Dengue introduction

DENGUEPresented By:Madiha Shafiq

Bs(Hons.), Final Semester

DENGUEPresented By:Madiha Shafiq

Bs (Hons.), Final Semester

Endemic in more than 100 tropical and subtropical countries.

Several epidemics since 1980s.

Pandemic began in South East Asia after WW II with subsequent global spread.

Distribution

The word dengue is derived from African word Denga: meaning fever with hemorrhage .

Is caused by virus transmitted by bites of female Aedes mosquito.

Dengue is a viral disease. It is caused by infective bite of female Aedes aegypti. Man develops disease after 5-6 days of being bitten by

infective mosquito. Dengue fever is a severe flu like illness. Dengue Hemorrhagic fever (DHF) is more severe form

of disease which can cause death.

What is Dengue?

1.Causes dengue and dengue hemorrhagic fever

2. It is an arbovirus 3.Transmitted by

mosquitoes 4.Composed of

single-stranded RNA

5.Has 4 serotypes (DEN-1, 2, 3, 4)

Dengue Virus

The most common epidemic vector of dengue in the world is the Aedes aegypti mosquito. It can be identified by the white bands or scale patterns on its legs and thorax.

• Dengue transmitted by infected female mosquito • Primarily a daytime feeder • Lives around human habitation

Aedes aegypti

Clean and stagnant water collections Breed mostly around human dwellings and

surroundings Lays eggs and produces larvae preferentially in

artificial containers

Egg laying places of Aedes are

Aedes mosquitoes (Tiger mosquito): distinguished by white stripes on black body.

Important members Aedes family:A. aegypti, A.vittatus and A. albopictus.

They are most abundant during rainy season. Lays egg singly, and eggs are cigar shaped. Female mosquito acts as vector. They do not fly over long distance- this factor

facilitates its eradication. It is a day biter

• Headache • Muscle and joint pain • Nausea/vomiting • Rash • Hemorrhagic manifestations • Fever

Symptoms of Dengue Fever

High continuous fever lasting for 2-7 days. Severe and continuous pain in abdomen Bleeding from the nose, mouth and gums or skin

bruising Frequent vomiting with or without blood Excessive thirst (dry mouth) Pale, cold skin Restlessness, or sleepiness

Symptoms of Dengue Haemorrhagic Fever (DHF)

1.The virus is inoculated into humans with the mosquito saliva.

2.The virus localizes and replicates in various target organs, for example, local lymph nodes and the liver.

3.The virus is then released from these tissues and spreads through the blood to infect white blood cells and other lymphatic tissues.

4.The virus is then released from these tissues and circulates in the blood.

Life Cycle

5.The mosquito ingests blood containing the virus.

6.The virus replicates in the mosquito midgut, the ovaries, nerve tissue and fat body. It then escapes into the body cavity, and later infects the salivary glands.

7.The virus replicates in the salivary glands and when the mosquito bites another human, the cycle continues.

Transmission

In most tropical areas Ae. aegypti is highly urbanized. They breed in fresh water like water stored for drinking

or bathing and in rain water collected in any container like tires etc.

Dengue viruses have also been recovered from Aedes- Albopictus.

Continued….

Outbreaks in the Pacific area have been attributed to several other Aedes species.

These species breed in water trapped in vegetation

Continued…

Mosquito control or eradication programs require the simultaneous use of two approaches:

Reduction in breeding sites Application of larvicides Alternatively, a significant reduction in

population may be effected by closely spaced application of adulticides

Control

Source reduction campaigns should be well organized, supervised, and evaluated.

Includes proper disposal of discarded cans, bottles, tires, and other potential breeding sites not used for storage of drinking or bathing water.

Drinking and bathing water storage containers and flower vases should be emptied completely once weekly

Continued…

Control

Most dengue cases are mild with flu like illness which can be treated and cured so no need to be panic.

Dengue id detected with Igm ELISA based test.

Labortary Diagnosis

There is no specific medicine to treat dengue infection. To reduce pain use of pain relievers with acetaminophen and

avoid medicines with aspirin, which could worsen bleeding. Rest, drink plenty of fluids. In case of Dengue Hemorrhagic fever hospitalization is a

must. The mortality rate in the absence of hospitalization can be as high as 50%. With proper treatment the mortality comes down to 3%.

Vaccines are being developed against all 4 serotypes and they will definitely be the most effective way to prevent the disease.

Treatment

THANK YOU

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