Dengue and the Aedes aegypti Mosquito

Overview

• Aedes aegypti is a mosquito species known for transmitting viruses like dengue fever.
• Female mosquitoes lay eggs in water-filled containers near homes, both indoors and outdoors.
• These mosquitoes thrive in tropical and subtropical climates throughout the year.

General Information

• Appearance: Small, dark with white lyre-shaped markings and banded legs.
• Biting Behavior: Prefer to bite indoors, primarily humans.
• Egg Laying:
  • Utilize both natural (treeholes, plant axils) and artificial water containers.
  • Lay eggs during the day in shaded, dark-colored containers with organic material in the water.
  • Eggs are laid just above the waterline, resistant to drying, and can survive over six months.
  • Larvae hatch when eggs are flooded with water.
• Lifecycle:
  • Immature cycle (egg to adult) can occur in 7-8 days.
  • Adult lifespan is approximately three weeks.
  • Egg production sites are near households.
• Climate Impact: Do not survive winters in colder climates.

Medical Importance

• Primary Vector: Historically a primary vector for diseases such as dengue fever, chikungunya, and yellow fever.
• Geographical Prevalence: Most common in tropical and subtropical areas.

Habitat

• Dependence on Water: Common in areas lacking piped water, using storage containers to lay eggs.
• Feeding: Males and females feed on nectar; females need blood to produce eggs.
• Egg Survival: Eggs survive drying, facilitating spread to new locations.
• Common Larval Habitats:
  • Artificial containers near humans: flower pots, discarded tires, rain gutters, fountains, etc.
  • Underground water collections: septic tanks, storm drains, wells.

Biting Behavior

• Active Times: Primarily bites during the day, especially 2 hours post-sunrise and pre-sunset, but can bite at night in well-lit areas.
• Biting Technique: Approaches from behind, targeting ankles and elbows.
• Targets: Prefers humans but also bites domestic animals (mostly mammals).
• Blood Requirement: Only females bite to obtain blood for egg-laying.

Mosquito Control

• Weekly Checks: Inspect yard for water-filled containers.
• Waste Management: Dispose or recycle unnecessary water-holding containers.
• Storage Precautions: Cover or invert large objects like boats to prevent water collection.
• Maintenance: Scrub bird baths, pet dishes weekly, and ensure gutters are not waterlogged.
• Natural Water Bodies: Fill tree holes with sand/soil to prevent water collection.
• Hidden Water Sources: Check wells, septic tanks, and drains.
• Authorities: Report unusual mosquito numbers to health officials.

Avoiding Bites

• Personal Protection:
  • Wear long sleeves, pants, socks, and shoes during active mosquito times.
  • Use repellents like DEET, picaridin, or oil of lemon eucalyptus on exposed skin/clothing.
  • Do not apply repellents under clothing.
• Additional Precautions:
  • Use mosquito nets over infant carriers and cribs.
  • Install or repair window and door screens to keep mosquitoes out.