Lyme Disease In Adults: Risks, Symptoms, And Care

Introduction

Parasites such as ticks are found worldwide and are responsible for transmitting various infectious diseases in humans. Specifically, ticks can cause vector-borne diseases by biting a person and transmitting specific pathogens that lead to illness.¹ Lyme disease, also known as Lyme borreliosis, is one of the most frequent diseases caused by tick bites of the genus Ixodes, which carry certain spirochetes bacteria named Borrelia burgdorferi. The infection with these bacteria can result in Lyme disease, which evolves in three stages; stage 1 or early localised disease, stage 2 or early disseminated disease, and stage 3 or late persistent disease. Symptoms of Lyme disease between the different stages vary in severity and duration and can involve skin, neurologic, joint, and cardiac problems. Individuals with tick bites and characteristic symptoms should seek medical care to diagnose and address the disease in its early stages to avoid potential complications.²

Lyme disease accounts for the most common vector-borne disease in the United States with 62,551 cases reported in 2022.³ Climate change and the expansion of the distribution of ticks in different geographical areas have caused an increase in Lyme disease cases around the United States and Canada in the last decades.¹ Lyme disease’s incidence is also raised in Europe particularly in specific localities of several nations with Finland, Belgium, the Netherlands, and Switzerland reporting more than 100 cases per 100,000 population annually.⁴ Therefore, identifying the risks and symptoms, and receiving adequate care for Lyme disease is pivotal for the public health of the worldwide population.

Lyme disease-associated risks

Risks of transmission

Ixodes ticks, also known as black-legged ticks, are the main vectors for transmitting Lyme disease in human adults. Distinct Ixodes species have been identified in different areas of the globe. Ixodes scapularis, or deer tick, is prevalent in the Northeast and Upper North America, Ixodes pacificus is found in the West of the United States, Ixodes ricinus, or sheep tick, is commonly found in Europe, and Ixodes persulcatus in Asia.⁵

The risk of transmission by infected ticks greatly depends on the period, geographical area, and life cycle of these organisms. Summer is considered the highest-risk season for transmission of Lyme disease. However,  precautions should also be taken during Spring and Autumn, particularly for people passing through or working in risk areas. Working in peri-urban spaces, outdoor activities in forested environments, and fragmented landscapes are all factors augmenting the risk of exposure to infected ticks.⁶ Specific locations can be considered endemic when the transmission risk is high and can reach infected rates up to more than 10%.⁷ Furthermore, in Europe, I. ricinus ticks in their nymph phase correspond to around 10% of infection cases, while adult ticks for 20%. Typically, the tick must feed for a minimum of 72 hours for the bacteria to be discovered on the tick’s saliva and transferred to the skin, hence Lyme disease is generally not contracted within the first hours of the tick bite. Therefore, the risk of infection is minimised when ticks are removed promptly and appropriately.⁵

Potential complications

Lyme disease evolves in three stages and manifests with numerous symptoms, which usually subside after treatment. Potential complications of the disease include arthritis, carditis, acrodermatitis chronica atrophicans, and neurological and ocular deficits.² In certain cases, particularly if Lyme disease is misdiagnosed, left untreated, or late-treated, symptom manifestation continues for months after the initial infection. Patients can develop general fatigue, joint pain and swelling, sensory changes, headache, and other physical difficulties impairing their quality of life and interfering with daily tasks. When these symptoms’ duration exceeds six months, patients are diagnosed with chronic Lyme disease and are characterised by an active infection or co-infection by multiple pathogens.⁸

Symptoms of Lyme disease

Stage 1: Early localised phase

Localised Lyme disease symptoms typically occur between one week to one month after the tick bite and include:²

• Rash referred to as erythema migrans: 

70% of patients develop this rash during the first days after the bite at the exact site of the bite. It is initially red and resembles a bull’s eye. It may initially cause burning and itching sensations or be asymptomatic. If left untreated, the rash may persist for a couple or more weeks and reform in other regions as well. 

