Dengue - Symptoms, Causes, Pathophysiology, Treatment, Prevention

Dengue Fever (Breakbone Fever)

Dengue fever is also called breakbone fever.  Dengue is the most common among arthropod-borne diseases. It is a mosquito-borne viral disease occurring in tropical and subtropical regions affecting urban and peri-urban (transition from rural to urban) areas.

 

Dengue fever is a mosquito-borne disease caused by the Dengue virus (DENV) by Aedes mosquitos.

According to World Health Report (WHR) increase of dengue and dengue haemorrhagic fever occurs due to increase population, urbanization, inappropriate water management, travel and trade.

 

Dengue virus is transmitted by Two main species of female mosquito  -

 

1. Aedes Aegypti

2. Aedes albopictus

 

These mosquitoes are also vectors of yellow fever, chikungunya and Zika viruses.

 

Primary symptoms of dengue include -  High fever and severe headache, with severe pain behind the eyes when trying to move the eyes,  vomiting, muscle, and joint pains, and a characteristic skin rash.

 

Other associated symptoms include–  Joint, muscle, and bone pain, rash, and mild bleeding.

Epidemiological Triad

Agent –Dengue fever caused by Dengue virus of Flaviviridae family.

Dengue is an acute febrile disease caused by the mosquito-borne dengue viruses (DENVs), consisting of four serotypes (distinct variation within a species) - DENV 1, DENV-2, DENV-3, DENV-4.

 

Host – Humans and mosquitoes.

Humans are the main reservoir host in causing urban cycles of dengue.

Dengue fever is a Acute viral infection. Aedes mosquito becomes infective after feeding on infective patient.

 

Environment – Rainy season when the feeding of mosquito is abundant

Stagnant water causes the breeding of mosquitoes

 

 

Mode of Transmission

 

Vector-borne transmission

 

Dengue viruses are spread to man through the bites of infected Aedes species mosquitoes (Aedes aegypti or Aedes albopictus).

Mosquito becomes infected when they bite infected humans and later transmit infections to other people, when they bite. Once Aedes mosquito is infective, it remains infective for life.

 

 

Incubation Period

 

The incubation period of Dengue virus is 3-10 days

Primary Symptoms of dengue typically begin 3 to 14 days after bite from an infected mosquito.

 

 

Clinical Manifestation

 

1. Classical Dengue fever 

 

1. High fever with chills

2. Intense headache

3. Muscle, joint and bone pain

4. Retro- orbital pain

5. Photophobia

6. Weakness/ Anorexia

7. Abdominal tenderness / Constipation

8. Altered taste sensation

9. Colicky pain - usually a sharp, localized gastrointestinal or urinary pain

10. Pain in inguinal region

11. Sore throat

12. Rash- diffuse, flushing, mottling (mark with spots ) 

 

B.  Dengue Haemorrhagic fever (DHF)

 

DHF includes all symptoms of classic dengue plus -

 

1. Damage to blood and lymph vessels

2. Bleeding from nose, gums or under the skin

 

C. Dengue shock syndrome (DSS)

 

DSS  includes all symptoms of dengue fever, dengue haemorrhagic fever plus -

1. Fluids leaking outside the vessels

2. Massive bleeding

3. Shock

 

 

Phases of Dengue Fever

 Dengue fever has follows 3 phases- 1. Febrile,  2. Critical,  3. Convalescent

1. Febrile 

This phase manifestation occurs biphasic fever (two phase), severe headache, retroorbital pain, muscle, joint, and bone pain, skin rash, petechiae and minor hemorrhagic,  ecchymosis (discoloration of the skin resulting from bleeding underneath, caused by bruising), purpura ((occurs when small blood vessels burst, causing blood to pool under the skin), epistaxis, bleeding gums, hematuria, or a positive tourniquet test result.

 

Warning signs of progression to severe dengue occur in the late febrile phase include persistent vomiting, severe abdominal pain, fluid accumulation, mucosal bleeding, difficulty breathing, lethargy/restlessness, postural hypotension, liver enlargement, and progressive increase in hematocrit.

 

2. Critical

Develop severe dengue as a result of a marked increase in vascular permeability, rapid weak pulse, narrows pulse pressure as diastolic blood pressure increases,  severe plasma leakage cause pleural effusions or ascites, hypoproteinemia, early signs of shock.

 

severe hemorrhagic manifestations including hematemesis( blood in vomiting) , bloody stool, melena (black stools result of gastrointestinal bleeding), or rare menorrhagia(heavy or prolonged menstrual bleeding).

