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Dengue/Dengue Haemorrhagic Fever/Dengue Shock Syndrome
by Dr. D K Taneja, Professor, Deptt. Of Community Medicine, Maulana Azad Medical College, New Delhi

What is Dengue

• Dengue is a viral disease
• It is transmitted by the infective bite of Aedes Aegypti mosquito
• Man develops disease after 3-14 days (usually 4-7 days) of being bitten by an infective mosquit
• It occurs in two forms: Dengue Fever and Dengue Haemorrhagic Fever(DHF)/Dengue Shock Syndrome(DSS).
• Dengue Fever is a severe, flu-like illness
• Dengue Haemorrhagic Fever (DHF)/DSS is a more severe form of disease, which may cause death
• Person suspected of having dengue fever or DHF must see a doctor at once

Signs & Symptoms Of Dengue Fever

• Abrupt onset of high fever
• Severe frontal headache
• Pain behind the eyes(retero-orbital pain) which worsens with eye movement
• Muscle and joint pains
• Loss of sense of taste and appetite
• Measles-like rash over chest and upper limbs
• Nausea and vomiting
• Minor hemorrhagic manifestations like petechae, bleeding from nose or gums may occur
• Lymphadenopathy with leukopenia and relative lymphocytosis are common.
  Thrombocytopenia(platelet count £ 100x103) and raised transaminases occur less frequently.

Signs & Symptoms Of Dengue Haemorrhagic Fever And Dengue Shock Syndrome

• Symptoms similar to dengue fever. Or history of recent fever. Illness is often biphasic beginning with fever with symptoms as in dengue. During recovery phase of fever patient’s condition worsens markedly with severe weakness, marked restlessness, facial pallor and often diaphoresis and circumoral cyanosis, severe continuous pain abdomen. Liver may be enlarged. Thrombocytopenia ( platelet count £ 100x103 ) also occurs during this phase.
• Haemmorhagic phenomenon are frequent and include positive tourniquet test, petechae, easy bruising, bleeding from venepuncture sites, epistaxis, bleeding from mouth & gums and skin rashes.
• Frequent vomiting with or without blood. Bleeding from GI tract is an ominous sign that usually follows a prolonged period of shock. There may be signs of plasma leakage indicated by small pleural effusion or ascites. Hepatomegaly is common but is not accompanied by jaundice.
• Patient may go into shock manifested by :Pale, cold or clammy skin,sleepiness and restlessness,patient feels thirsty and mouth becomes dry,rapid weak pulse and difficulty in breathing.

Clinical And Laboratory Diagnosis & Case Definitions

Dengue Fever :

• Suspect case : Acute onset and high fever of 2-7 days duration, and two or more of the following:
  Headache,retero-orbital pain, myalgia, arthralgia, rash, hemorrhagic manifestations, and leucopenia.
• Probable case : Suspect case and one or more of the following:
  Occurance of confirmed cases of dengue in the same place and time. Detection of IgM antibody. IgM antibody indicates current or recent infection and is detectable 6-7 days after onset of illness. If available Mc- Elisa test is more specific.
• Confirmed case : Suspect or probable case and one or more of the following:
  Isolation of virus or detection of viral genomic sequences. fourfold rise in titres of IgG or IgM antibody. For this at least 2 samples are to be taken- one at the time at the time of reporting to a clinic or a hospital and second shortly before discharge . The optimum interval between two samples should be 10 days. Although serological tests are simpler, they can give false positive results due to cross reaction between antibodies against dengue and other flaviviruses. Confirmatory tests are not necessary for management of cases and should be done to confirm the aetiology of the outbreak.

Dengue Haemmorhagic Fever

• Probable or confirmed case of dengue, and
• Haemorrhagic tendencies as described under DHF.
• Thrombocytopenia(platelet count £ 100x103 ).Evidence of plasma leakage due to increased vascular permeability, manifested one or more of the following: a rise in average haematocrit for age and sex ³20%, a ³20% drop in haematocrit following volume replacement compared to baseline, signs of plasma leakage indicated by pleural effusion or ascites ( demonstrated by ultrasonography or x-ray), hypoproteinemia. Slight elevation of liver enzymes, hypoproteinemia and low levels of C 3 comlement proteins are commonly observed. Prothrombin, partial thromboplastin, thrombin times may be prolonged in many cases. While a normal WBC count or leukopenia with neutrophils predominating is common initially, a relative lymphocytosis with more than 15% atypical lymphocytes is common when fever subsides.

Dengue Shock Syndrome

• All the criteria for DHF, and
• Evidence of circulatory failure as detailed under DSS

Grading And Severity Of Dengue/ Dhf

Note : DHF grade III & IV are also called DSS

Management Of Dengue Fever

• Early reporting of the suspected dengue fever
• Management of dengue fever is symptomatic & supportive.give paracetamol but NO aspirin or brufen. Keep temp. below 390 C. In cases with severe painanalgesics or mild sedatives are to be given. Bed rest is essntial. Oral fluids and electrolyte therapy are required for patients with excessive sweating or vomiting.Follow up for any change in platelet/haematocrit. During afebrile phase(2-3 days after febrile period) check platelet/haematocrit. In convalescent phase no special instructions. Normal diet. Patients almost always recover but often have prolonged asthenia and depression.

