Which of the statements are True/False regarding dengue fever? a) All four distinct dengue viruses have Aedes aegypti as their principal vector. b) A. aegypti usually inhabits dwellings and bites during the day. c) Severe myalgia that gave rise to the colloquial designation “break-bone fever”. d) A macular rash on the first day as well as adenopathy, palatal vesicles, and scleral injection. e) Epistaxis and scattered petechiae are features of complicated dengue.

**Core Concept**
Dengue fever is a mosquito-borne viral disease caused by four distinct serotypes of the dengue virus (DENV 1-4), primarily transmitted by the Aedes aegypti mosquito. The disease is characterized by a flu-like illness, which can progress to severe dengue, a potentially life-threatening condition.

**Why the Correct Answer is Right**
- Option **c** is correct because severe myalgia is a hallmark symptom of dengue fever, leading to the colloquial designation "break-bone fever." This symptom is due to the viral replication in muscle tissues and the subsequent activation of the immune response.
- Option **e** is correct as epistaxis (nosebleeds) and scattered petechiae (small spots due to blood leakage) are features of complicated dengue, which can occur due to vascular leakage and thrombocytopenia.
- All the other options are incorrect.

**Why Each Wrong Option is Incorrect**
**Option a:** All four distinct dengue viruses do not have Aedes aegypti as their principal vector; Aedes albopictus is also a significant vector for dengue virus transmission.
**Option b:** Aedes aegypti primarily bites during the day, but they can also bite at night, especially in areas with low light conditions. They usually inhabit dwellings and surrounding areas.
**Option d:** Macular rash, adenopathy, palatal vesicles, and scleral injection are not typical features of dengue fever. While some patients may present with a maculopapular rash, these specific features are not characteristic of the disease.

**Clinical Pearl / High-Yield Fact**
Dengue fever can be prevented by eliminating breeding sites of the Aedes mosquito, using insecticide-treated bed nets, and wearing protective clothing. Additionally, early recognition and management of severe dengue are critical to prevent complications and fatalities.

**Correct Answer: C. Severe myalgia that gave rise to the colloquial designation "break-bone fever".**

✓ Correct Answer: C. a,b,c,d-True & e-False