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DENGUE FEVERDr Deepak G BhosleProfessorDepartment of MedicineBharati Vidyapeeth Medical College & Bharati Hospital,Pune

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DENGUE IS ALSO KNOWN AS

Philippine hemorrhagic fever Thai hemorrhagic fever Singapore hemorrhagic fever Onyong- Nyang Fever West Nile Fever Dandy fever Break Bone Fever Dengue like Disease

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CAUSATIVE AGENT

Dengue virus is a Arbovirus from the genus Flavivirus

Single stranded RNA virus

Four species – Den 1,2,3,4

Infection with one serotype provides lifelong immunity for that species.

Transmitted by mosquito ,Aedes aegypticlosely associated with human habitation.

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ADES AEGYPTI MOSQUITO

Lays its eggs in clean, stagnant water. One distinct physical feature – black and

white stripes on its body and legs – Tiger mosquito

Bites during the day. On average, a female Aedes mosquito can

lay about 300 eggs during her life span of 14 to 21 days.

Only the female Aedes mosquito feeds on blood. This is because they need the protein found in blood to produce eggs. Male mosquitoes feed only on plant nectar

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EPEDIOMOLOGY

Rapid expansion of urbanization

Inadequate closed drainage

↑ movement of human population within and between countries

Insecticide resistance in mosquito vector populationare few of the reasons for ↑ dengue transmission in recent years

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CLINICAL FEATURES

a) Classic Dengue – Break Bone fever

Incubation period is 4 – 6 days ( range 3 -14)

Abrupt onset of fever, chills, headache, retro orbital pain and backache

Fever is 39 – 40◦ C; remission of 2days followed by second febrile phase for 1 -2 d.Biphasic curve or saddle back fever.Fever lasts for 5- 7 days

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Transient generalized erythematous rash – first 24 – 48 hrs. This morbilliform rash appears on trunk, spreads to face and limbs sparing palms and soles. It lasts for 1- 5 days.

Generalised myalgias, arthralgia and constitutional symptoms like anorexia, nausea, vomiting and dysgeusia may be +nt.

Relative bradycardia and generalised lymphadenopathy may be +nt.

Marked leucopenia and thrombocytopenia.↓ Platelets is due to impaired megakaryocyte production & ↑ platelet destruction.

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PETECHIA / PURPURA

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PETECHIA / PURPURA

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ECCHYMOSIS

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LARGE ECCHYMOSIS

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MORBILIFORM RASH

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b) Dengue Hemorrhagic fever Is defined as acute febrile illness with minor or

major bleeding, thrombocytopenia (platelet ≤ 1.0 lakh/mm) & evidence of plasma leakage ->hemoconcentration (↑ hematocrit ) & pleural or other effusions ( serositis).

Primarily in children and young adults.

Susceptibility ↓ after 12 yrs of age.

DHF, DSS develops arround 3rd to 7th day +ve Tournquet test – inflate the BP cuff

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on upper arm to midway between systolic and diastoic BP for 5 min. +ve test > 20 petechiae/ 2.5 cm square.

Also known as Hess Test.

Petechiae, bruised skin ,S/c bleeding at venepuncture site seen in most cases.

Transudate due to excessive capillary leakage leads to pleural effusion & ascites.

Progressively ↓platelet count, ↑ hematocrit indicate probability of impending shock.

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TOURNIQUET TEST

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c) Dengue shock syndrome DSS is DHF with signs of circulatory failure

Warning signs are intense, sustained abdominal pain, persistent vomiting, restlessness or lethargy & sudden change from fever to hypothermia with sweating and prostration.

Pt. may recover with i/v fluids, but shock may recur.

Once shock sets in ,mortality is high, 12 -44%

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WHO case definitions

Probable case – An acute febrile illness with 2 or more of following – Headache, retro-orbital pain, myalgia & arthralgia, nausea & vomiting, skin rash, hemorrhagic manifestations ; AND

supportive serology OR occurrence at the same location & time as other

confirmed cases of Dengue.

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Confirmed Case Confirmation of the Dengue case is based on Lab criteria. Virus isolation from serum or tissue samples.

OR Demonstration of 4 fold rise in IgG or IgM

antibody titers in paired serum samples. OR

Demonstration of Dengue antigen in tissue, CSF by immunocytochemistry or detection of genomic sequence by PCR.

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CRITERIA FOR DHF(ALL 4 CRITERIA ARE REQUIRED)

Fever or h/o fever lasting 2-7 days Hemorrhagic tendency

- a +ve tourniquet test- Petechae, ecchymosis, purpura- Bleeding per mucosa, GIT , etc.- Hematemesis, Malena

Thrombocytopenia, Platelets < 1.0 lakh/mm3 Plasma leakage

- rise in hematocrit > 20%- fall in hematocrit > 20% after i/v fluids- Pleural effusion, ascites, hypoalbuminemia.

