Thailand's Department of Disease Control has declared a Dengue fever epidemic. This year's outbreak is likely to be the worst in five years, with 38-thousand cases and 54 deaths reported so far. Dengue is a viral infection transmitted by the bite of an infected mosquito. And as Thailand is in the midst of its monsoon season, the rate of infection is likely to accelerate. Our correspondent Dusita Saokaew reports.

It's the rainy season. A time when monsoon rains bring respite from the sweltering summer heat. But it's also a time where a painful and sometimes deadly disease is an entrenched peril.

Dengue has always proven to be a silent killer, and this year's outbreak has become even more dangerous and is likely to be the worst in five years. A dengue epidemic has been declared.

PRATAP SINGHASIVANON DEAN OF FACULTY OF TROPICAL MEDICINE MAHIDOL UNIVERSITY "Thailand this year we have about 38000 cases and 54 already died. It is higher than last year. As you can see the number of cases rises in neighboring countries also."

When Boom was bitten by mosquitoes a week ago, Dengue fever was the furthest thing from his mind. A few days later, he was down with a high fever and bouts of nausea. A couple of days past and the fever refused to go away. He went for a blood test and the results confirmed he had dengue fever.

BOOM DENGUE PATIENT "I had a fever and my body was aching. It was not like anything I have ever experienced before. Then I got a rash all over my body. I was scared because I have never had it and Dengue can be fatal."

Cases like this reflect just how enigmatic dengue fever can be — almost impossible to trace and at times, tricky to diagnose, and hard to guard against.

With 4 strains of Dengue, the majority of this year's infections have been caused by the most virulent strain.

DUSITA SAOKAEW BANGKOK "This is the third line of defense to control the spread of Dengue by killing adult mosquitoes. But all this is pointless if mosquito breeding sites are not eliminated. Containers of stagnant water, like this, often found insides people's homes provide the perfect breeding ground for mosquitoes that carry the Dengue virus."

Climate change, urbanization, and changes in human populations have driven many treasured species to the brink of extinction. But the mosquito — is thriving. Once the mosquitoes have infested an area, it's typically not long before a serious mosquito-borne disease outbreak is declared.

And all it takes for breeding is a volume of water around the size of a small coin.

PRATAP SINGHASIVANON DEAN OF FACULTY OF TROPICAL MEDICINE MAHIDOL UNIVERSITY "It's even further complicated that the virus within the mosquito sometimes it can also transmit directly from the mosquito itself to the egg without biting. When it hatches, it already has the virus within its body."

There is no cure for Dengue. Vaccines have their limitations, as they are not as effective for those who have never been infected with the disease before.

While the vaccine loopholes wait to be fixed, the spraying goes on and the infectious journey of Dengue will be as unpredictable as the monsoon rains that fall.

Dusita Saokaew, CGTN, Bangkok, Thailand.