Every thing you want to know about Dengue Fever (Breakbone Fever/Hemorrhagic Fever/Dandy Fever/Infectious Thrombocytopenic Purpura)

Dengue Fever

(Breakbone Fever/Hemorrhagic Fever/Dandy Fever/Infectious Thrombocytopenic Purpura)

Ø  an acute febrile disease caused by infection with one of the serotypes of dengue virus which is transmitted by mosquito genus Aedes.

Ø  Dengue hemorrhagic fever – severe, sometimes fatal manifestation of dengue virus infection characterized by a bleeding diathesis & hypovolemic shock.

Etiologic Agent

·         Flavivirus 1, 2, 3, 4 – family of Togaviridae are small viruses that contain single strand RNA.

·         Arboviruses group B

Incubation Period: 3 – 14 days; commonly 7 – 10 days

Mode of Transmission

1.       By bite of an infected mosquito (Aedes Egypti)

a.       day biting mosquito (appear 2 hours after sunrise and 2 hours before sunset)

b.      it breeds on stagnant water.

c.       has limited & low-flying movement.

d.      has fine white dots at the base of the wings; with white bands on the legs.

Period of Communicability

·         Patients are usually infective to mosquito from a day before the febrile period to the end of it.

·         The mosquito becomes infective from day 8 to 12 after the blood meal and remains infective all throughout life.

Sources of Infection 

·         Infected persons – the virus is present in the blood of patients during the acute phase of the disease and will become a reservoir of virus, sucked by mosquitoes which may then transmit the disease.

·         Standing water – any stagnant water along the household and premises are usual breeding places of these mosquitoes.

Incidence

·         Age – may occur at any age, but is common among children and peaks between four to nine years old.

·         Sex – both sexes can be affected.

·         Season – more frequent during the rainy season.

·         Location – more prevalent in urban communities.

Pathogenesis and Pathology

·         Infectious virus is deposited in the skin by the vector and initial replication occurs at the site of infection and in local lymphatic tissues.

·         Within a few days, viremia occurs, lasting until the 4th or 5^th day after onset of symptoms.

·         Evidence indicates that macrophages are the principal site of replication.

·         At the site of petechial rash, non-specific changes are noted which include endothelial swelling, perivascular edema, and extravasation of blood.

5. There is marked increase in vascular permeability, hypotension, hemoconcentration, thrombocytopenia, with increased platelet agglutinability, and or moderate disseminated intravascular coagulation.

6. The most serious pathophysiological abnormality is hypovolemic shock resulting from increased permeability of the vascular endothelium and loss of plasma from the intravascular space.

Clinical Manifestations

A. Dengue fever

1. Prodromal symptoms characterized by:

a.       malaise and anorexia up to 12 hours

b.      fever and chills accompanied by severe frontal headache, ocular pain, myalgia with severe backache, & arthralgia.

2. Nausea and vomiting

3. Fever is non-remitting and persists for three to seven days.

4. Rash is more prominent on the extremities and the trunk.

5. Petechiae usually appears near the end of the febrile period and most common on the lower extremities.

Phases of the Illness

1. Initial febrile phase lasting from two to three days

a. fever (39 – 40C) accompanied by headache

b. febrile convulsions may appear

c. palms and sole are usually flushed

d. positive tourniquet test

e. anorexia, vomiting, myalgia

f. maculopapular or petechial rash maybe present that usually starts in the distal portion of the extremities, the skin appears purple with blanched areas with varied sizes, that’s the Herman’s sign.

g. generalized or abdominal pain

h. hemorrhagic manifestations like positive tourniquet test, purpura, epistaxis, and gum bleeding may be present

2. Circulatory Phase

a. there is a fall of temperature accompanied by profound circulatory changes usually on the 3rd to 5thday.

b. Patient becomes restless, with cool clammy skin.

c. cyanosis is present.

d. profound thrombocytopenia accompanies the onset of shock.

e. Bleeding diathesis may become more severe with GIT hemorrhage.

f. shock may occur due to loss of plasma from the intravascular spaces and hemoconcentration with markedly elevated hematocrit is present.

g. pulse is rapid and weak; pulse pressure becomes narrow and blood pressure may drop to an

unobtainable level

h. Untreated shock may result to comma, metabolic acidosis and death may occur within two days.

I. With effective therapy, recovery may follow in two to three days.

Classification according to Severity

Grade I

> There is fever accompanied with non-specific constitutional symptoms and the only hemorrhagic manifestation is positive in tourniquet test.

Grade II

> All signs of Grade I plus spontaneous bleeding from the nose, gums, GIT are present.

Grade III

> There is the presence of circulatory failure as manifested by weak pulse, narrow pulse pressure, hypotension, cold clammy skin and restlessness.

Grade IV

> There is profound shock, undetectable blood pressure, and pulse.

Diagnostic Tests

·         Tourniquet test – screening test, done by occluding the arm veins for about 5 minutes to detect capillary fragility.

·         Platelet count (decreased) – confirmatory test

·         Hemoconcentration – an increase of at least 20% in hematocrit or steady rise in hematocrit

·         Occult blood

·         Hemoglobin determination

Treatment Modalities

1. Analgesic drugs other than aspirin may be required for relief of headache, ocular pain, and myalgia.

2. Initial phase may require intravenous infusion to prevent dehydration and replacement of plasma.

3. Blood transfusion is indicated in patient with severe bleeding.

4. Oxygen therapy is indicated to all patients in shock.

5. Sedatives maybe needed to allay anxiety and apprehension.

Nursing Management

a. Patient should be kept in mosquito-free environment to avoid further transmission of infection.

b. Keep patient at rest during bleeding episodes.

c. Vital signs must be promptly monitored.

d. For nose bleeding, maintain patient’s position in elevated trunk, apply ice bag to the bridge of nose and to the forehead.

e. Observe signs of shock, such as slow pulse, cold clammy skin, prostration, and fall of blood

pressure.

f. Restore blood volume by putting the patient in Trendelenberg position to provide greater blood volume to the head part.

Prevention and Control

1. Early detection and treatment of cases will not worsen the victim’s condition.

2. Treat mosquito nets with insecticides.

3. House spraying is advised.

4. Eliminate vector by:

- changing water and scrubbing sides of flower bases once a week

- destroying the breeding places of mosquitoes by cleaning the surroundings

- keeping the water containers covered.

5. Avoid too many hanging clothes inside the house.