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CRITERIA FOR DSS

DSS requires all the DHF criteria in addition a circulatory failure manifested by

- Rapid and weak pulse- Narrow pulse pressure ( < 20 mm Hg)- Hypotension, For age > 5yrs < 90 mm Hg for age < 5 yrs < 80 mm Hg- Cold dry skin, restlessness

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LAB DIAGNOSIS

1. Culture of the virus from serum obtained during febrile phase. Remains detectable in blood during febrile period.

2. Serologic diagnosis – by demonstrating a rise in antibody titer in paired sera drawn 7 to 14 days apart (This could be by any method like haemagglutination inhibition, complement fixation or, neutralizing anibodies)Rise in IgM antibody is more specific for recent infection; rising titer more specific.

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3. Newer techniques like RT-PCR ( reverse transcriptase polymerase chain reaction) are very sensitive & specific for detecting viral RNA.

4. Thrombocytopenia & hemoconcentration

5. Drop in platelets to , 1.0lakh/mm3 is seen between 3rd to 8th day of illness

6. Hemoconcentration, with ↑ in hematocrit by 20% is definitive evidence of ↑ vascular permeability & plasma leakage

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7. Leucopenia (↓ TLC) & neutropenia; towards the end of febrile phase

8. Relative lymphocytosis

9. Deranged RFT & LFT & prolonged PT is seen in severe cases of DHF

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RAPID CARD TEST –USED IN PRACTICE

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In practice in a patient with acute febrile illness with thrombocytopenia and a positive rapid card test for Dengue IgM antibody or Dengue NS1 antigen is taken as evidence of Dengue fever

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RAPID CARD TEST

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RAPID CARD TEST

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RAPID CARD TEST

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DIFFERENTIAL DIAGNOSIS

Any acute febrile illness with thrombocytopenia

1. Malaria2. Leptospirosis3. Infectious mononucleosis4. Chickungunya5. Viral hepatitis6. Sepsis7. Meningococcimeia8. Influenza9. Other hemorrhagic fever

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DENGUE AND MALARIA DIFFERENCES

Dengue(n=75) Malaria (n=75)

1. Continuous fever 80% 66%

2. Myalgia 96% 66%

3.Palatal petechiae 78% 12%

4. Conjunctival suffusion

40% 7%

5. Magenta tongue 27% 0%

6. Maculopapular rash

26% 0%

7. Facial flush 20% 0%

8. Lymph nodes 26% 1%

Hepatomegaly, Spleenomegaly, Jaundice and Hypotension were common for both.

Adhikari Prabha; Dengue fever, Medicine Update, Vol 16,2006, API

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CLINICAL MARKERS OF DENGUE

Continuous fever Characteristic myalgia ( retro orbital &

interscapular) Palatal petechiae Conjunctival suffusion Magenta colored tongue Maculopapular rash Facial flush Hypotention Hemorrhage

Dengue feverAdhikari Prabha; Dengue fever, Medicine Update, Vol 16,2006, API

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TREATMENT

Symptomatic - Paracetamol for fever & myalgia.Aspirin, NSAIDS avoided due to risk of erosive gastritis and bleeding.

Rest

Oral rehydration

In DHF careful & repeated estimation of volume status & fluid replacement is corner-stone of management. Use isotonic i/v fluids.

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TREATMENT 2

Because patients have loss of plasma they must be given isotonic solution or plasma expanders.

Platelets are replaced if the count is less than 10000 /mm3 or clinical bleeding is +nt. It is better to give Single donor apheresis Platelets (SDAP) as compared to RDP to lower the risk of alloimmunization.

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TREATMENT 3

Besides bleeding other complications are ARDS, renal failure, hepatic failure & encephalopathy.

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PREVENTION AND CONTROL It is by control of mosquitoes which live & breed in

stagnant water in and around the house. Lays eggs preferentially in jars, discarded

containers, coconut shells, old tires etc. Year round breeding Tropical regions like India are its favorite zones. How to prevent mosquito spread?

Do not allow empty vessels, coconut shells, plastic containers, flower pots, tires etc to collect rain water in them

Frequently (once in 2-3 days) empty all water storage containers

Cover your overhead tanks to prevent mosquitoes breeding in fresh water

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PREVENTION AND CONTROL 2

Vector control can be done by simple measures like using insect repellants, indoor space spray insecticides .

How to prevent mosquito bites? Screen your homes with mosquito screens

like Netlon . Wear full clothing – long sleeves Apply mosquito repellents like Odomos,

Goodnignt Keep Dengue fever patient under mosquito

net

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If you think education is expensive ,Try Ignorance.

- Dereck Bok

dgbhosle@gmail.com