Modified mozzie to battle dengue
By Jason Major
TechNyou
We are about to release a modified mosquito in Nth Queensland that will potentially reduce the threat of dengue fever.
This is not a genetically modified mosquito, but one that has been deliberately infected with a bacteria that reduces its lifespan and hence its ability to transmit the dengue virus.
Last night’s 7:30 report on the ABC ran a story on this research – a reasonably good one that provided sufficient context to, I think, avoid being misleading, yet maintain the need to tell a good story. But then I am familiar with the research, some of which is occurring next door to my office.
This research is contrast to the recent announcement by a British company that it had released a genetically modified version of the same mosquito (Aedes aegypti) in an attempt to also solve the dengue fever problem. The company wants to start a second trial release of the GM mosquito in Malaysia. There are some questions hanging over this research, including the expected controversy simply because it involves a genetically modified mosquito. Some are technical, such as the fitness of the genetically modified individual and the reliability of their process to screen out males from females at the embryo stage. And of course, there is the concern that it is genetically modified – concerns that may be real or perceived.
Risk acceptability
I am interested to know from anyone who saw the 7:30 Report last night and what their thoughts are about the research. The report mentioned that the bacteria they infected the mosquito with is not naturally found in the mosquito, though it (or closely related strains) is found in most insects. This might trigger the responses, ‘are we tinkering with nature’ and ‘what might be the long-term consequences of this’.
Do people perceive this Australian research as different from genetic modification and therefore safer – or risker?
It is interesting that one of the sites of release is Gordonvale, the same place where the infamous canetoad was first emptied on our shores. Are we concerned about whether we might be unleashing another canetoad?
Whatever our concerns, what is driving them? Is it lack of trust in the scientists, science in general, the regulatory process, or CSIRO who performed the risk analysis…? Do you need more information to help you make an informed decision?
Do we think it is a splendid idea and if so why? How much risk is acceptable if it means we can reduce the damage caused by dengue fever?
All these questions equally apply for the genetically modified version. Is one more acceptable than the other? Why or why not?
Dengue: the fast facts
A aegypti occurs in more than 100 countries worldwide with over 40% of the world’s population at risk of infection from the virus. Australia is one of these countries.
50-100 million dengue cases are reported annually with 500,000 of these developing into dengue haemorrhagic fever which results in up to 25,000 deaths each year.
Wolbachia – the bacteria
I can’t help but think Wolbachia was a name dreamt up by an enthusiastic scientist who had pet names for his research subjects – his favourite he named Wol. I wonder if it had a brother named Chew?
Wolbachia occurs naturally in a number insect species. In the mid-1990s, scientists discovered that the Wolbachia strain found in fruit flies limits the lifespan of infected insects.
Wolbachia occurs naturally in many mosquito species. Interestingly, it does not occur naturally Aedes aegypti nor in mosquito species that are known to be of major importance in transmitting pathogens such as malaria.
Wolbachia is harmless to humans and animals (vertebrates). It is not infectious in the way a flu virus is. The bacterium is passed down between generations of mosquitoes inside their eggs, that is, from parent to offspring.
Only older female mosquitoes are able to transmit the dengue virus, so reducing the lifespan of the mosquitoes reduces the opportunities to transmit the disease.
The Australian research team has shown that when Wolbachia is present in the mosquito it directly interferes with the ability of dengue (and other human pathogens) from growing in the mosquito and therefore being transmitted between people.
More info
The research team has put together an informative website on their research and efforts to fight dengue fever.
Science Magazine research paper - WolbachiaScienceMag
Image: Eliminate DEngue web site
http://www.eliminatedengue.com/en/BACKGROUND/emAedesaegyptiem.aspx