Dengue

  1. Dengue is caused by four distinct subgroups of viruses 1 ,2, 3 and 4
    Dengue infection of humans occurs from bites of +mosquitoes
    The mosquito Feeds during day and has propensity for manmade habitats containing water.

Dengue viral infection can present as thee broad clinical patterns
1 Classical dengue.
2 Hemorrhagic dengue.
3 Undifferentiated dengue.

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Classical dengue (break down fever )

1. Prodromal symptoms like mild conjunctivitis and coryza follow an incubation period of 5 to 8 days
2. There is onset of fever wits splitting headache ,retro orbital pain ,backache and leg joint pain, headache aggravated by head movements and eye0by eye movements 3 additional symptoms are insomnia ,anorexia with loss of taste and weakness.
4. Examination revels conjunctival Tenderness on pressure on eye ball and patchy skin rashes.
5. 2 to 3 days after temp. may decreases and other symptoms disappear
remission typically lasts for 2 days followed by return of fever and other symptoms this is known as ‘saddle back’ fever
treatment of dengue fever entirely symptomatic with analgesics and proper hydration

Dengue hemorrhagic fever and dengue shock syndrome.
All four virus serotype can cause most imp. criteria for diagnose increased hemorrhagic fever is to demonstrate increased capillary permeability.

Pathogenesis Of Dengue

Occurs in persons who infected with one serotype of virus previously and therefore have antibodies against that particular serotype.
Antibody -virus complex taken up by macrophages
Production of vascular permeability factor by macrophage’s.
These factors induce plasma leakage resulting in DHF and shock.

Clinical features Of Dengue

General features includes fever headache(retro orbital )flushing myalgia, arthralgia and vomiting often DHF and DSS when fever comes down.
Bleeding manifestations.
Features of plasma leakage
Some pt. encephalopathy and encephalitis
Pt. with DDS develop cold clammy skin hypotension and shock abdomen Pain and tachycardia.

Tourniquet test
Apply BP cuff and mark a circle with area 2..5 cm square
Inflate cuff to a point mid way between systolic and diastolic pressure for 5 min.
Test considered positive when 20 or more petechiae appear in the circle.

WHO criteria for diagnosis of Dengue hemorrhagic fever & characteristic features

Positive tourniquet test.
Petechiae ecchymosis or purpura.
Bleeding from mucosa, inj. site or other site.
Hematemesis or melaena.
Thrombocytopenia.
Evidence of plasma leakage due to increased capillary permeability.

WHO clinical classification
Grade 1 – Fever , constitutional feature, +ive tourniquet test.
Grade 2 – Grade 1 + spontaneous bleeding.
Grade 3 – Grade 2+ circulatory failure, agitation.
Grade 4 – Grade 2 + profound shock.

Diagnosis Of Dengue

It is based on thrombocytopenia leukocytopenia , raised liver enzymes.
Hemoconcentration.
Abnormal coagulation profile.
Chest x ray may show evidence plural effusion.
Ultrasound for ascites gall stone wall thickness.

Treatment Of Dengue

It is entirely symptomatic with fluid replacement . Blood transfusion
Grade 1 -generally managed at home with oral oral rehydration.
Grade 2 require hospitalization. Following blood transfusion Ringer’s lactate At rate of 7 ml /kg over 1 hr. 5ml /hr. in next hr. then 3ml /hr. for 24-48hr.
Grade 3 and 4 – 10-20ml /kg RL over 1 hr. if mm improvement colloids or plasma 10ml /kg infused.

Prevention From Dengue

These are directed towards elimination of adult mosquitoes and their larvae.
During epidemics aerial /fogging.
Mosquitoes repellents.
Larval control use of Larvicidal.
Larvivores fish -Gambusia in water tanks and other water sources.