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Dengue Virus- Dengue hemorrhagic Fever

Group number: 4th Members : Amna shoukat 7211 Aneela shaukat 7215 Amina Bashir 7227 Faiqa Zafar 7259 Course Tittle: Virology Submitted to : Sir Usman Ali AshfaqSemester : 5th GCUF

DENGUE VIRUS &PREVALENCE

Virus classificationGroup:Group IV((+)ssRNA)Order:UnassignedFamily:FlaviviridaeGenus:FlavivirusSpecies:Dengue virus

Dengue Virus(DENV) A Flavivirus Flavivirus are spherical and 40- 60 nm in diameter. Genome Positive sense, single sense RNA, 11 kb in size. RNA infectious Enveloped virus . Three structural polypeptides Seven non structural Replication in cytoplasam .

History and prevalence of Dengue virusThis disease was first described in 1780. The virus was isolated by Sabin in 1944 in the tropical regions of Asia, Africa, and Central and South America.Dengue is prevalent throughout the tropics and subtropics including northern Argentina, northern Australia,Brazil,Panama, Philippines, Malaysia etc.

Prevalence of Dengue Infection

Outbreak in PakistanThe first case of Dengue Fever was detected in Pakistan in the year 1994 in Karachi.

The first outbreak of Dengue Fever was in the year 2006.

Since then dengue cases detected per year are on the rise.

Out break in Pakistan 2011Sr NoProvinceConfirmed Cases1.Punjab21702.Sindh1763.Khyber Pakhtoon Khuwa084.Azad Jammu Kashmir05

Serotypes4 serotypes of dengue virusesDENV-1DENV-2DENV-3DENV-4

A serotype is a group of viruses classified together based on their antigens on the surface of the virus. They have 60-80% homology between each other.

PATHOGENESIS, DENGUE FEVER&CLASSIFICATION

PathogenesisPresence of existing Dengue antibody, associated with fresh viral infection with new serotype complexes and forms within few days of the second dengue infection.

Non neutralizing enhancing antibodies promote infection of higher number of Mononuclear cells.

Dengue FeverDengue Hemorrhagic Fever is an acute infectious viral disease usually affecting infants and young children.Causative agent: Aedes aegypti and Aedes albopictus.Most favourable season for occurrence of this fever is mainly rainy season (sep &oct).

Flavi Virus

ALTERNATIVE NAMESHemorrhagic dengueDengue shock syndromePhilippine hemorrhagic feverThai hemorrhagic feverSingapore hemorrhagic fever

ClassificationSevere, frank type with flushing, sudden high fever, severe hemorrhage, followed by sudden drop of temperature, shock and terminating in recovery or death.Moderate with high fever, but less hemorrhage, no shock.Mild with slight fever, with or without petechial hemorrhage but epidemiologically related to typical cases usually discovered in the course of investigation of typical cases.

Vectors of Dengue FeverAedes aegypti Aedes aegypti is not found in Hong Kong at present. Aedes albopictus Aedes albopictus is very common in Hong Kong.

VectorsHabitual Behaviour of Aedes aegypti

Habitual Behaviour of Aedes aegypti

Habitual Behaviour of Aedes Albopictus Usually breed in stagnant water.

Usually active in dark or shaded places outdoors, but indoor activity is also possible.

Female mosquitoes feed on human blood.

They are most active 2 hours before sunset (around 5pm to 6pm) and at around 8am to 9am.

TRANSMISSION & LIFE CYCLES

TransmissionTransmitted to humans through bites of infective female Aedes mosquitoes.Aedes aegyptiAedes albopictusHumans are the main amplifying host.Incubation period 5-8 days.The virus circulates in the blood of infected humans for 2-7 days, at approximately the same time they have fever.

21Transmission

Infected personHealthy personInfected mosquito

Incubation Period: 3 to 14 daysMost commonly 4 to 7 days

21:()()(1999)

UNDERLYING MECHANISM:

Aedes aegyptiAedes albopictus

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Life cycle of Aedes Mosquito

Stagnant water

1-2 days

Eggs

Larvae

Pupae

2-3 days

4-5 days

LIFE CYCLE OF DENGUE FROM SPECIE TO SPECIE

SYMPTOMS,DIAGNOSTIC TESTS&TREATMENTS

Symptoms of Dengue Fever

DengueTriad

HeadachesHigh grade feverSwollen glandsVomitingMuscle joints painBasic symptoms in 90% of patientsSettles in two weeks

Diagnostic Lab TestDengue IgM test.Indirect IgG ELISA test.False positive dengue serology.Virus isolation.Non-structural protein-1 (NS1 Antigen).Polymerase chain reaction(PCR).Positive tourniquet test

29Treatment

At present, there is no drug that can treat dengue fever effectively. Patients infected with classical dengue usually recovers in 1 to 2 weeks.For serious cases, supportive treatments are provided by hospitals. If you suspect that you have dengue fever, you should seek medical treatment promptly.

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30Treatment Wiping the body with warm water and proper use of anti-fever drugs that can relieve the fever. Dont take aspirin-containing drugs because they worsen the haemorrhage.

Prevention of Dengue FeverFocus on vector controlUse spray and repellent oilDrain stagnant water sitesUse mosquito netsWear full clothes at dusk and dawnFumigation

Control of DengueControl of Mosquito breeding places.Anti mosquito measures.Use of Insecticides. Screened windows and doors can reduce exposure to vectors.

References

Ghai Essential Pediatrics, 7th Edition, CBS publication, page 196-200.Medicine Prep Manual for Undergraduates, 4th Edition, Elsevier Publication, page 751-755.Dengue haemorrhagic fever: diagnosis, treatment, prevention and control. 2nd edition. Geneva : World Health Organization. : http://www.who.int/csr/resources/publications/dengue/Denguepublication/en/index.htmlDengue- Guidelines for Diagnosis, Treatment, Prevention & Control. New Edition 2009. world Health Organization: http://whqlibdoc.who.int/publications/2009/9789241547871_eng.pdfhttp://www.who.int/csr/disease/dengue/en/Clinical Practice Guidelines- Management of Dengue Infection in Adults. Revised 2nd Edition. Ministry of Health Malaysia.: http: www.moh.gov.my