Friday, 20 June 2008

Mutant Mosquitoes, but what of ITNs, IRS?

Mutant Mosquitoes, but what of ITNs, IRS?

Malaria does not always capture the interest of the press, but for the last two days stories have appeared in a wide variety of sources about experiments to modify the DNA of mosquitoes to make them less able to transmit malaria. If eradication is to happen, new tools are needed. Consequently, Time Magazine reports that, “Faced with a losing battle against malaria, scientists are increasingly exploring new avenues that might have seemed far-fetched just a few years ago.”

Some have doubts about the potential of ITNs. An Associated Press story in the Baltimore Sun indicated that while “the United Nations recently announced a campaign to provide bed nets to anyone who needs them by 2010. Some scientists think creating mutant mosquitoes resistant to the disease might work better.”

ABC News quotes Jo Lines of the London School of Tropical Medicine and Hygiene who raises some doubts. “It’s a series of arms races that the parasite has consistently won. Whenever mosquitoes have developed genes resistant to the malaria-causing parasite, the parasite has always found a way around it, Lines said. Quantity might also be a problem. You are going to need to produce billions of these mosquitoes if this is ever going to work.”

The AP also talked with scientists who expressed concerns about the environmental consequences of modifying organisms and who worried about ‘fooling mother nature.’

malaria-vector-map-sm.gifClearly this is not a technology that can be implemented over night. There are numerous species of Anopheles mosquitoes that carry malaria. (see map from Kiszewksi et al.) And then too, we have several Plasmodium species to worry about. Mosquitoes have different feeding preferences (animals, humans), and although not every mosquito is an efficient malaria vector for human malaria, mosquitoes have been known to change their behavior and feeding preferences.

Interestingly, in areas where the mosquitoes still exist, but the parasite has been eliminated, genetic modification may be a way to get a head start to prevent the reintroduction of malaria. This approach might also be an answer to the continual problem of insecticide resistance.

So far we have no one magic bullet of an intervention to eliminate malaria. Should we now also include mutant mosquitoes in the mix?

Bill Brieger | 20 Jun 2008

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