Dengue fever (pronounced Den-gee) , also known as Dandy fever or Break bone fever, is a mosquito-borne infection that causes a severe flu-like illness. There are four different viruses that can cause dengue fever, all of which spread by a certain type of mosquito.

Spread

About 86 million people develop illness among 390 million who get infected every year. most of the infections being in the tropical regions.

The regions which are at high risk of  the disease are

• Southeast Asia
• Southern China
• Taiwan
• The Caribbean (except for Cuba)
• The Pacific islands
• Central and South America (Except Paraguay and Argentina)
• Mexico
• Africa

According to WHO:

• Approximately two-fifths of world’s population (2.5 billion) are at risk of contacting Dengue fever.
• It is now endemic in 100 countries
• The leading cause of death is dengue hemorrhagic fever in children in most of the Asian countries
• Dengue infection rates among people who have not been previously exposed to the virus are commonly 40% to 50%.
• The same  may go up to 80-90% during epidemics.
• Approximately half-a-million people with dengue hemorrhagic fever, are hospitalized each year, of whom many are children. About 2.5% of these patients die.
• Dengue hemorrhagic fever fatality reads may exceed 20% if untreated. If there is access to medical care with health care professionals trained in treating dengue hemorrhagic fever, the death rate may be less than 1%

Cause of Dengue Fever

The Dengue fever is caused by four strains of Dengue virus (DENV). These are carried from infected person through vector mosquito to healthy person.

Usually once infected by a virus human acquire life long immunity from that virus, in ease of Dengue Fever if infected once the next attack may be more severe with chances of developing hemorrhagic fever very high. This is highly unusual and most dangerous feature of this disease. Therefore, people living in the endemic areas are at a high risk of developing lethal condition in cases of outbreak of the disease.

Vector

The organism that carries disease in its body and transmits it without getting effected by it, is called a vector.

The vector in dengue fever is a specific species of mosquito called Aedes aegypti  or rarely by Aedes albopictus.

The natural habitat of this mosquito is near clean water bodies. it gives its eggs over the clear water where larvae hatch and stay till they can fly. Only the infected mosquitoes transmit disease, and to get infected they have to come in contact with a diseased person or to be born by an infected mosquito.

Symptoms of Dengue Fever

The symptoms of Dengue fever vary from mild flu like illness to severe hemorrhagic syndrome. This is discussed in detail in the following paragraphs. The symptoms usually begin four to six days after exposure to the virus and may last up to ten days.

According to severity of the disease one can classify Dengue fever as Mild Dengue fever, Dengue hemorrhagic fever or Dengue Shock syndrome.

Mild Dengue fever

The symptoms are:

• High grade fever
• Body rash may appear and disappear
• Joint pains
• Body aches
• Pain behind eyes
• Headaches of severe nature
• Nausea and vomiting

This is self limiting disease, may appear seven days after mosquito bite and may disappear after three to seven days

Dengue Hemorrhagic Fever

The mild Dengue fever symptoms may progress to more severe form in three to seven days.To the above list of symptoms there can be

• Bleeding from nose and gums
• Decreased body temperature
• Weak pulses
• Dark colored vomiting and stools ( due to internal bleeding)
• Decreased platelet count (the cells responsible to stop bleeding in the human body)
• Enlarged glands (lymph nodes)
• Small blood spots under skin (from bleeding of small vessels)
• Cold skin with clammy texture
• Easy fatigue-ability due to blood loss

If left unattended to, Dengue Hemorrhagic Fever (DHF) may cause death.

Dengue Shock Syndrome

The worst form of Dengue Fever which usually results in death of the patient. To all th symptms of DHF following may be added:

• Continues vomiting
• sudden hypotention (drop in blood pressure)
• Drowsiness
• Disorientation
• Severe stomach pain
• Generalized edema (body swelling) due to fluid leakage from blood vessels
• Death

Diagnosis of Dengue Fever

The diagnosis of Dengue fever is tricky as the symptoms may mimic simple flu like disease to Typhoid fever or Malaria, history of mosquito bite also complicates diagnosis pointing towrads malaria. following may be helpful for clinician as well as the common people to distinguish Dengue fever from other diseases.

