As of the end of July, number of Dengue cases in Bishan peaks 230, a figure significant enough to trigger red-alert level in the area. Despite the sophisticated surveillance and precaution measures taken by the government, the rising number of Dengue cases is alarming. There were 37 Dengue clusters, and seven of them have red-alert level which indicates 10 or more reported cases in those areas in the previous fortnight. At the top of the unwanted list were two clusters in Bishan, covering Bishan Street 22, 23, 24 and 25.

"When I opened the door (one time), there were a few mosquitoes and that's when I called the authorities to give them details, especially when they came in through the windows and door," said Daniel Ng, 58, who lives in Block 228 at Bishan Street 23.

Some residents relate the rising number of Dengue cases to the recent lift upgrading and repainting work, stating that these projects provided ideal breeding sites for Aedes mosquitoes. Some said the construction workers often wash equipment and dump the water at water points at HDB blocks, which accumulates when drains are clogged. The stagnant water thus becomes the breeding spot for Aedes mosquito.

The National Environment Agency (NEA) is urging residents, contractors and business owners to play their parts in eradicating sources of mosquito breeding habitats. Officers have been inspecting homes in Bishan and residents are given insect repellents and granular insecticide.


References:
http://www.channelnewsasia.com/news/singapore/more-dengue-cases/1959036.html
http://www.dengue.gov.sg/subject.asp?id=74

Did you know?

Dengue, as detrimental as it can be to human health, is preventable. To prevent the spread to this infectious disease is simply to stop the breeding of its vector, the Aedes mosquitoes. They are easily identifiable through their distinct black and white stripes on their bodies (although it remains debatable as to whether one could observe such trait outdoor, so often the Aedes mosquitoes strike before one can really take notice). Yet, despite the advance in medicine, the most effective and easiest measure to stop Dengue remains as taking cautious approach to stop the breeding of Aedes mosquitoes.

In Singapore, the government have started different campaigns and programs in hope of raising awareness of Dengue. For instant, the "Do the Mozzie Wipe-out" campaign was launched in 28 April 2013. In just slightly more than 2 years, there are more than 2000 Dengue Prevention Volunteer Group members being recruited, trained and engaged in over 1000 community events to promote Dengue awareness. Collaborating with NEA officers, these group of volunteers helped in explaining Dengue-associated risks to the public and what precautionary measures can be carried out. Interestingly, this was done through the use of exhibits, educational materials and collateral. To further reinforce the importance of Dengue prevention, a Dengue prevention skit was conceptualized and rolled out in July 2013 so as to engage with public with such interesting performances. The Dengue Information Push Carts, a creativity-infused project involving multi-purpose booths, was subsequently started and roved to the community. They showcases live mosquito exhibits, screens Dengue prevention videos and publicizes relevant social media platforms such as the Stop Dengue Now Facebook page. Such captivating idea to promote Dengue prevention and the use of user-friendly features have gained positive responses from the public.

To update, let's review some important statistics about Dengue in Singapore:


According to the graph above, the number of Dengue cases in Singapore peaked in 2014, and was closely matched by the number of cases in 2013. Though the number has subsided significantly in 2015, Dengue is still one of the main concerns among Singaporeans. Currently, the chance of Dengue virus transmission is higher due to the warmer weather, allowing the quicker breeding of mosquitoes while shortening the incubation period of Dengue virus. Yet, any major concern should be eradicated if safety precautions are carried out appropriately.

As mentioned in the previous post, Dengue virus is transmitted through the bites of female Aedes Aegypti and A.Albopictus mosquitoes. These species of mosquitoes are the vectors of Dengue virus. You may ask, what is a vector? A vector, in epidemiology term, refers to any agent, such as humans, animals or microorganisms, that are capable of carrying and transmitting infectious pathogens to other living organisms. The ability to infect is threatening, yet these arthropod vectors, upon acquiring the Dengue virus, are capable of transmitting the virus for the rest of their lives, to as many susceptible victims as they could find.

Dengue virus is an RNA virus with genome of 11 kilobases, some of which code for three different types of protein molecules that form the virus particle: core protein (C), membrane-associated protein (M) and envelope protein (E). In addition, there are 7 other essential proteins, namely NS1, NS2a, NS2b, NS3, NS4a, NS4b and NS5, that are active in infected host cells and bear the responsibility of viral replication. Classification of the serotypes of Dengue virus are according to difference in their antigenicity, with the four main strains being DENV-1, DENV-2, DENV-3, DENV-4. A new strain was discovered in 2013.

Unfortunately, Singapore is one of the countries where Dengue is endemic. Environmental factors such as climate and the failure to eliminate stagnant water provide the ideal breeding ground for Aedes mosquitoes. Dengue virus can be acquired via a single bite, with humans being the favorite target because they are the primary host of the virus.The virus lines gut of the infected mosquito, slowly spreading to different internal organs, such as the salivary gland, leading to the production of virus-containing saliva. All this happens within the infected mosquito while it is roaming around freely, feeding on blood meal while delivering the virus into susceptible, ill-fated targets. The minute size of this flying arthropod makes it hard to discover. Other modes of infection include organ donation from infected patient, blood transfusion and vertical transmission, in which the virus is passed from the mother to the fetus.

With each passing days, the number of Dengue cases continues to grow, both locally and around the world. Whether there is an efficient method of curbing the disease, it remains debatable. Taking safety precautions, such as removing stagnant water, can temporarily eradicate mosquito breeding spot, but surely, there are hidden places which they can grow as well. Another solution is applying insect repellent. Even so, one alarming fact about Dengue remains: the virus is completely harmless to infected mosquitoes, yet detrimental to us humans.  

References:
http://www.dengue.gov.sg/subject.asp?id=73
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3478998/

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