Zika & Wolbachia: Update

    Just a short update on our Wolbachia miniseries from last summer. Remember that question I posed a few months ago -- how effective will Wolbachia-infected mosquitoes be at limiting the spread of human disease? Three months later and we are already closer to getting some answers. Science's Kelly Servick recently reported that two different types of mosquitoes will be released in Brazil to try and prevent the spread of infectious diseases transmitted by the mosquito species Aedes aegypti. The data collected from these releases (in addition to others) will provide the data necessary to continue evaluating the effectiveness of various methods.

    The first release will focus on Wolbachia-infected mosquitoes (previously described here) and is being implemented by the nonprofit organization Eliminate Dengue. These mosquitoes are infected with a strain of Wolbachia that will spread through existing mosquito populations and prevent mosquitoes from transmitting diseases (such as Dengue and Zika). While these releases consist of females (that can bite), the effects of the release are longer lasting because Wolbachia should persist in the resident population of mosquitoes.

    The second release is a genetically modified mosquito developed by the for-profit company Oxitec. These are different from the Wolbachia-infected mosquitoes because their genome has been altered and now contains a modified gene (tTAV: tetracycline-repressible transcriptional activator variant) that kills developing mosquitoes. Males with this gene are released, they mate with females of the resident population, and then the males die. All offspring from these matings contain the modified gene and die before they reach reproductive maturity as adults. Thus, this method is different than the Wolbachia-infected mosquitoes because its goal is to control mosquito populations rather than eliminate their ability to transmit disease. This method may appeal to residents because it reduces mosquito populations and only introduces new males into the population (that cannot bite); however, once the males mate and die a new batch of males must be released. And this can get expensive.

   

  Again, the risks (and expense) associated with these methods needs to be considered in conjunction with the benefits. Preferably from objective third parties. I’ll keep you updated as the story continues to progress.