La Lyme diseasealso called Lyme borreliosisLeptospirosis, or tick-borne encephalitis, is a bacterial infection transmitted by ticks. It is receiving increasing attention, particularly in wooded areas of Europe, peri-urban areas, and city parks, due to the rising number of cases. While it is generally mild when treated promptly, it can lead to severe complications in later stages.

Each year in France, tens of thousands of people are affected by Lyme disease (In 2021, 47,000 cases were diagnosed*), an infection transmitted by a tick bite. A better understanding of this disease, its symptoms, and the preventive measures to adopt is essential. especially during the summer period.

Ticks of the genus Ixodes (Ixodes ricinus in France),

What is Lyme disease?

It's about a infectious disease caused by a bacterium of the complex Borrelia burgdorferiThis bacterium is transmitted to humans by the tick bite gender Ixodes (I(xodes ricinus in France), very common in natural wetlands or forests. Note that other species of Borrelia/Lyme disease They can also be transmitted by ticks, but they do not cause Lyme disease.

Once the bacteria is transmitted, it can diffuse throughout the body and affect different systems The skin, joints, nervous system, and even the heart (in rare cases) can all be affected. If treatment is started early, the disease is curable in most cases. However, diagnosis can be complex, hence the importance of prevention.

How is Lyme disease transmitted?

Lyme disease is contracted exclusively through the bite of an infected tickContrary to popular belief, tick bites are usually asymptomatic: the tick can remain attached to the skin for several days without being noticed. Transmission of the bacteria only occurs after a certain period of attachment, generally more than 24 hours.

Not all ticks are infected, but certain geographical areas present a higher risk, particularly in rural areas, wooded gardens, parks, or forests. Outdoor activities, especially between April and October, are the periods most conducive to exposure.

What are the symptoms of Lyme disease?

Lyme disease can develop gradually, in several stages. Symptoms vary depending on the stage of infection and the immune response of the affected person.

1. Localized early phase (a few days to a few weeks after the bite)

Le most characteristic signobserved in approximately 80% of cases in Europe, is theerythema migrans a red plate, often circularThis rash, which gradually spreads around the bite area, may disappear spontaneously. This phase may also be accompanied by mild fever, fatigue, headache, or muscle pain.

It should be noted that in the United States, erythema migrans is almost systematic, which facilitates early diagnosis of the disease.

Erythema migrans after a tick bite

2. Secondary Phase (weeks to months after infection)

If left untreated, the infection can spread throughout the body. The following may then be observed:

  • persistent joint pain, sometimes migrating;
  • neurological disorders (neuralgia, facial paralysis, meningitis);
  • secondary skin lesions or palpitations.

3. Tertiary phase (months to years after infection)

In rare cases, chronic complications may occur:

  • persistent inflammatory arthritis;
  • lasting neurological disorders (cognitive disorders, neuropathies);
  • cardiac or ophthalmic disorders.

How to diagnose Lyme disease?

The diagnosis is based primarily on the medical history and clinical observation. The presence of a erythema migrans This is usually sufficient to make the diagnosis and initiate treatment without further testing.
However, this can be problematic, as this symptom is only observed in about 80% of cases: the 20% of patients who do not have erythema may therefore not be diagnosed at this stage and may not benefit from a serological test.

In the absence of this typical symptom, or in the case of later signs, further examinations are necessary:

  • Serological tests (blood tests) to detect antibodies directed against Borrelia/Lyme disease ;
  • Further analyses (lumbar puncture, MRI, electromyogram) in case of neurological damage.

It is important to note that serological tests can be negative in the early stages, as antibodies are not yet present in detectable quantities. Their interpretation should always be performed by a healthcare professional.

What are the treatments for Lyme disease?

The earlier the disease is detected, the easier it is to treat. Treatment is based on a antibiotic therapy adapted, prescribed by a doctor.

  • In the early stagesOral antibiotic therapy (doxycycline or amoxicillin) for 10 to 14 days usually results in a complete cure.
  • In case of severe neurological or joint damageIntravenous antibiotic therapy may be necessary.

In the majority of cases, patients recover completely after treatment.

However, some may experience what is known as post-treatment Lyme disease syndrome (PTLDS (according to the acronym adopted by the French National Authority for Health). This syndrome is not limited to simple residual symptoms: it can lead to a lasting impairment of normal functioning and quality of life, with marked fatigue, diffuse pain, and even dysfunction of certain organs. PTLDS represents a significant public health challenge and remains at the heart of numerous scientific debates. Research is ongoing to better understand its mechanisms and improve its management.

Amoxicillin treatment for tick bites - Lyme disease

Lyme disease prevention: steps to take

Avoiding tick bites is the best way to protect yourself against Lyme disease. A few simple precautions can significantly reduce the risks:

Before the release:

  • Wear some covering clothing, further, clear and well-tailored ;
  • Apply a approved tick repellent ;
  • Stay on the trails. avoid tall grass.

After the exit:

  • Inspect the entire body carefully, paying particular attention to skin folds, the scalp and warm areas (armpits, groin, behind the knees…);
  • Take a quick shower to eliminate ticks that have not yet attached themselves;
  • Remove any ticks using a tick puller, by grasping it as close to the skin as possible, without any product.

In case of a sting : note the date, monitor the area for 1 month, and consult a healthcare professional if erythema or symptoms appear.

Forest walk - Lyme disease prevention

FAQ – Lyme Disease

symptoms of Lyme disease and the time it takes for symptoms to appear can vary from person to person after a bite from an infected tick.

early signs of Lyme disease They may include: a skin rash (called erythema migrans), fever, chills, fatigue, headaches, swollen lymph nodes, or muscle and joint pain.

early symptoms of Lyme disease Symptoms can appear 1 to 3 weeks after a bite from an infected tick. In 80% of cases, they include a erythema migrans (a circular red patch around the bite), as well as fever, fatigue, headaches and muscle pain.

