Mosquitoes have caused innumerable diseases from ancient times and humans have also tried their level best to eradicate the mosquitoes and their sources of proliferation. All this were done with the aim to eliminate mosquito borne diseases, so the community concerned can have better health. However, with change of time, everything around us has changed, including healthcare approaches for treating and preventing diseases. So, the latest method of controlling mosquito born diseases has ranged from newer and more effective drugs & technically advanced mosquito repellents to releasing more mosquitoes into a society. The last procedure mentioned, appears to be directly going against the goal targeted, but on closer look, it is not necessarily so.
Conventional measures of mosquito control in a big community, by means of fogging and fumigation, can be hazardous to human health and can cause ecological problems. With all-round progress occurring in all fields of medical science, a newer and healthier measure for mosquito control was required. Although the concept of voluntarily adding hordes of mosquito into a community, may look like an antithesis for good obtaining good health, but on closer inspection, the technique would start making a lot of sense.
Debug Fresno, is the name of the project, which was first started in 2017 in the United States of America, as a measure to control mosquito borne disease. To be more specific, the mosquito species targeted for this manoeuvre was Aedes aegypti. A very aggressive variety of mosquito, Aedes aegypti is notorious the world over for causing some really dangerous and debilitating diseases across the world, and – Dengue, Chikungunya, Yellow fever and Zika being the most common names, that is associated with this variety of mosquito species. As an initiative started by the company Verily, the target of Debug Fresno, is to decrease the adult population of the Aedes aegypti variant of the mosquito population.
As stated previously to decline the adult population of Aedes aegypti, the company plans to release male mosquitoes into the open, which would be carrying a commonly occurring naturally prevalent bacteria, known as Wolbachia (These special variants of mosquito’s have been created in San Francisco, by the laboratory division of Verily company). This bacterium would change the reproductive behaviour of the mosquitoes. Hence when this modified organism is released into an area, the numbers of the Aedes aegypti which are already present in the community gradually comes down.
These enhanced variants of mosquitoes wouldn’t harm humans (as they do not bite), but would mate with the females of the same species of mosquitoes, which are already present in the area. The eggs produced from these union would not hatch, so the population of the next generation of Aedes aegypti, in the specified area would decrease over time.
So, when these mosquitoes are released in the community, initially the visible mosquito levels would go up at the beginning stage, but later on, with passage of time, as the artificially introduced male mosquitoes compete with the ones already present in the targeted environment, the number of the next generation of mosquitoes would progressively go down. As these artificially introduced mosquitoes do not bite, so practical disturbance to the people staying in the specified area would be minimal.
Although the first targeted area in 2017, for this experimental study was Fresno county in California, but the success of the project encouraged the same techniques, to be tried again in 2018, when 3 neighbourhoods of Fresno and Clovis were selected, where millions of these artificially manipulated mosquitoes were released. The population of female mosquitoes, which actually bite people, fell by a significant 2/3rd of the original numbers, and was the reason for repeating the manoeuvres.
AS there is no genetic changes or genetic modification taking place, so this procedure has been believed to be very safe. In fact, similar manoeuvres in other species of mosquitoes, has already been used as a biopesticide measure. Sterile Insect Technique (SIT) is a well-known technique, used for pest control, where male sterile insects are released into a population to decrease the number of wild members of the same species. The male members in these procedures, were sterilized by irradiation and this procedure has been use since last 50 years. The use of the bacteria named Wolbachia (and its use in Aedes aegypti), is the only significant change, that has been used in the recent technique.
The project releases only modified male mosquitoes, which are practically harmless, as it is only the female mosquitoes that bite. The sterile male mosquitoes, even if they come in contact with skin in exposed body parts, cannot bite. So, apprehension of increased mosquito bite by this experiment is totally unfounded and people living in the area do not face any actual discomfort or health hazard.
Many other precautions have been taken to ensure that humans and the local ecosystem do not face any negative adverse effects from this procedure. On the contrary people would only benefit, by using this latest technique, as there is much less probability of exposure to dangerous diseases.
The second season of Debug Fresno, ended in the late 2018, but the results that were obtained have certainly been very impressive. Number of female Aedes aegypti mosquito population, which actually bite people and spread disease, in the concerned experimental area, fell by an astounding 95%. This becomes more important in view of the fact that the conventional measures taken to control Aedes aegypti population, had a very little success in the past due to their invasive nature. Hopefully success of this initial procedure by Debug Fresno, would encourage similar actions in different countries, across the world, so the diseases caused by Aedes aegypti mosquitoes vanish from the face of the world.
(Disclaimer – All the information written on this article, is based on the information made public by the company, undertaking the procedure. As this is a relatively new experimental procedure, so it is highly probable, that in coming few years, we may get to see more and more of new situations unfolding.)