Dengue is transmitted by the bite of an Aedes mosquito infected with any one of the four dengue viruses. It occurs in tropical and sub-tropical areas of the world. Symptoms appear 3—14 days after the infective bite. Dengue fever is a febrile illness that affects infants, young children and adults (WHO)
- Dengue is a mosquito-borne viral infection.
- The infection causes flu-like illness, and occasionally develops into a potentially lethal complication called severe dengue.
- The global incidence of dengue has grown dramatically in recent decades.
- About half of the world’s population is now at risk.
- Dengue is found in tropical and sub-tropical climates worldwide, mostly in urban and semi-urban areas.
- Severe dengue is a leading cause of serious illness and death among children in some Asian and Latin American countries.
- There is no specific treatment for dengue/ severe dengue, but early detection and access to proper medical care lowers fatality rates below 1%.
- Dengue prevention and control solely depends on effective vector control measures.
Other names of Dengue:
- H-Fever (Hemorrhagic Fever)
- Dengue Shock Syndrome
- Breakbone Fever due to prominent muscle and joint pain
- Dandy Fever
Dengue Fever/Dengue Fever Syndrome
Is a tropical disease caused by different strains of dengue virus which are transmitted by Aedes Aegypti mosquitos. It is an acute infectious disease characterized by severe pain behind the eye and the joints and bones and accompanied by rash. No bleeding occurs.
Dengue Shock Syndrome
Medical emergency due to loss of plasma and requires immediate administration of IVF to expand plasma volume.
Dengue Hemorrhagic Fever
Those cases with gross hemorrhages. A severe illness characterized by abnormal vascular permeability, hypovolemia and abnormal blood clotting mechanism
- 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
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.
- 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
- Standing water will serve as a breeding place for the mosquitoes
Mode of transmission
By the bit of an infective Aedes Aegypti mosquito
4-6 days (minimum: 3 days; maximum: 10days)
- 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
- 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
- Increased capillary permeability – loss of plasma from intravascular space
- Thrombocytopenia – acute excessive consumption of platelets due to generalized intravascular clotting
- 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
- 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
- Fever – acute in onset, high and continuous, lasting for 7-10 days
- Tourniquet test (Rumpel-Leede test)
- test to determine capillary fragility
- Presence of bleeding (petechiae, purpura, ecchymosis, epistaxis, gum bleeding, hematemesis, melena)
- thrombocytopenia – 100,000/ mm3 or less
- a increase of at least 20% in the hct
- steady rise in hematocrit
- Confirmatory test
- Serologic test – simplest and most rapid method of confirming clinical diagnosis of dengue infection
- Isolation of the virus – most reliable although this is complicated and requires time.
- No specific antiviral drugs
- 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 until the 3rd until patient is afebrile for 1-2 days.
d. Close surveillance – continuous monitoring of BP/Hct/Platelet
For Dengue Shock Syndrome
- IVF (5% Dextrose in 0.3 NaCl is initially given)
- Plasma volume expanders
- During fluid reabsorption phase (decreasing Hct)
- – slow down rate of administration of IVF
- – if fluid overload occurs, give Furosemide 1 mg/kg IV stat doses
d. Oxygen is indicated for all patients in shock
For Dengue Hemorrhagic Syndrome
- Blood Transfusion
- when significant bleeding occurs
- when platelet count is less than 50,000/mm3
- – prepare fresh whole blood
- – transfuse if active bleeding occurs and if hematocrit and hemoglobin level falls
- Oxygen – Indicated
- Grade I and II – Good
- Grade III – Guarded
- Grade IV – Serious
- Eradication of mosquitoes by eliminating breeding places
- Any disease or condition with hemorrhage is enough to cause alarm. Immediate control of hemorrhage enclose observation of the patient for the vital sign leading to shock
- For hemorrhage
- keep patient at rest during bleeding episodes
- observe for signs of deterioration
- control bleeding
4. For Shock
a. prevention is the best treatment
b. restore blood volume