DIAGNOSIS OF DENGUE FEVER AND DENGUE HEMORRHAGIC FEVER

DENGUE FEVER: Probable Diagnosis

Acute Febrile illness with two or More of the following:-

·         Headache

·         Retro orbital pain

·         Mylagia

·         Arthralgia / bone pain

·         Rash

·         Hemorrhagic manifestations

·         Leucopoenia (WBC<=5000 cells/mm3)

·         Thrombocytopenia (platelet count<150,000 cells/mm3)

·         Rising hematocrit (5-10%)

and at least one of following:

·         Supportive serology on single serum sample: titer > 1280 with hem agglutination inhibition test comparable lgG titre with enzymes-linked immunosorbent assay, (ELISA) or testing positive in lgM antibody test

·         Occurrence at the same location and time as confirmed cases of dengue fever

DENGUE FEVER: Confirmed diagnosis

Probable case and at least one of the following:

·         Isolation of dengue virus from serum, CSF or autopsy samples

·         Four-fold or greater increase in serum lgG (by hem agglutination inhibition test) or increase in lgM antibody specific to dengue virus.

·         Detection of dengue virus genomic sequences by reverse transcription-polymerase chain reaction (RT-PCR)

DENGUE HEMORRHAGIC FEVER

All of the following:-

·         Acute onset of fever of two to seven days duration

·         Hemorrhagic manifestations, shown by any of these: positive tourniquet test, petechiae, ecchymoses or purpura, or bleeding from mucosa, gastrointestinal tract, injection sites or other locations

·         Platelet count < 100,000 cells / mm3

·         Objective evidence of plasma leakage due to increased vascular permeability shown by any of the following:

Rising hematocrit / hemoconcentration > 20% from beseline or decrease in convalescence or evidence of plasma leakage such as pleural effusion, ascites or hypoproteinemia / albuminemia

DENGUE SHOCK SYNDROME

Criteria for dengue hemorrhagic fever as above with signs of shock:

·         Tachycardia, cool extremities delayed capillary refill, weak pulse, lethargy or restlessness which may be a sign of reduced brain perfusion.

·         Pulse pressure < 20 mmHg with increased diastolic pressure, e.g. 100/80 mmHg

·         Hypotension by age, defined as systolic pressure <80 mmHg for those aged < 5 years or 80 to 90 mmHg for older children and adults

INTERPRETATION OF DENGUE DIAGNOSTIC TEST

 HIGHLY SUGGESTIVE                                                                      

One of the following                                                                      

1              lgM+ve in a single serum sample                 

2              lgG+ve in a single serum sample with a        

                High titer of 1280 or greater                          

 CONFIRMED

   One of the following

  1    RT-PCR+ve

 2     Virus culture+ve  
                                                  
  3     lgG seroconversion in paired sera or   four fold lgG titer increase in paired sera

PRIMARY TRIAGE

1.       History of the duration (number of days) of fever and warning signs of high-risk patients

2.       Tourniquet test

3.       Vital signs, including temperature, BP, PR, RR and peripheral perfusion

4.       Do a CBC for:

a.       All febrile patients at the first visit to get the baseline HCT, WBC and PLT

b.      All patients with warning signs (see below)

c.       All patients with fever > 3 days

d.      All patient with circulatory disturbance / shock

Results of CBC:  WBC+/- PLT with warning signs—Immediate medical consultation

5.       Immediate medical consultation for:

a.       Shock

b.      Patients with warning signs especially those whose illness lasts for 4 days

6.       Decision for observation and treatment:

a.       Shock: Resuscitation and admission

b.      Hypoglycaemic patients without  WBC +/- PLT

c.       Those with warning signs

d.      High risk patients with  WBC +/- PLT

WHEN SHOULD A MEDICAL OFFICER REFER THE PATIENT TO A HOSPITAL

The decision for referral and admission must not be based on a single clinical parameter but should depend on the total assessment of the patient

SYMPTOMS:

·         Warning signs (see below)

·         Bleeding manifestations

·         Inability to tolerate oral fluids

·         Reduced urine output

·         Seizure

SIGNS:

·         Dehydration

·         Shock

·         Bleeding

·         Any organ failure

SPECIAL SITUATIONS

·         Patients with co-morbidity DM, HTN, IHD, CLD, COPD, Renal Failure, coagulopathies, Morbid Obesity, etc

·         Elderly (more than 65 years old)

·         Pregnancy

·         Social factors that limit follow-up e.g. living far from health facility, no transport, patient living alone etc

LABORATORY CRITERIA

·         Rising HCT accompanied by reducing platelet count

WARNING SIGNS

·         No clinical improvement or worsening just before or during transition to afebrile phase or as the disease progresses

·         Lethargy, restlessness, sudden behaviour changes

·         Bleeding: Epistaxis, melena, hematemesis, excessive menstrual bleeding, dark – colored urine, hematuria

·         Persistent vomiting, not drinking fluids

·         Severe abdominal pain

·         Giddiness / dizziness

·         Less/no urine output for 4-6 hours

·         Pale, cold and clammy hands and feet