Facilitator - WHO Western Pacific Region - World Health Organization

SLIDE
• 5:
•
Facilitator explains:
•
•Fever begins abruptly after incubation period and remains high without antipyretics.
•
•The fever lasts 3 to 5 days and coincides with viraemia.
•As antibodies clear the virus, viraemia level decreases and temperature begins to come down.
•
This is known as defervescence, i.e. temperature remains below 38°C without antipyretics.
•At
• this time, when the temperature is coming down, the disease declares its severity.
•
Facilitator explains two possible scenarios:
•For patients with dengue without warning signs, defervescence is accompanied by
•
improvement in general well-being and appetite.
•For some patients, as the temperature comes down, instead of feeling better as they would
with other viral illnesses, they begin to feel worse, and experience the warning signs and
effects of vascular permeability.
Defervescence
•
marks the start of the critical phase (the orange column).
•The temperature may continue to decrease to subnormal levels in patients who experience
•
shock.
•The duration of plasma leakage is about 24 to 48 hours.
•Towards the end of this period, some patients may experience another bout of fever, thus
•
giving the fever pattern a biphasic or saddleback picture.
•It
••
is important to note that not all patients will become afebrile during the critical phase.
Facilitator
explains that the upward-slanting line at the bottom of this slide shows the
antibody response to dengue.
• •Dengue IgM is negative in the early febrile phase but becomes increasingly positive; similarly,
•
the IgG response, is very increased in secondary dengue infections.
•Adults and older children may experience high temperatures through the plasma leakage
phase, a total of 7 to 10 days, before the fever subsides during the reabsorption phase.
SLIDE 6:
• • Facilitator asks participants, “How will you recognize the plasma leakage phase”
• • Facilitator gives participants a few minutes to respond, then goes on to explain:
• •There are three important laboratory changes that may indicate the plasma leakage phase:
1. White blood count (WBC): Starts to decrease towards day 3 or day 4 of illness and
continues to decrease into the start of the critical phase.
2. Platelet count: May have been normal in the first 1 to 2 days of illness but then starts
to decrease. With the advent of significant plasma leakage, the platelet count decreases
even more precipitously until it is below 100 000, and in severe cases, the platelet count
continues to decrease well below 50 000 and stays in that range throughout the critical
phase, before recovering during the recovery phase.
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