Modifying Mosquito Population Age Structure to Eliminate Dengue Transmission.
A research program funded through the Grand Challenges in Global Health initiative. The initiative's partners are the Bill & Melinda Gates Foundation, the Canadian Institutes of Health Research, the Foundation for the National Institutes of Health, and the Wellcome Trust.

The Grand Challenges in Global Health Initiative.
In January 2003 an initiative was announced by Bill Gates to fund research on diseases that disproportionately affect people in the developing world. The initiative takes as its model the grand challenges formulated more than 100 years ago by mathematician David Hilbert – a list of important unsolved mathematical problems that has encouraged innovative mathematics research ever since. Similarly, the Grand Challenges in Global Health initiative aims to engage creative minds from diverse scientific disciplines to work on 14 major challenges. The challenges range from creating new vaccines to developing accurate methods for measuring health status. A competitive granting process was established and in June 2005 it was announced that 43 projects would receive a total of US$440 million in funding for the next five years to attempt to solve these global health problems.

Our Grand Challenge.
One of the 14 Grand Challenges is to develop new approaches to control insects that transmit diseases to humans. Insects spread many serious diseases such as malaria, which infects 350-500 million people and causes more than one million deaths annually, primarily among young children in sub-Saharan Africa. Similarly, dengue fever infects up to 100 million people each year, and can cause fever, hemorrhaging, and death in severe cases. The main strategy for fighting these diseases has been to use insecticides to kill disease-transmitting insects. This approach has had mixed success and is increasingly ineffective as mosquitoes grow resistant to the insecticides that are available for widespread use. Alternative chemicals are often too expensive for developing countries to use in ongoing public health programs.
 
Our Research.
Our project focuses on dengue fever and the mosquitoes that transmit the virus to humans. It has long been known that only relatively old mosquitoes are capable of transmitting dengue (and other disease agents like malaria) to people. The reason for this is that adult mosquitoes must first acquire the virus when they take a blood meal from a person infected with dengue virus. The virus must then multiply in the mosquito, spreading through the mosquito’s body and into its salivary glands, before it can be transmitted to a new human in a subsequent blood meal. This entire process takes at least 10-12 days and considering that adult mosquitoes seldom live to be more than 30 days old in the wild, it is only the relatively old mosquitoes that can transmit the virus between humans.

Our approach to control dengue is to introduce a naturally occurring bacterial symbiont of insects into the mosquitoes that transmit dengue. Certain strains of this symbiont, known as Wolbachia, shorten the adult lifespan of the insects they infect. Wolbachia are inherited through the eggs of the mosquito and are able to spread into the mosquito population. Our overall project goal is to determine if life-shortening Wolbachia strains can be introduced into dengue mosquitoes, and once introduced, determine if they can reduce mosquito lifespan sufficiently to prevent dengue transmission.