What is dengue fever? Dengue Fever is an illness caused byinfection with a virus transmitted by the Aedes mosquito.
Symptoms of Dengue FeverExample of a skin rash due to dengue fever
Do you know…Dengue Fever (DF) and DengueHaemorrhagic Fever (DHF) are the mostcommon mosquito-borne viral disease in theworld.It can be fatal.
Characteristics of the Aedes MosquitoOne distinct physicalfeature – black andwhite stripes on itsbody and legs.Bites during the day.Lays its eggs in Close-up of an Aedes mosquitoclean, stagnant water.
Do you know…Only the female Aedes mosquitofeeds on blood. This is becausethey need the protein found inblood to produce eggs. Malemosquitoes feed only on plantnectar.On average, a female Aedesmosquito can lay about 300 eggsduring her life span of 14 to 21days.
Life cycle of the Aedes Mosquito1-2 days Pupae Larvae Eggs 4-5 days 2-3 days Stagnant water
How Do Aedes Mosquitoes Transmit Diseases...Mosquito bites and sucks And passes the virusblood containing the virus to healthy people from an infected person. when it bites them. Virus is carried in its body.
This is what youcan do to help…
Prevent Aedes from Breeding! Remove ALL sources of stagnant water. Deny the Aedes mosquito of any chance to breed.
10-Minute Mozzie Wipe-Out Exercise Turn over all pails and water storage containers.Clear blockages and put Bti insecticide in roof gutters monthly.Remove water from flowerpot plates on alternate days.Do not litter. Rubbish such as cups andbottles can collect rain water and breed mosquitoes.Change water in vases on alternate days.
Before you leave for holidays…
Before you leave for holidays…• Cover all toilet bowls in your home.• Seal off the overflow pipe of the flushing cistern.• Cover all gully/floor traps.• Add sand granular insecticide to places thatmosquitoes could potentially breed, such as flowervases and places where stagnant water could not beremoved.
Dengue fever• Dengue is an arthropod-borne disease caused by any one of four closely related viruses, (Arbovirus).• Characterized by fever, severe headache, backache joint pains nausea and vomiting, eye pain and rash• Occasionally produces shock and hemorrhage, leading to death.• Also called breakbone fever, dandy fever or dengue fever.
Dengue Viruses• Four closely related single-stranded RNA Dengue viruses (DEN-1, DEN-2, DEN-3 and DEN-4)• Each serotype provides specific lifetime immunity, and short-term cross-immunity (A person can be infected as many as four times, once with each serotype)• All serotypes can cause severe and fatal disease
Replication and Transmission of Dengue Virus1. Virus transmitted 1 to human in mosquito saliva 22. Virus replicates 4. Virus released and 4 in target organs circulates in blood 33. Virus infects white blood cells and lymphatic tissues
Aedes aegypti Mosquito
Aedes Mosquito• Dengue transmitted by infected female Aedes aegypti or Aedes albo pictos mosquito• Primarily, it is a daytime feeder• Highly domesticated tropical mosquito, lives around human habitation• Lays eggs and produces larvae preferentially in artificial water containers inside and around the houses for example; plastic containers, flower vases, buckets, used automobile tires,..
Dengue Clinical Syndromes• Undifferentiated fever (87% of Patients are asymptomatic or mild fever)• Classic dengue fever (DF)• Dengue hemorrhagic fever (DHF)• Dengue shock syndrome (DSS)
Clinical Characteristics of Dengue Classic Fever• Incubation period 3-14 days (commonly 4-7 days)• Fever• Headache• Muscle and joint pain• Nausea/vomiting• Rash• Hemorrhagic manifestations
Dengue Hemorrhagic Fever (DHF) 4 Necessary Criteria: • Fever, or recent history of acute fever • Hemorrhagic manifestations • Low platelet count (100,000/mm3 or less) • Objective evidence of “leaky capillaries:” – elevated hematocrit (20% or more over baseline) – low albumin – pleural or other effusions
Dengue Shock Syndrome (DSS)• 4 criteria for DHF• Evidence of circulatory failure.
Treatment of Dengue Fever• Antipyretics (Acetaminophen) preparations to manage the pain and fever.• Rest and drink plenty of fluids• Monitor blood pressure, hematocrit, platelet count,...• Keep patient in screened sickroom or under a mosquito net• Mosquito barriers are only needed until fever subsides, to prevent Aedes aegypti mosquitoes from biting patients and acquiring virus.
Prevention• Personal protection against mosquito biting by: – Screening doors and windows – Protective clothing – Application of mosquito repellents on exposed skin• However, the best preventive measure is vector control.
Vector Control Methods:• Biological control – Largely experimental – Option: place fish in containers to eat larvae• Environmental control – Elimination of larval habitats; Cover water holding containers, Discard artificial containers,… – It is the most likely method to be effective in the long term.
Vector Control Methods:• Chemical Control• Larvicides may be used to kill immature aquatic stages• Ultra-low volume fumigation is ineffective against adult mosquitoes as Aedes aegypti is fully domesticated• Mosquitoes may have resistance to commercial aerosol sprays.
Dengue Vaccine?• No licensed vaccine at present• Effective vaccine must be tetravalent• Field testing of an attenuated tetravalent vaccine currently underway• Effective, safe and affordable vaccine will not be available in the immediate future.
Community Participation• Active community involvement and participation to reduce larval breeding sources is the key for prevention and control.• Educate the public in the basics of dengue, such as: – Where the mosquito lays her eggs – The link between larvae and adult mosquitoes – General information about dengue transmission, symptoms and treatment
Public Education• Dengue fever is NOT contagious through person-to- person contact• Early hospitalization is important.• Reduce Aedes vector populations• Reduce exposure to Aedes. – Use insect repellent. – Sleep under a mosquito net in affected areas. – Wear protective clothing.• Vaccine is NOT available.