Dengue fever is not a new disease especially if you are living in a tropical country such as Malaysia. You can see a spike of dengue cases during the rainy season or after a flood. You might have known that dengue fever is caused by dengue virus through transmission of the virus by the Aedes mosquitoes but do you know that it is usually caused by infected female mosquitoes? A mosquito is said to be infected when it bites a human with dengue virus circulating in the human body. The infected mosquitoes spread the dengue virus by biting other humans. Dengue fever may seem harmless to some but it can definitely lead to life-threatening conditions such as dengue shock syndrome.
Dengue shock syndrome (DSS) is considered to be the severe form of dengue. In contrast with the typical dengue fever, dengue shock syndrome can be deadly and is responsible for death in dengue. To understand DSS, we must first understand dengue haemorrhagic fever (DHF). DHF is the continuation of dengue fever. This means that people with dengue fever have the chance to develop DHF. DHF includes signs of severe abdominal pain, marked change in temperature from fever to low temperature (hypothermia), signs of bleeding such as bleeding nose or gums and changes in alertness such as confusion or restlessness. According to the World Health Organization (WHO), DHF is defined when it fulfils any of the four criteria as stated below:
- Fever or recent history of fever for 2 to 7 days.
- Any signs of bleeding (hemorrhagic manifestation) as mild as a positive tourniquet test, skin changes (purpura, ecchymoses), bleeding gums to severe signs such as vomiting blood (hematemesis) and blood in stool (melena).
- Low count of platelets below 100 000/mm3 (thrombocytopenia).
- Increases vascular permeability such as fluid in the chest cavities (pleural effusion) or abdomen (ascites).
DSS is defined as any case that meets the four criteria for DHF and with evidence of circulatory failure. Circulatory failure is characterised by rapid, weak pulse and narrow pulse pressure or hypotension and cold with clammy skin. Mortality rates in DSS can be 10% or higher but this number is significantly diminished by less than 1% when it is detected early and treated.
People with dengue fever have the chance of developing DSS and this risk is high especially in the elderly and young children or those with medical conditions such as diabetes. DSS is also susceptible in those that have been infected by dengue infection before. This is because there is risk for cross-reaction immunity. This happens when a person is infected by the different serotypes of dengue virus from the previous infections. In general, dengue virus has four serotypes, DENV-1, DENV2, DENV3 and DENV-4. Thus, a person may have been infected by one of the serotypes and recovers which leads to a person having immunity against that one specific serotype only. When this person is infected by the other kind of serotypes, the antibodies cause cross reacting immunity. This further promotes a severe form of dengue.
Since there are no specific treatments for dengue fever including DHF and DSS, treatments provide stress on managing patients’ wellbeing and to prevent further circulatory issues and complications. Treatments aim to keep vital signs in check. Typically, fluid replacement therapy is emphasised through intravenous fluid to maintain hydration and to support the patient circulation system. Prescription of medicine such as paracetamol is common to ease the pain and to treat fever.
The best way to avoid DSS is to treat dengue fever at its early stage. Dengue fever at its early stage is usually marked by high-grade fever that lasts more than 2 to 7 days and is accompanied with symptoms such as headaches especially with pain behind the eyes (retro-orbital headaches), joint pain (arthralgia), muscle pain (myalgia) or skin rash. Whenever a person shows any symptoms of dengue fever, he or she should get checked by a doctor immediately. This is because these symptoms may seem to go away around the 3rd to 7th day which can be mistaken as a person has already healed from the dengue fever when in truth it could be a sign of a critical phase. Critical phase is a phase where most patients with dengue infection may develop a severe form of dengue. This phase lasts around 24 to 48 hours. Hence, it is important for a person with any signs of dengue fever to get themselves checked by a doctor and for them to stay in hospital during the critical phase so that healthcare professionals are able to make close observation and provide treatment.
In essence, dengue shock syndrome is indeed a severe form of dengue. A person is at risk of complications and death when DSS is not treated early. Identifying signs of dengue fever at its early stage can greatly reduce the risk of developing severe forms of dengue such as dengue shock syndrome and dengue haemorrhagic fever. Since there is no specific treatment that could treat dengue infections, early treatment is crucial. Taking preventative measures such as making sure there is no dengue breeding environment such as clearing all unwanted containers that could hold water, killing the mosquitoes by using insect repellent and minimising skin exposure to mosquito bites such as wearing long-sleeved clothes can greatly curb dengue infection.