Borreliosis ofLyme is the most common tick-borne infection. Focus on the symptoms and treatments of this disease with Professor Eric Caumes, infectiologist at the Hôtel-Dieu hospital in Paris.
With fine weather, we spend time in the forest, in the parks, but also in our garden. Places where you can be bitten by ticks, which can (rarely) transmit Lyme disease. We take stock.
What is the risk of catching Lyme disease when you have a tick bite?
When infected, some ticks can transmit bacteria, parasites and viruses to humans when they are bitten, if they remain attached long enough. In the majority of cases, the infectious agent in question is the bacterium Borrelia burgdorferi sensu lato which causes Lyme borreliosis. “Only the Ixodes ricinus tick transmits Lyme disease”, specifies Professor Eric Caumes, infectious disease specialist at the Hôtel-Dieu hospital in Paris, and author of Lyme disease: fact or sham (Editions Bouquins, May 2021).
In France, the prevalence of infection with Borrelia burgdorferi in ticks varies seasonally and regionally. “The tick hibernates in winter and has a period of activity between mid-spring and autumn. From one region to another and even from one forest to another, the tick infestation rate varies between 5 and 30%”, says the doctor. Lyme disease is very present in wooded and humid regions, particularly in the East (Alsace, Lorraine) and in the Center (Limousin, Auvergne). On the other hand, it is very little present around the Mediterranean and at altitude (>1500m).
The transmission of Lyme disease depends on the rate of infestation of the tick and its attachment time. The risk increases after 24 hours of attachment. “However, in 95% of cases of transmission, the immune system controls the infection and there is no disease“, informs Professor Caumes.
The number of Lyme disease cases has been increasing since 2009. The annual incidence rate of Lyme borreliosis was estimated at 91 cases per 100,000 population (60,033 estimated cases) in 2020.
What is Lyme disease?
Lyme disease is a zoonosis transmitted to humans by the bite of a tick of the genus Ixodes. A borrelia mainly, Borrelia burgdorferiis responsible for the infection: it is therefore a bacterial disease. “The disease can evolve in 3 phases: an early localized phase (the primary phase), and, in the absence of treatment, an early disseminated form and a late disseminated form”, specifies Professor Eric Caumes.
L’erythema migrans is the most common clinical manifestation of the disease. “In 95% of cases, people with Lyme disease have a primary form; the early and late disseminated phases account for approximately 800 hospitalizations per year”he reassures.
What are the symptoms of Lyme disease?
Symptoms of Lyme disease depend on the stage of the disease. In the localized phase, the sign of Lyme disease is erythema migrans. “After a delay of 7 days on average after the tick bite, an erythema develops at the site of the bite. It has a centrifugal extension with a clearing in the center and measures more than 5 cm in diameter”explains the infectiologist.
This erythema does not cause no itching. It may rarely be accompanied by flu-like symptoms: fever, fatigue, headache, and muscle or joint pain.
The early disseminated phase (less than 6 months after the appearance of the first symptoms) is manifested by joint signs. “It is especially the important joints that are affected, especially the knee”, specifies Professor Caumes. This phase can also give neurological (meningo-radiculitis, peripheral facial paralysis) and cutaneous symptoms. Cardiac (myocarditis) and ophthalmological (especially uveitis and optic neuropathy) attacks are very rare.
Late disseminated phase (more than 6 months after the onset of the first symptoms) is characterized by articular manifestations (chronic arthritis), neurological (meningo-radiculitis, meningo-encephalitis) and cutaneous (chronic atrophic acrodermatitis which is characterized by thinned skin with veins visible at the ends).
Diagnosis: how do you know if you have Lyme disease?
the diagnostic primarily based on clinical examination. “It is made on the observation of erythema migrans in the context of a tick bite, says Professor Caumes. Serology is not useful at this stage. It can be negative and become positive up to 6 weeks later. he specifies.
“For disseminated forms, the diagnosis is based on a range of epidemiological, clinical and biological arguments”, inform the infectiologist. The diagnosis is confirmed by blood serology (ELISA and if positive or doubtful result Western Blot) as well as other complementary examinations.
Persistent Lyme: what do we know?
Some people who have been potentially exposed to ticks show polymorphic clinical signs (muscle pain, headaches, fatigue, cognitive disorders), persistent, generally diffuse, unexplained, which can be disabling. In the current state of knowledge, it is not possible to know whether these signs are due to the existence of persistent Lyme borreliosis (after treatment or not) or to other pathogenic agents which would be transmitted by ticks or other diseases or syndromes. These non-specific symptoms have also been described during other infections. “It may be functional somatic disorders”, emphasizes Professor Eric Caumes.
What are the treatments for Lyme disease?
As with other bacterial infections, treatment is based on antibiotics (between 14 and 28 days depending on the form). “Early forms require antibiotic treatment for 14 days, early disseminated forms require antibiotic treatment for 21 days and late disseminated forms require antibiotic treatment for 28 days”, says the doctor.
Are we cured?
“The antibiotic treatment is very effective”, informs Professor Eric Caumes. Antibiotic therapy at the primary stage allows the healing of erythema migrans but also to interrupt the progression towards disseminated forms. There are no recorded cases of death from Lyme disease.
What patient care? For people with persistent polymorphic symptoms/syndrome after a possible tick bite or “PTSD”, the HAS recommended in 2018 to offer a treatment to relieve the symptoms, while waiting to learn more about the disease from which the patient suffers and to carry out an etiological assessment (which seeks the cause). In 2022, the HAS advises patients to move towards centers dedicated to the management of Lyme (5 centers in France).
How to prevent Lyme disease?
To prevent Lyme disease, it is recommended to follow a few instructions to avoid tick bites from spring to autumn, during your walks in the forest but also in the gardens (a quarter of tick bites occur in garden):
- use skin and clothing repellents,
- wear closed shoes and long, closed clothing,
- avoid walking in the middle of tall grass, bushes and low branches and favor marked paths,
- inspect yourself after a walk,
- Immediately detach a tick present with a tick remover ideally and monitor the bite area. If it has an erythema that extends, consult your doctor.
To know: you can send the photograph of the tick removed on the site citique.fr. “You receive information about the type of tick and the risks of diseases it can transmitinforms Professor Caumes.
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