**Question:** Spread by mosquitoes:

A. Dengue Fever
B. Malaria
C. Yellow Fever
D. Chikungunya

**Core Concept:** Mosquitoes are vectors for several infectious diseases, spreading pathogens from one host to another.

**Why the Correct Answer is Right:** Dengue Fever is spread by the Aedes aegypti mosquito, which is also responsible for other viral diseases like Zika and Chikungunya. The virus that causes dengue fever is transmitted to humans through the bite of an infected Aedes mosquito, leading to dengue infection.

**Why Each Wrong Option is Incorrect:**

B. Malaria: Malaria is caused by Plasmodium parasites transmitted by the Anopheles mosquito, not Aedes aegypti.
C. Yellow Fever: Yellow fever is caused by the Yellow Fever virus transmitted by the Haemagogus and Sabethes mosquitoes, not Aedes aegypti.
D. Chikungunya: Chikungunya is caused by the Chikungunya virus transmitted by the Aedes mosquito, but not Aedes aegypti, which is responsible for dengue fever.

**Clinical Pearl:** Dengue fever is a significant global health issue, affecting millions of people annually. Effective prevention includes controlling mosquito breeding sites, wearing protective clothing, and using insect repellents and bed nets.

**Correct Answer:** D. Chikungunya

**Explanation:** Dengue fever and chikungunya are both transmitted by the Aedes mosquito, but the correct answer is Chikungunya because it is transmitted by Aedes aegypti, the same mosquito species responsible for dengue fever. Aedes aegypti is a competent vector for Chikungunya virus transmission, contributing to its spread globally.