Attack of the drones

Pakistan is under attack of the Aedes mosquito.

Pakistan is under attack by sophisticated drones. Not the American ones — these drones are home-grown, and they’re far better at targeted stings. They have a very short range (less than 100 yards) and are produced in their millions in standing water.

We’re talking about the Aedes aegypti mosquito, the finicky beast which is the vector for the dengue virus. This mosquito likes relatively clean water and never travels far from where it was hatched. Aedes mosquitoes hide in cupboards and dark corners and sneak out during the daytime to gather their sole sustenance, human blood.

Dengue, once called the “breakbone fever” because of the muscle and joint pains it causes, is headline news in Pakistan now. Lahore has been caught napping. The city faces a big surge in cases — dozens of new ones every day — and is running short of fumigation machines, insecticides and personnel. Ill-performing civic agencies deserve part of the blame, as blocked drains and sewers have created open pools of water where Aedes and other mosquitoes breed. Dengue infections occur in urban areas.

Similar news, of an unprecedented rise in the number of dengue cases, is coming in from other parts of the Asia-Pacific, from the Philippines to Malaysia and even Australia. In Bangkok, the US army, the Thai government and universities, the Bill and Melinda Gates Foundation, drugs companies Sanofi-Aventis and GlaxoSmithKline, and other organisations, in various cooperative combinations, have set up a handful of labs to tackle the problem of inventing a dengue vaccine. One human trial is underway, and another is planned.

For the US army, the motive is plain: its soldiers fight in mosquito-ridden countries. But if the army’s money can help produce a cure, that will benefit the whole world. The World Health Organisation estimates 50 million infections every year, of whom 90 per cent experience no symptoms or only minor flu-like symptoms.

Dengue is well served by modern air travel. Scientists who track its spread have found that it closely follows flight routes and trade patterns. It is the second-commonest cause of the fevers with which Western tourists return home from developing nations.

One reason that a vaccine is so essential and is getting such focused support is that, although dengue is easily cured, patients require intensive medical supervision, which in poor countries places an impossible burden on already-stretched resources.