Lyme disease

Transmission

Lyme disease is transmitted to humans through the bite of infected ticks of the genus Ixodes, commonly known as blacklegged ticks or deer ticks. Ticks acquire the Borrelia bacteria when they feed on the blood of infected animals, such as deer, rodents or birds. They can then transmit the bacteria to humans during a bite.

Infection process

For transmission of Lyme disease to occur, the tick usually must be attached to the skin for at least 36 to 48 hours. Ticks in their immature stages (nymphs) most often transmit Borrelia, as they are small (less than 2 mm) and can go unnoticed, allowing them to attach for long periods without being detected.

Symptoms

Lyme disease develops in several stages, each with its own symptoms:

• Localised early stage (days to weeks after the bite):
  • Erythema migrans: This is the characteristic sign and appears in approximately 70-80% of cases. It is a skin rash that starts at the site of the bite and spreads in the form of a "bull's eye" (a red ring with a lighter centre).
  • Flu-like symptoms: Include fever, chills, fatigue, headache, muscle aches and joint pains.
• Early disseminated phase (weeks to months after the bite):
  • Multiple erythema migrans: In some cases, multiple similar rashes may appear on different parts of the body.
  • Neurological problems: These include facial paralysis (Bell's palsy), meningitis (inflammation of the membranes covering the brain and spinal cord), neck pain and numbness or weakness in the limbs.
  • Lyme Carditis: Involvement of the heart that can cause cardiac arrhythmias.
• Late stage (months to years after the bite):
  • Lyme arthritis: Inflammation of the joints, especially the knees, which can become chronic if left untreated.
  • Chronic neurological complications: such as peripheral neuropathy (damage to nerves outside the brain and spinal cord) and encephalopathy (impaired brain function).

Diagnosis

Diagnosis of Lyme disease is based on a combination of clinical factors, history of tick exposure and laboratory tests. Laboratory tests include:

• ELISA antibody test: Detects the presence of antibodies to Borrelia burgdorferi in the blood.
• Western Blot: Used to confirm the results of the ELISA test and is more specific for Lyme disease.

It is important to note that antibody tests may not be positive in the first few weeks of infection, which can complicate diagnosis in the early phase.

Treatment

Early treatment with antibiotics is crucial to prevent serious complications of Lyme disease. Commonly used antibiotics include:

• Doxycycline: For adults and children over 8 years of age.
• Amoxicillin: For pregnant women and children under 8 years of age.
• Cefuroxime: An alternative in case of penicillin allergy.

The course of treatment usually lasts between 14 and 28 days, depending on the stage and severity of the infection. In cases of advanced disease or neurological and cardiac complications, intravenous antibiotics may be necessary.

Prevention

Prevention of Lyme disease is based on avoiding tick bites and reducing exposure to ticks. Preventive measures include:

1. Avoiding tick-infested areas: Such as forests, tall grass and brushy areas, especially during the spring and summer months when ticks are most active.
2. Wear protective clothing: Light-coloured clothing to make it easier to spot ticks, long trousers tucked into socks and long sleeves.
3. Apply insect repellents: Use repellents containing DEET on exposed skin and permethrin on clothing.
4. Careful checks: Inspect the body for ticks after being outdoors, paying special attention to areas such as the scalp, behind the ears, armpits, waist and behind the knees.
5. Remove ticks correctly: If an attached tick is found, remove it as soon as possible with tweezers, holding it as close to the skin as possible and pulling upwards in a steady motion.

Significance of Lyme disease

Lyme disease is an important public health condition, especially in regions where Borrelia-carrying ticks are common. Early detection and appropriate treatment are critical to prevent long-term complications. In addition, awareness of preventive measures is key to reducing the risk of infection.

In summary, Lyme disease is a tick-borne bacterial infection with potentially serious complications if left untreated. Prevention through protection against tick bites and early recognition of symptoms are essential to avoid progression.

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