Dengue Fever

Dengue Fever

Dengue (pronounced DENgee) fever is a painful, debilitating mosquito-borne disease. There are four different viruses that can cause dengue fever (DEN 1, DEN 2, DEN 3, DEN 4),  all of which spread by a certain type of mosquito. These viruses are related to the viruses that cause West Nile infection and yellow fever. Dengue fever, also known as breakbone fever, causes a severe flu-like illness.Denguevirus microscope

Dengue fever can vary from mild to severe; from a self-limited Dengue Fever (DF) to a life-threatening syndrome called Dengue Hemorrhagic Fever (DHF) or Dengue Shock Syndrome (DSS). Patients who develop the more serious forms of dengue fever usually need to be hospitalized.

Dengue Haemorrhagic Fever was first recognized in the 1950s during dengue epidemics in the Philippines and Thailand. Today, severe dengue affects most Asian and Latin American countries and has become a leading cause of hospitalization and death among children in these regions.

Some Facts about Dengue

  • Around 2.5 billion people, or 40% of the world’s population, live in areas where there is a risk of dengue transmission.
  • Dengue is endemic in at least 100 countries in Asia, the Pacific, the Americas, Africa, and the Caribbean.
  • WHO estimates that 50-100 million infections occur yearly, including 500,000 dengue haemorraghic fever (DHF) cases and 22,000 deaths, mostly among children.

How it transmitted

The virus is transmitted to humans through the bites of infected striped Aedes aegypti female mosquitoes, Dengueoriginated in Africa.  Aedes albopictus, a secondary dengue vector found in Asia. These mosquitoes live in urban habitats and breeds mostly in man-made containers. Unlike other mosquitoes they are day-time feeders; their peak biting periods are early in the morning and in the evening before dusk. Female Ae. Aegypti bites multiple people during each feeding period. After virus incubation for 4–10 days, an infected mosquito is capable of transmitting the virus for the rest of its life.

The virus is not contagious and cannot be spread directly from person to person. It is mosquito-borne, so there must be a person-to-mosquito-to-another-person pathway. The full life cycle of the virus involves the mosquito as the vector (transmitter) and the human as the source of infection.

Infected humans are the main carriers and multipliers of the virus, serving as a source of the virus for uninfected mosquitoes. Patients who are already infected with the dengue virus can transmit the infection (for 4–5 days; maximum 12) via Aedes mosquitoes after their first symptoms appear.

The mosquito flourishes during rainy seasons but can breed in water-filled flower pots, plastic bags, and cans year-round. One mosquito bite can cause the disease.

Symptoms                                                                                                                                                             Dengue fever is a severe, flu-like illness that affects infants, young children and adults.

179471-dengue-fever-symptomsDengue should be suspected at a high fever (40°C/104°F). Symptoms usually last for 2–7 days, after an incubation period of 4–10 days after the bite from an infected mosquito.                                                                                   Severe dengue is a potentially deadly complication due to plasma leaking, fluid accumulation, respiratory distress, severe bleeding, or organ impairment. Warning signs occur 3–7 days after the first symptoms in conjunction with a decrease in temperature (below 38°C/100°F). The next 24–48 hours of the critical stage can be lethal; proper medical care is needed to avoid complications and risk of death.

As there are different severities of dengue fever, the symptoms can vary.

Mild dengue fever

Symptoms can appear up to seven days after the mosquito carrying the virus bites, and usually disappear after a week. This form of the disease hardly ever results in serious or fatal complications.

The symptoms of mild dengue fever are:

  • Aching muscles and joints
  • Body rash that can disappear and then reappear
  • High fever
  • Intense headache
  • Pain behind the eyes
  • Vomiting and feeling nauseous.

