COMPARATIVE STUDY OF TWO EPIDEMICS OF DENGUE FEVER IN SAME SETTING AT AN INTERVAL OF 2 YEARS
Narayanappa Professor & H.O.D.*, Rizwan Ahmed, P.G**
Department of pediatrics, J.S.S. Medical College, Mysore. Email: ahmed_rizwan59@rediffmail.com*, Department of pediatrics, J.S.S. Medical College, Mysore. Email: ahmed_rizwan59@rediffmail.com**
Introduction
Dengue is a very important arboviral disease of human beings. It is a vector borne disease transmitted mainly by Aedes Aegypti Mosquito. Four Serotypes of Dengue Viruses have been recognized - DEN-1, DEN-2, DEN-3, DEN-4.

First infection with any of the Serotypes of Dengue virus causes a self-limiting benign illness.

Recovery from first episode is accompanied by immune responses. These responses are characterized by development of homotypic neutralizing antibodies and heterotypic non neutralizing antibodies.

Homotypic antibodies confer life long immunity against infecting strain.

During infection by other strains, Heterotype non-neutralizing antibodies act as virus specific receptors promoting entry of viruses into Mononuclear phagocytes and thus convert mild infection into severe one. This mechanism where antibodies help in augmenting the infection is known as Antibody dependant enhancement.
Aims and Objectives
Aim was to study the clinical profile and outcome of epidemics of Dengue in and around Mysore and comparison of the outcome of 2 epidemics, 2 years apart in same setting.
Subjects & Methods
This was a prospective study done on cases of Dengue fever and Dengue Hemorrhagic Fever admitted in Dept. of Pediatrics, JSS Hospital Mysore from June 1, 2003 to September 03, 2003 and from June 1, 2005 to Nov. 15, 2005.

Children admitted with symptoms of Fever, Myalgia, Headache. Retro orbital pain, Bleeding, Altered sensorium, Shock or low platelet count were provisionally diagnosed as Dengue and investigated for IgM / IgG by Elisa or Dot method.

Those children testing +ve Either for IgM/ IgG were diagnosed as Dengue. They were included in the study and followed up for clinical profile from admission till discharge.

  • Children were grouped according to WHO Definition
  • A total no. of 70 cases were diagnosed as Dengue by Serology in both episodes
  • Lab investigations carried out included Hb , WBC Count, Differential WBC count, Platelet count, hematocrit


Platelet Transfusion was given to children having:

  1. Platelet count < 50,000 with bleeding
  2. Platelet Countl < 20,000 with / without bleeding

All children received iv fluids depending upon weight and Hydration status of the child. Virus isolation and Serotyping could not be done because of lack of lab facility.
Results
70 Seropositive cases were Diagnosed in both epidemics.

  • Outcomes of both epidemics were compared with respect to clinical features, complications, and mortality.
AGE DISTRIBUTION

Age

  2003 epidemic (% age)

  2005 epidemic (% age)

  <1 year

  4

  1

  1 to 3 years

  31

  16

  4 to 6 years

  27

  29

  7 to 9 years

  23

  27

  10 to 14 years

  15

  27



Clinical features:
Percentage of children affected

(a) Symptoms

  2005 epidemic (%)

  2003 epidemic (%)

  Fever

97

100

  Vomiting

30

42.3

  Pain abdomen

20

42.3

  Cough

14

27

  Bleeding Manifestation

10

23

  Headache

8.5

5.8

  Altered sensorium

4.2

5.7

  Body pain

4.2

9.6

  Convulsions

2.8

3.8

  (b) Signs

-
-

  Hepatomegaly

90

57.7

  Splenomegaly

70

21.2

  Lymphaedenopathy

50

5.6

  Ascitis

31.42

28.5

  Facial puffiness and Pedal edema

20

5.7

  Shock

17

10

  Conjuctival suffusion

14.2

15

  Rashes

14.2

36.5

  Bleeding Manifestation

8.5

11.5

  Hess test positive

1.3

4



  • Fever was the Commonest sympton followed by vomiting.
  • Hepatomegaly was the commonest sign followed by Splenomegaly and lymphaedenopathy.
  • Bleeding manifestations were seen in 10 % cases in the present epidemic whereas it was seen in 23% cases in previous epidemic.
  • Petechiae was the commonest bleeding manifestation seen in 3 cases in 2005 epidemic. Whereas hematemesis was the commonest bleeding manifestation in 2003 epidemic.
Thrombocytopenia (Platelet count < 1 lakh)

Present epidemic (2005): 43%

  Previous epidemic (2003):


Types of Dengue

2005 epidemic

2003 epidemic

Total no. of cases

70

70

             DF

74.2 %(52)

65.7 %(45)

             DHF

5.7 %(4)

20 %(14)

             DSS

17 %(12)

10 %(8)

             DFB

2.83 %(2)

4.3 %(3)



BFB stands for dengue fever with unusual bleed which mean patients of dengue having bleeding in absence of thrombocytopenia.

DF - Dengue fever, DHF - Dengue hemorrhagic fever,
DSS - Dengue shock syndrome

COMPLICATIONS

2005 epidemic (no. of cases)

2003 epidemic
(no. of cases)

          Meningoencephalitis

6

nil

          Adult Respiratory
        Distress Syndrome

7

nil

          Myocarditis

2

nil

          Pericarditis

1

nil

          Acute Renal failure

2

nil

          Hepatitis

1

nil

          Mortality

4 (5.7%)

nil



MORTALITY (2005 Epidemic)

  Cause of Death

Total no.

          Adult Respiratory Distress Syndrome

3

          DSS with Myocarditis

1

          Total

4 (5.7 %)

          Complications and mortality were nil in previous study

-
Discussion
In the present epidemic (2005) of dengue, complications like shock, ARDS, meningoencephalitis, ARF were seen. Mortality was also significant. Mortality and complications were nil in previous epidemics. Severe form of dengue in recent epidemic must be because of secondary dengue infection and antibody dependant enhancement. Because of lack of lab facility, virus isolation and serotyping could not be done.

ARDS was the commonest cause of death, hence child has to be watched carefully for respiratory distress.
Conclusions
  1. Be prepared to face a severe form of secondary dengue infection following a simple dengue epidemic.
  2. Advise Anti-mosquito measures to an individual who recovers simple dengue infection to prevent secondary dengue fever which threatens life.
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