Facilitator - WHO Western Pacific Region - World Health Organization

MODULE 3: Transmission of dengue and primary prevention
SLIDE 10: Breeding areas and transmission
•Facilitator
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explains:
•Immature stages are found in water-filled habitats (e.g. water jugs, plant pots) that are mainly
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associated with human dwellings).
•Most female Ae. aegypti mosquitoes spend their lifetime in or around the houses where they
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emerge as adults.
•Dengue outbreaks are often attributed to Ae. albopictus and Ae. polynesiensis.
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•People rather than mosquitoes rapidly move the virus within and between communities.
SLIDE 11: Life-cycle of Aedes aegypti
•Facilitator
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explains:
•Adult mosquito — Female lays an average of 100–120 eggs inside containers (above water) five
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times in her lifetime.
•Eggs can survive for up to 6 months (so can survive dry season). Eggs hatch when submerged
in water; this process takes less than 24 hours. It is important to not just empty water from
containers but also remove eggs; otherwise, eggs will simply hatch when the container is filled
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back up with rainwater.
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•Larvae develop into pupae in approximately 6 days.
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•Pupae develop into adults in another 2 days.
•The total time for development is dependent upon water temperature and food supply, and
typically ranges from 4 to 10 days. Larvae die at temperatures below 10°C and above 44°C .
SESSION 3.2: OTHER ROUTES OF TRANSMISSION
SLIDE 12: Other routes of transmission
•Facilitator
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presents:
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•Evidence of transmission of dengue via receipt of donor organs or tissue:
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One report of transmission following a bone marrow transplant in Puerto Rico.
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One report of transmission following a renal transplant.
•Evidence of transmission of dengue through receipt of blood products:
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One symptomatic recipient after RBC transfusion in China.
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Two PCR+ symptomatic recipients and one IgM+ asymptomatic recipient in Singapore.
•Evidence of occupational exposure in a health care setting:
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Five published reports of percutaneous transmission after needle-stick injuries.
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Two published reports of mucocutaneous transmission after being splashed in face with
blood.
•Facilitator
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explains:
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•If you suspect dengue, use standard universal precautions.
•DENV is known to be transmitted via occupational exposure to infected blood (e.g. needle stick
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injury, blood splashed in eyes).
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•It is unknown if DENV can be transmitted via contaminated instruments.
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•DENV is not spread via respiratory droplets, saliva or sexual contact.
•Prevent febrile, viraemic inpatients from being bitten by mosquitoes (e.g. bed net, screened
room).
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