How Dengue Fever is Transmitted
Dengue fever is transmitted primarily through the bite of infected day-biting Aedes mosquitoes, particularly Aedes aegypti and Aedes albopictus. 1, 2, 3
Primary Transmission Route
- Mosquito-borne transmission is the principal mode of dengue spread, occurring when an infected Aedes mosquito bites a human during daytime hours 1, 4
- The Aedes aegypti mosquito is the primary vector, with Aedes albopictus serving as a secondary vector in many regions 3, 5
- These mosquitoes are day-biting insects, distinguishing them from many other disease-carrying mosquitoes that feed at night 1
How the Transmission Cycle Works
- Mosquitoes acquire the dengue virus by feeding on infected humans during their viremic period 2, 6
- Humans are infectious to mosquitoes shortly before fever onset and for 3-5 days after fever begins 7
- Once infected, the mosquito can transmit the virus to other humans through subsequent bites 6
- Humans serve as the primary amplifying host in urban transmission cycles, unlike yellow fever where nonhuman primates play a major role 7
Rare Non-Mosquito Transmission Routes
While mosquito bites account for nearly all cases, dengue can theoretically be transmitted through:
- Blood transfusion from an infected donor during the viremic period 2
- Vertical transmission from mother to fetus during pregnancy 1
- Needlestick injuries in healthcare settings, though this is extremely rare 7
Important distinction: Unlike yellow fever virus which has sylvatic (jungle) cycles involving monkeys, dengue transmission is primarily an urban, human-to-mosquito-to-human cycle 7, 5
Geographic and Environmental Factors
- Dengue transmission occurs predominantly in tropical and subtropical regions where Aedes mosquitoes thrive 2, 4
- Unplanned urbanization and standing water collections create ideal breeding habitats for Aedes mosquitoes 5, 6
- Transmission intensifies during rainy seasons when mosquito breeding sites proliferate 3, 6
Critical Clinical Point
Direct person-to-person transmission does not occur through casual contact, respiratory droplets, or other typical human-to-human routes—an infected mosquito vector is required 2, 3