A sore throat that has lasted for three days, a fever that rises in the evening, a child who coughs incessantly at night: we often hesitate between waiting for it to pass and seeking emergency care. This hesitation stems from a lack of concrete benchmarks to distinguish a common infection from a signal that warrants prompt attention. Common illnesses share similar symptoms, but their treatments and prevention differ depending on the causative agent.
When fever points to a precise diagnosis
We spontaneously associate fever with the flu, but this reflex masks very different realities. A sudden fever above 39 °C with body aches and intense fatigue indeed suggests a flu syndrome. In contrast, a moderate fever accompanied by urinary burning indicates a bacterial urinary infection, which requires antibiotic treatment.
A common pitfall: self-treating a fever with paracetamol without seeking the cause. Fever is an indicator, not the disease itself. We save time by noting three elements before calling the doctor: the exact temperature, the time of onset, and associated symptoms (cough, localized pain, rash).
To better identify pathologies based on your symptoms, you can consult diseases on Ma Santé 360 and refine your understanding before a medical appointment.
Respiratory infections: flu, bronchitis, and RSV in infants
Respiratory infections are the leading reason for consultations in general medicine during the cold season. Seasonal flu remains the most well-known, but acute bronchitis (viral in the majority of cases, thus antibiotics are not useful) and especially respiratory syncytial virus (RSV) are often underestimated.
RSV is a common pathogen that affects nearly all children before the age of two. In infants, it can cause severe bronchiolitis. France adopted a strategy in 2023 combining vaccination of pregnant women and immunization of infants with monoclonal antibodies. The 2026 vaccination and immunization campaign against RSV will begin on September 14, 2026, in metropolitan France, with a schedule adjusted each year based on epidemiological data.
For the flu, prevention relies on annual vaccination, especially for at-risk individuals (over 65 years old, chronic illnesses, pregnant women). Treatment remains symptomatic in most cases: rest, hydration, antipyretics.
Distinguishing a viral infection from a bacterial infection
The confusion between the two types of infections leads to overconsumption of antibiotics. Feedback on this point varies among practitioners, but a few benchmarks help to guide:
- A viral infection (cold, flu, acute bronchitis) often comes with diffuse symptoms: runny nose, dry then productive cough, generalized fatigue. It resolves spontaneously in a few days.
- A bacterial infection (strep throat, otitis media, pneumonia) produces more localized and intense symptoms: targeted pain, persistent fever, purulent secretions.
- The rapid diagnostic orientation test (TROD), available in medical offices and now in pharmacies for strep throat, allows you to confirm or exclude a bacterial origin in a few minutes.
Sexually transmitted infections: a resurgence in Europe
STIs are not part of the diseases we associate with daily life, but their recent increase makes them a public health issue in their own right. Gonorrhea, chlamydia, and syphilis have seen a marked rise in Europe in recent years.
Regular screening remains the most effective prevention lever, particularly for asymptomatic infections like chlamydia, which can remain silent for months while causing complications (infertility, pelvic infections).
HIV now benefits from antiretroviral treatments that allow for viral load control, as well as pre-exposure prophylaxis (PrEP) for individuals at high risk. In practice, diagnosis relies on a serological test prescribed by a doctor or performed for free at a CeGIDD (Free Information, Screening, and Diagnostic Center).
Vector-borne diseases: dengue and chikungunya in metropolitan France
We rarely think of dengue or chikungunya when living in metropolitan France. Autochthonous cases (locally transmitted by the tiger mosquito Aedes albopictus, without prior travel) are identified each summer in the south of the country.
Autochthonous cases of chikungunya, dengue, and West Nile virus infections have been reported in recent years in metropolitan France. These numbers remain modest, but they confirm that the tiger mosquito is now an active vector of infectious diseases in metropolitan areas.
Prevention involves concrete actions around the home:
- Eliminate stagnant water (saucers under flower pots, clogged gutters, forgotten containers in the garden) where the tiger mosquito lays its eggs.
- Wear covering clothing and use skin repellents during mosquito activity (mainly at dawn and dusk).
- Consult quickly in case of fever, joint pain, or rash after a bite, informing the doctor of the geographical area of residence.
Epidemiological surveillance and evolving diagnostic tools
Since the end of 2024, a digital system called Orchidée, supported by AP-HP, has been used for the surveillance of severe acute respiratory infections in 37 Parisian hospitals. The indicators are automatically transmitted each week to Santé publique France. This type of tool changes the speed of epidemic detection and allows for quicker adaptation of health responses.
Mpox also illustrates the need for continuous monitoring of infectious diseases. In France, 320 cases have been reported since the beginning of 2026. Diagnosis relies on a skin sample analyzed by PCR, and vaccination remains recommended for individuals at high risk of exposure.
Preventing common diseases is not limited to a single action. It combines targeted vaccination, screening tailored to risk profiles, daily hygiene, and early consultation as soon as symptoms deviate from the usual pattern. It is this combination, adjusted to each situation, that truly reduces the risk of complications.
