Among many mosquito-borne diseases, dengue fever is a common type which is also known as break bone fever. It is an acute viral infection caused by four serotypes of dengue virus. It is transmitted to people by the bite of infected mosquito mainly by Aedes aegypti and in few cases, by Aedes albopictus which are found throughout the world. Dengue fever can differ from mild to severe infection; the more severe forms include dengue shock syndrome and dengue hemorrhagic fever (DHF). Dengue mostly affects infants, young children and adults with symptoms appearing 3-14 days after the infective bite.
What are the types of Dengue fever?
Symptoms may not occur even after infection but sometimes it may lead to three types of dengue fever.
Classical Dengue Fever
This is mild form of dengue fever. Major symptoms include sudden onset with chills and high fever (39 – 40°C), intense headache, muscle and joint pain. Other common symptoms include extreme weakness, loss of appetite, constipation, altered taste sensation, sore throat, skin rashes may be seen in 80% cases.
Dengue Hemorrhagic Fever
It is severe form of dengue fever caused by infection with more than one dengue mostly affecting children. It begins with high fever and facial flushing with headache, loss of appetite, vomiting, abdominal discomfort, and generalized abdominal pain are common. Initially, it resembles like classical dengue fever but rashes are less common. Occasionally temperature may rise up to 40-41°C and febrile convulsion may be seen particularly in infants. DHF can result in death if not treated in time. Other symptoms include bleeding from mouth/gums, nosebleeds, damaged lymph, along with blood vessels and internal bleeding, In addition, it may result in black vomit and feces, lower number of platelets (cells that help clot blood) etc.
Dengue Shock Syndrome
This is the also the severe form of dengue characterized by shock which can also result in death, mild dengue fever symptoms may appear, but others probable to appear are intense stomach pain, disorientation, sudden lowered blood pressure, heavy bleeding, regular vomiting, restlessness etc.
Magnitude of the problem
The global incidence of dengue has grown dramatically in recent decades. About half of the world’s population is now at risk. It is found in tropical and sub-tropical climates arpund the globe mostly in urban and semi-urban areas. Severe dengue is a leading cause of serious illness and death among children in some Asian and Latin American countries. Furthermore, it is endemic in at least 100 countries in Asia, the Pacific, the Americas, Africa, and the Caribbean. According to WHO, the number of cases reported increased from 2.2 million in 2010 to 3.2 million in 2015. Not only is the number of cases increasing as the disease spreads to new areas, but explosive outbreaks are occurring.
Prevention and Control
One dengue vaccine has been registered in several countries (CYD-TDV, or Dengvaxia®); this is a live attenuated vaccine. Several other dengue vaccine candidates are in clinical development. Nevertheless, the best method of protection is to avoid mosquito bites and to reduce the mosquito population through:
- Preventing mosquitoes from access of egg-laying habitats by environmental management and modification;
- Proper disposal of solid waste and removing artificial man-made habitats;
- Covering, emptying and cleaning of domestic water storage containers on a weekly basis;
- Application of appropriate insecticides to water storage outdoor containers;
- Using personal household protection such as window screens, full-sleeved clothes, insecticide treated materials, coils and vaporizers;
- Improving community participation and mobilization for sustained vector control;
- Application insecticides as space spraying during outbreaks as one of the emergency vector-control measures;
- Active monitoring and surveillance of vectors should be carried out to determine effectiveness of control interventions.
Early diagnosis and sufficient treatment is of crucial importance. As there is no specific anti viral treatment for dengue fever, symptomatic and supportive treatment is given. For severe form of dengue, medical care by physicians and nurses experienced with the effects and progression of the disease can save lives – decreasing mortality rates from more than 20% to less than 1%. Moreover, maintenance of the patient’s body fluid volume is critical to severe dengue care.