Dengue Hemorrhagic Fever 2

Topics: Blood, Coagulation, Dengue fever Pages: 5 (939 words) Published: July 24, 2013
Dengue Hemorrhagic Fever
Those cases with gross hemorrhages. A severe illness characterized by abnormal vascular permeability, hypovolemia and abnormal blood clotting mechanism  
Causative Agent
* 4 serotype of the dengue virus (1,2,3 and 4 Group B Arbovirus) * the 4 viruses are antigenically close to each other however, they only give partial cross protection after being infected by any of them Aedes Aegypti

Bite of the Female Aedes Aegypti (day biting, low flying, breeds in stagnant water, in urban areas). Why female? It is because that they use the blood obtained for laying of eggs. It is the primary vector for the transmission of dengue. Sources:

1. Infected Persons – virus is present in the blood of patients during the acute phase of the disease and will become a reservoir of the virus 2. Standing water will serve as a breeding place for the mosquitoes Mode of transmission

By the bit of an infective Aedes Aegypti mosquito
Incubation Period
4-6 days (minimum: 3 days; maximum: 10days)
Pathophysiology
* Each of the 4 types of Dengue virus can cause either classical or dengue hemorrhagic fever. * Virus enters the blood stream
* Neutralizing antibodies are produced principally against the virus type * Because of the production of antibodies, and the response of the immune system to the initial attack, constitutional signs and symptoms are manifested * Because of the increasing antigen-antibody complex

1. Increased capillary fragility – brought about by a strong immune complex reaction the produce toxic substance like histamine, serotonin and bradykinin which damages the capillary wall à in an attempt to repair lesions, clotting occurs à DISSEMINATED INTRAVASCULAR COAGULATION 2. Increased capillary permeability – loss of plasma from intravascular space 3. Thrombocytopenia – acute excessive consumption of platelets due to generalized intravascular clotting 4. Decreased blood coagulation factors – initiated by lesions in the capillary wall SIGNS AND SYMPTOMS OF DENGUE HEMORRHAGIC FEVER

Signs and symptoms depend on the Grade:
Grade I – (+) fever lasting 3 – 5 days
* Abdominal pain
* Anorexia, nausea and vomiting
* Pain behind the eyes
* Joint pains
* (+) eveidence of vascular changes
* petechiae
* Herman’s sign – general flushing of the skin
 
Grade II – signs and symptoms of Grade I + Bleeding
* Gum bleeding, epistaxis, hematemesis, melena, hematochezia  
Grade III – signs and symptoms of Grade II + Circulatory failure * Hypotension, rapid but weak pulse
 
Grade IV – signs and symptoms of  Grade III + Shock
 
Diagnosis
1. Clinical
1. Fever – acute in onset, high and continuous, lasting for 7-10 days 2. Tourniquet test (Rumpel-Leede test)
* test to determine capillary fragility
1. Presence of bleeding (petechiae, purpura, ecchymosis, epistaxis, gum bleeding, hematemesis, melena) 1. Laboratory
1. thrombocytopenia – 100,000/ mm3 or less
2. Hemoconcentration
*
*
* a increase of at least 20% in the hct
* steady rise in hematocrit
1. Confirmatory test
1. Serologic test – simplest and most rapid method of confirming clinical diagnosis of dengue infection 2. Isolation of the virus – most reliable although this is complicated and requires time.  

Treatment:
1. Symptomatic
2. No specific antiviral drugs
3. In most cases, early and most effective replacement of plasma loss with plasma expander and or fluid electrolytes solution results in a favorable outcome.  
For Dengue Fever Syndrome
a. Oral fluid and electrolyte replacement
* - encouraged to prevent and correct dehydration which results from fever b. For fever –
* antipyretics like Acetaminophen but not aspirin
c. Hematocrit Determination
* useful guide in therapy as this reflects the degree of plasma leakage and the need for IV fluid * test is recommended daily...
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