A seriously exciting experiment started last week. If it works it could launch something of a revolution in global health. It has particular relevancy to people’s daily lives and local current events. Australian too.
Now the mainstream media did cover it, which is certainly not always the case. However, an awful lot of outlets managed to miss the most significant part of the research, which is also the most interesting IMHO.
Here’s a typical example. It’s kind of accurate as far as it goes. Mosquitoes have been infected with strains of Wolbachia bacteria. They will be released into the wild. It is hoped that they will breed with local mosquitoes and spread the bacteria. It is also hoped that the bacteria will prevent the spread of dengue fever. The timing is excellent with the huge floods in Queensland. With mosquitoes in plauge numbers up and down the coast it also has particular interest value. So far so good.
Laboratory research has shown that Wolbachia acts like a vaccine for the mosquito, by monopolising resources needed by the dengue virus.
That’s true, but it’s something of a secondary effect. The initial research into wolbachia started because it kills mosquitoes, but does it slowly. This is important. If you kill any species quickly, particularly a short-lived one like mosquitoes, it is almost inevitable that some will be immune, at least partially. These will survive, and freed from competition with their vulnerable cousins will come to dominate the ecological niche. Soon you have an entire population that is immune. This is why DDT has not proved the wonder chemical for wiping out malaria many thought it would be (and some right-wing activists still claim it is).
However, if you kill a species slowly, so that they still have time to breed, resistance builds up much, much more slowly. On the other hand, mosquitoes can only transmit disease if they are old (by mosquito standards). They have to bite an animal infected with the disease, have the parasite or virus evolve for a time inside them, and then bite someone else. If you can kill them between the first bite and the second you limit the growth of resistance, while still stopping the disease. That’s the idea with Wolbachia. The bacteria takes a while to do it’s work – hopefully hitting the window.
Personally I find this fascinating, but it is also very exciting. Because the same technique should theoretically work against all mosquito-borne diseases. Stopping dengue would be marvelous. But if we find a method to stop dengue, and malaria, and Ross River virus, and yellow fever and… well we might just have the greatest public health advance since the elimination of smallpox.