• Fever
• Muscle pain (myalgia)
• Neck stiffness
• Headache
• Eye redness

Stage 2: Early disseminated phase

Early disseminated Lyme disease symptoms appear between 3 to 12 weeks after the tick bite and include:²

• Fever
• Neurological problems such as dizziness and headache
• Muscle pain
• Cardiac problems including chest pain, palpitations, and difficulty in breathing
• Cranial neuropathy manifesting as double vision
• Joint pain
• Bell palsy observed in 5% of patients
• Encephalopathy

Stage 3: Late persistent phase

Late Lyme disease symptoms occur months to years after the infection and can include:²

• Neurological problems
• Rheumatic problems
• Aseptic meningitis
• Bell palsy
• Arthritis particularly observed in the knee
• Dysesthesia
• Cognitive deficits
• Cardiac problems manifesting with arrhythmias or heart block
• Acrodermatitis chronica atrophicans is mostly seen in the inner hands and feet

Treatment and care

What to do if you get bitten by a tick

After the initial tick bite, remove the tick as soon as possible to reduce the chances of contracting Lyme disease. The following steps guide you on how to carefully remove the tick:⁹

• To remove the tick, apply a proper tick removal tool, pointed tweezers, or a fine thread on the head of the tick, as near to the skin as possible, without squeezing the tick’s body. It is important to avoid squeezing its body to limit exposure to the tick’s saliva and stomach contents that contain the Lyme disease-causing bacteria.
• Do not attempt to burn the tick, apply petroleum jelly, or use your fingernails to remove the tick as these methods may cause further saliva discharge and increase the risk of contracting Lyme disease.
• Clean the site of the bite with soap and water after removing the tick.
• You can save the tick in a container in case your doctor wants to inspect it, you can send it for identification and surveillance, or you can dispose of it cautiously without squeezing its body or touching it with your hands.
• In case you see small parts of the tick still on your skin, it is advised to leave it so that they naturally get expelled by your body.
• Follow your doctor’s advice. You may need a specific treatment plan if you develop symptoms approximately two weeks after the tick bite.

Treatment of Lyme disease

After a tick bite, there are chances of contracting Lyme disease and developing its associated symptoms. Specific guidelines have been established for the treatment of the disease based on its stage. For early localised disease, antibacterial agents such as doxycycline or amoxicillin are administered orally for two weeks. Early disseminated disease manifesting with facial nerve palsy, multiple rash locations, and cardiac problems without complete heart block is also treated with oral agents. Late disease, often associated with arthritis, is treated with the same oral agents in addition to non-steroidal anti-inflammatory medications to alleviate symptoms. Additionally, intravenous therapy usually with ceftriaxone may be indicated for more severe symptoms including Lyme meningitis, myocarditis, and heart block.⁵

Typically, patients in all stages of Lyme disease respond optimally to treatment, particularly if treated promptly. However, there are cases where patients experience persistent and long-term symptoms months after being treated for Lyme disease. In this case, a potential tick-borne co-infection with another disease may be responsible for the symptom insistency. Further antimicrobial therapy is usually not recommended in these cases, although specific treatment regimens are yet to be established. Symptomatic management with pharmacological agents for improving symptoms such as fibromyalgia, pain, sleep deficits, fatigue, and anxiety may be provided. Moreover, non-pharmacological interventions like cognitive-behavioural therapy can be beneficial for easing the associated stress in patients with chronic Lyme disease.¹⁰

Summary

Climate change and urban expansion by landscape fragmentation have significantly contributed to the rise in the distribution of ticks in different locations around the globe, augmenting the risk of Lyme disease transmission. Particularly, black-legged ticks of the genus Ixodes of different species around North America, Europe, and Asia, are potential carriers of Borrelia burgdorferi bacteria, responsible for causing Lyme disease, the most common vector-borne illness caused by a tick bite.

Lyme disease progresses in three stages, with symptoms such as rash, fever, muscle pain, and neck stiffness prevailing in the early stage; fever, neurological and cardiac issues observed in the early disseminated stage; and more severe neurological, cardiac, and rheumatological problems involved in the late stage of the disease. Prompt tick removal and appropriate treatment with antibiotics are usually adequate steps for a complete recovery and offer a good prognosis. However, misdiagnosed, untreated, or late-treated Lyme disease can result in persistent symptoms that negatively influence a patient’s quality of life. Post-treatment symptoms lingering for months after the initial infection may indicate chronic Lyme disease and may require further pharmacological and non-pharmacological treatment approaches.