Clinical manifestation

4 dengue clinical syndromes:

  1. Undifferentiated fever;
  2. Classic dengue fever;
  3. Dengue hemorrhagic fever, or DHF; and
  4. Dengue shock syndrome, or DSS.

Dengue shock syndrome is actually a severe form of DHF.

 

1.Undifferentiated Fever

  • May be the most common manifestation of dengue
  • Prospective study found that 87% of students infected were either asymptomatic or only mildly symptomatic
  • Other prospective studies including all age-groups also demonstrate silent transmission

Source: DS Burke, et al. A prospective study of dengue infections in Bangkok. Am J Trop Med Hyg 1988; 38:172-80.

Dengue fever is an acute viral illness characterized by:

  1. Fever, often with sudden onset;
  2. Severe headache, often described as retro-ocular;
  3. Myalgias and arthralgias that can be very severe;
  4. Nausea and vomiting;
  5. A rash that may present at different stages of the illness, and whose appearance can be variable—it may be maculopapular, petechial, or erythematous. And
  6. Hemorrhagic manifestations, which will be discussed in more detail later.

Patients may also report other symptoms, such as itching and aberrations in the sense of taste, particularly a metallic taste. In addition, there have been reports of severe depression after the acute phase of the illness.

 

2.Dengue Fever

Dengue fever is an acute viral illness characterized by:

  1. Fever, often with sudden onset;
  2. Severe headache, often described as retro-ocular;
  3. Myalgias and arthralgias that can be very severe;
  4. Nausea and vomiting;
  5. A rash that may present at different stages of the illness, and whose appearance can be variable—it may be maculopapular, petechial, or erythematous. And
  6. Hemorrhagic manifestations, which will be discussed in more detail later.

Patients may also report other symptoms, such as itching and aberrations in the sense of taste, particularly a metallic taste. In addition, there have been reports of severe depression after the acute phase of the illness.

Some cases may present with or develop encephalitic or encephalopathic signs and symptoms, such as:

  • Decreased level of consciousness—including lethargy, confusion, and coma;
  • Seizures;
  • Nuchal rigidity; and
  • Paresis.

Some of these cases may subsequently develop typical dengue hemorrhagic fever.

 

3.Dengue Hemorrhagic fever

  • Skin hemorrhages:
    petechiae, purpura, ecchymoses
  • Gingival bleeding
  • Nasal bleeding
  • Gastrointestinal bleeding:
    hematemesis, melena, hematochezia
  • Hematuria
  • Increased menstrual flow

 

Clinical Case Definition for Dengue Hemorrhagic Fever

4 Necessary Criteria:

  1. Fever, or recent history of acute fever
  2. Hemorrhagic manifestations
  3. Low platelet count (100,000/mm3 or less)
  4. Objective evidence of “leaky capillaries:”
    • elevated hematocrit (20% or more over baseline)
    • low albumin
    • pleural or other effusions

4.Dengue Shock Syndrome

  • 4 criteria for DHF
  • Evidence of circulatory failure manifested indirectly by all of the following:
    • Rapid and weak pulse
    • Narrow pulse pressure (< 20 mm Hg) OR
      hypotension for age
    • Cold, clammy skin and altered mental status
  • Frank shock is direct evidence of circulatory failure

 

 

4 Grades of DHF

  • Grade 1
    • Fever and nonspecific constitutional symptoms
    • Positive tourniquet test is only hemorrhagic manifestation
  • Grade 2
    • Grade 1 manifestations + spontaneous bleeding
  • Grade 3
    • Signs of circulatory failure (rapid/weak pulse, narrow pulse pressure, hypotension, cold/clammy skin)
  • Grade 4
    • Profound shock (undetectable pulse and BP)

 

Danger Signs in Dengue Hemorrhagic Fever

Most DHF patients do not go into shock. Observations of many patients with DHF have shown that many of those who progress to shock present with certain danger signs prior to manifesting circulatory failure. These danger signs include:

  1. Abdominal pain that is intense and sustained;
  2. Persistent vomiting;
  3. Abrupt change from fever to hypothermia, with sweating and prostration; and
  4. Change in the mental status of the patient, going to be restlessness or somnolence.

All of these are signs of impending shock and should alert clinicians that the patient needs close observation and fluids.

Source: Martínez Torres E. Salud Pública Mex 37 (supl):29-44, 1995.

 

Warning Signs for Dengue Shock

This thermometer illustrates the developments in the illness that are progressive warning signs that DSS may occur.

  • The initial evaluation is made by determining how many days have passed since the onset of symptoms. Most patients who develop DSS do so 3-6 days after onset of symptoms. Therefore, if a patient is seven days into the illness, it is likely that the worst is over.
  • If the fever goes between three and six days after the symptoms began, this is a warning signal that the patient must be closely observed, as shock often occurs at or around the disappearance of fever. Other early warning signs to be alert for include a drop in platelets, an increase in hematocrit, or other signs of plasma leakage.
  • If you document hemoconcentration and thrombocytopenia and other signs of DHF and the patient meets the criteria for DHF, the prognosis and the patient’s risk category have changed. Though dengue fever does not often cause fatalities, a greater proportion of DHF cases are fatal.
  • The next concern would be observation of the danger signs—severe abdominal pain, change in mental status, vomiting and abrupt change from fever to hypothermia. These often herald the onset of DSS.
  • The goal of treatment is to prevent shock. The plasma leakage syndrome is self-limited. If you can support the patient through the plasma leakage phase and provide sufficient fluids to prevent shock, the illness will resolve itself.

 

Unusual Presentations of Severe Dengue Fever

Some unusual presentations of severe dengue fever have been documented that have high lethality without progressing through DHF. These patients may present with:

  • Encephalopathy;
  • Liver failure or fulminant hepatitis, demonstrated by increased transaminases and bilirubin, and prolonged prothrombin time (PT and PTT);
  • Cardiomyopathy—conduction defects, myocarditis; or
  • Severe gastrointestinal hemorrhage.

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