Le early diagnosis Diagnosis is based on clinical signs and epidemiology. Immediate antibiotic treatment is effective. Conversely, the absence of treatment allows progression to a chronic form.

late symptoms of Lyme disease Symptoms can appear anywhere from a few days to a few months after being bitten by an infected tick. They may include:

  • Skin rashes
  • Severe dizziness and headaches
  • Pain (joints, bones, tendons, muscles)
  • Arthritis (knees, ankles, elbows, wrists)
  • Cognitive impairments (memory loss, inability to think clearly)

Lyme disease can manifest itself gradually, in several stages:

  • The localized early phase (days to weeks after the bite): appearance of erythema migrans, a red, often circular, rash that spreads around the bite area
  • The secondary phase (weeks to months after infection): persistent joint pain, neurological disorders, secondary skin lesions, or palpitations
  • The tertiary phase (months to years after infection): persistent inflammatory arthritis, lasting neurological disorders, cardiac or ophthalmic involvement

La a change. Prevention relies on simple actions: apply tick repellent and wear protective clothing when in wooded or grassy areas. After each outing, thoroughly inspect your body, as well as those of children and animals. If bitten, remove the tick immediately with a tick remover (without crushing it, perpendicular to the skin) and disinfect the area. Prompt removal, ideally within 24 hours, drastically reduces the risk of bacterial transmission. Borrelia/Lyme disease.

No, Lyme disease is not contagious.

It is caused by a bacterium called Borrelia burgdorferi, transmitted to humans through the bite of an infected tick. The tick itself becomes infected by feeding on the blood of animals carrying the bacteria, such as certain rodents.

Yes, Lyme disease can be cured.The earlier the disease is detected, the easier it is to treat. Treatment is based on a antibiotic therapy adapted, prescribed by a doctor.

In the early stages, taking antibiotics for 10 to 21 days generally allows for full recoveryIf the disease is more advanced, treatment can last several weeks, sometimes involving intravenous antibiotics.

Lyme disease is not fatal, but can leave disabling after-effects if left untreated.

In very rare cases, Lyme disease can lead to death due to complications related to a heart infection.

In the absence of erythema migrans, the diagnosis is based on a blood serology in two steps: an ELISA test followed by a Western blot for confirmation. In the presence of neurological manifestationsA PCR test can be performed on cerebrospinal fluid to detect the bacteria's DNA. Finally, exposure to ticks in an endemic area is a major factor strengthening diagnostic suspicion. These tests are essential to distinguish Lyme disease from other inflammatory or infectious conditions.

A blood test may be done 4 to 6 weeks after a tick bite.

However, a negative blood test does not rule out a diagnosis of Lyme disease. It is recommended to undergo further testing. skin biopsy (taking a small piece of skin from around the bite) or to a lumbar puncture (analysis of cerebrospinal fluid) to establish the diagnosis.

 

The time it takes to get the results of a Lyme disease blood test generally varies from 24 hours to one weekIf the first screening test is negative, you will be notified of the result quickly (within 24 to 48 hours). If the first test is positive, further tests will be carried out, which may lengthen the time it takes to receive the results.

A latent infection rarely progresses without initial clinical signs. If late manifestations occur months, or even exceptionally years later, they generally follow a primary phase (erythema migrans) that went unnoticed.

It is crucial to consult a doctor if unexplained chronic symptoms coincide with a history of insect bites. Diagnosis is based on serological testing, and antibiotic treatment is then necessary.

Prevention (covering clothing, repellents, skin examination) remains the best protection against these disseminated forms.

Taking antibiotics is not automatic after every tick bite. Preventive treatment may sometimes be recommended if the tick has been attached for a long time (more than 36 hours) in an area where the disease is very common. A medical consultation is then necessary to assess whether this treatment is appropriate for you. In all cases, monitor the bite area for thirty days: if a red rash develops (erythema migrans), consult your doctor promptly.

Currently, conventional antibiotics These treatments remain the only validated standard of care. Their duration varies depending on the severity of the symptoms. Although scientific research is exploring new therapeutic avenues to target the bacteria more effectively, no revolutionary treatment has yet been approved by health authorities.

To date, early detection and rapid treatment from the first signs remain the best ways to ensure a complete recovery.

Lyme disease can affect the nervous system we then speak of neuroborreliosisSymptoms include intense pain along the nerves (radiculitis), facial paralysis, or persistent headaches related to meningitis. Less commonly, memory problems, difficulty concentrating, or extreme fatigue may occur. These signs require urgent medical attention to confirm the diagnosis with serological testing and to begin appropriate antibiotic treatment to prevent long-term complications.

Research on Lyme disease at the Pasteur Institute of Lille

The Pasteur Institute of Lille is not currently conducting specific research on Lyme disease. However, some research areas address mechanisms common to several pathogenic bacteria transmitted by vectors. Dr. Sébastien Bontemps-Gallo, who in his previous work focused on the bacterium Borrelia burgdorferi, studies today Yersinia pestis, the agent responsible for the plague, and its vector, the flea.

“My goal is to understand how a bacterium ‘knows’ where it is, and how it adapts its genetic program to establish an infection transmissible by arthropods. These mechanisms are shared by many pathogenic bacteria, and this opens up avenues for developing new treatments or prophylactic measures,” he explains.

* In 2021, 47,000 cases were diagnosed (according to Public Health France)