Down with Dengue

As I showed in a phylogenetic tree in February 2016, Zika virus is closely related to a handful of other human pathogens including West Nile Virus, Yellow Fever Virus and Dengue Fever Virus. Dengue is a tropical disease, we're safe in Dublin, Denver and Dnipropetrovsk Дніпропетровськ. The vector only flies within the Winter 10^oC isotherm and not even in all regions within those lines:

Dengue has always been with us, transmitted, like Zika by Aedes aegypti the Asian tiger mosquito. It has been on the increase since WWII for reasons that are not entirely clear but may have to do with the flight to city barrios and A. aegypti's preference for urban environments. Like other mosquitoes they lay eggs on water but Aedes is happy with a puddle, a used tire or a bucket forgotten under a veranda.

Anyway Dengue is now 30x more common than it was 50 years ago. There is no cure and no vaccination available but with palliative care and hydration therapy mortality is reduced to close to zero - 0.2%. But the number of work-days lost and general misery continues to increase. The obvious place to disrupt the viral transmission is by nobbling the vector and we've seen an example of that using Wolbachia spp. bacteria to control the fertility of males to reduce the incidence of Zika. Same vector, different disease; same technique, different mechanism. Scott O'Neill from Monash U in Australia noticed years ago that Wolbachia infection of Drosophila prevented the flies from transmitting any RNA virus. For such a tiny genome, Wolbachia has a peculiarly useful tool-kit! O'Neill has spent the last two decades trying for identify a strain of Wolbachia that will carry out the same trick in Aedes. The double-smart angle has been to get the bacteria to go forth and multiply in wild mosquito populations, so that, once kick-started, no further interventions are required. The Zika/Wolbachia story and down with screwworm drive, by contrast, required continual inputs which were profitable for the program participants / suppliers as well has benefitting the end 'consumers'.

The Monash team have had some success in filed trials. Check out the Eliminate Dengue site for details. I particularly like this approach because it aspires to being a precision intervention against a particular aspect of normal Aedes function. By keeping virus-disabled mosquitoes in place, they maintain the ecological balance. Killing the mosquitoes or preventing them from breeding [same thing really] could potentially void a niche in the ecosystem that will be filled by who-knows-what nameless eyeball-eating tropical monster.