Dengue Fever

Dengue infection is caused by an Arbovirus called Dengue virus of which there are 4 strains – Type 1,2,3,4. Infection with a particular strain will confer immunity to that strain but does not confer cross protection to the other strains. Therefore it is possible to have Dengue infection 4 times in a lifetime but this is rare because we have one predominant strain in Singapore and a lesser proportion of a second strain here. Infection is caused by a bite from an infected Aedes mosquito, which is the vector for transmission of Dengue. Very rarely, human to human transmission is reported (via vertical transmission, mother to child or blood transfusion). The incubation period is 3 – 7 days.

Symptoms of Dengue include:

• Fever with muscle aches, headaches
• Reddish rash and sometimes bruising and bleeding into the skin
• Eyeball pain (eye muscle pain)
• Vomiting, diarrhoea and swollen hands and feet
• Bleeding gums,nose bleeding and rarely vomiting blood

There are 3 syndromes in Dengue infection:

• Classic Dengue Fever: usually mild with rash and slightly low platelets
• Dengue Hemorrhagic Fever with more rash, bleeding and lower platelet count as well as fluid leakage into lungs, extremities and abdominal bloating (capillary leak)
• Dengue Shock Syndrome which is the most severe form of Dengue infection resulting in shock, bleeding, very low platelets, multi-organ failure and death.

Your platelet levels are usually in the normal range of between 140 – 440 X 10⁹/L. However, in Dengue infection, it can drop to a very low level and the patient can start bleeding. Sometimes, they will need a platelet transfusion if there is bleeding. When the platelets have dropped to < 100,000 /ml, daily monitoring is recommended.