Management Of Dhf Grade I & Ii

• Duration is 2-3 days after the febrile phase. Treat on OPD/ inpatient basis. Give ORS. Check platelet/haematocrit.If Hct ³20% start IV therapy. Monitor vitals, urine output, haematocrit .

Management Of Dhf Grade Iii & Iv

• Duration is 2-3 days after the febrile phase. Check platelet/haematocrit. Start IV therapy. Monitor vitals, urine output, haematocrit If Hct is increasing change IV fluid to colloidal solution preferably dextran or plasma. If Hct is decreasing from initial value, give fresh whole blood transfusion. In case of profound give IV fluid bolus one or two times. Give oxygen therapy.

Epidemiology

Distribution Of Dengue/Dhf In India

• Disease is prevalent throughout India in most of the metropolitan cities and towns
• Outbreaks have also been reported from rural areas of Haryana, Maharashtra & Karnataka

Magnitude Of The Problem

• During 1996 a severe outbreak of Dengue/DHF occurred in Delhi wherein about 10252 cases and 423 deaths were reported
• Till date, more then 80 outbreaks have been reported from 16 States/UTs

Causative Agent

It is caused by flaviviruse which has four serotypes; DEN1, DEN2, DEN3, and DEN4. Infection with one serotype provides life long immunity against that serotype but not against other serotypes. Thus people may aquire multiple dengue infections. When there are circulating antibodies against one serotype due to earlier infection and later there is infection with another serotype, it may result in dengue haemorrhagic fever / dengue shock syndrome.

Period Of Communicability

Infected person with Dengue becomes infective to mosquitoes 6 to 12 hours before the onset of the disease and remains so upto 3 to 5 days.

Age & Sex Group Affected

• All age groups & both sexes are affected
• Deaths are more in children during DHF outbreak

Vector Of Dengue/Dengue Haemorrhagic Fever

• Aedes aegypti is the principal vector of dengue / dengue haemorrhagic fever. Aedes albopictus also transmits the disease...
• It is a small, black mosquito with white stripes and is approximately 5 mm in size.
• It takes about 7 to 8 days to develop the virus in its body(extrinsic incubation period) and transmit the disease.

Feeding Habit

• Day biter with increased biting activity 2 hours after sunrise and several hours before sunset.
• Mainly feeds on human beings in domestic and peridomestic situations
• Bites repeatedly

Resting Habit

• Rests in the domestic and peridomestic situations
• Rests in the dark corners of the houses, on hanging objects like clothes, umbrella, etc. or under the furniture

Breeding Habits

• Aedes aegypti mosquito breeds in any type of man made containers or storage containers having even a small quantity of water
• Eggs of Aedes aegypti can live without water for more then one year

Favoured Breeding Places

Desert coolers, Drums, Jars, Pots, Buckets, Flower vases, Plant saucers, Tanks, Cisterns, Bottles, Tins, Tyres, Roof gutters, Refrigerator drip pans, Cement blocks, Cemetery urns, Bamboo stumps, Coconut shells, Tree holes and many more places where rainwater collects or is stored.

Control Of Dengue / Dengue Haemorrhagic Fever

• Report suspected/probable cases to the health authority, eg. Zonal Health Office of MCD
• No drug or vaccine is available for the treatment of Dengue/DHF. A tetravalent vaccine is under develoment and is undergoing phase I & II trials.
• The control of Aedes Aegypti mosquito is the only method of choice
• With early detection and proper case management and symptomatic treatment, mortality can be reduced substantially

Vector Control Measures

Personal Prophylatic Measures

• Use of mosquito repellent creams, liquids, coils, mats etc.
• Wearing of full sleeve shirts and full pants with socks
• Use of bednets for sleeping infants and young children during day time to prevent mosquito bite

Vector Control

• As Aedes aegypti breeds in containers and receptacles detection & elimination of mosquito breeding sources is the most important activity.
• Management of roof tops, porticos and sunshades
• Proper covering of stored water
• Reliable water supply
• Observation of weekly dry day

Health Education And Community Participation

• Impart knowledge to common people regarding the disease and vector through various media sources like T.v., Radio, Cinema slides, etc. Sensitilizing and involving the community for detection of Aedes breeding places and their elimination.

Do’s And Don’ts

• Remove water from coolers and other small containers at least once in a week
• Use aerosol during day time to prevent the bites of mosquitoes
• Do not wear clothes that expose arms and legs
• Children should not be allowed to play in shorts and half sleeved clothes
• Use mosquito nets or mosquito repellents while sleeping during day time

Early Warning Signals For Df/Dhf Outbreak

• Sudden increase in reporting of suspected cases with clutering in time and place and fitting into endemicity/ seasonality of disease.
• Enhanced vector density as indicated through household larvae index/ container index / Breteau index with reference to vector mosquito.
• Detection of viral activity either in vector or man.