What is dengue fever?
Dengue fever is one of the most contagious infectious diseases caused by dengue viruses that spread from person to person through the bite of an infected Aedes mosquito. Because mosquitoes are the most important part of the outbreak, over 70% of the people at risk of the disease are in Southeast Asia and the Western Pacific Regions. Thailand has reported more than 24,030 infections and over 20 deaths since this early year. The Ministry of Public Health (MoPH) has issued a warning that the increase in cases could result in a three-year high.
How are these diseases spread?
Dengue viruses are spread to people through one bite from infected female mosquitoes, primarily the Aedes aegypti mosquito, which breeds and lives in stagnant water in objects around the house like jars, garbage, and bowls. Another species, Aedes albopictus, whose habitat is stagnant water like tree stumps or leaves in the garden, is also a carrier but does not play an important role.
If temperature and humidity conditions are suitable, particularly during the rainy season, just a few mosquitoes can spread dengue virus throughout the entire family.
There are four strains of Dengue virus: DENV-1, DENV-2, DENV-3, and DENV-4. Every outbreak contains all these strains. Therefore, each person can get dengue fever more than once, with the possibility of all four strains of infection.
What are Dengue symptoms?
Dengue fever is also known as "Breakbone fever" because it is not just a high fever but also comes with severe pain like a severe headache, pain behind the eyes, and muscle and joint pains. These symptoms appear 4–10 days after infection and last for 2–7 days.
Although about one in four people infected with dengue will get sick with mild symptoms, this is not the case for children or adults who are re-infected. They are more likely to develop severe dengue illnesses known as dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS). There are some warning signs to look out for, which usually begin in the 24-48 hours after your fever has gone away, including belly pain, tenderness, vomiting (at least 3 times in 24 hours), bleeding from the nose or gums, vomiting blood, or blood in the stool, as well as feeling tired, restless, or irritable. It is very important to get a diagnosis from a physician as soon as possible with appropriate treatment to decrease the chance of developing a severe illness that leads to death.
Who are at risk of dengue infection?
According to the Disease Control Department, Dengue fever cases have been reported in any age group. The highest dengue incidence rate was reported in children aged 5–14 years, followed by young adults aged between 15–24 years. Children have little protection against the dengue virus, making them very susceptible to infection. Therefore, children are the most affected population, with the highest case fatality rate. However, the dengue incidence in the older age groups gradually increased and is more likely to be associated with severe dengue illness, particularly in the elderly with chronic health conditions.
What is dengue vaccine?
There are currently two live attenuated vaccines available in Thailand which have different in main structures (backbone), but both are targeting the four dengue virus serotypes:
- Chimeric dengue vaccine in a yellow fever 17D backbone
This vaccine must be administered as a three-shot series over a period of six months (at 0, 6, and 12 months) to children and adults between the ages of 9 and 45 with a history of dengue infection or serological testing for past dengue infection.
- Dengue tetravalent vaccine with dengue serotype 2 virus backbone
This vaccine must be administered as a two-shot series with a 3-month interval (at 0 and 3 months) to children and adults between the ages of 4 and 60, with or without previously being infected with dengue. Therefore, a laboratory-confirmed dengue infection is not necessary.
Overall, the dengue vaccines can protect people from dengue infection around 60–80%, prevent severe dengue leading to hospitalizations around 70%–90%. Booster studies are ongoing.
However, there is still a need to communicate to people that this vaccination does not offer complete protection. Therefore, self-protection from carrier mosquitoes is still important and should not be overlooked.
What are the possible side effects of the dengue vaccine?
The dengue vaccine causes some possible side effects within a few days, such as soreness, itchiness, pain in the injection site, headaches, a lack of energy, and general discomfort. Some people might faint after vaccinations. Tell physician if you feel dizzy, have vision changes, or have ringing in the ears. As with any medicine, there is a chance of a vaccine causing a severe allergic reaction or other serious injuries.
For more information, please contact Drug Information Service (24 hours).
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