2018 Blog
Dengue Fever

Overview:

  • ​Dengue is a mosquito-borne viral infection transmitted by the bite of Aedes aegypti mosquito.
  • The Aedes aegypti mosquito is not the main cause of the disease, it is the vector that transmits the virus.
  • The infection causes flu-like symptoms, and develops into severe dengue.
  • There is no specific treatment for dengue, but access to proper medical care reduces mortality rates.
  • The best way to prevent dengue is to avoid mosquito bites.​

Introduction:

Dengue is a mosquito-borne viral infection. It is found in tropical and sub-tropical climates, spreading rapidly in urban poor areas, suburbs and rural areas. 
Other names of the disease:
Dengue, dandy fever, bouquet fever, break bone fever and Aden fever.  
Causes:
There are four distinct serotypes of the dengue virus (DEN 1, DEN 2, DEN 3 and DEN 4). The transfer of one of them via the female mosquito (Aedes aegypti) is the main cause of dengue. In rare cases, the virus can be spread via the white-striped body Asian tiger mosquito (Aedes albopictus).   
Methods of Disease Transmission:
It is transmitted from one person to another by the bites of Aedes aegypti mosquitos that generally acquire the virus while feeding on the blood of an infected person. The mosquito then can transmit the virus while biting a healthy person and feeding on his blood.  Patients who are already infected with the dengue virus can transmit the infection via the mosquitoes after the first symptoms appear during 4-5 days (up to 7 days). 
Aedes aegypti Mosquito:
  • ​It is a dark-colored mosquito with white markings on its legs and white dots on its body.
  • The mosquito is not the main cause of the disease, but is just a vector for transmitting the virus form one person to another.
  • Within the mosquito, the virus infects the mosquito mid-gut and subsequently spreads to the salivary glands over an incubation period of 8-12 days, and then can transmit the disease for the rest of its life.
  • The peak periods for mosquito bites are early morning and before sunset. 
  • Every time a female mosquito needs food, it will bite several people.
Incubation Period:
Symptoms begin to appear 4-10 days after the bite from an infected mosquito.
Symptoms:
Dengue causes flu-like symptoms and infection is suspected with high fever (above 40°C) and at least two of the following symptoms:
  • ​Severe headache.
  • Pain behind the eyes.
  • Muscle and joint pain.
  • Nausea.
  • Vomiting.
  • Rash.
Symptoms usually last for 2-7 days.

When to see a doctor?
When you develop emergency symptoms after returning from a visit to a region infected with the disease, including:
  • ​Severe abdominal pain.
  • Persistent vomiting.
  • Gums and nose bleeding.
  • Blood in your urine, stools or vomit.
  • Bleeding under the skin, which might look like bruising.
  • Difficult or rapid breathing.
  • Cold or pale skin.
  • Fatigue.
Diagnosis:
  • ​Diagnosing dengue fever can be difficult, because its signs and symptoms can be easily confused with those of other diseases such as malaria, but the doctor will ask the patient about his medical history and regions and countries he visited recently.
  • Laboratory tests: Blood test can detect evidence of the dengue viruses, but test results usually come back too late to help direct treatment decisions.
Risk Factors:
  • ​Living or traveling in tropical areas.
  • Previous infection with a dengue fever virus increases your risk of having severe symptoms if you're infected again. 
Complications:
The disease may develop into severe dengue fever, causing damage to the blood vessels, fluids leaking through them, reducing the number of platelets, leading to severe bleeding and sudden hypotension or failure of one of body organs and death.  
Treatment:
There is no specific treatment for dengue fever, so prevention is the most important step to be followed, and when you develop the disease the followings are recommended:  
  • ​Get some rest.
  • Fluid intake.
  • Take painkillers.
  • Avoid blood thinners such aspirin.
  • Avoid mosquito bites, to prevent the spread of the disease. 
For severe dengue, medical care and replacement of lost fluids will help to prevent progression of the disease and maintain the patient's life. 
Prevention:
  • ​In some countries, vaccination is approved for those aged 9 to 45 who live in areas with a high incidence of dengue fever.
  • Prevention of dengue fever is highly dependent on combatting the Aedes aegypti mosquito which is a vector for transmitting the disease.
  • The best way of prevention is to avoid the mosquito bites through: 
    • Disposal of mosquito breeding places such as water basins whether inside or outside the home.
    • Covering, emptying and cleaning all domestic water tanks and basins weekly, including the water of vases.
    • Applying insect repellent cream inside and outside the house. 
    • Wearing long-sleeved clothing.
    • Ensuring that window screens have no holes that allow insects to enter.
    • Applying insecticides during outbreaks. 
  • ​To prevent the spread of the virus from the infected person to the mosquito and then to other people, patients who are already infected with the dengue virus should be protected against the mosquito. If a member of family has dengue fever, more precautions should be taken to prevent the spread of the infection. He should sleep in a mosquito net and apply mosquito repellent cream.
  • In humans recovery from infection by one dengue virus provides lifelong immunity against that particular virus serotype. However, this immunity confers only partial and transient protection against subsequent infection by the other three serotypes of the virus. Evidence points to the fact that sequential infection increases the risk of developing severe dengue. 
Frequently Asked Questions:
  • ​Are there any registered cases in the Kingdom? Is it high?
    • ​Yes. Several cases were registered in the Kingdom since the occurrence of the disease in 1994. Cases are registered annually, not at a high rate, thank Allah.
  • Do all mosquitos spread dengue fever?
    • ​No. Only the Aedes aegypti is the species of mosquito which is primarily responsible for spreading dengue in the Kingdom of Saudi Arabia.
Misconceptions:
  • ​The infected person can spread the infection to others by direct contact with him
    • Fact: Dengue cannot be spread directly from person to person, but via the bites of infected mosquitos. 





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