Dengue Fever

Dengue (DENG-gee) fever, also known as “Breakbone fever” is a viral fever caused by dengue virus transmitted by the bite of mosquito named Aedes aegypti (A.aegypti) in the tropical and subtropical areas. Open water sources are the main breeding places for mosquitos (A.aegypti), the main culprit of the dengue fever.

Introduction & Background Dengue fever, also known as “Breakbone fever” is a viral infection caused by

dengue virus transmitted by the bite of mosquito named Aedes aegypti

(A.aegypti) in the tropical and subtropical areas. Typical symptoms of the dengue

fever include fever, headache, characteristic skin rash, generalized muscle and

joint pain and pain behind the eyes. Dengue fever may be in mild form or may be

in severe form depending upon the infection. The dengue fever is wide spread in

its distribution throughout the world but it is especially notorious in tropical as

well as in subtropical areas, such as

South east Asia

India

Pakistan

Sri Lanka

Mexico

China

Taiwan

Central and South America

Caribbean Islands

Africa

Pacific lands

Millions of cases of dengue fever occur worldwide every year. Dengue fever is

most common in Asia (mainly Pakistan, Sri Lanka & India) and Pacific islands, but

its incidence is increasing in America and Africa as well.

Dengue virus is a single stranded RNA virus that belongs to family Flavivridae,

genus Flavivirus. Dengue has 5 serotypes and all the 5 serotypes can cause

dengue fever. The genome of dengue virus consists of 11000 bases that code for

structural as well as non-structural proteins. There are three basic structural

proteins of dengue virus, capsid protein C, membrane protein M and envelope

protein E. There are also 7 other main non-structural proteins such as NS1, NS2a,

NS2b, NS3, NS4a, NS4b, NS5. Short coding regions are present on both 3’ and 5’

end of the genome.

What is Dengue Fever Dengue fever is a viral infection caused by dengue virus that is transmitted by the

mosquito (A.aegypti). Dengue fever may be of mild form or may be severe form in

terms of its severity depending upon the infection. The symptoms of the mild

form of dengue fever include sudden onset of fever, headache, generalized body

rash, joint and muscle pain throughout the body and pain behind the eyes. In

small proportion of people the dengue fever may become life threatening and is

known as dengue hemorrhagic fever. Dengue hemorrhagic fever is the sever form

of the dengue fever. Dengue hemorrhagic fever has some additional signs and

symptoms in addition to the typical symptoms of mild form of dengue fever, such

as bleeding from the nose and mouth, significant fall in blood pressure which

results in shock and this this condition is known as “dengue shock syndrome”.

Signs & Symptoms of Dengue Fever Most of the people (80%) affected with dengue virus are asymptomatic i.e., they

do not show the typical symptoms of dengue fever. The incubation period of the

dengue fever ranges from 3-14 days but may be of short duration (4-7 days). Signs

and symptoms of dengue fever may vary depending upon the severity of the

disease. The dengue fever may be in mild form or may appear in severe form

which is also known as “Dengue hemorrhagic fever”. Children may show signs and

symptoms that may be quite similar to that of common cold and gastroenteritis

i.e., vomiting and diarrhea etc. The characteristic signs and symptoms of dengue

fever are fever which is of sudden onset form, rash, headache and joint pain etc.

The signs and symptoms of dengue fever are following,

Headache

Malaise

Fever (106 °F or 41 °C)

Pain behind the eyes

Joint pain

Bleeding from nose or gums

Rash all over the body

Nausea

Vomiting

The fever present in dengue fever is characteristically biphasic in nature i.e.,

breaking and then again returning within one or two days.

Most of the people show mild form of dengue fever and recover within a week or

sometimes more. In some cases, the symptoms persist and worsen and may

become life-threatening for the patient. The platelet count is decreased which

results in bleeding from nose and mouth due to leaky blood vessels. Other sign

and symptoms in “Dengue hemorrhagic fever” form of dengue fever are

following,

Bleeding from mouth and nose

Continuous vomiting

Abdominal pain

Petechial hemorrhages under the skin (Minor bleeding under the skin)

There may be complications of the heart, liver and lungs

When to See Your Doctor Headache need not concern much if you are generally healthy and got signs and

symptoms of joint pain, generalized body rash and pain behind the eyes, and then

visit your doctor because it may be life threatening for you if you ignore these

symptoms. International or national travel history is very important for the

diagnosis.

