Dengue fever has existed for more than 300 years. During most of that time, it was described as unpleasant, but seldom a deadly disease. However, once a lethal variant called dengue haemorrhagic fever or DHF appeared in the 1950s, the intensity, frequency and deadliness of the disease outbreaks have started.
According to recent statistics, dengue cases are now 50 times as frequent as they were in the 60s. Back then, dengue deaths never exceeded 210 a year. In 2013, dengue has killed more 22,000 people and infected over 3 million. Despite these shocking statistics, no vaccine or treatments has been developed for the disease.
Scientists believe that the sudden rise in the diseases’ intensity and frequency might’ve been a result of a century worth of globalization. As people were moving between continents, genetic mutation in the dengue virus has resulted, enabling the virus to survive and adapt to various climate. Beside those abilities, the virus has also developed the lethal ability of causing haemorrhage in the affected individuals.
Only female mosquito bites human. But that of the Aedes aegypti species carries the dengue virus. When a mosquito sucks the blood of an infected host, it consumes enough of the virus to itself and become infected. The dengue virus then leaves the mosquito guts, spreads throughout its body and eventually reaches to its salivary glands, a process which takes about a week. The carrier mosquito then finds another host to feed on and infect it with the virus, thus continuing the cycle.
The booming of the tourism industry in past decade has helped four strains of the dengue virus to circulate the globe. People who contracted one of these strains develop antibodies, thus resistance to that strain. But they also develop a higher risk of contracting the lethal variant, dengue haemorrhagic fever, if they later catch one of the other three strains. Once that happens; instead of attacking the virus, the antibodies produced from the first infection bind to it. These antibodies effectively transform into weapons for the virus, enabling it to replicate faster, hijack the immune system and invade the organs, a process that will eventually make patients sicker and, sometimes, put them in life a threatening condition.
The question left on the mind is why the seriousness of dengue hasn’t been realized earlier? The answer lies in the nature of the disease itself. Dengue symptoms can be easily confused with that of other common diseases such as flue, measles and Typhoid fever. Besides, the disease was yet to develop its most serious symptom, which the haemorrhagic fever.
Dengue case and deaths are now exponentially rising and currently, there is no way of telling how long this will continue. Yet, the real questions that burdens authorities and global health organization is whether we will ever find a cure for dengue or a treatment that can significantly reduce the mortality rate inflicted by the disease. We hope a cure for dengue becomes a reality, but meanwhile, prevention via mosquito control and precaution will remain our only shields against dengue.