EACH year, about 25,000 deaths are reported worldwide due to dengue virus infection. The virus itself is said to be found in more than 100 countries and the 2007 Report of the Intergovernmental Panel on Climate Changes estimates that by 2080, some five billion people worldwide will be exposed to risk of dengue infection due to population increase and climate changes.

It looks like the war on dengue will be a long and tough one for many more years in view of the ongoing climate change which favours Aedes mosquito breeding. It is, therefore, time we looked at alternative methods of controlling or eradicating the Aedes threat.

The proposal put forward last year by medical researchers to introduce male transgenic mosquitoes carrying lethal genes to mate with wild female mosquitoes ought to be given serious consideration, especially since our efforts to eradicate Aedes mosquitoes by fogging and destroying their breeding grounds have their limitations.

Nor can we rely entirely on insecticides, the overuse of which might help build up resistance in the Aedes population. Furthermore, massive fogging and increased strengths of insecticide application has a downside in environmental pollution and degradation.

What is more disturbing to note is a report in the journal Emerging Infectious Diseases (Vol 15 1, January 2009) which highlighted the risk of dengue infection through blood transfusions in Singapore. Using a mathematical model, Dr Annelies et al estimated that in 10,000 blood transfusions, about two to six individuals were at risk of contracting dengue infection in Singapore in 2005. However, they were quick to point out that the level of viramia (total number of virus) required to cause clinical dengue cases varies from individual to individual.

In view of the increasing danger this disease poses to the population at large — and the emergence now of the chikungunya virus which is spread by the Aedes mosquito as well — we need to take bold and innovative steps to check the Aedes mosquito.

I appeal, therefore, to all parties concerned to view the bigger picture. The risk is substantial and under the circumstances, we have no choice but to take certain bold steps to safeguard public health. The proposal to use transgenic mosquitoes to reduce the Aedes population in endemic areas is worth reconsidering if it is found to be relatively safe and effective.

S. PARAM, Ipoh

Source: NST – February 27, 2009