PHASES AND SYMPTOMS OF DENGUE FEVER
Febrile phase
Patients typically develop high-grade fever suddenly. This acute febrile phase usually lasts 2–7 days and is often accompanied by
- Facial flushing
- Skin erythema (redness of the skin due to congestion of the tiny blood vessel)
- Generalized body ache
- Myalgia (Muscular pain)
- Arthralgia (pain in joints)
- Headache
Some patients may have -
- Sore throat,
- Infected pharynx
- Conjunctival injection.
- Anorexia (decreased appetite)
- Nausea and vomiting
It can be difficult to distinguish dengue clinically from non-dengue febrile diseases in the early febrile phase.
Critical phase
DHF that deteriorate into shock is called Dengue Shock Syndrome (DSS). About one third of the patients with DHF will develop shock. It usually occurs around the time when the fever subsides. The patient can rapidly go into shock.
Acute abdominal pain is a frequent complaint shortly before the onset of shock. Shock occurs when a critical volume of plasma is lost through leakage. It is often preceded by warning signs. The body temperature may be subnormal when shock occurs. With prolonged shock, the consequent organ hypo perfusion results in progressive organ impairment, metabolic acidosis and disseminated intravascular coagulation. This in turn leads to severe hemorrhage causing the haematocrit to decrease in severe shock.Around the time of remission of fever, when the temperature drops to 37.5–38˚C or less and remains below this level, usually on days 3–7 of illness, an increase in capillary (tiny blood vessels) permeability in parallel with increasing haematocrit (the percentage volume of red blood cells in the blood) levels may occur. This marks the beginning of the critical phase. The period of clinically significant plasma leakage usually lasts 24–48 hours. Progressive leucopenia (decreased number of total white blood cells in the blood) followed by a rapid decrease in platelet count usually precedes plasma leakage. At this point patients without an increase in capillary permeability will improve, while those with increased capillary permeability may become worse as a result of lost plasma volume. The degree of plasma leakage varies. This condition is called Dengue Hemorrhagic Fever (DHF).
The signs are: cool blotchy skin which is also clammy; circumoral cyanosis may be present; the pulse rate increases and is weak; blood pressure is low and falls; the patient is lethargic initially and becomes restless as the condition deteriorates. If shock is not recognized and treated in time, the patient passes into a state of profound shock when pulse becomes imperceptible and blood pressure unrecordable. The patient usually remains conscious even at a very late stage of shock. Both the onset and progression of shock is rapid. If uncorrected, the patient typically dies within 12 to 24 hours. Late correction can result in a stormy and complicated course with the development of metabolic acidosis, gastrointestinal bleeding, intracranial hemorrhage and convulsions from metabolic causes. Timely correction with volume replacement results in rapid recovery.
Recovery phase
If the patient survives the 24–48 hour critical phase, a gradual re-absorption of extra vascular compartment fluid takes place in the following 48–72 hours. General well-being improves, appetite returns, gastrointestinal symptoms abate, hemodynamic status stabilizes and diuresis ensues. Some patients may have a rash of “isles of white in the sea of red”. Some may experience generalized pruritus. Bradycardia and electrocardiographic changes are common during this stage.
White blood cell count usually starts to rise soon after remission of fever but the recovery of platelet count is typically later than that of white blood cell count.
Alarming signs and symptoms: Alarming signs and symptoms are situations where extra caution is needed. In a dengue outbreak, the following can be alarming signs and symptoms:
- Abdominal Pain : Nonspecific complaints of epigastric and generalized abdominal discomfort are not uncommon. However acute abdominal pain is a frequent complaint shortly before the onset of shock. When it occurs just around the time of the fever subsiding, suspicion must be raised.
- Bleeding : Bleeding phenomenon to watch out for and to monitor are epistaxis, bleeding gums, gastrointestinal bleeding and menorrhagia. Presence of easy bruising, petechiae and a positive tourniquet test indicate the presence of hemorrhagic phenomenon. The patient may have developed DHF.
- In DHF, the critical phase of illness often occurs at the end of the febrile period. After days of fever, a rapid fall in temperature may be accompanied by signs of circulatory failure of variable levels of distress.
Pathophysiology of Dengue Hemorrhagic Fever
