluenza).

• Bacterial tonsillitis, pharyngitis, sinusitis, otitis.

• Bacterial pneumonia.

• Infectious mononucleosis.

• Meningitis or encephalitis in case of neurological signs.

• Fever upon returning from travel (malaria, dengue).

Treatment of influenza

Treatment is primarily symptomatic. Antivirals are only indicated in certain situations.

Symptomatic treatment

• Rest, abundant hydration.

• Paracetamol for fever and pain (to be preferred over aspirin, especially in children — risk of Reye's syndrome).

• NSAIDs can be used occasionally, but should be avoided in case of signs of bacterial co-infection.

• Cough suppressants, nasal decongestants: depending on symptoms, for a short duration.

Antiviral treatment

Oseltamivir (Tamiflu®) and zanamivir (Relenza®) are indicated within 48 hours following the onset of symptoms, mainly in patients at risk of complications or in case of a severe form. They shorten the duration of symptoms by 1 to 2 days and reduce the risk of complications.

Antibiotics

They are only indicated in cases of bacterial co-infection (otitis, sinusitis, pneumonia). Flu alone is never treated with antibiotics.

Prevention of influenza

• Annual influenza vaccination, recommended from autumn, especially for people at risk, healthcare professionals, and those close to fragile individuals.

• Regular hand washing with soap or hydroalcoholic solution.

• Cover your mouth with your elbow when coughing or sneezing.

• Use single-use tissues.

• Regular ventilation of rooms.

• Limit close contact with sick people.

• Wearing a surgical mask in the presence of symptoms or around vulnerable people.

• Stay home in case of flu-like symptoms to avoid contagion.

Possible complications

Complications occur mainly in fragile people: viral pneumonia (influenza-related) or secondary bacterial pneumonia (pneumococcus, Staphylococcus aureus), ENT co-infections (otitis, sinusitis), bronchitis, exacerbation of asthma or COPD, decompensation of heart failure or diabetes, myocarditis, encephalitis, Guillain-Barré syndrome. In pregnant women, the flu increases the risk of prematurity. Deaths related to the flu occur almost exclusively in high-risk patients.

When to contact a doctor for the flu

The flu does not systematically justify a consultation. Here is the procedure to follow:

• As a first resort: contact your primary care physician, particularly if you belong to a high-risk population or if symptoms are severe.

• If your primary care physician is unavailable (evenings, weekends, holidays), Docadom offers an emergency consultation by a home doctor. Call 021 845 45 45 or make your request via our mobile app, available for free on the App Store and Google Play.

• In case of signs of severity (dyspnea, chest pain, confusion, loss of consciousness), dial 144 without delay.

Conclusion: vaccination and hygiene, the two keys

The flu is a common seasonal viral infection, generally mild but potentially serious in fragile people. It is characterized by a sudden onset with high fever, body aches, headaches, cough, and intense fatigue, which can lead to complications such as pneumonia, decompensation of a chronic illness, or death. Annual vaccination, hand hygiene, and limiting contact during epidemics are the best ways to protect yourself.

In case of severe flu syndrome or doubt, contact your primary care physician first. If they are not available, Docadom provides an emergency doctor at home 7 days a week: call 021 845 45 45 or use our mobile app (App Store, Google Play) to request an emergency consultation.