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Dengue and Dengue Hemorrhagic Fever - Diagnosis

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Diagnosis of Dengue and Dengue Hemorrhagic Fever

Confirmed diagnosis of dengue infection requires lab tests:


1. Platelet count: Any fever not settling down after three or four days should invite further tests like a blood count, a routine urine and chest x-ray.

In countries like India one should also keep in mind malaria and do test to rule out the infection. Dengue fever is usually charcterised by lowering of platelets in the blood. It is due to the lack of platelets that the person is more prone to bleeding episodes. The platelets plug the bleeding points and their lack can lead to bleeding. Thrombocytopenia or platelets less than 100 000 cells per mm3maybe seen in dengue. The platelet count may need to be repeated everyday if they show a lowering trend. If these keep going down it is best to hospitalise the patient for further treatment. In severe cases platelet transfusion maybe required.

2. Hematocrit Test: Hemorrhagic dengue fever leads to leakage from blood vessels and this can lead to increased vascular permeability. This is manifested by one or more of the following - Increase by more than 20% in average hematocrit for age and sex.


3. Detecting specific antibodies: Serologic diagnosis requires collection of serum within 6 days after onset of symptoms. The serum is tested for detecting specific anti-dengue antibodies by Enzyme-linked Immunosorbent assay (ELISA). Increase of a fourfold concentration of IgG or IgM antibody titers to one or more of the dengue virus antigens in serum sample is diagnostic of dengue fever.

4. Isolation of the virus: Isolation of virus requires collection of serum sample from patients within 5 days after appearance of symptoms. To do the isolation of virus a 'Polymerase Chain Reaction (PCR)' is done. This detects the viral genomic sequence from Serum samples.

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please inform if age is 54 women, High blood pressure and chronic disease, She has Fever and body pain.She is in ICU for three days.is it advised to get her discharged.Platelet count 1 lac. How severe dengue can be in her condition?
As my Mother in ICU>Please Reply


Dear Yousaf,with Hypertension,another chronic disease,and age above 50,the afebrile period is significant,the patient should be advised about the warning signs for plasma leakaga,i.e, the reduced BP,or reduced pulse pressure[the difference between the upper-systolic and lower-diastolic one,e.g. if it comes down to 100/90.the increased capillary refilling time, the tender liver,and or hemmhorages,reduced urinary output,blood in vomiting,altered mentation,increasing respiratory disconfort. All these may indicate her transition towards shock,which is actually far more important than platelts,particularly in absence of internal or external bleeding . Observe your patient for all this,and then decide about discharge. Regards . P-dopp Peoples Doctors @ facebook.


The platelet count is not the only important determinant of bleeding.

Indications for blood/platelet transfusion as recommended in clinical practice guidelines are:

In cases with significant clinical bleeding, which require blood transfusion. Usually bleeding is > 10% of total blood volume (> 6-8 ml/kg of ideal body weight)
In adults with underlying hypertension or coronary heart diseases and platelet 1.3-1.5, which is the result of liver failure: Major contributing factor for massive bleeding.
There is no evidence to support the use of blood components such as platelet concentrates, fresh frozen plasma or cryoprecipitate. Its use could contribute to fluid overload.

Important instructions for treatment of DHF as per WHO/SEARO guidelines:

If the patient’s condition becomes worse despite giving 20ml/kg/hr crystalloid solution for one hour, replace crystalloid solution with colloid solution such as Dextran or Plasma. As soon as improvement occurs, replace with crystalloid.

In case of severe bleeding; give blood transfusion @ 20ml/kg for two hours. Then give crystalloid IV fluids @ 10 ml/kg/hr for a short time (30 - 60 minutes) and later reduce the speed.

If hematocrit falls, give blood transfusion 10 ml/kg and then give crystalloid IV fluids at the rate of 10 ml/kg/hr. The volume of blood administered should be just enough to raise the red blood cell concentration to normal.

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