Differential Diagnosis
- Single most likely diagnosis
- Lyme disease: This is the most likely diagnosis given the patient's history of tick exposure in November, followed by the development of a rash, fatigue, joint pain, and fever. The rash, likely erythema migrans, is a characteristic symptom of Lyme disease, and the other symptoms are also consistent with the disease.
- Other Likely diagnoses
- Southern tick-associated rash illness (STARI): This condition is also associated with tick bites and can cause a rash similar to erythema migrans. However, it is less likely than Lyme disease given the patient's symptoms of fatigue, joint pain, and fever.
- Rocky Mountain spotted fever (RMSF): This disease is also transmitted by ticks and can cause fever, headache, and rash. However, the rash in RMSF typically appears within a few days of the fever, whereas the patient's rash appeared 3 weeks after tick exposure.
- Anaplasmosis: This is a tick-borne disease that can cause fever, headache, and fatigue. However, it is less likely than Lyme disease given the patient's symptoms of joint pain and rash.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Tularemia: This is a rare but potentially deadly disease that can be transmitted by ticks. It can cause fever, rash, and pneumonia, and can be fatal if left untreated.
- Ehrlichiosis: This is a tick-borne disease that can cause fever, headache, and fatigue, and can be fatal if left untreated.
- Babesiosis: This is a rare but potentially deadly disease that can be transmitted by ticks. It can cause fever, fatigue, and anemia, and can be fatal if left untreated.
- Rare diagnoses
- Tick-borne relapsing fever (TBRF): This is a rare disease that can be transmitted by ticks. It can cause fever, headache, and rash, but is less likely than other diagnoses given the patient's symptoms.
- Powassan virus disease: This is a rare but potentially deadly disease that can be transmitted by ticks. It can cause fever, headache, and encephalitis, but is less likely than other diagnoses given the patient's symptoms.