Dengue haemorrhagic fever (DHF)

Symptoms during onset may be mild, but gradually worsen after a number of days. DHF can result in death if not treated in time. Mild dengue fever symptoms may occur in DHF, as well as the ones listed below:

  • Bleeding from your mouth/gums
  • Nosebleeds
  • Clammy skin
  • Considerably damaged lymph and blood vessels
  • Internal bleeding, which can result in black vomit and feces (stools)
  • Lower number of platelets in blood – these are the cells that help clot your blood
  • Sensitive stomach
  • Small blood spots under your skin
  • Weak pulse.

Dengue shock syndrome

This is the worst form of dengue which can also result in death, again mild dengue fever symptoms may appear, but others likely to appear are:

  • Intense stomach pain
  • Disorientation
  • Sudden hypotension(fast drop in blood pressure)
  • Heavy bleeding
  • Regular vomiting
  • Blood vessels leaking fluid
  • Death


There is no vaccine to protect against dengue. However, major progress has been made in developing a vaccine against dengue/severe dengue. Three tetravalent live-attenuated vaccines are under development in phase II and phase III clinical trials, and 3 other vaccine candidates (based on subunit, DNA and purified inactivated virus platforms) are at earlier stages of clinical development. WHO provides technical advice and guidance to countries and private partners to support vaccine research and evaluation.


There is no specific treatment for dengue fever. However there are things the patient or the doctor can do to help, depending on the severity of the disease.

For milder forms of dengue fever the treatment methods are:

  • Prevent dehydration– high fever and vomiting can dehydrate the body. Make sure you drink clean (ideally bottled) water rather than tap water. Rehydration salts can also help replace fluids and minerals.
  • Painkillers– this can help lower fever and ease pain. As some NSAIDs (non-steroidal anti-inflammatory drugs), such as aspirin or ibuprofen can increase the risk of internal bleeding, patients are advised to use Tylenol (paracetamol) instead.

The following treatment options are designed for the more severe forms of dengue fever:

  • Intravenous fluid supplementation (IV drip) – in some harsher cases of dengue the patient is unable to take fluids orally (via the mouth) and will need to receive an IV drip.
  • Blood transfusion– a blood transfusion may be recommended for patients with severe dehydration.
  • Hospital care– it is important that you be treated by medical professionals, this way you can be properly monitored (e.g. fluid levels, blood pressure) in case your symptoms worsen. If the patient is cared for by physicians and nurses experienced with the effects and complications of hemorrhagic fever, lives can be saved.


At present there is no dengue vaccine, the best method of prevention is to avoid being bitten by mosquitoes

  • Be sure to wear long trousers/pants, long sleeved shirts, and socks
  • Apply insect repellent on your skin while indoors or out
  • Use Mosquito repellents
  • Use a mosquito net when you go to sleep
  • Try to avoid being outside at dawn, dusk and early evening.
  • Make sure window and door screens are secure and without holes.
  • Use coils and mosquito vaporizers
  • If available, use air-conditioning.

Stagnant water

The Aedes mosquito prefers to breed in clean, stagnant water. It is important to frequently check and remove stagnant water in your home/premises. Here are some tips for this:

  • Covering, emptying and cleaning of domestic water storage containers on a weekly basis;
  • Applying appropriate insecticides to water storage outdoor containers;
  • Turn pails (buckets) and watering cans over; store them under shelter so water cannot accumulate in them.
  • Remove the water from plant pot plates. To remove mosquito eggs, clean and scrub them thoroughly. Ideally, do not use plant pot plates.
  • Loosen soil from potted plants. This will prevent puddles from developing on the surface of hard soil
  • Do not place receptacles under or on top of any air-conditioning unit.
  • Flower vases – change the water every other day. When you do so, scrub the inside of the vase thoroughly and rinse it out.
  • Get rid of places where mosquitoes can breed. These include old tires, cans, or flower pots that collect rain.

If someone in your home gets dengue fever, be especially vigilant about efforts to protect yourself and other family members from mosquitoes. Mosquitoes that bite the infected family member could spread the infection to others in your home.