When diagnosing Lyme disease in a patient with a recent tick bite, the key clinical feature to consider is the presence of erythema migrans NICE NG95. This is a red rash that typically increases in size and may sometimes have a central clearing NICE NG95. It is usually not itchy, hot, or painful NICE NG95. The rash usually becomes visible 1 to 4 weeks after a tick bite, but can appear from 3 days to 3 months, and lasts for several weeks NICE NG95. It is typically located at the site of the tick bite NICE NG95.
It is important to be aware that a rash which is not erythema migrans can develop as a reaction to a tick bite NICE NG95. This type of rash usually develops and recedes within 48 hours of the bite and is more likely to be hot, itchy, or painful NICE NG95. It may be caused by an inflammatory reaction or infection with a common skin pathogen NICE NG95.
If erythema migrans is present, Lyme disease can be diagnosed and treated without laboratory testing NICE NG95,NICE CKS.
In people without erythema migrans, consider the possibility of Lyme disease if they present with several of the following symptoms, as Lyme disease is a possible but uncommon cause NICE NG95:
- Fever and sweats NICE NG95
- Swollen glands NICE NG95
- Malaise NICE NG95
- Fatigue NICE NG95
- Neck pain or stiffness NICE NG95
- Migratory joint or muscle aches and pain NICE NG95
- Cognitive impairment (e.g., memory problems, difficulty concentrating) NICE NG95
- Headache NICE NG95
- Paraesthesia NICE NG95
Also, consider Lyme disease in people presenting with symptoms and signs relating to one or more organ systems (focal symptoms), as it is a possible but uncommon cause of NICE NG95:
- Neurological symptoms, such as facial palsy, other unexplained cranial nerve palsies, meningitis, mononeuritis multiplex, or other unexplained radiculopathy; or rarely encephalitis, neuropsychiatric presentations, or unexplained white matter changes on brain imaging NICE NG95
- Inflammatory arthritis affecting one or more joints that may be fluctuating and migratory NICE NG95
- Cardiac problems, such as heart block or pericarditis NICE NG95
- Eye symptoms, such as uveitis or keratitis NICE NG95
- Skin rashes such as acrodermatitis chronica atrophicans or lymphocytoma NICE NG95
When assessing, explore how long the person has had symptoms and their history of possible tick exposure, including activities that might have exposed them to ticks or travel to highly prevalent areas NICE NG95. However, do not rule out Lyme disease if there is no clear history of tick exposure NICE NG95. Do not diagnose Lyme disease in people without symptoms, even if they have had a tick bite NICE NG95.