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Dengue Hemorrhagic Syndrome  Symptoms, Causes and Treatment

Apr 06, 2023

DENGUE - Symptoms, Causes and Treatment - NEET PG Microbiology

As a medical professional in India, you must be an expert in the symptoms, causes, diagnosis, management and treatment of Dengue. Dengue is a viral infection that spreads from mosquitoes to people and is a common occurrence in tropical and subtropical climates. The most common symptoms are high fever, headache, body aches, nausea and rash. 

Read this blog post carefully till the end if you want to elevate your microbiology preparation for NEET PG exam

Dengue fever is a mosquito-borne disease that affects tropical and subtropical regions of the world. A high temperature and flu-like symptoms are brought on by mild dengue fever. The severe variety of dengue fever, also known as dengue hemorrhagic fever, can result in severe bleeding, a sharp drop in blood pressure (shock), and even death.

Each year, dengue infections affect millions of people globally. Southeast Asia, the islands of the western Pacific, Latin America, and Africa are where dengue fever is most prevalent. Localised occurrences of the illness have been reported in Europe and the southern United States, among other new locations.

Epidemiological Determinants


  • Flavivirus - 1, 2, 3, 4 serotypes
  • No cross-immunity among serotypes
  • Recovery from one serotype can only give immunity to that serotype in particular.

Vector – 

  • Aedes Mosquito
    • Aedes aegypti - It is comparatively less aggressive and it is Discordant feeder that is it needs more than 1 feed.
    • Aedes albopictus - It is More aggressive and it is Concordant feeder that is 1 feed is enough
DENGUE - Symptoms, Causes and Treatment - NEET PG Microbiology

Features of Aedes aegypti 

  • Hunchback appearance
  • White stripes on black body
  • Artificial collection of water
  • Flight range - 100 meters
  • Eggs - Single and cigar-shaped
  • Larvae - Siphon tube
  • Reservoir of infection: Man and mosquito
  • Transmission cycle: Man-mosquito-man
  • Incubation period: 3 to 10 days

Host factors 

All ages

  • Birth genders
  • Children have a milder disease than adults.

Environmental factors 

Humidity - 60 to 80%

  • Temperature - 16 to 30 C

Also Read: HELMINTHOLOGY : Structure, Classification, Growth, and Development : NEET PG Microbiology

Clinical Features

  • Break bone fever - Classical dengue fever
  • Retro orbital pain
  • Arthralgia
  • Myalgia
  • Bimodal presentation of fever - It Peaks on day 1-2 and Resurges on day 5-6. Recovery occurs  within 7-10 days.
  • Recovery within 7-10 days.
  • Dengue fever + hemorrhagic manifestations (bleeding from any orifice)
  • Rash: Maculopapular/ rubelliform 
  • Lab diagnosis
    • 20% increase in hematocrit
    • Thrombocytopenia (platelet count <100000)
  • Clinical diagnosis
    • Tourniquet test (>10 petechiae/ sq inch area)

Dengue Shock Syndrome

  • Pulse pressure - <90
  • Blood pressure - <80 mmHg


Within 1-5 days- NS antigen test

  • >5 days - IgM ELISA


Symptomatic treatment 

  • IV fluid resuscitation
    • Crystalloids preferred.
    • Initial - 0.9% Normal saline
    • Maintenance - Ringer lactate

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Prevention and Control 

Larval Surveillance 

  • Sampling unit: Houses or premises searches for water-holding containers.
    • House index: Number of houses positive for aedes larvae/ Number of houses searched.
    • Container index: Number of containers positive/ Number of containers checked.
    • Breteau index: Number of containers positive for larva or pupa/ Number of houses checked.
    • Aedes Aegypti Index 
      • Other name: House index
      • Percentage of houses and their premises showing actual breeding of aedes aegypti larvae.
      • Should not be >1%
      • Airports and seaports in endemic areas should be kept at least 400m around their premises free from the breeding of Aedes aegypti.

Vector Control 

Integrated vector management 

  • Anti adult measures
  • Anti larval measures
  • Personal protection


1st dengue vaccine - Dengvaxia (CYD-TDV. It is for Age group of 9-45 years. It is Not used in India on a routine basis.

And that is everything you need to know about Dengue for your Microbiology preparation. For more interesting and informative blog posts like this, download the PrepLadder App and keep following our blog. 

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