How Dengue Fever is diagnosed? The dengue fever is diagnosed clinically on the basis of clinical signs and

symptoms as well as on the basis of physical examination. Early symptoms of

dengue fever are difficult to differentiate from other viral infections. A probable

diagnosis is made on the symptoms of fever, nausea, vomiting, rash, malaise, joint

pain and low platelet count.

Diagnosis is made in the persons who were being in the subtropical or tropical

areas representing with fever within a week or so. Dengue fever is difficult to

differentiate from Chikungunya. For this clinical investigations are done to

differentiate between these two conditions. Similarly, laboratory investigations

are required to exclude other similar conditions such as,

Malaria

Influenza

Typhoid fever

Measles

Viral hemorrhagic fever

Leptospirosis

Meningococcal disease

The initial detectable change on laboratory investigation is the fall in white blood

cells (WBCs) count. Elevated levels of aminotransferases (AST & ALT) are also

associated with fall in platelet count and plasma leakage. While plasma leakage in

return is associated with pleural effusion or ascites.

The diagnosis of dengue fever is confirmed by laboratory investigations.

Following laboratory investigations are performed to diagnose dengue fever,

Cell cultures

PCR for nucleic acid detection

Specific antigens detection

Specific antibody detection

For first 7 days, specific antigens and PCR are most accurate tests for the

diagnosis of the acute dengue fever. Laboratory investigations for dengue specific

antibodies are also helpful. IgM and IgG are also helpful in the diagnosis. A rise in

titer of IgM is associated with primary infection with dengue virus.

Risk Factors The factors which can predispose a person to dengue fever are following,

1. Travelling to subtropical or tropical areas of the world

2. Previous infection with dengue virus

3. Compromised immune system

4. Female sex

5. High body mass index (BMI)

6. Diabetes

7. Asthma

Complications In the severe form of dengue fever, the dengue virus can affect heart, liver and

lungs. The blood pressure may fall to a dangerous level, the condition known as

dengue shock syndrome. There is a risk of inflammation of brain by dengue virus.

Other rare complications associated with dengue fever are following,

Guillain-Barŕe syndrome

Transverse myelitis

Acute liver failure

Infection of the heart

Treatment There is no specific medication for the treatment of dengue fever except

maintaining fluid level of the body. Over the counter (OTC) pain killers are advised

to relieve the joint pain, headache and pain behind the eyes but those painkillers

are contraindicated in dengue fever which increase the bleeding tendency such as

aspirin, naproxen and ibuprofen. Paracetamol (acetaminophen) is used for the

treatment of fever.

The patients with severe dengue fever are admitted to intensive care unit (ICU)

and then following interventions are required,

Blood pressure monitoring and maintenance

Supportive care

Maintaining body fluid level

Preventions Do not come outside wearing half sleeves shirt.

Ensure that public health bodies and communities are strengthened.

There should be adequate collaboration between the health and other

sectors (public and private).

Maximize use of health resources to control disease with an integrated

approach.

Decisions should be made to ensure that all interventions are targeted

appropriately.

Provide an adequate response to the local situation.

Open water sources are the breeding places of the mosquitoes.

Eliminate the breeding places of mosquitoes.

Spraying with organophosphorus insecticides.

The main method of controlling A. aegypti, main cause of dengue

fever, is by eliminating its natural breeding places. This is mainly done by

eliminating open sources of water.

Always wear long sleeves shirts and long pants in the areas of

mosquitoes.

Stay in well screened rooms in order to avoid mosquitoes.

Always use mosquito repellents.

Lifestyle modifications & Home Remedies The juice of papaya leaf has been seen to inhibit the destruction of

platelets.

The main method of controlling A. aegypti, main cause of dengue fever, is

by eliminating its natural breeding places of mosquitos. This is mainly done

by eliminating open sources of water.

Always wear long sleeves shirts and long pants in the areas of mosquitos.

Stay in well screened rooms in order to avoid mosquitos.

Use mosquito repellents.

Open water sources are the breeding places of the mosquitos. Eliminate

the breeding places of mosquitos.

Spraying with organophosphorus insecticides.

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