Dengue

What is Dengue?

• Dengue is a viral disease
• It is  transmitted by the infective bite of Aedes Aegypti  mosquito
• Man develops disease after 5-6 days of being bitten by an infective mosquito
• It occurs in two forms: Dengue Fever and Dengue Haemorrhagic Fever(DHF)
• Dengue Fever is a severe, flu-like illness
• Dengue Haemorrhagic Fever (DHF) is a more severe form of disease,  which  may cause death
• Person suspected of having dengue fever or DHF must see a doctor at once

Signs & Symptoms of Dengue Fever

• Abrupt onset of high fever
• Severe frontal headache
• Pain behind the eyes which worsens with eye movement
• Muscle and joint pains
• Loss of sense of taste and appetite
• Measles-like rash over chest and upper limbs
• Nausea and vomiting

Signs & Symptoms of Dengue Haemorrhagic Fever and Shock Syndrome

• Symptoms similar to dengue fever
• Severe  continuous stomach pains
• Skin  becomes  pale, cold or clammy
• Bleeding from   nose, mouth & gums and skin rashes
• Frequent vomiting with or without blood
• Sleepiness and restlessness
• Patient feels thirsty and mouth becomes dry
• Rapid weak pulse
• Difficulty in breathing

Transmission Cycle of Dengue

Distribution of Dengue/DHF in India

• Disease is prevalent throughout India in most of the metropolitan cities and towns
• Outbreaks have also been reported from rural areas of Haryana, Maharashtra & Karnataka

Period of Communicability

Infected person with Dengue becomes infective to mosquitoes 6 to 12 hours before the onset of the disease and remains so upto 3 to 5 days.

Age & Sex Group Affected

• All age groups & both sexes are affected
• Deaths are more in children during DHF outbreak

Vector of Dengue/Dengue Haemorrhagic Fever

• Aedes aegypti is the vector of dengue / dengue haemorrhagic fever.
• It is a small, black mosquito with white stripes and is approximately 5 mm in size.
• It takes about 7 to 8 days to develop the virus in its body and transmit the disease.

Feeding Habit

• Day biter
• Mainly feeds on human beings in domestic and peridomestic situations
• Bites repeatedly

Resting Habit

• Rests in the domestic and peridomestic situations
• Rests  in the dark corners of the houses, on hanging objects like clothes, umbrella, etc. or under the furniture

Breeding Habits

• Aedes aegypti mosquito breeds in any  type of man made containers or storage containers having even a small quantity of water
• Eggs of Aedes aegypti can live without water for more then one year

Favoured breeding places

Desert coolers, Drums, Jars, Pots, Buckets, Flower vases, Plant saucers, Tanks, Cisterns, Bottles, Tins, Tyres, Roof gutters, Refrigerator drip pans,   Cement blocks, Cemetery urns, Bamboo stumps, Coconut shells, Tree holes and many more places where rainwater collects or is stored.

Control of Dengue/   Dengue Haemorrhagic Fever

• Prevention is better than cure
• No drug or vaccine is available for the treatment of Dengue/DHF
• The control of Aedes Aegypti mosquito is the only method of choice
• With early detection and proper case management and symptomatic treatment, mortality can be reduced substantially

Vector control measures

1.PERSONAL PROPHALATIC MEASURES

• Use of mosquito repellent creams, liquids, coils, mats etc.
• Wearing of full sleeve shirts and full pants with socks
• Use of bednets for sleeping infants and young children during day time to prevent mosquito bite

2.  BIOLOGICAL CONTROL

• Use of larvivorous fishes in ornamental tanks, fountains, etc.
• Use of biocides

3.  CHEMICAL CONTROL

• Use of chemical larvicides like abate in big breeding containers
• Aerosol space spray during day time

4. ENVIRONMENTAL MANAGEMENT & SOURCE REDUCTION METHODS

• Detection & elimination of mosquito breeding sources
• Management of roof tops, porticos and sunshades
• Proper covering of stored water
• Reliable water supply
• Observation of weekly dry day
• It is proved that leaf extract of Agave americana has a larvicidal efficacy. Plant extract is eco-friendly and biodegradable. Therefore it is recommended to use crushed leaf pieces (1-2 inches in size) in cotton muslin drawstring reusable bags and put in the desert coolers, plastic containers and water holding containers so that leaf extract will be released in the water, which will prevent the mosquito breeding. This process may be repeated at interval of 3-4 days.

5.  HEALTH EDUCATION

• Impart knowledge to common people regarding the disease and vector through various media sources like T.V., Radio, Cinema slides, etc.

6.  COMMUNITY PARTICIPATION

• Sensitilizing and involving the community for detection of Aedes breeding places and their elimination

MANAGEMENT OF DENGUE CASE

• Early reporting of the suspected dengue fever
• Management of dengue fever is symptomatic & supportive
• In dengue shock syndrome, the following treatment is recommended:
• Replacement of plasma losses
• Correction of electrolyte and metabolic disturbances
• Blood transfusion

Do's and Don'ts

• Remove water from coolers and other small containers at least once in a week
• Use aerosol during day time to prevent the bites of mosquitoes
• Do not wear clothes that expose arms and legs
• Children should not be allowed to play in shorts and half sleeved clothes
• Use mosquito nets or mosquito repellents while sleeping during day time

Source: National Vector Borne Diseases Control Program, Ministry of Health & Family Welfare

Related Resources

1. National Guidelines for Clinical Management of Dengue Fever
2. Mosquito proof desert cooler (NICD Cooler)