Colorado Tic fever is caused by:
**Core Concept**
Colorado Tick Fever (CTF) is a viral disease caused by a specific tick-borne pathogen, which affects the hematopoietic system and leads to symptoms like fever, headache, and rash. It is a zoonotic disease, meaning it can be transmitted from animals to humans.
**Why the Correct Answer is Right**
The correct answer is due to the presence of a unique virus transmitted by the bite of an infected wood tick (Dermacentor andersoni). This virus, Colorado Tick Fever Virus (CTFV), is a member of the Reoviridae family and has a specific tropism for hematopoietic cells. The virus replicates in the bone marrow, leading to a decrease in platelet count and subsequent symptoms.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not correct as Colorado Tick Fever is not caused by a bacterial agent.
**Option B:** This option is incorrect as the disease is not caused by a fungal pathogen.
**Option C:** This option is not correct as Colorado Tick Fever is not caused by a protozoan parasite.
**Clinical Pearl / High-Yield Fact**
The key aspect of Colorado Tick Fever is its association with tick bites and its hematologic manifestations, which can mimic other tick-borne diseases like Rocky Mountain Spotted Fever. Clinicians should consider this diagnosis in patients presenting with fever, headache, and rash after exposure to ticks in endemic areas.
**Correct Answer: D. Colorado Tick Fever Virus**