Dengue is the most prevalent, life-threatening mosquito-borne viral disease that is affecting human today. A global burden, the number of dengue cases in the past decade has soared sky-high, with an estimation of 390 millions dengue infections per year (WHO, 2015). Another study on the prevalence of dengue also shows that around 3900 millions people, in 128 different countries, are at risk of contracting dengue. This, together with the fact that there were only 9 countries that had experienced severe dengue epidemics prior to 1970, highlights the appalling effect of dengue. More importantly, it proves that future escalation of the disease is highly possible.

Dengue virus is transmitted through only the bites of female mosquitoes but does not spread from person to person. The species involved are A. Albopictus and  Aedes Aegypti  mosquitoes, with the latter being the main viral carrier. Due to the growing population, uncontrolled urbanization, temperature fluctuation, and other important factors such as rainfall, dengue virus is able to proliferate and spread. While dengue virus could cause a spectrum of diseases, dengue hemorrhagic fever is mainly the cause of fatalities. Symptoms of dengue include high fever, sever headache, muscle and joint pains, vomiting, nausea or rash, which can last for 2-7 days, after an incubation period of 4-10 days. Without proper medical care, dengue can become severe and lethal.

Dengue virus consists of 4 closely-related serotypes  that manifest with similar symptoms. They are DEN-1, DEN-2, DEN-3, DEN-4. Although recovery from infection by any one of these serotypes guarantee lifelong immunity against the similar serotype, subsequent infection by other viral serotypes is possible, and the chance of increased severity is very likely. A cause of concern about dengue is that there is no available vaccine against the virus, thus providing no protection even though the number of patients contracted with the disease is increasing. However, developed countries, together with the guidance and technical support from World Health Organisation (WHO), are still trying to develop a vaccine, with three tetravalent live-attenuated vaccine under development in phase II and phase III of clinical trials, offering a glimpse of hope.

In today's world, infectious diseases are prevalent. Even then, more diseases are being discovered and nobody knows how disease-causing bacteria are evolving through mutation each day. What we can hope for is that WHO and CDC, through collaboration with a network of laboratories, could come out with effective vaccines to combat such infectious diseases, which include the deadly yet incurable dengue.



References:
http://www.who.int/mediacentre/factsheets/fs117/en/
http://www.ncbi.nlm.nih.gov/pubmed/20513545\
http://pre06.deviantart.net/fa03/th/pre/f/2011/099/9/a/dengue_fly_of_war_by_japoneis202-d3dkdzj.jpg