A lady presented with fever and rashes, she returned from the USA gives a history of exposure to ticks. Most probable diagnosis is
**Core Concept**
Lyme disease is a tick-borne illness caused by the bacterium Borrelia burgdorferi, characterized by fever, rash, and joint pain, with a distinctive "bull's-eye" rash (erythema migrans) in its early stage.
**Why the Correct Answer is Right**
The correct diagnosis is Lyme disease due to the patient's exposure to ticks in the USA, where Lyme disease is endemic. The bacterium Borrelia burgdorferi is transmitted to humans through the bite of infected black-legged ticks (Ixodes scapularis). The characteristic "bull's-eye" rash (erythema migrans) is a hallmark of early Lyme disease, which appears within 3-30 days of the tick bite. The patient's symptoms, including fever and rashes, are consistent with this diagnosis.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not match the clinical presentation and epidemiology of Lyme disease.
* **Option B:** This option is incorrect because it does not account for the patient's exposure to ticks in the USA and the characteristic "bull's-eye" rash of Lyme disease.
* **Option C:** This option is incorrect because it does not match the patient's symptoms and the epidemiology of Lyme disease.
* **Option D:** This option is incorrect because it does not account for the patient's exposure to ticks in the USA and the characteristic "bull's-eye" rash of Lyme disease.
**Clinical Pearl / High-Yield Fact**
Lyme disease is the most common tick-borne illness in the USA, with over 30,000 cases reported annually. The characteristic "bull's-eye" rash (erythema migrans) is a key diagnostic feature of early Lyme disease.
**Correct Answer:** C.