A 32-year-old woman from Kerala presents with sudden onset fever, severe arthralgia affecting wrists, ankles, and small joints of hands, and a maculopapular rash. Serology shows IgM antibodies against an alphavirus. Which is the most common arthropod vector responsible for transmission of this infection?

Explanation

## Vector Identification in Alphavirus Transmission **Key Point:** Chikungunya is transmitted primarily by *Aedes aegypti* mosquitoes, which are the most common urban vector for this alphavirus in India. ### Epidemiological Context Chikungunya (CHIKV) is an alphavirus that causes epidemic polyarthralgia. The clinical presentation of severe, prolonged arthralgia (especially in small joints of hands and wrists) combined with fever and rash is pathognomonic for chikungunya in endemic areas like Kerala. ### Vector Characteristics | Vector | Primary Disease | Habitat | Activity Pattern | |--------|-----------------|---------|------------------| | *Aedes aegypti* | Dengue, Chikungunya, Zika | Urban/periurban | Daytime, indoors | | *Aedes albopictus* | Dengue, Chikungunya, Zika | Periurban/rural | Daytime, outdoors | | *Culex quinquefasciatus* | Japanese encephalitis, Lymphatic filariasis | Urban/rural | Nocturnal | | *Anopheles stephensi* | Malaria | Urban/periurban | Nocturnal | **High-Yield:** *Aedes aegypti* is the **primary and most common vector** for chikungunya in urban India. It is anthropophilic (prefers human blood), breeds in stagnant water in artificial containers, and has a high competence for CHIKV transmission. ### Clinical Pearl The 2006 chikungunya epidemic in India and subsequent outbreaks have been predominantly associated with *Aedes aegypti*. The virus has also adapted to *Aedes albopictus* in some regions, but *Aedes aegypti* remains the most frequent vector globally and in India. **Mnemonic: AEDES = Arthralgia, Epidemic, Daytime-active, Domestic, Eggs in water** — captures the key features of the vector responsible for chikungunya.