Dengue is a flu-like illness caused by any of four closely related antigenically different dengue viruses (DEN 1, DEN 2, DEN 3 or DEN 4). The virus is transmitted to humans by the bite of an infected female mosquito. The incubation period of dengue fever normally ranges from between 3 to 14 days. Many patients infected with the dengue virus remain asymptomatic (90%).

The common symptoms of dengue fever include high-grade fever, severe headache, severe pain behind the eyes, joint pain, muscle pain, bone pain, nausea, vomiting, rash and sometimes mild bleeding.

DHF is the more severe form of dengue illness, characterized by a fever that lasts from 2 to 7 days, in addition to the symptoms of simple dengue fever; which include persistent vomiting, severe abdominal pain, difficulty in breathing, dizziness, bleeding etc. There should be evidence of plasma leakage to detect the presence of DHF. Its clinical course changes as the disease progresses and consists of three stereotypic phases: Febrile phase, Critical phase and Convalescent Phase.

It is difficult to differentiate DF from DHF during the febrile phase of the illness. A patient with DHF may enter into the critical phase of the illness where the small blood vessels become leaky allowing the fluid component of the blood to leak into chest and abdominal cavities. This can lead to a reduction in the volume of blood and therefore poor blood supply to vital organs, such as the brain, kidneys & liver. This may lead to failure of the circulatory system and shock, followed by death if circulatory failure is not corrected.

Dengue is transmitted to humans by the bite of an infected female Aedes mosquito. The mosquito becomes infected when it bites a person who has the dengue virus in their blood. After about a week, the mosquito can transmit the virus while biting a healthy person. Person-to-person transmission of DF and DHF does not occur.

DF is transmitted through a mosquito. Therefore, the best way to avoid dengue infection is to prevent mosquito bites. Still, there is no vaccine or preventive drug available for dengue infection. Hence, the following tips are useful:

Avoid mosquito bites during the daytime by wearing protective clothing and by using mosquito repellents, Use mosquito nets when sleeping (both day and night), Get rid of mosquito breeding sites regularly in and around your household. These usually include discarded tyres, plastic containers, coconut shells, leaf axils, blocked roof gutters, bird baths, flower vases and other places that allow for the collection of rainwater.

If a person needs to complain regarding a possible dengue mosquito breeding place, it is always encouraged to have a discussion with the owner or the person responsible for the location where the breeding place is at regarding the problem. If it is not satisfactory, inform the relevant Public Health Inspector (PHI) and Medical Officer of Health (MOH) of the particular area. If it is a problem regarding the disposal of solid waste, inform the Local Government institutions (i.e. Municipal Council/town Council / Pradeshiya Sabha, etc).