Medical History

History of travel, mosquito bite and being from the endemic area is very important. This may help in initiateting the right course of treatment at proper time.

Signs and symptoms

The symptoms of bleeding being peculiar to dengue hemorrhagic fever and other complicated disease course makes diagnosing DHF earlier possible, at the same time any kind of complicated sepsis can have same features.

Laboratory

Assessing following may help diagnosing

• Complete blood count
• Bleeding time

Following are expensive but definitive in the diagnosis

• ELISA (enzyme-linked immunosorbent assay)
• HI assay (hem agglutination inhibition assay)
• RT-PCR (reverse transcriptase-polymerase chain reaction)

TREATMENT OF DENGUE FEVER

Dengue fever is a viral illness therefore there is no cure for the disease, most treatment is directed towards relieving of symptoms and avoiding complications of the disease. Such treatment is called supportive care.

Mild disease

For mild disease dorm the treatment is directed towards

Pain control: Acetaminophin (paracetamol/Tylenol) is the drug of choice as the larger group of pain killers (NSAIDS) aspirin or ibuprofen may increase the risk of internal bleeding.

Dehydration: Fever and vomiting cause loss of fluids from the body which may be replaced with oral intake of fluids and oral re-hydration salts, in severe forms intravenous fluids can be administered.

Severe Disease

Hospital admission: To monitor bleeding, complications, and blood pressure patient may require to stay within the hospital.

Fluids: Replacing the fluids, in some, may be the only intervention required to avoid severe form of the disease.

Blood and blood products: To control bleeding and limit bleeding internally blood products as FFPs (Fresh Frozen Plasma) and Platelets may be transfused.

Drugs: No drug is available yet for curing dengue fever.

PREVENTION

As said very wisely “Prevention is better than cure” Dengue fever is a preventable disease. Prevention by vaccine is still under development due to four strains of the same virus. Biting by mosquitoes especially in endemic areas is the main line of prevention.

Following figure taken from Medical News Today website explains the preventive methods for avoiding mosquito bite

Prevention from being bitten by mosquitoes can be attempted as following:

• Clothing
  • Exposing minimum skin as possible
  • Wearing lose clothing
  • Light colors are less attractive for mosquitoes
• Mosquito repellants
  • Exposed skins can be covered by readily available repellants
• Use mosquito traps and nets
  • Studies have shown tht sleepin in nets reduce chances of being bitten by mosquitoes
  • Nets treated with repellants are available
  • untreated nets are significantly less effective
• Camping
  • Camping espicially in tropical endemic areas may pose very high risk
  • Using treated tents, clothings and repellant coils can be helpful.
• Windows
  • Kep closed
  • Use screens
• Fragrance
  • Avoid using strong fragrance
• Day times
  • Aedes mosquito has tendency to bite at dawn, dusk and early evenings.
  • Avoid being at open places during these hours
• Stagnant water
  • Clean and stagnant water is the breeding site for Aedes mosquito. It can be prevented from doing so by
    • Loosening soil from potted plants. This will prevent puddles from developing on the surface of hard soil.
    • Turning pails (buckets) and watering cans over; storing them under shelter so water cannot accumulate in them.
    • Not placing receptacles under or on top of any air-conditioning unit.
    • Removing the water from plant pot plates. To remove mosquito eggs, clean and scrub them thoroughly.
    • Changing the water every other day for Flower vases. While doing so, scrub the inside of the vase thoroughly and rinse it out.
    • Making sure leaves are not blocking anything which may result in the accumulation of puddles or stagnant water
    • Covering the gully traps that are rarely used; replace gully traps with non-perforated ones, and install anti-mosquito valves.

Hopefully this account of the Dengue fever may help preventing many cases this year, if you still have doubts feel free to ask directly.