Dengue is a viral fever caused by the dengue virus, which is transmitted to humans through the bite of infected Aedes mosquitoes.

These mosquitoes breed in stagnant water like pails, vases and flowerpot plates. They are most active during daylight hours and usually bite just after sunrise and around sunset.

Many people who get dengue do not develop symptoms. For those who do, the most common symptoms include high fever, headache, muscle and joint pains, nausea and rashes. These usually resolve within a week or two.

In severe cases, however, dengue can lead to internal bleeding or even death.

Those who get infected a second time are at a greater risk of severe dengue.

There are four strains of the dengue virus and healing from one would only protect you from that specific strain, says Kapila Kannangara, director of Sri Lanka's Dengue Control Unit.

"That immunity does not extend to other strains of the virus. That means someone infected by one strain of the virus could still get dengue again if infected by a mosquito carrying another strain."

"This could mean that they get an even more serious infection," he tells BBC Sinhala.

As there is no universal vaccine for dengue, treatment often involves managing pain with medication such as paracetamol. Patients who develop severe symptoms would often require careful monitoring in hospital, as complications can be lethal.