3. Convalescent

Patient enters the convalescent phase in which patient well-being improves, hemodynamic status stabilizes. The patient’s hematocrit stabilizes and the white cell count usually starts to rise, followed by a recovery of the platelet count. The convalescent phase rash may desquamate (fade) and be pruritic (Itchy).

 

 

Laboratory Diagnosis

 

1. Blood test for platelets and haematocrit - Platelets count below 100,000/mm3 (per microlitre of blood) will be in dengue haemorrhagic fever or or dengue shock syndrome and haematpocrit increased by 20% or more.

2. Dengue NS1 Antigen tets - This is a blood test to detect the dengue virus early in the course of an infection.

3. Serologic tests; ELISA test -  Immunoglobulin M (IgM) , Immunoglobulin G (IgG)

4. Dengue RNA PCR test

5. Nucleic acid amplification tests (NAATs)

 

 

Pathophysiology of Dengue

 

1. Bite of Aedes Aegypti - Virus is inoculated into humans with bite of Aedes Aegypti mosquito saliva

2. Virus localizes and replicates in various target organ, lymph nodes and liver

3. Virus infects and replicates inside the langerhans cell

4. Langerhans cells release interferon

5. Infected langerhans cells got to the lymphatic system and circulation

6. Result in viremia- High levels of virus in bloodstream

7. Dengue virus replicates within coenocytes, mast cell and fibroblasts

8. Decrease neutrophils and white blood cells

9. Release of pyrogen cause fever and increased blood pressure in vessels, cause crash of blood vessels become damaged and leaky

10. Dengueoccurs

 

Treatment of Dengue

 

There is no specific medication to treat dengue infection.  For l dengue, the treatment is done with the relief of the symptoms and signs.

 

Symptomatic and Supportive treatment includes-

 

1. Anti-pyretics -  Acetaminophen (paracetamol) is recommended for treatment of pain and fever.

 

2. Hyderotherapy  - using water as therapy

3. Intravenous oral fluids – in case of vomiting, diarrhoea or excessive sweating

4. Blood transfusion – in case of persistent Shock

5. Fluid intake (oral rehydration)

 

Note - Aspirin, other salicylates, and NSAIDs (nonsteroidal anti-inflammatory drugs) should be avoided.

 

Patients with DHF (dengue hemorrhagic fever) or DSS (dengue shock syndrome) may require intravenous volume replacement.

 

Prevention and Control of Dengue

 

1. Active surveillance

2. Mosquito control

3. Prevention in dengue in travelers

5. Use repellents

6. Early diagnosis and treatment

 

 

Nursing management in case of Dengue fever, DHF and DSS

 

Nursing management of Dengue fever (DF), Dengue hemorrhagic fever (DHF), Dengue shock syndrome (DSS) include- 

 

1. Assess for signs/symptoms of G.I bleeding

2. Check for the secretions

3. Observe the colour and consistency of Stool or vomitus

4. Monitor vital signs Such as pulse and blood pressure

5. Observe the presence of petechiae, ecchymosis, bleeding from one or more sites.

6. Avoid use of asprin

7. Note any change in mentioned level of consciousness

8. Avoid rectal temperature

9.  Be gentle with G.I intubation

10. Avoid Straining for Stool and forceful nose blow

11. Monitor, Hb, hematocrit  (Hct ) and clotting factors

 

 

Dengue - Frequently Asked Questions

 

1. What is the causative agent of Dengue fever?

Dengue fever is a mosquito-borne disease, the causative agent is Dengue virus (DENV) by Aedes mosquitos.

 

2. How does dengue transmitted?

 

Dengue viruses are transmitted to people through the bites of infected Aedes species mosquitoes (Aedes aegypti or Aedes albopictus) and mosquito infected when they bite infected people and transmit infections to other people, when they bite. Once Aedes mosquito is infected, it remains infective for life.

 

 3. What are the symptoms of Dengue?

Symptoms of Dengue fever include High fever with chills, Intense headache, Retro- orbital pain, Abdominal tenderness, Altered taste sensation, Pain in inguinal region, Rash- diffuse, flushing, Bleeding from nose, gums or under the skin.

 

4. What are the treatments available for Dengue?

 

There is no specific medication to treat dengue fever. Dengu treatment is done with the relief of the symptoms and signs and provide supportive treatment include-

1. Anti-pyretics - Acetaminophen for treatment of pain and fever.

2. Hyderotherapy  - using water as therapy

3. Intravenous oral fluids – in case of vomiting, diarrhoea or excessive sweating

4. Blood transfusion – in case of persistent Shock

5. Fluid intake – to prevent dehydration

 

 

Malaria is also arthropod-borne diseases caused by a plasmodium parasite, transmitted by the bite of infected mosquitoes