Lyme disease: how it is contracted, its course, and treatments

It is a bacterial infection that can be transmitted to humans by infected ticks.

As the Italian National Institute of Health (ISS) points out, Lyme disease—named after the American town of the same name where the first cases were reported in 1975— can present with a variety of symptoms, the most common being severe headaches and neck stiffness, accompanied by a rash with erythema migrans on other areas of the body. Other symptoms include facial paralysis, with drooping on one or both sides of the face; arthritis, with severe joint pain and swelling, especially in the knees, elbows, and other large joints; intermittent pain (which comes and goes) in tendons, muscles, joints, and bones; and heart palpitations.

Given the wide variability of the disorders and the long development times, Lyme disease is a difficult disease to diagnose: caused by a bacterium of the Borrelia genus, of which there are several species, it is very widespread in the United States, but is also present in Europe, China, Japan and the former Soviet Union.

Infection occurs through the bite of a tick (vector) that has previously been a host to an infected animal (mammals, birds, rodents, but also dogs and cats). To spread the bacterium to humans, the tick must remain attached for at least 36-48 hours . The ticks that most frequently cause infection in humans and animals belong to the Ixodes genus (Ixodes ricinus and I. persulcatus), which are widespread in Europe and Italy.

At the site of the bite, the characteristic erythema migrans usually appears (75% of cases), a red rash that increases in size and may sometimes have a central paler area, taking on the characteristic bull's-eye appearance . It is usually not painful or itchy, but may feel warm to the touch. It usually becomes visible 1-4 weeks after the tick bite, but it may appear 3 days or 3 months later and last for several weeks.

Without treatment, erythema migrans typically clears up within 3 to 4 weeks. The rash may be accompanied by fever, chills, fatigue, body aches, headache, neck stiffness, and swollen lymph nodes.

Beware of the “late phase”

If the disease is not diagnosed and treated, a later or late phase may occur: the latter can appear weeks to years after the fever and erythema migrans have disappeared and is characterized by a wide range of disorders affecting the joints, heart, and nervous system, the organs most affected in this phase.

The most feared complication, although rare, is late-onset neuroborreliosis, characterized by neurological changes that cause memory impairment, attention deficit, and behavioral problems. The most common presentations are meningoradiculitis and facial nerve damage. Much more rarely, neuroborreliosis can manifest as meningitis, encephalitis, myelitis, vasculitis, or polyneuropathy.

Most deaths associated with Lyme disease are attributed to the onset of serious cardiac arrhythmias, which are, however, relatively rare manifestations.

The castor bean tick (Ixodes ricinus) that sucks blood from human skin can cause Lyme disease and tick-borne encephalitis . (GettyImages)

Lyme disease is treated with antibiotics : according to the ISS website, starting treatment early generally leads to a quicker and more complete recovery. In the early stages of the disease, antibiotics such as doxycycline are used for adults and children over 8 years old, or amoxicillin or cefuroxime for adults, younger children, and pregnant or breastfeeding women. The prescription must be made by a doctor based on the patient's condition, and antibiotics are usually prescribed for 14–21 days.

If the disease involves the central nervous system (neuroborreliosis), treatment with an intravenous antibiotic for 14-28 days may be recommended.

Prevention is based on reducing the risk of being bitten by ticks. The National Institute of Health recommends, when hiking or walking: try to walk in the center of the trail to avoid bushes and grass; be careful in areas where there are grazing animals (sheep, cattle) or wild animals (rodents, roe deer, deer, etc.); wear light-colored protective clothing so you can easily see any ticks that attach; and wear a long-sleeved shirt and long pants.

Tuck your shirt into your pants and your pant legs into your socks; use specific repellents on exposed skin and spray your clothing with permethrin-based repellents. Finally, after a hike, carefully inspect any exposed areas, clothing, and the equipment used during the hike.

If one or more ticks are found on either people or pets, they must be removed immediately and the area disinfected, since the longer the tick remains on the host, the greater the chance it will transmit the infection.

To remove a tick , you can contact your doctor or emergency room, or use fine-tipped tweezers to avoid crushing the tick's body (tick removal kits are available commercially). Grasp the tick as close to the skin as possible to prevent its head from remaining in the wound, and then pull it upwards to remove it. Then wash the area with soap and water. It's important to avoid using traditional or homemade medications such as oil, vinegar, alcohol, or baking soda on the tick, or attempting to burn it. These actions can promote infection and cause irritation or wounds.