Clinical Assessment and Risk Stratification

Patients classically present with a red rash that increases in size with central clearing, known as erythema migrans, usually at the site of tick bite. This rash is non-pruritic, and neither hot nor painful.

The rash commonly appears within one to four weeks of the bite (but can present from anywhere between 3 days to 3 months after) and can last several weeks.

Figure 3: Lyme disease: erythema migrans

However, patients can also present with a rash that appears and recedes within the first 48 hours of their outdoor activity. This rash represents a reaction to the tick bite itself. It is more often red, hot, painful and itchy than erythema migrans.

Although this rash is not that of erythema migrans, it would be ideal to check for ticks at this time of presentation. It is worth noting that the original tick bite may have gone unnoticed by the patient.

The possibility of Lyme disease should be considered in patients who present with a combination of the following symptoms because Lyme disease, although uncommon, could be responsible:

• Fevers
• Swollen lymph nodes
• Malaise and/or fatigue
• Nick pain and/or stiffness
• Joint or muscle aches and/or pains that are migratory in nature
• Cognitive impairment such as memory problems and/or difficulty concentrating
• Headache
• Paraesthesia