Saturday, March 21, 2009

Dengue in Singapore - Why no progress in labour?

"Rare dengue type on the rise" proclaimed Jessica Jaganathan in the Straits Times on Friday. And today's ST reported on Ms Yong Ying-I, permanent sec for health, commenting on the dengue epidemic in her speech at the conference on the genetics and genomics of infectious diseases.

Somehow I think perhaps most people are missing the point here. Sure, it is important to track the disease, particularly the dengue serotypes. Sure, it is important that we do all we can to control the vectors that transmit the disease. Sure, it is very important for us to have in place programmes and processes to control future epidemics (this was somewhat deficient during SARS).

But the point here is really not about the usual dengue infections. This while troubling and produces some degree of morbidity is part and parcel of life, and living with microbes in the world. What is the real problem in dengue is that a small number of patients get a fatal haemorrhagic disease. Dengue haemorrhagic fever (DHF) is really quite diferent from the run of the mill dengue fever (DF). This is not necessarily related to the serotypes of the virus. The immunologists have postulates about this. Prof Halsteadt writing in 1981, proposed the idea of sequential infections as being behind the fatal haemorrhagic manifestations of dengue. But this is does not explain the haemrrhagic fatalities in children who catch the disease for the very first time (naivetes). Vaccinations are not necessarily the answer to the dengue problem, and may even predispose to the haemorrhagic manifestations.

There remains a lot we do not understand about the disease. For example, why does the disease predominantly affect an older population in theAmericas than compared to South East Asia? Or why are the haemorrhagic manifestations more common in South East Asia? The DHF variety is seen in only about 0.3% of the total dengue infections, while in Singapore, the DHF variety can be as common as almost 3% of total dengue infections? Why??? Do Asians have a genetic predisposition?

Why did the Straits Times miss the opportunity to interview Prof Halsteadt who has researched many of these questions? Instead, they concentrated on reporting on meaningless numbers, and talk of producing vaccines etc etc.

More research money should be directed to answering some of these questions. Let me say again....the question is not about preventing dengue infections, but really about preventing DHF and the fatalities associated with dengue.

The difficulty, I believe in addressing many of these questions is that too much research money is going into empty and false promises of vaccine breakthroughs. The lure of quick megabuck patents is far too tempting for scientists to refocus their minds on less eye catching epidemiological and genetic studies (not on the virus but on our local population). All backroom stuff....plodding detective work...but essential backroom stuff that helps us understand and hopefully prevent deaths in the future.

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