(CNS): There has been a dramatic fall in the number of Aedes aegypti mosquitoes in West Bay, where genetically modified bugs have been released in a pilot project to get as near as possible to eradicating the disease-spreading pest. Over the last six months the MRCU, in partnership with a private UK bio-technology firm, has released millions of genetically altered male insects in a selected area of West Bay, where the population has now fallen by almost 90% when compared to nearby areas where the GM bugs were not released.
Preliminary results published this week revealed that the Aedes aegypti population in the project area is now just 12% of the numbers found in the comparative non-treatment study area also in West Bay. The technique involves releasing large numbers of sterile engineered male mosquitoes into an area with a wild population to mate with the females. Then, as almost all of the larvae dies before reaching maturity and because the life-cycle of a mosquito is short, it’s not long before the population begins to fall.
Dr Bill Petrie, the director of the Mosquito Research and Control Unit, told the media Thursday during an update on the pilot project that the operational roll-out of Oxitec’s bio-engineered insects was “going better than expected”.
Petrie said that on average, the appearance of the fluorescent monitoring markers in the larvae produced by the natural females who mate with the GM bugs has now increased and is being spotted in most batches of eggs in the treatment area, which means that the natural population is now in rapid decline. Last week the number of Aedes aegypti eggs collected in traps in the treatment area was 88% less than the nearby non-treatment area, while the fluorescent larvae has averaged 94% during the last two months in samples.
“Both these statistics show that the programme is working as we anticipated,” said Petrie. “We expect to see this pattern continue and the population of Aedes aegypti fall even further in the treatment area.”
Many of the mosquitoes that people may be seeing in the project area are going to be the GM males. The hunt to find females seems to be getting harder and harder as the non-pesticide technology appears to be doing what the scientists from Oxitec claimed it would.
Despite the lingering opposition to the project, the MRCU boss said he was pleased with the preliminary results and was certain that this technology was “the safest and most efficient way” to tackle Aedes aegypti, which continues to be a major public health risk here and around the world.
Over the last few weeks the Zika epidemic has abated and Cayman has not seen a new case of the disease since November. Most scientists still believe there is sufficient research to support a link to birth defects in babies whose mothers contracted Zika in pregnancy. But there are other major health concerns about the Aedes aegypti mosquito, as it transmits several unpleasant and dangerous viruses, such as chikungunya, dengue fever and West Nile virus. It is also believed to be responsible for transmitting the Mayaro virus, which recently appeared in this region for the first time in Haiti.
But public health officials globally, regionally and locally are now concerned about dengue.
The WHO is warning that this could be a serious problem this year. Given that type 3 dengue fever is now emerging in this region, those who have contracted type 1 and 2 dengue, the more common forms in this part of the world, are now at greater risk if they are exposed to type 3.
The transmission by the Aedes aegypti of documented viruses, changing and mutating viruses and even viruses that are not yet known or newly emerging ones, means it remains a public health challenge that must be controlled. But as the mosquito is increasingly resistant to pesticides, using toxic chemicals is becoming a losing battle in the effort to control the pest.
The preliminary findings from the first full operational deployment of the bio-engineered bugs appears to show the project is working. The Oxitec scientists also insist that the technique is very safe, much more so than chemical pesticides, and despite the fears and environmental concerns, no evidence has emerged from anywhere that indicates that the use of these bio-engineered bugs poses any risk to humans or the environment, mostly because there is no long-term impact. The GM bugs live such a short time and leave almost nothing behind as they are sterile and because, as males, they cannot bite.
Petrie said he was looking forward to more figures over the next few weeks to give even stronger data but he was confident about the trend and the success of the project.
With the positive impact in the pilot treatment area already apparent, Petrie confirmed that he still hoped to see a national roll-out using the Oxitec bugs island-wide to bring down the population of Aedes aegypti to the point where it will be all but eradicated. Then the MRCU will focus on stopping the numbers from ever rising again, which Petrie said would be much easier and cheaper to achieve with the bio-engineered bugs than with the pesticides currently being used.
The mosquito boss said discussions were now underway to create a seamless phased roll-out. He said that to suddenly stop using the bio-bugs for any lengthy period after such great results in West Bay would be disappointing, as the population would begin to increase relatively quickly once the GM bugs disappear since the surrounding areas were not treated.
The next phase will require further licensing and funding, but government has said it is fully behind the project and the MRCU has cash to see this project through until October.
In a press release from the premier’s ministry, which is responsible for the MRCU, Alden McLaughlin offered his support and said he was pleased about the results so far.
“We must protect our people from viruses such as Zika, so I am proud of the work being done by MRCU in conjunction with Oxitec,” he said.